1WTNT44 KNHC 232052 2TCDAT4 3 4TROPICAL STORM DEBBY DISCUSSION NUMBER 1 5NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 6400 PM CDT SAT JUN 23 2012 7 8AIRCRAFT RECONNAISSANCE...SATELLITE...AND BUOY DATA INDICATE THAT 9THE CIRCULATION ASSOCIATED WITH THE AREA OF LOW PRESSURE IN THE 10GULF OF MEXICO HAS BECOME SUFFICIENTLY DEFINED TO CLASSIFY THIS 11SYSTEM AS A TROPICAL STORM. THE INITIAL INTENSITY IS BASED ON A 12HIGHEST 1000-FT FLIGHT-LEVEL WIND OF 61 KT AND SFMR WINDS NEAR 45 13KT. THESE WINDS ARE ONLY OCCURRING TO THE EAST OF THE CENTER. 14 15DEBBY IS MOVING SLOWLY NORTHWARD...OR 360 DEGREES AT 5 KT. THE 16CYCLONE IS IN A WEAK STEERING ENVIRONMENT BETWEEN TWO MID-LEVEL 17RIDGES LOCATED OVER THE GREATER ANTILLES AND THE SOUTHERN UNITED 18STATES...AND DEBBY IS NOT EXPECTED TO MOVE MUCH DURING THE NEXT 19COUPLE OF DAYS. THE TRACK GUIDANCE IS SPLIT IN TWO BRANCHES...WITH 20THE GFS AND GFDL SHOWING AN EASTWARD MOTION ACROSS FLORIDA...AND 21THE REST OF THE MODELS BRINGING DEBBY WESTWARD ACROSS THE NORTHERN 22GULF TOWARDS TEXAS. EVEN THOUGH THE DETERMINISTIC GFS SHOWS AN 23EASTWARD TRACK...MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS ARE IN 24AGREEMENT WITH THE WESTWARD-MOVING MODELS...MAKING THE WESTWARD 25SCENARIO SEEM MORE LIKELY. IT IS IMPORTANT TO NOTE TOO THAT THE 26ECMWF MODEL SHOWS A FASTER WESTWARD MOTION THAN INDICATED IN THE 27NHC FORECAST...SO IT IS POSSIBLE THAT DEBBY COULD REACH THE COAST 28EARLIER THAN INDICATED. 29 30DEBBY IS CURRENTLY A SHEARED CYCLONE WITH NEARLY ALL OF THE DEEP 31CONVECTION LOCATED IN A CURVED BAND TO THE EAST OF THE CENTER. 32HOWEVER...AN UPPER-LEVEL LOW OVER THE NORTHWESTERN GULF OF MEXICO 33IS FORECAST TO DIG SOUTHWESTWARD...WHICH WILL RESULT IN A DECREASE 34OF VERTICAL SHEAR AFFECTING THE SYSTEM...AND A GREATER CHANCE OF 35INTENSIFICATION OVER THE NEXT FEW DAYS. BECAUSE THE OFFICIAL TRACK 36FORECAST IS SO DIFFERENT FROM THE GFS SOLUTION...THE GFS FIELDS USED 37BY THE SHIPS AND LGEM MODELS ARE NOT LIKELY TO BE REPRESENTATIVE OF 38THE CONDITIONS ENCOUNTERED BY DEBBY. THE NHC FORECAST THEREFORE 39SHOWS MORE STRENGTHENING THAN INDICATED BY THE INTENSITY GUIDANCE. 40 41DEBBY IS THE EARLIEST 4TH STORM IN THE HISTORICAL RECORDS... 42SURPASSING HURRICANE DENNIS OF 2005...WHICH BECAME A TROPICAL STORM 43ON JULY 5TH. 44 45 46FORECAST POSITIONS AND MAX WINDS 47 48INIT 23/2100Z 26.2N 87.6W 45 KT 50 MPH 49 12H 24/0600Z 26.9N 87.8W 45 KT 50 MPH 50 24H 24/1800Z 27.3N 88.1W 50 KT 60 MPH 51 36H 25/0600Z 27.4N 88.5W 50 KT 60 MPH 52 48H 25/1800Z 27.5N 89.5W 55 KT 65 MPH 53 72H 26/1800Z 27.5N 91.5W 55 KT 65 MPH 54 96H 27/1800Z 27.5N 93.5W 60 KT 70 MPH 55120H 28/1800Z 27.5N 95.0W 60 KT 70 MPH 56 57$$ 58FORECASTER BERG/AVILA 59 60 61WTNT44 KNHC 240257 62TCDAT4 63 64TROPICAL STORM DEBBY DISCUSSION NUMBER 2 65NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 661000 PM CDT SAT JUN 23 2012 67 68DEBBY IS GRADUALLY SHOWING SIGNS OF IMPROVED ORGANIZATION AS THE 69UPPER-LEVEL SHEAR SHIFTS FROM SOUTHWESTERLY TO MORE OF A SOUTHERLY 70COMPONENT. SHIP ZCDJ2 LOCATED ABOUT 80 NMI EAST OF THE CENTER AND 71NEAR NOAA BUOY 42003 REPORTED A PRESSURE OF 1001.6 MB AND 38 KT 72WINDS AT 24/00Z. BASED ON THIS INFORMATION...THE CENTRAL PRESSURE 73IS CONSERVATIVELY ESTIMATED TO BE 998 MB. AIRCRAFT RECONNAISSANCE 74DATA AT 23/2020Z INDICATED 850 MB FLIGHT-LEVEL WINDS OF 61 KT IN 75THE NORTHEAST QUADRANT...WHICH IS EQUAL TO ABOUT 49 KT SURFACE 76WINDS. CONVECTION WAS SOMEWHAT MEAGER AT THAT...BUT SINCE THEN HAS 77INCREASED RATHER MARKEDLY IN THAT AREA. THEREFORE THE INITIAL 78INTENSITY ESTIMATE IS A SOLID 45 KT. 79 80DEBBY HAS BEEN NEARLY STATIONARY DURING THE PAST 6 HOURS. MULTIPLE 81LOW-LEVEL VORTICES HAVE BEEN OUT FROM UNDERNEATH THE EASTERN 82SEMICIRCLE CONVECTIVE CLOUD MASS ABOUT A MEAN CENTER OF ROTATION OF 83A LARGER GYRE...AND THE LOCATION OF THE LARGER STATIONARY GYRE IS 84THE ADVISORY POSITION. ALTHOUGH THERE MAY BE SOME SLIGHT 85NORTHEASTWARD MOTION DUE TO REDEVELOPMENT OF THE CENTER CLOSER TO 86THE DEEP CONVECTION...THE GENERAL MOTION FOR THE NEXT 24 HOURS OR 87SO SHOULD BE SLOWLY POLEWARD. THE LONGWAVE PATTERN ACROSS THE U.S. 88HAS A DEEPENING TROUGH OFF THE WEST COAST...WHICH IS CREATING 89DOWNSTREAM RIDGING ACROSS THE CENTRAL AND EASTERN UNITED STATES. 90THIS INCREASED RIDGING IS REFLECTED BY 20-40 METER 500 MB HEIGHT 91RISES AT 00Z ACROSS THE CENTRAL AND SOUTHERN PLAINS...AND EXTENDING 92AS FAR EAST AS THE CAROLINA COASTS. THIS BLOCKING RIDGE PATTERN TO 93THE NORTH OF DEBBY IS EXPECTED TO GRADUALLY TURN THE CYCLONE 94WESTWARD ACROSS THE NORTH-CENTRAL GULF OF MEXICO BY 36-48 95HOURS...WITH A CONTINUED WESTWARD MOTION ACROSS THE NORTHWESTERN 96GULF AFTER THAT. ALL OF THE AVAILABLE NHC MODEL GUIDANCE...EXCEPT 97FOR THE GFS AND GFS-ENSEMBLE MODELS...SUPPORTS THE GENERAL WESTWARD 98MOTION SCENARIO. THE MAIN REASON THAT THE GFS MOVES DEBBY EASTWARD 99ACROSS THE NORTHEASTERN GULF IS DUE TO IT HAVING A WEAKER AND MORE 100VERTICALLY SHALLOW STORM DEPICTED IN THE MODEL. GIVEN THE EXPECTED 101FAVORABLE UPPER-LEVEL FLOW PATTERN WITH WEAKER VERTICAL SHEAR 102FORECAST TO DEVELOP AFTER 24 HOURS...A DEEPER AND MORE ROBUST 103WESTWARD MOVING TROPICAL CYCLONE AS DEPICTED IN THE 104ECMWF...UKMET... NOGAPS MODELS SEEMS A MORE REASONABLE SCENARIO. 105THE OFFICIAL FORECAST TRACK IS JUST AN UPDATE OF THE PREVIOUS 106ADVISORY TRACK. 107 108MODERATE SOUTHWESTERLY VERTICAL WIND SHEAR IS EXPECTED TO GRADUALLY 109GIVE WAY TO SOUTHERLY AND EVENTUALLY SOUTHEASTERLY WEAKER WIND 110SHEAR BY 36-48 HOURS AS AN UPPER-LEVEL LOW NORTHWEST OF THE CYCLONE 111MOVES SOUTHWESTWARD...WHICH ALLOWS DEBBY TO MOVE UNDERNEATH A 200 112MB RIDGE AXIS. THE OFFICIAL INTENSITY FORECAST LEANS TOWARD THE 113ECMWF MODEL...WHICH IS FORECASTING A HURRICANE CENTRAL PRESSURE BY 11496 HOURS...AND IS ABOVE THE GFS-BASED SHIPS AND LGEM MODELS SINCE 115THAT OUTPUT LIKELY DOES NOT REPRESENT THE ENVIRONMENTAL CONDITIONS 116THAT DEBBY WILL ENCOUNTER. THE OFFICIAL INTENSITY FORECAST IS A 117LITTLE HIGHER THAN THE PREVIOUS ADVISORY...AND BRINGS DEBBY TO 118HURRICANE STRENGTH BY 72 HOURS. 119 120 121FORECAST POSITIONS AND MAX WINDS 122 123INIT 24/0300Z 26.3N 87.5W 45 KT 50 MPH 124 12H 24/1200Z 26.7N 87.8W 50 KT 60 MPH 125 24H 25/0000Z 27.0N 88.1W 50 KT 60 MPH 126 36H 25/1200Z 27.1N 88.8W 55 KT 65 MPH 127 48H 26/0000Z 27.2N 89.8W 60 KT 70 MPH 128 72H 27/0000Z 27.2N 91.8W 65 KT 75 MPH 129 96H 28/0000Z 27.2N 93.7W 70 KT 80 MPH 130120H 29/0000Z 27.2N 95.2W 70 KT 80 MPH 131 132$$ 133FORECASTER STEWART 134 135 136WTNT44 KNHC 240837 137TCDAT4 138 139TROPICAL STORM DEBBY DISCUSSION NUMBER 3 140NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 141400 AM CDT SUN JUN 24 2012 142 143THE CLOUD PATTERN OF THE TROPICAL STORM HAS NOT BECOME SIGNIFICANTLY 144BETTER ORGANIZED OVER THE PAST FEW HOURS. DEBBY HAS BEEN PRODUCING 145VERY COLD-TOPPED DEEP CONVECTION BUT THESE THUNDERSTORMS...AND 146LIKELY THE STRONGEST WINDS...ARE OCCURRING SOME 100 TO 150 MILES 147NORTHEAST OF THE LOW-LEVEL CENTER. THE CURRENT INTENSITY IS KEPT 148AT 45 KT...WHICH IS IN AGREEMENT WITH DATA FROM AN ASCAT PASS 149SEVERAL HOURS AGO. NO CHANGE IS MADE TO THE PREVIOUS INTENSITY 150FORECAST...HOWEVER THIS FORECAST IS BASED ON THE PREMISE THAT THE 151VERTICAL SHEAR WILL DECREASE OVER THE NEXT FEW DAYS AND THE GLOBAL 152MODELS ARE NOT UNANIMOUS ON THIS. THE OFFICIAL WIND SPEED FORECAST 153IS CLOSEST TO THE MOST RECENT HWRF GUIDANCE...AND IT SHOULD BE 154NOTED THAT WE HAVE LIMITED SKILL IN PREDICTING TROPICAL CYCLONE 155INTENSITY CHANGE. 156 157WITH INFRARED IMAGERY THE CENTER...ALTHOUGH PARTIALLY EXPOSED...HAS 158BECOME A LITTLE MORE DIFFICULT TO LOCATE AND THE FIXES FROM TAFB 159AND SAB ARE ABOUT 50 MILES APART. MY BEST ESTIMATE OF INITIAL 160MOTION IS SLOWLY NORTHWARD...OR 360/3. THE TRACK FORECAST FOR THIS 161STORM IS EXTREMELY CHALLENGING. THE SYNOPTIC REASONING IN PREVIOUS 162ADVISORIES WAS BASED ON A MID-LEVEL RIDGE BUILDING TO THE NORTH OF 163THE TROPICAL CYCLONE...WHICH WOULD CAUSE DEBBY TO MOVE TOWARD THE 164NORTHWEST GULF OF MEXICO COAST IN SEVERAL DAYS. THAT TRACK 165SCENARIO WAS SUPPORTED BY THE ECMWF MODEL...WHICH HAS BEEN THE 166BEST-PERFORMING GUIDANCE OVER THE PAST FEW YEARS. HOWEVER...THE 1670000 RUN OF THAT MODEL HAS SHIFTED SUBSTANTIALLY TO THE NORTH AND 168EAST OF THE PREVIOUS RUNS. THE U.K. MET. OFFICE MODEL HAS ALSO 169SHIFTED SIGNIFICANTLY TO THE RIGHT. IN FACT...ONLY THE HWRF MODEL 170IS CLOSE TO THE PREVIOUS OFFICIAL FORECASTS...AND EVEN IT IS TO THE 171NORTH OF THEM. THEREFORE AN UNUSUALLY LARGE RIGHTWARD ADJUSTMENT 172TO THE NHC FORECAST IS REQUIRED...AND ADDITIONAL SHIFTS TO THE 173NORTH AND EAST MAY BE NECESSARY IN SUBSEQUENT ADVISORY PACKAGES. 174 175NEEDLESS TO SAY...THIS IS A LOW CONFIDENCE FORECAST. 176 177FORECAST POSITIONS AND MAX WINDS 178 179INIT 24/0900Z 27.3N 87.3W 45 KT 50 MPH 180 12H 24/1800Z 27.5N 87.4W 50 KT 60 MPH 181 24H 25/0600Z 27.9N 87.8W 50 KT 60 MPH 182 36H 25/1800Z 28.2N 88.4W 55 KT 65 MPH 183 48H 26/0600Z 28.3N 89.0W 60 KT 70 MPH 184 72H 27/0600Z 28.5N 90.5W 65 KT 75 MPH 185 96H 28/0600Z 28.5N 92.0W 70 KT 80 MPH 186120H 29/0600Z 28.5N 93.5W 70 KT 80 MPH 187 188$$ 189FORECASTER PASCH 190 191 192WTNT44 KNHC 241159 193TCDAT4 194 195TROPICAL STORM DEBBY SPECIAL DISCUSSION NUMBER 4 196NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 197700 AM CDT SUN JUN 24 2012 198 199THE PURPOSE OF THIS SPECIAL ADVISORY IS TO ISSUE A TROPICAL STORM 200WARNING FROM THE MISSISSIPPI ALABAMA BORDER EASTWARD TO THE 201OCHOLOCKONEE RIVER. THIS IS BASED ON THE EXPANSION OF TROPICAL 202STORM FORCE WINDS IN THE NORTHEAST QUADRANT. THERE HAVE BEEN NO 203CHANGES TO THE FORECAST TRACK NOR INTENSITY. 204 205 206FORECAST POSITIONS AND MAX WINDS 207 208INIT 24/1200Z 27.5N 87.0W 50 KT 60 MPH 209 12H 24/1800Z 27.5N 87.4W 50 KT 60 MPH 210 24H 25/0600Z 27.9N 87.8W 50 KT 60 MPH 211 36H 25/1800Z 28.2N 88.4W 55 KT 65 MPH 212 48H 26/0600Z 28.3N 89.0W 60 KT 70 MPH 213 72H 27/0600Z 28.5N 90.5W 65 KT 75 MPH 214 96H 28/0600Z 28.5N 92.0W 70 KT 80 MPH 215120H 29/0600Z 28.5N 93.5W 70 KT 80 MPH 216 217$$ 218FORECASTER AVILA 219 220 221WTNT44 KNHC 241458 222TCDAT4 223 224TROPICAL STORM DEBBY DISCUSSION NUMBER 5 225NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 2261000 AM CDT SUN JUN 24 2012 227 228IT IS A VERY DIFFICULT AND HIGHLY UNCERTAIN FORECAST THIS MORNING. 229DEBBY HAS BEEN MOVING VERY SLOWLY TOWARD THE NORTHEAST...040 AT 3 230KNOTS...WHILE THE WIND RADII HAVE BEEN EXPANDING IN THE EASTERN 231SEMICIRCLE. THIS HAS PROMPTED ADDITIONAL TROPICAL STORM WARNINGS 232AND WATCHES FOR PORTIONS OF THE FLORIDA COAST. 233 234DEBBY CONTINUES TO BE SHEARED WITH MOST OF THE THUNDERSTORM ACTIVITY 235NORTH AND EAST OF THE CENTER. THIS SHEAR IS EXPECTED TO CONTINUE 236FOR THE NEXT DAY OR SO...ALTHOUGH SOME DECREASE IN THE SHEAR IS 237POSSIBLE AFTER THAT...PARTICULARLY IF THE ECMWF VERIFIES. THE 238OFFICIAL FORECAST IS A LITTLE LESS AGGRESSIVE THAN THE PREVIOUS 239FORECAST...BUT REMAINS ABOVE MOST OF THE EXPLICIT INTENSITY 240GUIDANCE. 241 242THE TRACK FORECAST IS EVEN MORE COMPLEX. THE GFS INSISTS ON A TRACK 243TOWARD THE NORTHEAST AS DEBBY BECOMES EMBEDDED WITHIN A LARGE 244MID-LATITUDE TROUGH. HOWEVER...THE ECMWF AND THE HWRF BUILD A RIDGE 245TO THE NORTH OF DEBBY AND FORECAST A WESTWARD TRACK. GIVEN THE 246WESTWARD TURN INHERITED FROM THE PREVIOUS FORECAST...AS WELL AS THE 247HISTORICAL STRONG RECORD OF THE ECMWF...THE NEW OFFICIAL FORECAST 248MOVES DEBBY INITIALLY A LITTLE BIT TO THE NORTHEAST TO REFLECT 249CURRENT TRENDS BUT THEN TURNS THE CYCLONE BACK TOWARD THE WEST OR 250WEST-NORTHWEST IN 24 TO 36 HOURS. A MAJORITY OF THE GFS ENSEMBLE 251MEMBERS NOW ARE CONSISTENT WITH THE DETERMINISTIC RUN...WHICH WAS 252NOT THE CASE YESTERDAY...MAKING A STRONGER CASE FOR THE EASTWARD 253SOLUTION. WE MUST BE READY TO MAKE A CHANGE OF THE FORECAST TRACK 254AT ANY TIME. 255 256 257FORECAST POSITIONS AND MAX WINDS 258 259INIT 24/1500Z 28.0N 86.2W 50 KT 60 MPH 260 12H 25/0000Z 28.5N 85.8W 50 KT 60 MPH 261 24H 25/1200Z 28.5N 85.8W 50 KT 60 MPH 262 36H 26/0000Z 28.5N 86.2W 55 KT 65 MPH 263 48H 26/1200Z 28.7N 87.0W 60 KT 70 MPH 264 72H 27/1200Z 29.0N 88.4W 65 KT 75 MPH 265 96H 28/1200Z 29.5N 90.5W 45 KT 50 MPH 266120H 29/1200Z 30.0N 91.5W 30 KT 35 MPH 267 268$$ 269FORECASTER AVILA 270 271 272WTNT44 KNHC 242034 273TCDAT4 274 275TROPICAL STORM DEBBY DISCUSSION NUMBER 6 276NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 277400 PM CDT SUN JUN 24 2012 278 279THERE HAS BEEN A SIGNIFICANT CHANGE IN THE FORECAST TRACK WITH THIS 280ADVISORY. THE OFFICIAL FORECAST NO LONGER BRINGS DEBBY WESTWARD 281ALONG THE NORTHERN GULF OF MEXICO AND INSTEAD KEEPS THE CYCLONE 282MEANDERING OVER THE NORTHEASTERN GULF FOR THE NEXT 3 TO 4 DAYS. 283THIS FORECAST IS A COMPROMISE BETWEEN THE CONSISTENT EASTWARD 284SOLUTION PROVIDED BY THE GFS FOR THE PAST SEVERAL DAYS AND THE NEW 285TWIST OF THE ECMWF. THE ECMWF MODEL...WHICH HAS BEEN 286FORECASTING DEBBY TO MOVE WESTWARD ALONG THE GULF OF MEXICO... NOW 287HAS THE CYCLONE MEANDERING FOR THE NEXT 3 DAYS OVER THE 288NORTHEASTERN GULF. SINCE THESE TWO RELIABLE MODELS ARE IN 289MARGINALLY BETTER AGREEMENT...I AM A LITTLE MORE CONFIDENT...BUT 290NOT COMPLETELY...THAT DEBBY IS NOT GOING TO TURN WESTWARD OVER THE 291GULF. HOWEVER...NEW OFFICIAL TRACK REMAINS A LOW-CONFIDENCE 292FORECAST. 293 294DEBBY IS A SPRAWLING SYSTEM...WITH MOST OF THE THUNDERSTORM ACTIVITY 295IN A CURVED BAND WELL REMOVED FROM THE CENTER. DATA FROM THE 296RECONNAISSANCE PLANE A FEW HOURS AGO INDICATE THAT THE INITIAL 297INTENSITY REMAINS 50 KNOTS. THE SHEAR IS NOT EXPECTED TO CHANGE 298MUCH FOR THE NEXT DAY OR SO...BUT BECAUSE DEBBY IS FORECAST TO 299REMAIN OVER WATER...THERE WILL BE SOME OPPORTUNITY FOR A SLIGHT 300STRENGTHENING BEFORE THE CENTER MOVES INLAND. HOWEVER...THE CYCLONE 301WILL LOCATED BE NORTH OF THE AREA OF HIGH OCEANIC HEAT CONTENT AND 302THE UPWELLING COULD HALT THE INTENSIFICATION. 303 304 305FORECAST POSITIONS AND MAX WINDS 306 307INIT 24/2100Z 28.4N 85.8W 50 KT 60 MPH 308 12H 25/0600Z 28.7N 85.5W 50 KT 60 MPH 309 24H 25/1800Z 29.0N 85.5W 50 KT 60 MPH 310 36H 26/0600Z 29.0N 85.5W 55 KT 65 MPH 311 48H 26/1800Z 29.0N 85.5W 60 KT 70 MPH 312 72H 27/1800Z 29.5N 85.5W 60 KT 70 MPH 313 96H 28/1800Z 30.0N 85.5W 40 KT 45 MPH 314120H 29/1800Z 30.5N 85.5W 30 KT 35 MPH...INLAND 315 316$$ 317FORECASTER AVILA 318 319 320WTNT44 KNHC 250258 321TCDAT4 322 323TROPICAL STORM DEBBY DISCUSSION NUMBER 7 324NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 3251000 PM CDT SUN JUN 24 2012 326 327THE APPEARANCE OF DEBBY IN SATELLITE AND RADAR IMAGERY HAS DEGRADED 328SIGNIFICANTLY THIS EVENING AS A SHARP MID-LEVEL DRY INTRUSION HAS 329WORKED ITS WAY INTO THE CENTER OF THE CYCLONE AND ERODED ALL OF THE 330INNER CORE DEEP CONVECTION. THE INITIAL INTENSITY IS BEING HELD AT 33150 KT FOR THIS FORECAST PACKAGE BASED MAINLY ON CONTINUITY WITH THE 332PREVIOUS ADVISORY AND THE RELATIVELY LOW CENTRAL PRESSURE OF 991 MB 333REPORTED BY AN AIR FORCE RESERVE RECON AIRCRAFT THIS EVENING. 334 335DEBBY HAS BEEN NEARLY STATIONARY SINCE THE LAST ADVISORY. BOTH 18Z 336AND 00Z UPPER-AIR DATA INDICATE MID-LEVEL RIDGING HAS CONTINUED TO 337BUILD ACROSS THE SOUTHEASTERN U.S. TO THE NORTH OF DEBBY...AND THIS 338HAS LIKELY BEEN THE REASON FOR THE LACK OF ANY SIGNIFICANT MOTION 339OVER THE PAST SEVERAL HOURS. ALL OF THE NHC MODEL GUIDANCE...EXCEPT 340FOR THE GFS AND GFS-ENSEMBLE MODELS...INDICATE THIS BLOCKING PATTERN 341ACROSS THE CENTRAL AND EASTERN U.S. SHOULD CONTINUE AS FAST-MOVING 342SHORTWAVE TROUGHS PASS WELL TO THE NORTH OF DEBBY. THE RESULT 343SHOULD BE THAT THE CYCLONE WILL MOVE LITTLE DURING THE NEXT COUPLE 344OF DAYS...AND THEN ONLY DRIFT SLOWLY NORTHWARD AFTER THAT AS THE 345RIDGE OVER THE SOUTHEASTERN U.S. GRADUALLY BREAKS DOWN. ALTHOUGH THE 346GFS MODEL HAS BEEN VERY CONSISTENT WITH A FAST NORTHEASTWARD MOTION 347ACROSS NORTH FLORIDA THE PAST FEW DAYS...THE LARGE SPRAWLING NATURE 348OF THE CYCLONE AND THE BLOCKING RIDGE TO THE NORTH WOULD SUGGEST 349THAT THE GFS MODEL MAY BE LIFTING OUT DEBBY TOO QUICKLY. THE 350OFFICIAL FORECAST TRACK IS SIMILAR TO BUT SLIGHTLY LEFT OF THE 351PREVIOUS ADVISORY TRACK...MAINLY DUE TO THE MORE WESTWARD INITIAL 352POSITION. 353 354DEBBY HAS FINALLY CONSOLIDATED ALL OF THE MULTIPLE SMALL SWIRLS INTO 355A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER. THE GLOBAL MODELS ARE 356FORECASTING THE AFOREMENTIONED DEEP DRY SLOT TO GRADUALLY MOISTEN 357UP OVER THE NEXT 48 HOURS AS DEEP MOISTURE AND INSTABILITY 358CURRENTLY OVER THE FLORIDA PENINSULA ADVECTS WESTWARD INTO THE 359INNER CORE. THE COMBINATION OF THESE TWO FEATURES MAY ALLOW FOR 360SOME SLIGHT STRENGTHENING BEFORE DEBBY BEGINS TO INTERACT WITH LAND 361OR COLD UPWELLING BENEATH THE CYCLONE OCCURS. THE OFFICIAL 362INTENSITY FORECAST IS IDENTICAL TO THE PREVIOUS ADVISORY AND 363FOLLOWS A BLEND OF THE SHIPS/LGEM STATISTICAL MODELS AND THE 364HWRF/GFDL REGIONAL MODELS. 365 366FORECAST POSITIONS AND MAX WINDS 367 368INIT 25/0300Z 28.3N 85.9W 50 KT 60 MPH 369 12H 25/1200Z 28.6N 85.8W 50 KT 60 MPH 370 24H 26/0000Z 28.7N 85.8W 50 KT 60 MPH 371 36H 26/1200Z 28.8N 85.8W 55 KT 65 MPH 372 48H 27/0000Z 28.9N 85.8W 60 KT 70 MPH 373 72H 28/0000Z 29.4N 85.8W 55 KT 65 MPH 374 96H 29/0000Z 29.9N 85.8W 35 KT 40 MPH...NEAR COAST 375120H 30/0000Z 30.4N 85.6W 30 KT 35 MPH...INLAND 376 377$$ 378FORECASTER STEWART 379 380 381WTNT44 KNHC 250838 382TCDAT4 383 384TROPICAL STORM DEBBY DISCUSSION NUMBER 8 385NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 386400 AM CDT MON JUN 25 2012 387 388DEBBY HAS A HIGHLY UNIMPRESSIVE APPEARANCE ON SATELLITE IMAGERY. 389ALTHOUGH RADAR DATA CONTINUE TO DEPICT SOME SHOWER ACTIVITY OVER 390THE CIRCULATION...THESE SHOWERS ARE BEING PRODUCED BY SHALLOW 391CONVECTION AS THE ENHANCED IR IMAGES DO NOT SHOW ANY SIGNIFICANT 392AREAS OF COLD CLOUD TOPS. AIRCRAFT DATA FROM SEVERAL HOURS AGO 393ALONG WITH SYNOPTIC OBSERVATIONS INDICATE THAT THE MAXIMUM SURFACE 394WINDS HAVE DECREASED...AND THE CURRENT INTENSITY IS SET AT 45 KT. 395DEBBY IS LOCATED NORTH OF THE AREA OF MAXIMUM OCEANIC HEAT 396CONTENT...BUT AS LONG AS THE CYCLONE REMAINS OVER WATER AND IS ABLE 397TO REGENERATE SOME DEEP CONVECTION THERE IS A POTENTIAL FOR AT 398LEAST SLIGHT RE-INTENSIFICATION. THE CURRENT NHC INTENSITY 399FORECAST IS A LITTLE LOWER THAN THE PREVIOUS ONES...BUT A LITTLE 400HIGHER THAN MOST OF THE NUMERICAL GUIDANCE. 401 402BEST GUESS AT INITIAL MOTION IS QUASI-STATIONARY. DEBBY REMAINS IN 403A COL REGION OF THE MID-TROPOSPHERIC STEERING FLOW BETWEEN TWO 404ANTICYCLONES...AND IS LIKELY TO REMAIN SO FOR THE NEXT COUPLE OF 405DAYS. THEREFORE LITTLE MOTION IS ANTICIPATED DURING AT LEAST THE 406FIRST HALF OF THE FORECAST PERIOD. IN THE LONGER-TERM...THE TRACK 407GUIDANCE CONTINUES TO BE ALL OVER THE PLACE...WITH SOME MODELS 408TAKING DEBBY WEST AND NORTH OF ITS CURRENT POSITION AND OTHERS 409MOVING EAST OR NORTHEAST AND ULTIMATELY INTO THE ATLANTIC. THE 410LATTER SCENARIO ASSUMES THAT DEBBY WILL EVENTUALLY BE INFLUENCED BY 411A MID-TROPOSPHERIC TROUGH OVER THE NORTHEASTERN UNITED STATES. 412THIS SCENARIO SEEMS MORE LIKELY SINCE IT IS SUPPORTED BY BOTH THE 413GFS AND THE ECMWF MODELS. REGARDLESS OF WHICH SCENARIO PLAYS 414OUT...THE CYCLONE DOES NOT SEEM TO BE GOING ANYWHERE ANYTIME SOON. 415 416FORECAST POSITIONS AND MAX WINDS 417 418INIT 25/0900Z 28.6N 85.8W 45 KT 50 MPH 419 12H 25/1800Z 28.8N 85.7W 45 KT 50 MPH 420 24H 26/0600Z 28.9N 85.6W 50 KT 60 MPH 421 36H 26/1800Z 29.0N 85.5W 50 KT 60 MPH 422 48H 27/0600Z 29.2N 85.4W 55 KT 65 MPH 423 72H 28/0600Z 29.4N 85.3W 55 KT 65 MPH 424 96H 29/0600Z 29.7N 85.2W 45 KT 50 MPH...INLAND 425120H 30/0600Z 30.2N 85.0W 30 KT 35 MPH...INLAND 426 427$$ 428FORECASTER PASCH 429 430 431WTNT44 KNHC 251451 432TCDAT4 433 434TROPICAL STORM DEBBY DISCUSSION NUMBER 9 435NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 4361000 AM CDT MON JUN 25 2012 437 438THERE HAS BEEN NO SIGNIFICANT DEEP CONVECTION NEAR THE CENTER OF 439DEBBY FOR OVER 12 HOURS. WHAT CONVECTION REMAINS IS PRIMARILY 440LOCATED IN A FRAGMENTED BAND WELL EAST OF THE CENTER...AND 441SOUNDINGS ALONG THE GULF COAST INDICATE THAT THE ENTRAINMENT OF DRY 442MID-LEVEL AIR IS AFFECTING THE STORM. IN ADDITION...THE SLOW 443MOVEMENT OF DEBBY HAS INDUCED OCEANIC UPWELLING AND COOLING 444UNDERNEATH THE CYCLONE AND MAY HAVE CONTRIBUTED TO THE OBSERVED 445WEAKENING. LATEST DATA FROM THE RECONNAISSANCE AIRCRAFT INDICATE 446THAT THE MAXIMUM WINDS ARE NEAR 40 KT. WITH DRY AIR LURKING AND 447WESTERLY SHEAR ON THE INCREASE OVER THE NEXT COUPLE DAYS... 448SIGNIFICANT RE-INTENSIFICATION OF THE CYCLONE PRIOR TO LANDFALL 449SEEMS UNLIKELY. THE NEW NHC FORECAST IS ADJUSTED DOWNWARD IN LINE 450WITH CURRENT TRENDS AND THE LATEST INTENSITY GUIDANCE. 451 452AIRCRAFT AND SATELLITE FIXES HAVE SHOWN LITTLE OVERALL MOVEMENT OVER 453THE PAST 12 TO 18 HOURS... ALTHOUGH RECENT SATELLITE IMAGERY 454INDICATES AN EAST-NORTHEASTWARD TO NORTHEASTWARD SHORT-TERM MOTION. 455AT THE MOMENT...IT IS UNCLEAR WHETHER THE CURRENT MOTION REPRESENTS 456A MEANDERING OR A MORE DECIDED MOTION. ON THE LARGE SCALE...DEBBY 457IS TRAPPED IN A REGION OF WEAK STEERING IN BETWEEN A STRONG 458MID-LEVEL RIDGE OVER THE PLAINS AND ONE OVER THE SUBTROPICAL 459CENTRAL ATLANTIC. GLOBAL MODELS DEPICT AN AMPLIFYING TROUGH 460OFFSHORE THE EASTERN SEABOARD CAUSING DEBBY TO MOVE GENERALLY 461EASTWARD THROUGH THE FORECAST PERIOD...WITH THE CENTER EMERGING 462OVER THE SOUTHWEST ATLANTIC BY DAY 5. THE ECMWF/GFS SOLUTIONS BEGIN 463TO LIFT OUT THE WESTERN ATLANTIC TROUGH IN ABOUT 72 HOURS...WHICH 464COULD LEAVE DEBBY IN WEAK STEERING CURRENT AGAIN AFTER THAT TIME. 465SINCE YESTERDAY... THE GUIDANCE HAS COME INTO BETTER 466AGREEMENT...WITH ONLY THE UKMET NOW SHOWING A WESTWARD MOTION. IN 467ADDITION...THE LATEST GFS ENSEMBLE MEMBERS FAVOR AN EASTWARD MOTION 468BY ABOUT A 3 TO 1 RATIO. THE NEW FORECAST TRACK REPRESENTS A 469SUBSTANTIAL CHANGE FROM THE PREVIOUS ONE BUT IS STILL SLOWER THAN 470THE MULTI-MODEL CONSENSUS IN THE SHORT TERM. 471 472 473FORECAST POSITIONS AND MAX WINDS 474 475INIT 25/1500Z 28.6N 85.2W 40 KT 45 MPH 476 12H 26/0000Z 28.8N 85.1W 35 KT 40 MPH 477 24H 26/1200Z 28.9N 84.9W 35 KT 40 MPH 478 36H 27/0000Z 29.0N 84.7W 35 KT 40 MPH 479 48H 27/1200Z 29.2N 84.4W 35 KT 40 MPH 480 72H 28/1200Z 29.5N 83.5W 35 KT 40 MPH 481 96H 29/1200Z 29.5N 82.5W 30 KT 35 MPH...INLAND 482120H 30/1200Z 29.5N 81.0W 30 KT 35 MPH 483 484$$ 485FORECASTER KIMBERLAIN/FRANKLIN 486 487 488WTNT44 KNHC 252052 489TCDAT4 490 491TROPICAL STORM DEBBY DISCUSSION NUMBER 10 492NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 493400 PM CDT MON JUN 25 2012 494 495SATELLITE IMAGERY INDICATES THAT DEBBY HAS CHANGED LITTLE IN 496ORGANIZATION TODAY. THE CENTER OF THE CYCLONE IS A LITTLE HARDER TO 497LOCATE...WITH AT LEAST A COUPLE OF SMALL VORTICES ROTATING AROUND A 498MEAN CENTER. THERE HAD BEEN VIRTUALLY NO CONVECTION ASSOCIATED WITH 499THE CENTER OF THE CYCLONE EITHER...BUT A BURST OF DEEP CONVECTION 500HAS RECENTLY FORMED OVER LAND TO THE NORTH OF THE CENTER. EARLIER 501AIRCRAFT DATA SHOWED PEAK FLIGHT-LEVEL WINDS OF 57 KT AT 850MB... 502WITH MAXIMUM SFMR VALUES AROUND 40 KT. GIVEN THESE DATA AND THE 503LACK OF STRUCTURAL CHANGES TO THE CYCLONE...THE INITIAL INTENSITY 504REMAINS 40 KT. THE CURRENT STRUCTURE...COMBINED WITH AN INCREASE 505IN WESTERLY SHEAR AND ADDITIONAL DRY AIR POSSIBLY WRAPPING INTO THE 506STORM CIRCULATION...WOULD SEEM TO PRECLUDE MUCH SHORT-TERM 507RE-INTENSIFICATION OF DEBBY...AND THE SHIPS AND LGEM MODELS SHOW NO 508APPRECIABLE CHANGE IN STRENGTH PRIOR TO LANDFALL. MARGINALLY 509FAVORABLE ENVIRONMENTAL CONDITIONS COULD PROVIDE AN OPPORTUNITY FOR 510RE-STRENGTHENING OVER THE WESTERN ATLANTIC AT THE END OF THE 511FORECAST PERIOD. 512 513A SMOOTHING OF RECENT AIRCRAFT AND SATELLITE FIXES YIELDS A SLOW 514NORTHEASTWARD MOTION OF 040/04. LARGE-SCALE MODELS SHOW DEBBY 515CONTINUING ON AN EAST-NORTHEASTWARD TO NORTHEASTWARD COURSE OVER 516THE NEXT FEW DAYS IN RESPONSE TO AN AMPLIFYING TROUGH OFFSHORE OF 517THE U.S. EAST COAST. AS THE WESTERN ATLANTIC TROUGH BEGINS TO LIFT 518OUT IN 2-3 DAYS...DEBBY IS EXPECTED TO SLOW DOWN AND BE LEFT BEHIND 519OVER THE SOUTHWESTERN ATLANTIC. WITH THE EXCEPTION OF THE GFS 520ENSEMBLE MEMBERS...THE MODEL GUIDANCE IS IN BETTER AGREEMENT 521OVERALL ON AN EASTWARD TRACK...ALTHOUGH SIGNIFICANT SPEED 522DIFFERENCES REMAIN. THE GFS IS CONSIDERABLY SLOWER THAN THE MODEL 523CONSENSUS...AND SHOWS DEBBY TAKING FIVE DAYS TO MOVE OFFSHORE THE 524FLORIDA ATLANTIC COAST. INTERESTINGLY...THE ECMWF IS NOW ONE OF THE 525FASTEST MODELS TO THE EAST. THE NHC OFFICIAL TRACK FORECAST IS NOT 526AS FAST AS THE MULTI-MODEL CONSENSUS IN DEFERENCE TO CONTINUITY AND 527THE GFS. 528 529 530FORECAST POSITIONS AND MAX WINDS 531 532INIT 25/2100Z 29.3N 85.1W 40 KT 45 MPH 533 12H 26/0600Z 29.4N 84.9W 40 KT 45 MPH 534 24H 26/1800Z 29.5N 84.7W 40 KT 45 MPH 535 36H 27/0600Z 29.6N 84.4W 40 KT 45 MPH 536 48H 27/1800Z 29.7N 83.8W 40 KT 45 MPH 537 72H 28/1800Z 29.8N 82.5W 30 KT 35 MPH...INLAND 538 96H 29/1800Z 29.8N 81.0W 30 KT 35 MPH 539120H 30/1800Z 30.0N 79.0W 35 KT 40 MPH 540 541$$ 542FORECASTER KIMBERLAIN/ 543 544 545WTNT44 KNHC 260300 546TCDAT4 547 548TROPICAL STORM DEBBY DISCUSSION NUMBER 11 549NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 5501000 PM CDT MON JUN 25 2012 551 552AFTER AN INTENSE BURST OF DEEP CONVECTION NEAR AND NORTH OF THE 553LOW-LEVEL CENTER THIS LATE AFTERNOON AND EVENING...THE CONVECTIVE 554CLOUD SHIELD IS SHOWING SIGNS OF SLOWLY PULLING AWAY FROM CENTER OF 555CIRCULATION DUE TO MODERATE TO STRONG SOUTHWESTERLY VERTICAL WIND 556SHEAR. THE HIGHEST RELIABLE SFMR WINDS REPORTED BY AN AIR FORCE 557RESERVE RECON AIRCRAFT THIS EVENING HAS BEEN 42 KT TO THE WEST AND 558WELL SOUTHEAST OF THE CENTER...ALONG WITH 59-KT AND 56-KT 559FLIGHT-LEVEL WINDS...RESPECTIVELY. ALTHOUGH THE TALLAHASSEE DOPPLER 560WEATHER RADAR HAS BEEN INDICATING LARGE WINDS OF 60-65 VELOCITIES 561BETWEEN 2000 AND 6500 FT IN SOME RATHER VIGOROUS CONVECTION...THOSE 562CONDITIONS HAVE BEEN OVER LAND. THEREFORE...THE INITIAL INTENSITY 563WILL REMAIN AT 40 KT. 564 565THE MOTION ESTIMATE IS A SLOW DRIFT TO THE NORTHEAST OR 040/02 KT 566OVER THE PAST 12 HOURS. THERE IS NO SIGNIFICANT CHANGE TO THE 567PREVIOUS TRACK REASONING. UPPER-AIR DATA AT 18Z AND 00Z INDICATE 568DEBBY REMAINS TRAPPED IN A BLOCKING RIDGE PATTERN THAT EXTENDS 569ACROSS THE SOUTHEASTERN U.S. AND INTO THE EASTERN GULF OF MEXICO 570AND WESTERN ATLANTIC. THE RESULTANT WEAK STEERING FLOW SHOULD KEEP 571DEBBY MOVING VERY SLOWLY NORTHEAST OR EASTWARD AT LESS THAN 5 KT 572THROUGHOUT THE FORECAST PERIOD. IN FACT...DEBBY WILL LIKELY REMAIN 573OVER THE NORTHEASTERN GULF OF MEXICO FOR AT LEAST THE NEXT 2 DAYS 574BEFORE IT CREEPS SLOWLY ACROSS NORTH FLORIDA IN DAYS 3-4. IN THE 575ABSENCE OF ANY LARGE-SCALE STEERING FLOW...THE LOW-LEVEL CENTER OF 576DEBBY WILL CLOSELY FOLLOW ANY DEEP CONVECTION THAT DEVELOPS...WHICH 577SHOULD REMAIN PRIMARILY TO NORTHEAST OF THE CENTER. THE OFFICIAL 578FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK THROUGH 579DAY 3...AND IS THEN A LITTLE NORTH OF THE PREVIOUS TRACK AND CLOSE 580TO THE NHC MODEL CONSENSUS. 581 582THE PRESENCE OF DRY MID-LEVEL AIR WRAPPING INTO THE WESTERN AND 583SOUTHERN PORTION OF THE CIRCULATION...ALONG WITH SOUTHWESTERLY 584VERTICAL WIND SHEAR OF 20-25 KT FOR THE NEXT 48 HOURS OR SO SHOULD 585INHIBIT ANY SIGNIFICANT DEVELOPMENT WHILE DEBBY REMAINS OVER WATER. 586THE SHEAR DECREASES SIGNIFICANTLY BY 72 HOURS AND BEYOND...BUT 587DEBBY WILL BE OVER OR INTERACTING WITH LAND AT DAYS 3 AND 4...SO 588THAT WILL PREVENT THE CYCLONE FROM TAKING ADVANTAGE OF THE 589IMPROVING SHEAR CONDITIONS. BY DAY 5...HOWEVER...DEBBY IS EXPECTED 590TO BE MOVING OVER THE WARMER WATERS OF THE GULFSTREAM...WHICH MAY 591ALLOW FOR SOME MODEST STRENGTHENING TO OCCUR AFTER HAVING WEAKENED 592OVER LAND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE 593PREVIOUS ADVISORY AND CLOSELY FOLLOWS THE LGEM INTENSITY MODEL. 594 595 596FORECAST POSITIONS AND MAX WINDS 597 598INIT 26/0300Z 29.2N 85.1W 40 KT 45 MPH 599 12H 26/1200Z 29.3N 84.9W 40 KT 45 MPH 600 24H 27/0000Z 29.4N 84.6W 40 KT 45 MPH 601 36H 27/1200Z 29.5N 84.2W 40 KT 45 MPH 602 48H 28/0000Z 29.6N 83.6W 40 KT 45 MPH 603 72H 29/0000Z 29.8N 82.3W 30 KT 35 MPH...INLAND 604 96H 30/0000Z 30.1N 80.7W 35 KT 40 MPH...OVER WATER 605120H 01/0000Z 30.8N 78.7W 40 KT 45 MPH 606 607$$ 608FORECASTER STEWART 609 610 611WTNT44 KNHC 232052 612TCDAT4 613 614TROPICAL STORM DEBBY DISCUSSION NUMBER 1 615NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 616400 PM CDT SAT JUN 23 2012 617 618AIRCRAFT RECONNAISSANCE...SATELLITE...AND BUOY DATA INDICATE THAT 619THE CIRCULATION ASSOCIATED WITH THE AREA OF LOW PRESSURE IN THE 620GULF OF MEXICO HAS BECOME SUFFICIENTLY DEFINED TO CLASSIFY THIS 621SYSTEM AS A TROPICAL STORM. THE INITIAL INTENSITY IS BASED ON A 622HIGHEST 1000-FT FLIGHT-LEVEL WIND OF 61 KT AND SFMR WINDS NEAR 45 623KT. THESE WINDS ARE ONLY OCCURRING TO THE EAST OF THE CENTER. 624 625DEBBY IS MOVING SLOWLY NORTHWARD...OR 360 DEGREES AT 5 KT. THE 626CYCLONE IS IN A WEAK STEERING ENVIRONMENT BETWEEN TWO MID-LEVEL 627RIDGES LOCATED OVER THE GREATER ANTILLES AND THE SOUTHERN UNITED 628STATES...AND DEBBY IS NOT EXPECTED TO MOVE MUCH DURING THE NEXT 629COUPLE OF DAYS. THE TRACK GUIDANCE IS SPLIT IN TWO BRANCHES...WITH 630THE GFS AND GFDL SHOWING AN EASTWARD MOTION ACROSS FLORIDA...AND 631THE REST OF THE MODELS BRINGING DEBBY WESTWARD ACROSS THE NORTHERN 632GULF TOWARDS TEXAS. EVEN THOUGH THE DETERMINISTIC GFS SHOWS AN 633EASTWARD TRACK...MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS ARE IN 634AGREEMENT WITH THE WESTWARD-MOVING MODELS...MAKING THE WESTWARD 635SCENARIO SEEM MORE LIKELY. IT IS IMPORTANT TO NOTE TOO THAT THE 636ECMWF MODEL SHOWS A FASTER WESTWARD MOTION THAN INDICATED IN THE 637NHC FORECAST...SO IT IS POSSIBLE THAT DEBBY COULD REACH THE COAST 638EARLIER THAN INDICATED. 639 640DEBBY IS CURRENTLY A SHEARED CYCLONE WITH NEARLY ALL OF THE DEEP 641CONVECTION LOCATED IN A CURVED BAND TO THE EAST OF THE CENTER. 642HOWEVER...AN UPPER-LEVEL LOW OVER THE NORTHWESTERN GULF OF MEXICO 643IS FORECAST TO DIG SOUTHWESTWARD...WHICH WILL RESULT IN A DECREASE 644OF VERTICAL SHEAR AFFECTING THE SYSTEM...AND A GREATER CHANCE OF 645INTENSIFICATION OVER THE NEXT FEW DAYS. BECAUSE THE OFFICIAL TRACK 646FORECAST IS SO DIFFERENT FROM THE GFS SOLUTION...THE GFS FIELDS USED 647BY THE SHIPS AND LGEM MODELS ARE NOT LIKELY TO BE REPRESENTATIVE OF 648THE CONDITIONS ENCOUNTERED BY DEBBY. THE NHC FORECAST THEREFORE 649SHOWS MORE STRENGTHENING THAN INDICATED BY THE INTENSITY GUIDANCE. 650 651DEBBY IS THE EARLIEST 4TH STORM IN THE HISTORICAL RECORDS... 652SURPASSING HURRICANE DENNIS OF 2005...WHICH BECAME A TROPICAL STORM 653ON JULY 5TH. 654 655 656FORECAST POSITIONS AND MAX WINDS 657 658INIT 23/2100Z 26.2N 87.6W 45 KT 50 MPH 659 12H 24/0600Z 26.9N 87.8W 45 KT 50 MPH 660 24H 24/1800Z 27.3N 88.1W 50 KT 60 MPH 661 36H 25/0600Z 27.4N 88.5W 50 KT 60 MPH 662 48H 25/1800Z 27.5N 89.5W 55 KT 65 MPH 663 72H 26/1800Z 27.5N 91.5W 55 KT 65 MPH 664 96H 27/1800Z 27.5N 93.5W 60 KT 70 MPH 665120H 28/1800Z 27.5N 95.0W 60 KT 70 MPH 666 667$$ 668FORECASTER BERG/AVILA 669 670 671WTNT44 KNHC 240257 672TCDAT4 673 674TROPICAL STORM DEBBY DISCUSSION NUMBER 2 675NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 6761000 PM CDT SAT JUN 23 2012 677 678DEBBY IS GRADUALLY SHOWING SIGNS OF IMPROVED ORGANIZATION AS THE 679UPPER-LEVEL SHEAR SHIFTS FROM SOUTHWESTERLY TO MORE OF A SOUTHERLY 680COMPONENT. SHIP ZCDJ2 LOCATED ABOUT 80 NMI EAST OF THE CENTER AND 681NEAR NOAA BUOY 42003 REPORTED A PRESSURE OF 1001.6 MB AND 38 KT 682WINDS AT 24/00Z. BASED ON THIS INFORMATION...THE CENTRAL PRESSURE 683IS CONSERVATIVELY ESTIMATED TO BE 998 MB. AIRCRAFT RECONNAISSANCE 684DATA AT 23/2020Z INDICATED 850 MB FLIGHT-LEVEL WINDS OF 61 KT IN 685THE NORTHEAST QUADRANT...WHICH IS EQUAL TO ABOUT 49 KT SURFACE 686WINDS. CONVECTION WAS SOMEWHAT MEAGER AT THAT...BUT SINCE THEN HAS 687INCREASED RATHER MARKEDLY IN THAT AREA. THEREFORE THE INITIAL 688INTENSITY ESTIMATE IS A SOLID 45 KT. 689 690DEBBY HAS BEEN NEARLY STATIONARY DURING THE PAST 6 HOURS. MULTIPLE 691LOW-LEVEL VORTICES HAVE BEEN OUT FROM UNDERNEATH THE EASTERN 692SEMICIRCLE CONVECTIVE CLOUD MASS ABOUT A MEAN CENTER OF ROTATION OF 693A LARGER GYRE...AND THE LOCATION OF THE LARGER STATIONARY GYRE IS 694THE ADVISORY POSITION. ALTHOUGH THERE MAY BE SOME SLIGHT 695NORTHEASTWARD MOTION DUE TO REDEVELOPMENT OF THE CENTER CLOSER TO 696THE DEEP CONVECTION...THE GENERAL MOTION FOR THE NEXT 24 HOURS OR 697SO SHOULD BE SLOWLY POLEWARD. THE LONGWAVE PATTERN ACROSS THE U.S. 698HAS A DEEPENING TROUGH OFF THE WEST COAST...WHICH IS CREATING 699DOWNSTREAM RIDGING ACROSS THE CENTRAL AND EASTERN UNITED STATES. 700THIS INCREASED RIDGING IS REFLECTED BY 20-40 METER 500 MB HEIGHT 701RISES AT 00Z ACROSS THE CENTRAL AND SOUTHERN PLAINS...AND EXTENDING 702AS FAR EAST AS THE CAROLINA COASTS. THIS BLOCKING RIDGE PATTERN TO 703THE NORTH OF DEBBY IS EXPECTED TO GRADUALLY TURN THE CYCLONE 704WESTWARD ACROSS THE NORTH-CENTRAL GULF OF MEXICO BY 36-48 705HOURS...WITH A CONTINUED WESTWARD MOTION ACROSS THE NORTHWESTERN 706GULF AFTER THAT. ALL OF THE AVAILABLE NHC MODEL GUIDANCE...EXCEPT 707FOR THE GFS AND GFS-ENSEMBLE MODELS...SUPPORTS THE GENERAL WESTWARD 708MOTION SCENARIO. THE MAIN REASON THAT THE GFS MOVES DEBBY EASTWARD 709ACROSS THE NORTHEASTERN GULF IS DUE TO IT HAVING A WEAKER AND MORE 710VERTICALLY SHALLOW STORM DEPICTED IN THE MODEL. GIVEN THE EXPECTED 711FAVORABLE UPPER-LEVEL FLOW PATTERN WITH WEAKER VERTICAL SHEAR 712FORECAST TO DEVELOP AFTER 24 HOURS...A DEEPER AND MORE ROBUST 713WESTWARD MOVING TROPICAL CYCLONE AS DEPICTED IN THE 714ECMWF...UKMET... NOGAPS MODELS SEEMS A MORE REASONABLE SCENARIO. 715THE OFFICIAL FORECAST TRACK IS JUST AN UPDATE OF THE PREVIOUS 716ADVISORY TRACK. 717 718MODERATE SOUTHWESTERLY VERTICAL WIND SHEAR IS EXPECTED TO GRADUALLY 719GIVE WAY TO SOUTHERLY AND EVENTUALLY SOUTHEASTERLY WEAKER WIND 720SHEAR BY 36-48 HOURS AS AN UPPER-LEVEL LOW NORTHWEST OF THE CYCLONE 721MOVES SOUTHWESTWARD...WHICH ALLOWS DEBBY TO MOVE UNDERNEATH A 200 722MB RIDGE AXIS. THE OFFICIAL INTENSITY FORECAST LEANS TOWARD THE 723ECMWF MODEL...WHICH IS FORECASTING A HURRICANE CENTRAL PRESSURE BY 72496 HOURS...AND IS ABOVE THE GFS-BASED SHIPS AND LGEM MODELS SINCE 725THAT OUTPUT LIKELY DOES NOT REPRESENT THE ENVIRONMENTAL CONDITIONS 726THAT DEBBY WILL ENCOUNTER. THE OFFICIAL INTENSITY FORECAST IS A 727LITTLE HIGHER THAN THE PREVIOUS ADVISORY...AND BRINGS DEBBY TO 728HURRICANE STRENGTH BY 72 HOURS. 729 730 731FORECAST POSITIONS AND MAX WINDS 732 733INIT 24/0300Z 26.3N 87.5W 45 KT 50 MPH 734 12H 24/1200Z 26.7N 87.8W 50 KT 60 MPH 735 24H 25/0000Z 27.0N 88.1W 50 KT 60 MPH 736 36H 25/1200Z 27.1N 88.8W 55 KT 65 MPH 737 48H 26/0000Z 27.2N 89.8W 60 KT 70 MPH 738 72H 27/0000Z 27.2N 91.8W 65 KT 75 MPH 739 96H 28/0000Z 27.2N 93.7W 70 KT 80 MPH 740120H 29/0000Z 27.2N 95.2W 70 KT 80 MPH 741 742$$ 743FORECASTER STEWART 744 745 746WTNT44 KNHC 240837 747TCDAT4 748 749TROPICAL STORM DEBBY DISCUSSION NUMBER 3 750NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 751400 AM CDT SUN JUN 24 2012 752 753THE CLOUD PATTERN OF THE TROPICAL STORM HAS NOT BECOME SIGNIFICANTLY 754BETTER ORGANIZED OVER THE PAST FEW HOURS. DEBBY HAS BEEN PRODUCING 755VERY COLD-TOPPED DEEP CONVECTION BUT THESE THUNDERSTORMS...AND 756LIKELY THE STRONGEST WINDS...ARE OCCURRING SOME 100 TO 150 MILES 757NORTHEAST OF THE LOW-LEVEL CENTER. THE CURRENT INTENSITY IS KEPT 758AT 45 KT...WHICH IS IN AGREEMENT WITH DATA FROM AN ASCAT PASS 759SEVERAL HOURS AGO. NO CHANGE IS MADE TO THE PREVIOUS INTENSITY 760FORECAST...HOWEVER THIS FORECAST IS BASED ON THE PREMISE THAT THE 761VERTICAL SHEAR WILL DECREASE OVER THE NEXT FEW DAYS AND THE GLOBAL 762MODELS ARE NOT UNANIMOUS ON THIS. THE OFFICIAL WIND SPEED FORECAST 763IS CLOSEST TO THE MOST RECENT HWRF GUIDANCE...AND IT SHOULD BE 764NOTED THAT WE HAVE LIMITED SKILL IN PREDICTING TROPICAL CYCLONE 765INTENSITY CHANGE. 766 767WITH INFRARED IMAGERY THE CENTER...ALTHOUGH PARTIALLY EXPOSED...HAS 768BECOME A LITTLE MORE DIFFICULT TO LOCATE AND THE FIXES FROM TAFB 769AND SAB ARE ABOUT 50 MILES APART. MY BEST ESTIMATE OF INITIAL 770MOTION IS SLOWLY NORTHWARD...OR 360/3. THE TRACK FORECAST FOR THIS 771STORM IS EXTREMELY CHALLENGING. THE SYNOPTIC REASONING IN PREVIOUS 772ADVISORIES WAS BASED ON A MID-LEVEL RIDGE BUILDING TO THE NORTH OF 773THE TROPICAL CYCLONE...WHICH WOULD CAUSE DEBBY TO MOVE TOWARD THE 774NORTHWEST GULF OF MEXICO COAST IN SEVERAL DAYS. THAT TRACK 775SCENARIO WAS SUPPORTED BY THE ECMWF MODEL...WHICH HAS BEEN THE 776BEST-PERFORMING GUIDANCE OVER THE PAST FEW YEARS. HOWEVER...THE 7770000 RUN OF THAT MODEL HAS SHIFTED SUBSTANTIALLY TO THE NORTH AND 778EAST OF THE PREVIOUS RUNS. THE U.K. MET. OFFICE MODEL HAS ALSO 779SHIFTED SIGNIFICANTLY TO THE RIGHT. IN FACT...ONLY THE HWRF MODEL 780IS CLOSE TO THE PREVIOUS OFFICIAL FORECASTS...AND EVEN IT IS TO THE 781NORTH OF THEM. THEREFORE AN UNUSUALLY LARGE RIGHTWARD ADJUSTMENT 782TO THE NHC FORECAST IS REQUIRED...AND ADDITIONAL SHIFTS TO THE 783NORTH AND EAST MAY BE NECESSARY IN SUBSEQUENT ADVISORY PACKAGES. 784 785NEEDLESS TO SAY...THIS IS A LOW CONFIDENCE FORECAST. 786 787FORECAST POSITIONS AND MAX WINDS 788 789INIT 24/0900Z 27.3N 87.3W 45 KT 50 MPH 790 12H 24/1800Z 27.5N 87.4W 50 KT 60 MPH 791 24H 25/0600Z 27.9N 87.8W 50 KT 60 MPH 792 36H 25/1800Z 28.2N 88.4W 55 KT 65 MPH 793 48H 26/0600Z 28.3N 89.0W 60 KT 70 MPH 794 72H 27/0600Z 28.5N 90.5W 65 KT 75 MPH 795 96H 28/0600Z 28.5N 92.0W 70 KT 80 MPH 796120H 29/0600Z 28.5N 93.5W 70 KT 80 MPH 797 798$$ 799FORECASTER PASCH 800 801 802WTNT44 KNHC 241159 803TCDAT4 804 805TROPICAL STORM DEBBY SPECIAL DISCUSSION NUMBER 4 806NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 807700 AM CDT SUN JUN 24 2012 808 809THE PURPOSE OF THIS SPECIAL ADVISORY IS TO ISSUE A TROPICAL STORM 810WARNING FROM THE MISSISSIPPI ALABAMA BORDER EASTWARD TO THE 811OCHOLOCKONEE RIVER. THIS IS BASED ON THE EXPANSION OF TROPICAL 812STORM FORCE WINDS IN THE NORTHEAST QUADRANT. THERE HAVE BEEN NO 813CHANGES TO THE FORECAST TRACK NOR INTENSITY. 814 815 816FORECAST POSITIONS AND MAX WINDS 817 818INIT 24/1200Z 27.5N 87.0W 50 KT 60 MPH 819 12H 24/1800Z 27.5N 87.4W 50 KT 60 MPH 820 24H 25/0600Z 27.9N 87.8W 50 KT 60 MPH 821 36H 25/1800Z 28.2N 88.4W 55 KT 65 MPH 822 48H 26/0600Z 28.3N 89.0W 60 KT 70 MPH 823 72H 27/0600Z 28.5N 90.5W 65 KT 75 MPH 824 96H 28/0600Z 28.5N 92.0W 70 KT 80 MPH 825120H 29/0600Z 28.5N 93.5W 70 KT 80 MPH 826 827$$ 828FORECASTER AVILA 829 830 831 832WTNT44 KNHC 241458 833TCDAT4 834 835TROPICAL STORM DEBBY DISCUSSION NUMBER 5 836NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 8371000 AM CDT SUN JUN 24 2012 838 839IT IS A VERY DIFFICULT AND HIGHLY UNCERTAIN FORECAST THIS MORNING. 840DEBBY HAS BEEN MOVING VERY SLOWLY TOWARD THE NORTHEAST...040 AT 3 841KNOTS...WHILE THE WIND RADII HAVE BEEN EXPANDING IN THE EASTERN 842SEMICIRCLE. THIS HAS PROMPTED ADDITIONAL TROPICAL STORM WARNINGS 843AND WATCHES FOR PORTIONS OF THE FLORIDA COAST. 844 845DEBBY CONTINUES TO BE SHEARED WITH MOST OF THE THUNDERSTORM ACTIVITY 846NORTH AND EAST OF THE CENTER. THIS SHEAR IS EXPECTED TO CONTINUE 847FOR THE NEXT DAY OR SO...ALTHOUGH SOME DECREASE IN THE SHEAR IS 848POSSIBLE AFTER THAT...PARTICULARLY IF THE ECMWF VERIFIES. THE 849OFFICIAL FORECAST IS A LITTLE LESS AGGRESSIVE THAN THE PREVIOUS 850FORECAST...BUT REMAINS ABOVE MOST OF THE EXPLICIT INTENSITY 851GUIDANCE. 852 853THE TRACK FORECAST IS EVEN MORE COMPLEX. THE GFS INSISTS ON A TRACK 854TOWARD THE NORTHEAST AS DEBBY BECOMES EMBEDDED WITHIN A LARGE 855MID-LATITUDE TROUGH. HOWEVER...THE ECMWF AND THE HWRF BUILD A RIDGE 856TO THE NORTH OF DEBBY AND FORECAST A WESTWARD TRACK. GIVEN THE 857WESTWARD TURN INHERITED FROM THE PREVIOUS FORECAST...AS WELL AS THE 858HISTORICAL STRONG RECORD OF THE ECMWF...THE NEW OFFICIAL FORECAST 859MOVES DEBBY INITIALLY A LITTLE BIT TO THE NORTHEAST TO REFLECT 860CURRENT TRENDS BUT THEN TURNS THE CYCLONE BACK TOWARD THE WEST OR 861WEST-NORTHWEST IN 24 TO 36 HOURS. A MAJORITY OF THE GFS ENSEMBLE 862MEMBERS NOW ARE CONSISTENT WITH THE DETERMINISTIC RUN...WHICH WAS 863NOT THE CASE YESTERDAY...MAKING A STRONGER CASE FOR THE EASTWARD 864SOLUTION. WE MUST BE READY TO MAKE A CHANGE OF THE FORECAST TRACK 865AT ANY TIME. 866 867 868FORECAST POSITIONS AND MAX WINDS 869 870INIT 24/1500Z 28.0N 86.2W 50 KT 60 MPH 871 12H 25/0000Z 28.5N 85.8W 50 KT 60 MPH 872 24H 25/1200Z 28.5N 85.8W 50 KT 60 MPH 873 36H 26/0000Z 28.5N 86.2W 55 KT 65 MPH 874 48H 26/1200Z 28.7N 87.0W 60 KT 70 MPH 875 72H 27/1200Z 29.0N 88.4W 65 KT 75 MPH 876 96H 28/1200Z 29.5N 90.5W 45 KT 50 MPH 877120H 29/1200Z 30.0N 91.5W 30 KT 35 MPH 878 879$$ 880FORECASTER AVILA 881 882 883WTNT44 KNHC 242034 884TCDAT4 885 886TROPICAL STORM DEBBY DISCUSSION NUMBER 6 887NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 888400 PM CDT SUN JUN 24 2012 889 890THERE HAS BEEN A SIGNIFICANT CHANGE IN THE FORECAST TRACK WITH THIS 891ADVISORY. THE OFFICIAL FORECAST NO LONGER BRINGS DEBBY WESTWARD 892ALONG THE NORTHERN GULF OF MEXICO AND INSTEAD KEEPS THE CYCLONE 893MEANDERING OVER THE NORTHEASTERN GULF FOR THE NEXT 3 TO 4 DAYS. 894THIS FORECAST IS A COMPROMISE BETWEEN THE CONSISTENT EASTWARD 895SOLUTION PROVIDED BY THE GFS FOR THE PAST SEVERAL DAYS AND THE NEW 896TWIST OF THE ECMWF. THE ECMWF MODEL...WHICH HAS BEEN 897FORECASTING DEBBY TO MOVE WESTWARD ALONG THE GULF OF MEXICO... NOW 898HAS THE CYCLONE MEANDERING FOR THE NEXT 3 DAYS OVER THE 899NORTHEASTERN GULF. SINCE THESE TWO RELIABLE MODELS ARE IN 900MARGINALLY BETTER AGREEMENT...I AM A LITTLE MORE CONFIDENT...BUT 901NOT COMPLETELY...THAT DEBBY IS NOT GOING TO TURN WESTWARD OVER THE 902GULF. HOWEVER...NEW OFFICIAL TRACK REMAINS A LOW-CONFIDENCE 903FORECAST. 904 905DEBBY IS A SPRAWLING SYSTEM...WITH MOST OF THE THUNDERSTORM ACTIVITY 906IN A CURVED BAND WELL REMOVED FROM THE CENTER. DATA FROM THE 907RECONNAISSANCE PLANE A FEW HOURS AGO INDICATE THAT THE INITIAL 908INTENSITY REMAINS 50 KNOTS. THE SHEAR IS NOT EXPECTED TO CHANGE 909MUCH FOR THE NEXT DAY OR SO...BUT BECAUSE DEBBY IS FORECAST TO 910REMAIN OVER WATER...THERE WILL BE SOME OPPORTUNITY FOR A SLIGHT 911STRENGTHENING BEFORE THE CENTER MOVES INLAND. HOWEVER...THE CYCLONE 912WILL LOCATED BE NORTH OF THE AREA OF HIGH OCEANIC HEAT CONTENT AND 913THE UPWELLING COULD HALT THE INTENSIFICATION. 914 915 916FORECAST POSITIONS AND MAX WINDS 917 918INIT 24/2100Z 28.4N 85.8W 50 KT 60 MPH 919 12H 25/0600Z 28.7N 85.5W 50 KT 60 MPH 920 24H 25/1800Z 29.0N 85.5W 50 KT 60 MPH 921 36H 26/0600Z 29.0N 85.5W 55 KT 65 MPH 922 48H 26/1800Z 29.0N 85.5W 60 KT 70 MPH 923 72H 27/1800Z 29.5N 85.5W 60 KT 70 MPH 924 96H 28/1800Z 30.0N 85.5W 40 KT 45 MPH 925120H 29/1800Z 30.5N 85.5W 30 KT 35 MPH...INLAND 926 927$$ 928FORECASTER AVILA 929 930 931WTNT44 KNHC 250258 932TCDAT4 933 934TROPICAL STORM DEBBY DISCUSSION NUMBER 7 935NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 9361000 PM CDT SUN JUN 24 2012 937 938THE APPEARANCE OF DEBBY IN SATELLITE AND RADAR IMAGERY HAS DEGRADED 939SIGNIFICANTLY THIS EVENING AS A SHARP MID-LEVEL DRY INTRUSION HAS 940WORKED ITS WAY INTO THE CENTER OF THE CYCLONE AND ERODED ALL OF THE 941INNER CORE DEEP CONVECTION. THE INITIAL INTENSITY IS BEING HELD AT 94250 KT FOR THIS FORECAST PACKAGE BASED MAINLY ON CONTINUITY WITH THE 943PREVIOUS ADVISORY AND THE RELATIVELY LOW CENTRAL PRESSURE OF 991 MB 944REPORTED BY AN AIR FORCE RESERVE RECON AIRCRAFT THIS EVENING. 945 946DEBBY HAS BEEN NEARLY STATIONARY SINCE THE LAST ADVISORY. BOTH 18Z 947AND 00Z UPPER-AIR DATA INDICATE MID-LEVEL RIDGING HAS CONTINUED TO 948BUILD ACROSS THE SOUTHEASTERN U.S. TO THE NORTH OF DEBBY...AND THIS 949HAS LIKELY BEEN THE REASON FOR THE LACK OF ANY SIGNIFICANT MOTION 950OVER THE PAST SEVERAL HOURS. ALL OF THE NHC MODEL GUIDANCE...EXCEPT 951FOR THE GFS AND GFS-ENSEMBLE MODELS...INDICATE THIS BLOCKING PATTERN 952ACROSS THE CENTRAL AND EASTERN U.S. SHOULD CONTINUE AS FAST-MOVING 953SHORTWAVE TROUGHS PASS WELL TO THE NORTH OF DEBBY. THE RESULT 954SHOULD BE THAT THE CYCLONE WILL MOVE LITTLE DURING THE NEXT COUPLE 955OF DAYS...AND THEN ONLY DRIFT SLOWLY NORTHWARD AFTER THAT AS THE 956RIDGE OVER THE SOUTHEASTERN U.S. GRADUALLY BREAKS DOWN. ALTHOUGH THE 957GFS MODEL HAS BEEN VERY CONSISTENT WITH A FAST NORTHEASTWARD MOTION 958ACROSS NORTH FLORIDA THE PAST FEW DAYS...THE LARGE SPRAWLING NATURE 959OF THE CYCLONE AND THE BLOCKING RIDGE TO THE NORTH WOULD SUGGEST 960THAT THE GFS MODEL MAY BE LIFTING OUT DEBBY TOO QUICKLY. THE 961OFFICIAL FORECAST TRACK IS SIMILAR TO BUT SLIGHTLY LEFT OF THE 962PREVIOUS ADVISORY TRACK...MAINLY DUE TO THE MORE WESTWARD INITIAL 963POSITION. 964 965DEBBY HAS FINALLY CONSOLIDATED ALL OF THE MULTIPLE SMALL SWIRLS INTO 966A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER. THE GLOBAL MODELS ARE 967FORECASTING THE AFOREMENTIONED DEEP DRY SLOT TO GRADUALLY MOISTEN 968UP OVER THE NEXT 48 HOURS AS DEEP MOISTURE AND INSTABILITY 969CURRENTLY OVER THE FLORIDA PENINSULA ADVECTS WESTWARD INTO THE 970INNER CORE. THE COMBINATION OF THESE TWO FEATURES MAY ALLOW FOR 971SOME SLIGHT STRENGTHENING BEFORE DEBBY BEGINS TO INTERACT WITH LAND 972OR COLD UPWELLING BENEATH THE CYCLONE OCCURS. THE OFFICIAL 973INTENSITY FORECAST IS IDENTICAL TO THE PREVIOUS ADVISORY AND 974FOLLOWS A BLEND OF THE SHIPS/LGEM STATISTICAL MODELS AND THE 975HWRF/GFDL REGIONAL MODELS. 976 977FORECAST POSITIONS AND MAX WINDS 978 979INIT 25/0300Z 28.3N 85.9W 50 KT 60 MPH 980 12H 25/1200Z 28.6N 85.8W 50 KT 60 MPH 981 24H 26/0000Z 28.7N 85.8W 50 KT 60 MPH 982 36H 26/1200Z 28.8N 85.8W 55 KT 65 MPH 983 48H 27/0000Z 28.9N 85.8W 60 KT 70 MPH 984 72H 28/0000Z 29.4N 85.8W 55 KT 65 MPH 985 96H 29/0000Z 29.9N 85.8W 35 KT 40 MPH...NEAR COAST 986120H 30/0000Z 30.4N 85.6W 30 KT 35 MPH...INLAND 987 988$$ 989FORECASTER STEWART 990 991 992WTNT44 KNHC 250838 993TCDAT4 994 995TROPICAL STORM DEBBY DISCUSSION NUMBER 8 996NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 997400 AM CDT MON JUN 25 2012 998 999DEBBY HAS A HIGHLY UNIMPRESSIVE APPEARANCE ON SATELLITE IMAGERY. 1000ALTHOUGH RADAR DATA CONTINUE TO DEPICT SOME SHOWER ACTIVITY OVER 1001THE CIRCULATION...THESE SHOWERS ARE BEING PRODUCED BY SHALLOW 1002CONVECTION AS THE ENHANCED IR IMAGES DO NOT SHOW ANY SIGNIFICANT 1003AREAS OF COLD CLOUD TOPS. AIRCRAFT DATA FROM SEVERAL HOURS AGO 1004ALONG WITH SYNOPTIC OBSERVATIONS INDICATE THAT THE MAXIMUM SURFACE 1005WINDS HAVE DECREASED...AND THE CURRENT INTENSITY IS SET AT 45 KT. 1006DEBBY IS LOCATED NORTH OF THE AREA OF MAXIMUM OCEANIC HEAT 1007CONTENT...BUT AS LONG AS THE CYCLONE REMAINS OVER WATER AND IS ABLE 1008TO REGENERATE SOME DEEP CONVECTION THERE IS A POTENTIAL FOR AT 1009LEAST SLIGHT RE-INTENSIFICATION. THE CURRENT NHC INTENSITY 1010FORECAST IS A LITTLE LOWER THAN THE PREVIOUS ONES...BUT A LITTLE 1011HIGHER THAN MOST OF THE NUMERICAL GUIDANCE. 1012 1013BEST GUESS AT INITIAL MOTION IS QUASI-STATIONARY. DEBBY REMAINS IN 1014A COL REGION OF THE MID-TROPOSPHERIC STEERING FLOW BETWEEN TWO 1015ANTICYCLONES...AND IS LIKELY TO REMAIN SO FOR THE NEXT COUPLE OF 1016DAYS. THEREFORE LITTLE MOTION IS ANTICIPATED DURING AT LEAST THE 1017FIRST HALF OF THE FORECAST PERIOD. IN THE LONGER-TERM...THE TRACK 1018GUIDANCE CONTINUES TO BE ALL OVER THE PLACE...WITH SOME MODELS 1019TAKING DEBBY WEST AND NORTH OF ITS CURRENT POSITION AND OTHERS 1020MOVING EAST OR NORTHEAST AND ULTIMATELY INTO THE ATLANTIC. THE 1021LATTER SCENARIO ASSUMES THAT DEBBY WILL EVENTUALLY BE INFLUENCED BY 1022A MID-TROPOSPHERIC TROUGH OVER THE NORTHEASTERN UNITED STATES. 1023THIS SCENARIO SEEMS MORE LIKELY SINCE IT IS SUPPORTED BY BOTH THE 1024GFS AND THE ECMWF MODELS. REGARDLESS OF WHICH SCENARIO PLAYS 1025OUT...THE CYCLONE DOES NOT SEEM TO BE GOING ANYWHERE ANYTIME SOON. 1026 1027FORECAST POSITIONS AND MAX WINDS 1028 1029INIT 25/0900Z 28.6N 85.8W 45 KT 50 MPH 1030 12H 25/1800Z 28.8N 85.7W 45 KT 50 MPH 1031 24H 26/0600Z 28.9N 85.6W 50 KT 60 MPH 1032 36H 26/1800Z 29.0N 85.5W 50 KT 60 MPH 1033 48H 27/0600Z 29.2N 85.4W 55 KT 65 MPH 1034 72H 28/0600Z 29.4N 85.3W 55 KT 65 MPH 1035 96H 29/0600Z 29.7N 85.2W 45 KT 50 MPH...INLAND 1036120H 30/0600Z 30.2N 85.0W 30 KT 35 MPH...INLAND 1037 1038$$ 1039FORECASTER PASCH 1040 1041 1042WTNT44 KNHC 251451 1043TCDAT4 1044 1045TROPICAL STORM DEBBY DISCUSSION NUMBER 9 1046NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 10471000 AM CDT MON JUN 25 2012 1048 1049THERE HAS BEEN NO SIGNIFICANT DEEP CONVECTION NEAR THE CENTER OF 1050DEBBY FOR OVER 12 HOURS. WHAT CONVECTION REMAINS IS PRIMARILY 1051LOCATED IN A FRAGMENTED BAND WELL EAST OF THE CENTER...AND 1052SOUNDINGS ALONG THE GULF COAST INDICATE THAT THE ENTRAINMENT OF DRY 1053MID-LEVEL AIR IS AFFECTING THE STORM. IN ADDITION...THE SLOW 1054MOVEMENT OF DEBBY HAS INDUCED OCEANIC UPWELLING AND COOLING 1055UNDERNEATH THE CYCLONE AND MAY HAVE CONTRIBUTED TO THE OBSERVED 1056WEAKENING. LATEST DATA FROM THE RECONNAISSANCE AIRCRAFT INDICATE 1057THAT THE MAXIMUM WINDS ARE NEAR 40 KT. WITH DRY AIR LURKING AND 1058WESTERLY SHEAR ON THE INCREASE OVER THE NEXT COUPLE DAYS... 1059SIGNIFICANT RE-INTENSIFICATION OF THE CYCLONE PRIOR TO LANDFALL 1060SEEMS UNLIKELY. THE NEW NHC FORECAST IS ADJUSTED DOWNWARD IN LINE 1061WITH CURRENT TRENDS AND THE LATEST INTENSITY GUIDANCE. 1062 1063AIRCRAFT AND SATELLITE FIXES HAVE SHOWN LITTLE OVERALL MOVEMENT OVER 1064THE PAST 12 TO 18 HOURS... ALTHOUGH RECENT SATELLITE IMAGERY 1065INDICATES AN EAST-NORTHEASTWARD TO NORTHEASTWARD SHORT-TERM MOTION. 1066AT THE MOMENT...IT IS UNCLEAR WHETHER THE CURRENT MOTION REPRESENTS 1067A MEANDERING OR A MORE DECIDED MOTION. ON THE LARGE SCALE...DEBBY 1068IS TRAPPED IN A REGION OF WEAK STEERING IN BETWEEN A STRONG 1069MID-LEVEL RIDGE OVER THE PLAINS AND ONE OVER THE SUBTROPICAL 1070CENTRAL ATLANTIC. GLOBAL MODELS DEPICT AN AMPLIFYING TROUGH 1071OFFSHORE THE EASTERN SEABOARD CAUSING DEBBY TO MOVE GENERALLY 1072EASTWARD THROUGH THE FORECAST PERIOD...WITH THE CENTER EMERGING 1073OVER THE SOUTHWEST ATLANTIC BY DAY 5. THE ECMWF/GFS SOLUTIONS BEGIN 1074TO LIFT OUT THE WESTERN ATLANTIC TROUGH IN ABOUT 72 HOURS...WHICH 1075COULD LEAVE DEBBY IN WEAK STEERING CURRENT AGAIN AFTER THAT TIME. 1076SINCE YESTERDAY... THE GUIDANCE HAS COME INTO BETTER 1077AGREEMENT...WITH ONLY THE UKMET NOW SHOWING A WESTWARD MOTION. IN 1078ADDITION...THE LATEST GFS ENSEMBLE MEMBERS FAVOR AN EASTWARD MOTION 1079BY ABOUT A 3 TO 1 RATIO. THE NEW FORECAST TRACK REPRESENTS A 1080SUBSTANTIAL CHANGE FROM THE PREVIOUS ONE BUT IS STILL SLOWER THAN 1081THE MULTI-MODEL CONSENSUS IN THE SHORT TERM. 1082 1083 1084FORECAST POSITIONS AND MAX WINDS 1085 1086INIT 25/1500Z 28.6N 85.2W 40 KT 45 MPH 1087 12H 26/0000Z 28.8N 85.1W 35 KT 40 MPH 1088 24H 26/1200Z 28.9N 84.9W 35 KT 40 MPH 1089 36H 27/0000Z 29.0N 84.7W 35 KT 40 MPH 1090 48H 27/1200Z 29.2N 84.4W 35 KT 40 MPH 1091 72H 28/1200Z 29.5N 83.5W 35 KT 40 MPH 1092 96H 29/1200Z 29.5N 82.5W 30 KT 35 MPH...INLAND 1093120H 30/1200Z 29.5N 81.0W 30 KT 35 MPH 1094 1095$$ 1096FORECASTER KIMBERLAIN/FRANKLIN 1097 1098 1099 1100WTNT44 KNHC 252052 1101TCDAT4 1102 1103TROPICAL STORM DEBBY DISCUSSION NUMBER 10 1104NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1105400 PM CDT MON JUN 25 2012 1106 1107SATELLITE IMAGERY INDICATES THAT DEBBY HAS CHANGED LITTLE IN 1108ORGANIZATION TODAY. THE CENTER OF THE CYCLONE IS A LITTLE HARDER TO 1109LOCATE...WITH AT LEAST A COUPLE OF SMALL VORTICES ROTATING AROUND A 1110MEAN CENTER. THERE HAD BEEN VIRTUALLY NO CONVECTION ASSOCIATED WITH 1111THE CENTER OF THE CYCLONE EITHER...BUT A BURST OF DEEP CONVECTION 1112HAS RECENTLY FORMED OVER LAND TO THE NORTH OF THE CENTER. EARLIER 1113AIRCRAFT DATA SHOWED PEAK FLIGHT-LEVEL WINDS OF 57 KT AT 850MB... 1114WITH MAXIMUM SFMR VALUES AROUND 40 KT. GIVEN THESE DATA AND THE 1115LACK OF STRUCTURAL CHANGES TO THE CYCLONE...THE INITIAL INTENSITY 1116REMAINS 40 KT. THE CURRENT STRUCTURE...COMBINED WITH AN INCREASE 1117IN WESTERLY SHEAR AND ADDITIONAL DRY AIR POSSIBLY WRAPPING INTO THE 1118STORM CIRCULATION...WOULD SEEM TO PRECLUDE MUCH SHORT-TERM 1119RE-INTENSIFICATION OF DEBBY...AND THE SHIPS AND LGEM MODELS SHOW NO 1120APPRECIABLE CHANGE IN STRENGTH PRIOR TO LANDFALL. MARGINALLY 1121FAVORABLE ENVIRONMENTAL CONDITIONS COULD PROVIDE AN OPPORTUNITY FOR 1122RE-STRENGTHENING OVER THE WESTERN ATLANTIC AT THE END OF THE 1123FORECAST PERIOD. 1124 1125A SMOOTHING OF RECENT AIRCRAFT AND SATELLITE FIXES YIELDS A SLOW 1126NORTHEASTWARD MOTION OF 040/04. LARGE-SCALE MODELS SHOW DEBBY 1127CONTINUING ON AN EAST-NORTHEASTWARD TO NORTHEASTWARD COURSE OVER 1128THE NEXT FEW DAYS IN RESPONSE TO AN AMPLIFYING TROUGH OFFSHORE OF 1129THE U.S. EAST COAST. AS THE WESTERN ATLANTIC TROUGH BEGINS TO LIFT 1130OUT IN 2-3 DAYS...DEBBY IS EXPECTED TO SLOW DOWN AND BE LEFT BEHIND 1131OVER THE SOUTHWESTERN ATLANTIC. WITH THE EXCEPTION OF THE GFS 1132ENSEMBLE MEMBERS...THE MODEL GUIDANCE IS IN BETTER AGREEMENT 1133OVERALL ON AN EASTWARD TRACK...ALTHOUGH SIGNIFICANT SPEED 1134DIFFERENCES REMAIN. THE GFS IS CONSIDERABLY SLOWER THAN THE MODEL 1135CONSENSUS...AND SHOWS DEBBY TAKING FIVE DAYS TO MOVE OFFSHORE THE 1136FLORIDA ATLANTIC COAST. INTERESTINGLY...THE ECMWF IS NOW ONE OF THE 1137FASTEST MODELS TO THE EAST. THE NHC OFFICIAL TRACK FORECAST IS NOT 1138AS FAST AS THE MULTI-MODEL CONSENSUS IN DEFERENCE TO CONTINUITY AND 1139THE GFS. 1140 1141 1142FORECAST POSITIONS AND MAX WINDS 1143 1144INIT 25/2100Z 29.3N 85.1W 40 KT 45 MPH 1145 12H 26/0600Z 29.4N 84.9W 40 KT 45 MPH 1146 24H 26/1800Z 29.5N 84.7W 40 KT 45 MPH 1147 36H 27/0600Z 29.6N 84.4W 40 KT 45 MPH 1148 48H 27/1800Z 29.7N 83.8W 40 KT 45 MPH 1149 72H 28/1800Z 29.8N 82.5W 30 KT 35 MPH...INLAND 1150 96H 29/1800Z 29.8N 81.0W 30 KT 35 MPH 1151120H 30/1800Z 30.0N 79.0W 35 KT 40 MPH 1152 1153$$ 1154FORECASTER KIMBERLAIN/ 1155 1156 1157WTNT44 KNHC 260300 1158TCDAT4 1159 1160TROPICAL STORM DEBBY DISCUSSION NUMBER 11 1161NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 11621000 PM CDT MON JUN 25 2012 1163 1164AFTER AN INTENSE BURST OF DEEP CONVECTION NEAR AND NORTH OF THE 1165LOW-LEVEL CENTER THIS LATE AFTERNOON AND EVENING...THE CONVECTIVE 1166CLOUD SHIELD IS SHOWING SIGNS OF SLOWLY PULLING AWAY FROM CENTER OF 1167CIRCULATION DUE TO MODERATE TO STRONG SOUTHWESTERLY VERTICAL WIND 1168SHEAR. THE HIGHEST RELIABLE SFMR WINDS REPORTED BY AN AIR FORCE 1169RESERVE RECON AIRCRAFT THIS EVENING HAS BEEN 42 KT TO THE WEST AND 1170WELL SOUTHEAST OF THE CENTER...ALONG WITH 59-KT AND 56-KT 1171FLIGHT-LEVEL WINDS...RESPECTIVELY. ALTHOUGH THE TALLAHASSEE DOPPLER 1172WEATHER RADAR HAS BEEN INDICATING LARGE WINDS OF 60-65 VELOCITIES 1173BETWEEN 2000 AND 6500 FT IN SOME RATHER VIGOROUS CONVECTION...THOSE 1174CONDITIONS HAVE BEEN OVER LAND. THEREFORE...THE INITIAL INTENSITY 1175WILL REMAIN AT 40 KT. 1176 1177THE MOTION ESTIMATE IS A SLOW DRIFT TO THE NORTHEAST OR 040/02 KT 1178OVER THE PAST 12 HOURS. THERE IS NO SIGNIFICANT CHANGE TO THE 1179PREVIOUS TRACK REASONING. UPPER-AIR DATA AT 18Z AND 00Z INDICATE 1180DEBBY REMAINS TRAPPED IN A BLOCKING RIDGE PATTERN THAT EXTENDS 1181ACROSS THE SOUTHEASTERN U.S. AND INTO THE EASTERN GULF OF MEXICO 1182AND WESTERN ATLANTIC. THE RESULTANT WEAK STEERING FLOW SHOULD KEEP 1183DEBBY MOVING VERY SLOWLY NORTHEAST OR EASTWARD AT LESS THAN 5 KT 1184THROUGHOUT THE FORECAST PERIOD. IN FACT...DEBBY WILL LIKELY REMAIN 1185OVER THE NORTHEASTERN GULF OF MEXICO FOR AT LEAST THE NEXT 2 DAYS 1186BEFORE IT CREEPS SLOWLY ACROSS NORTH FLORIDA IN DAYS 3-4. IN THE 1187ABSENCE OF ANY LARGE-SCALE STEERING FLOW...THE LOW-LEVEL CENTER OF 1188DEBBY WILL CLOSELY FOLLOW ANY DEEP CONVECTION THAT DEVELOPS...WHICH 1189SHOULD REMAIN PRIMARILY TO NORTHEAST OF THE CENTER. THE OFFICIAL 1190FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK THROUGH 1191DAY 3...AND IS THEN A LITTLE NORTH OF THE PREVIOUS TRACK AND CLOSE 1192TO THE NHC MODEL CONSENSUS. 1193 1194THE PRESENCE OF DRY MID-LEVEL AIR WRAPPING INTO THE WESTERN AND 1195SOUTHERN PORTION OF THE CIRCULATION...ALONG WITH SOUTHWESTERLY 1196VERTICAL WIND SHEAR OF 20-25 KT FOR THE NEXT 48 HOURS OR SO SHOULD 1197INHIBIT ANY SIGNIFICANT DEVELOPMENT WHILE DEBBY REMAINS OVER WATER. 1198THE SHEAR DECREASES SIGNIFICANTLY BY 72 HOURS AND BEYOND...BUT 1199DEBBY WILL BE OVER OR INTERACTING WITH LAND AT DAYS 3 AND 4...SO 1200THAT WILL PREVENT THE CYCLONE FROM TAKING ADVANTAGE OF THE 1201IMPROVING SHEAR CONDITIONS. BY DAY 5...HOWEVER...DEBBY IS EXPECTED 1202TO BE MOVING OVER THE WARMER WATERS OF THE GULFSTREAM...WHICH MAY 1203ALLOW FOR SOME MODEST STRENGTHENING TO OCCUR AFTER HAVING WEAKENED 1204OVER LAND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE 1205PREVIOUS ADVISORY AND CLOSELY FOLLOWS THE LGEM INTENSITY MODEL. 1206 1207 1208FORECAST POSITIONS AND MAX WINDS 1209 1210INIT 26/0300Z 29.2N 85.1W 40 KT 45 MPH 1211 12H 26/1200Z 29.3N 84.9W 40 KT 45 MPH 1212 24H 27/0000Z 29.4N 84.6W 40 KT 45 MPH 1213 36H 27/1200Z 29.5N 84.2W 40 KT 45 MPH 1214 48H 28/0000Z 29.6N 83.6W 40 KT 45 MPH 1215 72H 29/0000Z 29.8N 82.3W 30 KT 35 MPH...INLAND 1216 96H 30/0000Z 30.1N 80.7W 35 KT 40 MPH...OVER WATER 1217120H 01/0000Z 30.8N 78.7W 40 KT 45 MPH 1218 1219$$ 1220FORECASTER STEWART 1221 1222 1223WTNT44 KNHC 232052 1224TCDAT4 1225 1226TROPICAL STORM DEBBY DISCUSSION NUMBER 1 1227NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1228400 PM CDT SAT JUN 23 2012 1229 1230AIRCRAFT RECONNAISSANCE...SATELLITE...AND BUOY DATA INDICATE THAT 1231THE CIRCULATION ASSOCIATED WITH THE AREA OF LOW PRESSURE IN THE 1232GULF OF MEXICO HAS BECOME SUFFICIENTLY DEFINED TO CLASSIFY THIS 1233SYSTEM AS A TROPICAL STORM. THE INITIAL INTENSITY IS BASED ON A 1234HIGHEST 1000-FT FLIGHT-LEVEL WIND OF 61 KT AND SFMR WINDS NEAR 45 1235KT. THESE WINDS ARE ONLY OCCURRING TO THE EAST OF THE CENTER. 1236 1237DEBBY IS MOVING SLOWLY NORTHWARD...OR 360 DEGREES AT 5 KT. THE 1238CYCLONE IS IN A WEAK STEERING ENVIRONMENT BETWEEN TWO MID-LEVEL 1239RIDGES LOCATED OVER THE GREATER ANTILLES AND THE SOUTHERN UNITED 1240STATES...AND DEBBY IS NOT EXPECTED TO MOVE MUCH DURING THE NEXT 1241COUPLE OF DAYS. THE TRACK GUIDANCE IS SPLIT IN TWO BRANCHES...WITH 1242THE GFS AND GFDL SHOWING AN EASTWARD MOTION ACROSS FLORIDA...AND 1243THE REST OF THE MODELS BRINGING DEBBY WESTWARD ACROSS THE NORTHERN 1244GULF TOWARDS TEXAS. EVEN THOUGH THE DETERMINISTIC GFS SHOWS AN 1245EASTWARD TRACK...MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS ARE IN 1246AGREEMENT WITH THE WESTWARD-MOVING MODELS...MAKING THE WESTWARD 1247SCENARIO SEEM MORE LIKELY. IT IS IMPORTANT TO NOTE TOO THAT THE 1248ECMWF MODEL SHOWS A FASTER WESTWARD MOTION THAN INDICATED IN THE 1249NHC FORECAST...SO IT IS POSSIBLE THAT DEBBY COULD REACH THE COAST 1250EARLIER THAN INDICATED. 1251 1252DEBBY IS CURRENTLY A SHEARED CYCLONE WITH NEARLY ALL OF THE DEEP 1253CONVECTION LOCATED IN A CURVED BAND TO THE EAST OF THE CENTER. 1254HOWEVER...AN UPPER-LEVEL LOW OVER THE NORTHWESTERN GULF OF MEXICO 1255IS FORECAST TO DIG SOUTHWESTWARD...WHICH WILL RESULT IN A DECREASE 1256OF VERTICAL SHEAR AFFECTING THE SYSTEM...AND A GREATER CHANCE OF 1257INTENSIFICATION OVER THE NEXT FEW DAYS. BECAUSE THE OFFICIAL TRACK 1258FORECAST IS SO DIFFERENT FROM THE GFS SOLUTION...THE GFS FIELDS USED 1259BY THE SHIPS AND LGEM MODELS ARE NOT LIKELY TO BE REPRESENTATIVE OF 1260THE CONDITIONS ENCOUNTERED BY DEBBY. THE NHC FORECAST THEREFORE 1261SHOWS MORE STRENGTHENING THAN INDICATED BY THE INTENSITY GUIDANCE. 1262 1263DEBBY IS THE EARLIEST 4TH STORM IN THE HISTORICAL RECORDS... 1264SURPASSING HURRICANE DENNIS OF 2005...WHICH BECAME A TROPICAL STORM 1265ON JULY 5TH. 1266 1267 1268FORECAST POSITIONS AND MAX WINDS 1269 1270INIT 23/2100Z 26.2N 87.6W 45 KT 50 MPH 1271 12H 24/0600Z 26.9N 87.8W 45 KT 50 MPH 1272 24H 24/1800Z 27.3N 88.1W 50 KT 60 MPH 1273 36H 25/0600Z 27.4N 88.5W 50 KT 60 MPH 1274 48H 25/1800Z 27.5N 89.5W 55 KT 65 MPH 1275 72H 26/1800Z 27.5N 91.5W 55 KT 65 MPH 1276 96H 27/1800Z 27.5N 93.5W 60 KT 70 MPH 1277120H 28/1800Z 27.5N 95.0W 60 KT 70 MPH 1278 1279$$ 1280FORECASTER BERG/AVILA 1281 1282 1283WTNT44 KNHC 240257 1284TCDAT4 1285 1286TROPICAL STORM DEBBY DISCUSSION NUMBER 2 1287NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 12881000 PM CDT SAT JUN 23 2012 1289 1290DEBBY IS GRADUALLY SHOWING SIGNS OF IMPROVED ORGANIZATION AS THE 1291UPPER-LEVEL SHEAR SHIFTS FROM SOUTHWESTERLY TO MORE OF A SOUTHERLY 1292COMPONENT. SHIP ZCDJ2 LOCATED ABOUT 80 NMI EAST OF THE CENTER AND 1293NEAR NOAA BUOY 42003 REPORTED A PRESSURE OF 1001.6 MB AND 38 KT 1294WINDS AT 24/00Z. BASED ON THIS INFORMATION...THE CENTRAL PRESSURE 1295IS CONSERVATIVELY ESTIMATED TO BE 998 MB. AIRCRAFT RECONNAISSANCE 1296DATA AT 23/2020Z INDICATED 850 MB FLIGHT-LEVEL WINDS OF 61 KT IN 1297THE NORTHEAST QUADRANT...WHICH IS EQUAL TO ABOUT 49 KT SURFACE 1298WINDS. CONVECTION WAS SOMEWHAT MEAGER AT THAT...BUT SINCE THEN HAS 1299INCREASED RATHER MARKEDLY IN THAT AREA. THEREFORE THE INITIAL 1300INTENSITY ESTIMATE IS A SOLID 45 KT. 1301 1302DEBBY HAS BEEN NEARLY STATIONARY DURING THE PAST 6 HOURS. MULTIPLE 1303LOW-LEVEL VORTICES HAVE BEEN OUT FROM UNDERNEATH THE EASTERN 1304SEMICIRCLE CONVECTIVE CLOUD MASS ABOUT A MEAN CENTER OF ROTATION OF 1305A LARGER GYRE...AND THE LOCATION OF THE LARGER STATIONARY GYRE IS 1306THE ADVISORY POSITION. ALTHOUGH THERE MAY BE SOME SLIGHT 1307NORTHEASTWARD MOTION DUE TO REDEVELOPMENT OF THE CENTER CLOSER TO 1308THE DEEP CONVECTION...THE GENERAL MOTION FOR THE NEXT 24 HOURS OR 1309SO SHOULD BE SLOWLY POLEWARD. THE LONGWAVE PATTERN ACROSS THE U.S. 1310HAS A DEEPENING TROUGH OFF THE WEST COAST...WHICH IS CREATING 1311DOWNSTREAM RIDGING ACROSS THE CENTRAL AND EASTERN UNITED STATES. 1312THIS INCREASED RIDGING IS REFLECTED BY 20-40 METER 500 MB HEIGHT 1313RISES AT 00Z ACROSS THE CENTRAL AND SOUTHERN PLAINS...AND EXTENDING 1314AS FAR EAST AS THE CAROLINA COASTS. THIS BLOCKING RIDGE PATTERN TO 1315THE NORTH OF DEBBY IS EXPECTED TO GRADUALLY TURN THE CYCLONE 1316WESTWARD ACROSS THE NORTH-CENTRAL GULF OF MEXICO BY 36-48 1317HOURS...WITH A CONTINUED WESTWARD MOTION ACROSS THE NORTHWESTERN 1318GULF AFTER THAT. ALL OF THE AVAILABLE NHC MODEL GUIDANCE...EXCEPT 1319FOR THE GFS AND GFS-ENSEMBLE MODELS...SUPPORTS THE GENERAL WESTWARD 1320MOTION SCENARIO. THE MAIN REASON THAT THE GFS MOVES DEBBY EASTWARD 1321ACROSS THE NORTHEASTERN GULF IS DUE TO IT HAVING A WEAKER AND MORE 1322VERTICALLY SHALLOW STORM DEPICTED IN THE MODEL. GIVEN THE EXPECTED 1323FAVORABLE UPPER-LEVEL FLOW PATTERN WITH WEAKER VERTICAL SHEAR 1324FORECAST TO DEVELOP AFTER 24 HOURS...A DEEPER AND MORE ROBUST 1325WESTWARD MOVING TROPICAL CYCLONE AS DEPICTED IN THE 1326ECMWF...UKMET... NOGAPS MODELS SEEMS A MORE REASONABLE SCENARIO. 1327THE OFFICIAL FORECAST TRACK IS JUST AN UPDATE OF THE PREVIOUS 1328ADVISORY TRACK. 1329 1330MODERATE SOUTHWESTERLY VERTICAL WIND SHEAR IS EXPECTED TO GRADUALLY 1331GIVE WAY TO SOUTHERLY AND EVENTUALLY SOUTHEASTERLY WEAKER WIND 1332SHEAR BY 36-48 HOURS AS AN UPPER-LEVEL LOW NORTHWEST OF THE CYCLONE 1333MOVES SOUTHWESTWARD...WHICH ALLOWS DEBBY TO MOVE UNDERNEATH A 200 1334MB RIDGE AXIS. THE OFFICIAL INTENSITY FORECAST LEANS TOWARD THE 1335ECMWF MODEL...WHICH IS FORECASTING A HURRICANE CENTRAL PRESSURE BY 133696 HOURS...AND IS ABOVE THE GFS-BASED SHIPS AND LGEM MODELS SINCE 1337THAT OUTPUT LIKELY DOES NOT REPRESENT THE ENVIRONMENTAL CONDITIONS 1338THAT DEBBY WILL ENCOUNTER. THE OFFICIAL INTENSITY FORECAST IS A 1339LITTLE HIGHER THAN THE PREVIOUS ADVISORY...AND BRINGS DEBBY TO 1340HURRICANE STRENGTH BY 72 HOURS. 1341 1342 1343FORECAST POSITIONS AND MAX WINDS 1344 1345INIT 24/0300Z 26.3N 87.5W 45 KT 50 MPH 1346 12H 24/1200Z 26.7N 87.8W 50 KT 60 MPH 1347 24H 25/0000Z 27.0N 88.1W 50 KT 60 MPH 1348 36H 25/1200Z 27.1N 88.8W 55 KT 65 MPH 1349 48H 26/0000Z 27.2N 89.8W 60 KT 70 MPH 1350 72H 27/0000Z 27.2N 91.8W 65 KT 75 MPH 1351 96H 28/0000Z 27.2N 93.7W 70 KT 80 MPH 1352120H 29/0000Z 27.2N 95.2W 70 KT 80 MPH 1353 1354$$ 1355FORECASTER STEWART 1356 1357 1358WTNT44 KNHC 240837 1359TCDAT4 1360 1361TROPICAL STORM DEBBY DISCUSSION NUMBER 3 1362NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1363400 AM CDT SUN JUN 24 2012 1364 1365THE CLOUD PATTERN OF THE TROPICAL STORM HAS NOT BECOME SIGNIFICANTLY 1366BETTER ORGANIZED OVER THE PAST FEW HOURS. DEBBY HAS BEEN PRODUCING 1367VERY COLD-TOPPED DEEP CONVECTION BUT THESE THUNDERSTORMS...AND 1368LIKELY THE STRONGEST WINDS...ARE OCCURRING SOME 100 TO 150 MILES 1369NORTHEAST OF THE LOW-LEVEL CENTER. THE CURRENT INTENSITY IS KEPT 1370AT 45 KT...WHICH IS IN AGREEMENT WITH DATA FROM AN ASCAT PASS 1371SEVERAL HOURS AGO. NO CHANGE IS MADE TO THE PREVIOUS INTENSITY 1372FORECAST...HOWEVER THIS FORECAST IS BASED ON THE PREMISE THAT THE 1373VERTICAL SHEAR WILL DECREASE OVER THE NEXT FEW DAYS AND THE GLOBAL 1374MODELS ARE NOT UNANIMOUS ON THIS. THE OFFICIAL WIND SPEED FORECAST 1375IS CLOSEST TO THE MOST RECENT HWRF GUIDANCE...AND IT SHOULD BE 1376NOTED THAT WE HAVE LIMITED SKILL IN PREDICTING TROPICAL CYCLONE 1377INTENSITY CHANGE. 1378 1379WITH INFRARED IMAGERY THE CENTER...ALTHOUGH PARTIALLY EXPOSED...HAS 1380BECOME A LITTLE MORE DIFFICULT TO LOCATE AND THE FIXES FROM TAFB 1381AND SAB ARE ABOUT 50 MILES APART. MY BEST ESTIMATE OF INITIAL 1382MOTION IS SLOWLY NORTHWARD...OR 360/3. THE TRACK FORECAST FOR THIS 1383STORM IS EXTREMELY CHALLENGING. THE SYNOPTIC REASONING IN PREVIOUS 1384ADVISORIES WAS BASED ON A MID-LEVEL RIDGE BUILDING TO THE NORTH OF 1385THE TROPICAL CYCLONE...WHICH WOULD CAUSE DEBBY TO MOVE TOWARD THE 1386NORTHWEST GULF OF MEXICO COAST IN SEVERAL DAYS. THAT TRACK 1387SCENARIO WAS SUPPORTED BY THE ECMWF MODEL...WHICH HAS BEEN THE 1388BEST-PERFORMING GUIDANCE OVER THE PAST FEW YEARS. HOWEVER...THE 13890000 RUN OF THAT MODEL HAS SHIFTED SUBSTANTIALLY TO THE NORTH AND 1390EAST OF THE PREVIOUS RUNS. THE U.K. MET. OFFICE MODEL HAS ALSO 1391SHIFTED SIGNIFICANTLY TO THE RIGHT. IN FACT...ONLY THE HWRF MODEL 1392IS CLOSE TO THE PREVIOUS OFFICIAL FORECASTS...AND EVEN IT IS TO THE 1393NORTH OF THEM. THEREFORE AN UNUSUALLY LARGE RIGHTWARD ADJUSTMENT 1394TO THE NHC FORECAST IS REQUIRED...AND ADDITIONAL SHIFTS TO THE 1395NORTH AND EAST MAY BE NECESSARY IN SUBSEQUENT ADVISORY PACKAGES. 1396 1397NEEDLESS TO SAY...THIS IS A LOW CONFIDENCE FORECAST. 1398 1399FORECAST POSITIONS AND MAX WINDS 1400 1401INIT 24/0900Z 27.3N 87.3W 45 KT 50 MPH 1402 12H 24/1800Z 27.5N 87.4W 50 KT 60 MPH 1403 24H 25/0600Z 27.9N 87.8W 50 KT 60 MPH 1404 36H 25/1800Z 28.2N 88.4W 55 KT 65 MPH 1405 48H 26/0600Z 28.3N 89.0W 60 KT 70 MPH 1406 72H 27/0600Z 28.5N 90.5W 65 KT 75 MPH 1407 96H 28/0600Z 28.5N 92.0W 70 KT 80 MPH 1408120H 29/0600Z 28.5N 93.5W 70 KT 80 MPH 1409 1410$$ 1411FORECASTER PASCH 1412 1413 1414WTNT44 KNHC 241159 1415TCDAT4 1416 1417TROPICAL STORM DEBBY SPECIAL DISCUSSION NUMBER 4 1418NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1419700 AM CDT SUN JUN 24 2012 1420 1421THE PURPOSE OF THIS SPECIAL ADVISORY IS TO ISSUE A TROPICAL STORM 1422WARNING FROM THE MISSISSIPPI ALABAMA BORDER EASTWARD TO THE 1423OCHOLOCKONEE RIVER. THIS IS BASED ON THE EXPANSION OF TROPICAL 1424STORM FORCE WINDS IN THE NORTHEAST QUADRANT. THERE HAVE BEEN NO 1425CHANGES TO THE FORECAST TRACK NOR INTENSITY. 1426 1427 1428FORECAST POSITIONS AND MAX WINDS 1429 1430INIT 24/1200Z 27.5N 87.0W 50 KT 60 MPH 1431 12H 24/1800Z 27.5N 87.4W 50 KT 60 MPH 1432 24H 25/0600Z 27.9N 87.8W 50 KT 60 MPH 1433 36H 25/1800Z 28.2N 88.4W 55 KT 65 MPH 1434 48H 26/0600Z 28.3N 89.0W 60 KT 70 MPH 1435 72H 27/0600Z 28.5N 90.5W 65 KT 75 MPH 1436 96H 28/0600Z 28.5N 92.0W 70 KT 80 MPH 1437120H 29/0600Z 28.5N 93.5W 70 KT 80 MPH 1438 1439$$ 1440FORECASTER AVILA 1441 1442 1443 1444WTNT44 KNHC 241458 1445TCDAT4 1446 1447TROPICAL STORM DEBBY DISCUSSION NUMBER 5 1448NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 14491000 AM CDT SUN JUN 24 2012 1450 1451IT IS A VERY DIFFICULT AND HIGHLY UNCERTAIN FORECAST THIS MORNING. 1452DEBBY HAS BEEN MOVING VERY SLOWLY TOWARD THE NORTHEAST...040 AT 3 1453KNOTS...WHILE THE WIND RADII HAVE BEEN EXPANDING IN THE EASTERN 1454SEMICIRCLE. THIS HAS PROMPTED ADDITIONAL TROPICAL STORM WARNINGS 1455AND WATCHES FOR PORTIONS OF THE FLORIDA COAST. 1456 1457DEBBY CONTINUES TO BE SHEARED WITH MOST OF THE THUNDERSTORM ACTIVITY 1458NORTH AND EAST OF THE CENTER. THIS SHEAR IS EXPECTED TO CONTINUE 1459FOR THE NEXT DAY OR SO...ALTHOUGH SOME DECREASE IN THE SHEAR IS 1460POSSIBLE AFTER THAT...PARTICULARLY IF THE ECMWF VERIFIES. THE 1461OFFICIAL FORECAST IS A LITTLE LESS AGGRESSIVE THAN THE PREVIOUS 1462FORECAST...BUT REMAINS ABOVE MOST OF THE EXPLICIT INTENSITY 1463GUIDANCE. 1464 1465THE TRACK FORECAST IS EVEN MORE COMPLEX. THE GFS INSISTS ON A TRACK 1466TOWARD THE NORTHEAST AS DEBBY BECOMES EMBEDDED WITHIN A LARGE 1467MID-LATITUDE TROUGH. HOWEVER...THE ECMWF AND THE HWRF BUILD A RIDGE 1468TO THE NORTH OF DEBBY AND FORECAST A WESTWARD TRACK. GIVEN THE 1469WESTWARD TURN INHERITED FROM THE PREVIOUS FORECAST...AS WELL AS THE 1470HISTORICAL STRONG RECORD OF THE ECMWF...THE NEW OFFICIAL FORECAST 1471MOVES DEBBY INITIALLY A LITTLE BIT TO THE NORTHEAST TO REFLECT 1472CURRENT TRENDS BUT THEN TURNS THE CYCLONE BACK TOWARD THE WEST OR 1473WEST-NORTHWEST IN 24 TO 36 HOURS. A MAJORITY OF THE GFS ENSEMBLE 1474MEMBERS NOW ARE CONSISTENT WITH THE DETERMINISTIC RUN...WHICH WAS 1475NOT THE CASE YESTERDAY...MAKING A STRONGER CASE FOR THE EASTWARD 1476SOLUTION. WE MUST BE READY TO MAKE A CHANGE OF THE FORECAST TRACK 1477AT ANY TIME. 1478 1479 1480FORECAST POSITIONS AND MAX WINDS 1481 1482INIT 24/1500Z 28.0N 86.2W 50 KT 60 MPH 1483 12H 25/0000Z 28.5N 85.8W 50 KT 60 MPH 1484 24H 25/1200Z 28.5N 85.8W 50 KT 60 MPH 1485 36H 26/0000Z 28.5N 86.2W 55 KT 65 MPH 1486 48H 26/1200Z 28.7N 87.0W 60 KT 70 MPH 1487 72H 27/1200Z 29.0N 88.4W 65 KT 75 MPH 1488 96H 28/1200Z 29.5N 90.5W 45 KT 50 MPH 1489120H 29/1200Z 30.0N 91.5W 30 KT 35 MPH 1490 1491$$ 1492FORECASTER AVILA 1493 1494 1495WTNT44 KNHC 242034 1496TCDAT4 1497 1498TROPICAL STORM DEBBY DISCUSSION NUMBER 6 1499NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1500400 PM CDT SUN JUN 24 2012 1501 1502THERE HAS BEEN A SIGNIFICANT CHANGE IN THE FORECAST TRACK WITH THIS 1503ADVISORY. THE OFFICIAL FORECAST NO LONGER BRINGS DEBBY WESTWARD 1504ALONG THE NORTHERN GULF OF MEXICO AND INSTEAD KEEPS THE CYCLONE 1505MEANDERING OVER THE NORTHEASTERN GULF FOR THE NEXT 3 TO 4 DAYS. 1506THIS FORECAST IS A COMPROMISE BETWEEN THE CONSISTENT EASTWARD 1507SOLUTION PROVIDED BY THE GFS FOR THE PAST SEVERAL DAYS AND THE NEW 1508TWIST OF THE ECMWF. THE ECMWF MODEL...WHICH HAS BEEN 1509FORECASTING DEBBY TO MOVE WESTWARD ALONG THE GULF OF MEXICO... NOW 1510HAS THE CYCLONE MEANDERING FOR THE NEXT 3 DAYS OVER THE 1511NORTHEASTERN GULF. SINCE THESE TWO RELIABLE MODELS ARE IN 1512MARGINALLY BETTER AGREEMENT...I AM A LITTLE MORE CONFIDENT...BUT 1513NOT COMPLETELY...THAT DEBBY IS NOT GOING TO TURN WESTWARD OVER THE 1514GULF. HOWEVER...NEW OFFICIAL TRACK REMAINS A LOW-CONFIDENCE 1515FORECAST. 1516 1517DEBBY IS A SPRAWLING SYSTEM...WITH MOST OF THE THUNDERSTORM ACTIVITY 1518IN A CURVED BAND WELL REMOVED FROM THE CENTER. DATA FROM THE 1519RECONNAISSANCE PLANE A FEW HOURS AGO INDICATE THAT THE INITIAL 1520INTENSITY REMAINS 50 KNOTS. THE SHEAR IS NOT EXPECTED TO CHANGE 1521MUCH FOR THE NEXT DAY OR SO...BUT BECAUSE DEBBY IS FORECAST TO 1522REMAIN OVER WATER...THERE WILL BE SOME OPPORTUNITY FOR A SLIGHT 1523STRENGTHENING BEFORE THE CENTER MOVES INLAND. HOWEVER...THE CYCLONE 1524WILL LOCATED BE NORTH OF THE AREA OF HIGH OCEANIC HEAT CONTENT AND 1525THE UPWELLING COULD HALT THE INTENSIFICATION. 1526 1527 1528FORECAST POSITIONS AND MAX WINDS 1529 1530INIT 24/2100Z 28.4N 85.8W 50 KT 60 MPH 1531 12H 25/0600Z 28.7N 85.5W 50 KT 60 MPH 1532 24H 25/1800Z 29.0N 85.5W 50 KT 60 MPH 1533 36H 26/0600Z 29.0N 85.5W 55 KT 65 MPH 1534 48H 26/1800Z 29.0N 85.5W 60 KT 70 MPH 1535 72H 27/1800Z 29.5N 85.5W 60 KT 70 MPH 1536 96H 28/1800Z 30.0N 85.5W 40 KT 45 MPH 1537120H 29/1800Z 30.5N 85.5W 30 KT 35 MPH...INLAND 1538 1539$$ 1540FORECASTER AVILA 1541 1542 1543WTNT44 KNHC 250258 1544TCDAT4 1545 1546TROPICAL STORM DEBBY DISCUSSION NUMBER 7 1547NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 15481000 PM CDT SUN JUN 24 2012 1549 1550THE APPEARANCE OF DEBBY IN SATELLITE AND RADAR IMAGERY HAS DEGRADED 1551SIGNIFICANTLY THIS EVENING AS A SHARP MID-LEVEL DRY INTRUSION HAS 1552WORKED ITS WAY INTO THE CENTER OF THE CYCLONE AND ERODED ALL OF THE 1553INNER CORE DEEP CONVECTION. THE INITIAL INTENSITY IS BEING HELD AT 155450 KT FOR THIS FORECAST PACKAGE BASED MAINLY ON CONTINUITY WITH THE 1555PREVIOUS ADVISORY AND THE RELATIVELY LOW CENTRAL PRESSURE OF 991 MB 1556REPORTED BY AN AIR FORCE RESERVE RECON AIRCRAFT THIS EVENING. 1557 1558DEBBY HAS BEEN NEARLY STATIONARY SINCE THE LAST ADVISORY. BOTH 18Z 1559AND 00Z UPPER-AIR DATA INDICATE MID-LEVEL RIDGING HAS CONTINUED TO 1560BUILD ACROSS THE SOUTHEASTERN U.S. TO THE NORTH OF DEBBY...AND THIS 1561HAS LIKELY BEEN THE REASON FOR THE LACK OF ANY SIGNIFICANT MOTION 1562OVER THE PAST SEVERAL HOURS. ALL OF THE NHC MODEL GUIDANCE...EXCEPT 1563FOR THE GFS AND GFS-ENSEMBLE MODELS...INDICATE THIS BLOCKING PATTERN 1564ACROSS THE CENTRAL AND EASTERN U.S. SHOULD CONTINUE AS FAST-MOVING 1565SHORTWAVE TROUGHS PASS WELL TO THE NORTH OF DEBBY. THE RESULT 1566SHOULD BE THAT THE CYCLONE WILL MOVE LITTLE DURING THE NEXT COUPLE 1567OF DAYS...AND THEN ONLY DRIFT SLOWLY NORTHWARD AFTER THAT AS THE 1568RIDGE OVER THE SOUTHEASTERN U.S. GRADUALLY BREAKS DOWN. ALTHOUGH THE 1569GFS MODEL HAS BEEN VERY CONSISTENT WITH A FAST NORTHEASTWARD MOTION 1570ACROSS NORTH FLORIDA THE PAST FEW DAYS...THE LARGE SPRAWLING NATURE 1571OF THE CYCLONE AND THE BLOCKING RIDGE TO THE NORTH WOULD SUGGEST 1572THAT THE GFS MODEL MAY BE LIFTING OUT DEBBY TOO QUICKLY. THE 1573OFFICIAL FORECAST TRACK IS SIMILAR TO BUT SLIGHTLY LEFT OF THE 1574PREVIOUS ADVISORY TRACK...MAINLY DUE TO THE MORE WESTWARD INITIAL 1575POSITION. 1576 1577DEBBY HAS FINALLY CONSOLIDATED ALL OF THE MULTIPLE SMALL SWIRLS INTO 1578A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER. THE GLOBAL MODELS ARE 1579FORECASTING THE AFOREMENTIONED DEEP DRY SLOT TO GRADUALLY MOISTEN 1580UP OVER THE NEXT 48 HOURS AS DEEP MOISTURE AND INSTABILITY 1581CURRENTLY OVER THE FLORIDA PENINSULA ADVECTS WESTWARD INTO THE 1582INNER CORE. THE COMBINATION OF THESE TWO FEATURES MAY ALLOW FOR 1583SOME SLIGHT STRENGTHENING BEFORE DEBBY BEGINS TO INTERACT WITH LAND 1584OR COLD UPWELLING BENEATH THE CYCLONE OCCURS. THE OFFICIAL 1585INTENSITY FORECAST IS IDENTICAL TO THE PREVIOUS ADVISORY AND 1586FOLLOWS A BLEND OF THE SHIPS/LGEM STATISTICAL MODELS AND THE 1587HWRF/GFDL REGIONAL MODELS. 1588 1589FORECAST POSITIONS AND MAX WINDS 1590 1591INIT 25/0300Z 28.3N 85.9W 50 KT 60 MPH 1592 12H 25/1200Z 28.6N 85.8W 50 KT 60 MPH 1593 24H 26/0000Z 28.7N 85.8W 50 KT 60 MPH 1594 36H 26/1200Z 28.8N 85.8W 55 KT 65 MPH 1595 48H 27/0000Z 28.9N 85.8W 60 KT 70 MPH 1596 72H 28/0000Z 29.4N 85.8W 55 KT 65 MPH 1597 96H 29/0000Z 29.9N 85.8W 35 KT 40 MPH...NEAR COAST 1598120H 30/0000Z 30.4N 85.6W 30 KT 35 MPH...INLAND 1599 1600$$ 1601FORECASTER STEWART 1602 1603 1604WTNT44 KNHC 250838 1605TCDAT4 1606 1607TROPICAL STORM DEBBY DISCUSSION NUMBER 8 1608NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1609400 AM CDT MON JUN 25 2012 1610 1611DEBBY HAS A HIGHLY UNIMPRESSIVE APPEARANCE ON SATELLITE IMAGERY. 1612ALTHOUGH RADAR DATA CONTINUE TO DEPICT SOME SHOWER ACTIVITY OVER 1613THE CIRCULATION...THESE SHOWERS ARE BEING PRODUCED BY SHALLOW 1614CONVECTION AS THE ENHANCED IR IMAGES DO NOT SHOW ANY SIGNIFICANT 1615AREAS OF COLD CLOUD TOPS. AIRCRAFT DATA FROM SEVERAL HOURS AGO 1616ALONG WITH SYNOPTIC OBSERVATIONS INDICATE THAT THE MAXIMUM SURFACE 1617WINDS HAVE DECREASED...AND THE CURRENT INTENSITY IS SET AT 45 KT. 1618DEBBY IS LOCATED NORTH OF THE AREA OF MAXIMUM OCEANIC HEAT 1619CONTENT...BUT AS LONG AS THE CYCLONE REMAINS OVER WATER AND IS ABLE 1620TO REGENERATE SOME DEEP CONVECTION THERE IS A POTENTIAL FOR AT 1621LEAST SLIGHT RE-INTENSIFICATION. THE CURRENT NHC INTENSITY 1622FORECAST IS A LITTLE LOWER THAN THE PREVIOUS ONES...BUT A LITTLE 1623HIGHER THAN MOST OF THE NUMERICAL GUIDANCE. 1624 1625BEST GUESS AT INITIAL MOTION IS QUASI-STATIONARY. DEBBY REMAINS IN 1626A COL REGION OF THE MID-TROPOSPHERIC STEERING FLOW BETWEEN TWO 1627ANTICYCLONES...AND IS LIKELY TO REMAIN SO FOR THE NEXT COUPLE OF 1628DAYS. THEREFORE LITTLE MOTION IS ANTICIPATED DURING AT LEAST THE 1629FIRST HALF OF THE FORECAST PERIOD. IN THE LONGER-TERM...THE TRACK 1630GUIDANCE CONTINUES TO BE ALL OVER THE PLACE...WITH SOME MODELS 1631TAKING DEBBY WEST AND NORTH OF ITS CURRENT POSITION AND OTHERS 1632MOVING EAST OR NORTHEAST AND ULTIMATELY INTO THE ATLANTIC. THE 1633LATTER SCENARIO ASSUMES THAT DEBBY WILL EVENTUALLY BE INFLUENCED BY 1634A MID-TROPOSPHERIC TROUGH OVER THE NORTHEASTERN UNITED STATES. 1635THIS SCENARIO SEEMS MORE LIKELY SINCE IT IS SUPPORTED BY BOTH THE 1636GFS AND THE ECMWF MODELS. REGARDLESS OF WHICH SCENARIO PLAYS 1637OUT...THE CYCLONE DOES NOT SEEM TO BE GOING ANYWHERE ANYTIME SOON. 1638 1639FORECAST POSITIONS AND MAX WINDS 1640 1641INIT 25/0900Z 28.6N 85.8W 45 KT 50 MPH 1642 12H 25/1800Z 28.8N 85.7W 45 KT 50 MPH 1643 24H 26/0600Z 28.9N 85.6W 50 KT 60 MPH 1644 36H 26/1800Z 29.0N 85.5W 50 KT 60 MPH 1645 48H 27/0600Z 29.2N 85.4W 55 KT 65 MPH 1646 72H 28/0600Z 29.4N 85.3W 55 KT 65 MPH 1647 96H 29/0600Z 29.7N 85.2W 45 KT 50 MPH...INLAND 1648120H 30/0600Z 30.2N 85.0W 30 KT 35 MPH...INLAND 1649 1650$$ 1651FORECASTER PASCH 1652 1653 1654WTNT44 KNHC 251451 1655TCDAT4 1656 1657TROPICAL STORM DEBBY DISCUSSION NUMBER 9 1658NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 16591000 AM CDT MON JUN 25 2012 1660 1661THERE HAS BEEN NO SIGNIFICANT DEEP CONVECTION NEAR THE CENTER OF 1662DEBBY FOR OVER 12 HOURS. WHAT CONVECTION REMAINS IS PRIMARILY 1663LOCATED IN A FRAGMENTED BAND WELL EAST OF THE CENTER...AND 1664SOUNDINGS ALONG THE GULF COAST INDICATE THAT THE ENTRAINMENT OF DRY 1665MID-LEVEL AIR IS AFFECTING THE STORM. IN ADDITION...THE SLOW 1666MOVEMENT OF DEBBY HAS INDUCED OCEANIC UPWELLING AND COOLING 1667UNDERNEATH THE CYCLONE AND MAY HAVE CONTRIBUTED TO THE OBSERVED 1668WEAKENING. LATEST DATA FROM THE RECONNAISSANCE AIRCRAFT INDICATE 1669THAT THE MAXIMUM WINDS ARE NEAR 40 KT. WITH DRY AIR LURKING AND 1670WESTERLY SHEAR ON THE INCREASE OVER THE NEXT COUPLE DAYS... 1671SIGNIFICANT RE-INTENSIFICATION OF THE CYCLONE PRIOR TO LANDFALL 1672SEEMS UNLIKELY. THE NEW NHC FORECAST IS ADJUSTED DOWNWARD IN LINE 1673WITH CURRENT TRENDS AND THE LATEST INTENSITY GUIDANCE. 1674 1675AIRCRAFT AND SATELLITE FIXES HAVE SHOWN LITTLE OVERALL MOVEMENT OVER 1676THE PAST 12 TO 18 HOURS... ALTHOUGH RECENT SATELLITE IMAGERY 1677INDICATES AN EAST-NORTHEASTWARD TO NORTHEASTWARD SHORT-TERM MOTION. 1678AT THE MOMENT...IT IS UNCLEAR WHETHER THE CURRENT MOTION REPRESENTS 1679A MEANDERING OR A MORE DECIDED MOTION. ON THE LARGE SCALE...DEBBY 1680IS TRAPPED IN A REGION OF WEAK STEERING IN BETWEEN A STRONG 1681MID-LEVEL RIDGE OVER THE PLAINS AND ONE OVER THE SUBTROPICAL 1682CENTRAL ATLANTIC. GLOBAL MODELS DEPICT AN AMPLIFYING TROUGH 1683OFFSHORE THE EASTERN SEABOARD CAUSING DEBBY TO MOVE GENERALLY 1684EASTWARD THROUGH THE FORECAST PERIOD...WITH THE CENTER EMERGING 1685OVER THE SOUTHWEST ATLANTIC BY DAY 5. THE ECMWF/GFS SOLUTIONS BEGIN 1686TO LIFT OUT THE WESTERN ATLANTIC TROUGH IN ABOUT 72 HOURS...WHICH 1687COULD LEAVE DEBBY IN WEAK STEERING CURRENT AGAIN AFTER THAT TIME. 1688SINCE YESTERDAY... THE GUIDANCE HAS COME INTO BETTER 1689AGREEMENT...WITH ONLY THE UKMET NOW SHOWING A WESTWARD MOTION. IN 1690ADDITION...THE LATEST GFS ENSEMBLE MEMBERS FAVOR AN EASTWARD MOTION 1691BY ABOUT A 3 TO 1 RATIO. THE NEW FORECAST TRACK REPRESENTS A 1692SUBSTANTIAL CHANGE FROM THE PREVIOUS ONE BUT IS STILL SLOWER THAN 1693THE MULTI-MODEL CONSENSUS IN THE SHORT TERM. 1694 1695 1696FORECAST POSITIONS AND MAX WINDS 1697 1698INIT 25/1500Z 28.6N 85.2W 40 KT 45 MPH 1699 12H 26/0000Z 28.8N 85.1W 35 KT 40 MPH 1700 24H 26/1200Z 28.9N 84.9W 35 KT 40 MPH 1701 36H 27/0000Z 29.0N 84.7W 35 KT 40 MPH 1702 48H 27/1200Z 29.2N 84.4W 35 KT 40 MPH 1703 72H 28/1200Z 29.5N 83.5W 35 KT 40 MPH 1704 96H 29/1200Z 29.5N 82.5W 30 KT 35 MPH...INLAND 1705120H 30/1200Z 29.5N 81.0W 30 KT 35 MPH 1706 1707$$ 1708FORECASTER KIMBERLAIN/FRANKLIN 1709 1710 1711 1712WTNT44 KNHC 252052 1713TCDAT4 1714 1715TROPICAL STORM DEBBY DISCUSSION NUMBER 10 1716NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1717400 PM CDT MON JUN 25 2012 1718 1719SATELLITE IMAGERY INDICATES THAT DEBBY HAS CHANGED LITTLE IN 1720ORGANIZATION TODAY. THE CENTER OF THE CYCLONE IS A LITTLE HARDER TO 1721LOCATE...WITH AT LEAST A COUPLE OF SMALL VORTICES ROTATING AROUND A 1722MEAN CENTER. THERE HAD BEEN VIRTUALLY NO CONVECTION ASSOCIATED WITH 1723THE CENTER OF THE CYCLONE EITHER...BUT A BURST OF DEEP CONVECTION 1724HAS RECENTLY FORMED OVER LAND TO THE NORTH OF THE CENTER. EARLIER 1725AIRCRAFT DATA SHOWED PEAK FLIGHT-LEVEL WINDS OF 57 KT AT 850MB... 1726WITH MAXIMUM SFMR VALUES AROUND 40 KT. GIVEN THESE DATA AND THE 1727LACK OF STRUCTURAL CHANGES TO THE CYCLONE...THE INITIAL INTENSITY 1728REMAINS 40 KT. THE CURRENT STRUCTURE...COMBINED WITH AN INCREASE 1729IN WESTERLY SHEAR AND ADDITIONAL DRY AIR POSSIBLY WRAPPING INTO THE 1730STORM CIRCULATION...WOULD SEEM TO PRECLUDE MUCH SHORT-TERM 1731RE-INTENSIFICATION OF DEBBY...AND THE SHIPS AND LGEM MODELS SHOW NO 1732APPRECIABLE CHANGE IN STRENGTH PRIOR TO LANDFALL. MARGINALLY 1733FAVORABLE ENVIRONMENTAL CONDITIONS COULD PROVIDE AN OPPORTUNITY FOR 1734RE-STRENGTHENING OVER THE WESTERN ATLANTIC AT THE END OF THE 1735FORECAST PERIOD. 1736 1737A SMOOTHING OF RECENT AIRCRAFT AND SATELLITE FIXES YIELDS A SLOW 1738NORTHEASTWARD MOTION OF 040/04. LARGE-SCALE MODELS SHOW DEBBY 1739CONTINUING ON AN EAST-NORTHEASTWARD TO NORTHEASTWARD COURSE OVER 1740THE NEXT FEW DAYS IN RESPONSE TO AN AMPLIFYING TROUGH OFFSHORE OF 1741THE U.S. EAST COAST. AS THE WESTERN ATLANTIC TROUGH BEGINS TO LIFT 1742OUT IN 2-3 DAYS...DEBBY IS EXPECTED TO SLOW DOWN AND BE LEFT BEHIND 1743OVER THE SOUTHWESTERN ATLANTIC. WITH THE EXCEPTION OF THE GFS 1744ENSEMBLE MEMBERS...THE MODEL GUIDANCE IS IN BETTER AGREEMENT 1745OVERALL ON AN EASTWARD TRACK...ALTHOUGH SIGNIFICANT SPEED 1746DIFFERENCES REMAIN. THE GFS IS CONSIDERABLY SLOWER THAN THE MODEL 1747CONSENSUS...AND SHOWS DEBBY TAKING FIVE DAYS TO MOVE OFFSHORE THE 1748FLORIDA ATLANTIC COAST. INTERESTINGLY...THE ECMWF IS NOW ONE OF THE 1749FASTEST MODELS TO THE EAST. THE NHC OFFICIAL TRACK FORECAST IS NOT 1750AS FAST AS THE MULTI-MODEL CONSENSUS IN DEFERENCE TO CONTINUITY AND 1751THE GFS. 1752 1753 1754FORECAST POSITIONS AND MAX WINDS 1755 1756INIT 25/2100Z 29.3N 85.1W 40 KT 45 MPH 1757 12H 26/0600Z 29.4N 84.9W 40 KT 45 MPH 1758 24H 26/1800Z 29.5N 84.7W 40 KT 45 MPH 1759 36H 27/0600Z 29.6N 84.4W 40 KT 45 MPH 1760 48H 27/1800Z 29.7N 83.8W 40 KT 45 MPH 1761 72H 28/1800Z 29.8N 82.5W 30 KT 35 MPH...INLAND 1762 96H 29/1800Z 29.8N 81.0W 30 KT 35 MPH 1763120H 30/1800Z 30.0N 79.0W 35 KT 40 MPH 1764 1765$$ 1766FORECASTER KIMBERLAIN/ 1767 1768 1769WTNT44 KNHC 260300 1770TCDAT4 1771 1772TROPICAL STORM DEBBY DISCUSSION NUMBER 11 1773NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 17741000 PM CDT MON JUN 25 2012 1775 1776AFTER AN INTENSE BURST OF DEEP CONVECTION NEAR AND NORTH OF THE 1777LOW-LEVEL CENTER THIS LATE AFTERNOON AND EVENING...THE CONVECTIVE 1778CLOUD SHIELD IS SHOWING SIGNS OF SLOWLY PULLING AWAY FROM CENTER OF 1779CIRCULATION DUE TO MODERATE TO STRONG SOUTHWESTERLY VERTICAL WIND 1780SHEAR. THE HIGHEST RELIABLE SFMR WINDS REPORTED BY AN AIR FORCE 1781RESERVE RECON AIRCRAFT THIS EVENING HAS BEEN 42 KT TO THE WEST AND 1782WELL SOUTHEAST OF THE CENTER...ALONG WITH 59-KT AND 56-KT 1783FLIGHT-LEVEL WINDS...RESPECTIVELY. ALTHOUGH THE TALLAHASSEE DOPPLER 1784WEATHER RADAR HAS BEEN INDICATING LARGE WINDS OF 60-65 VELOCITIES 1785BETWEEN 2000 AND 6500 FT IN SOME RATHER VIGOROUS CONVECTION...THOSE 1786CONDITIONS HAVE BEEN OVER LAND. THEREFORE...THE INITIAL INTENSITY 1787WILL REMAIN AT 40 KT. 1788 1789THE MOTION ESTIMATE IS A SLOW DRIFT TO THE NORTHEAST OR 040/02 KT 1790OVER THE PAST 12 HOURS. THERE IS NO SIGNIFICANT CHANGE TO THE 1791PREVIOUS TRACK REASONING. UPPER-AIR DATA AT 18Z AND 00Z INDICATE 1792DEBBY REMAINS TRAPPED IN A BLOCKING RIDGE PATTERN THAT EXTENDS 1793ACROSS THE SOUTHEASTERN U.S. AND INTO THE EASTERN GULF OF MEXICO 1794AND WESTERN ATLANTIC. THE RESULTANT WEAK STEERING FLOW SHOULD KEEP 1795DEBBY MOVING VERY SLOWLY NORTHEAST OR EASTWARD AT LESS THAN 5 KT 1796THROUGHOUT THE FORECAST PERIOD. IN FACT...DEBBY WILL LIKELY REMAIN 1797OVER THE NORTHEASTERN GULF OF MEXICO FOR AT LEAST THE NEXT 2 DAYS 1798BEFORE IT CREEPS SLOWLY ACROSS NORTH FLORIDA IN DAYS 3-4. IN THE 1799ABSENCE OF ANY LARGE-SCALE STEERING FLOW...THE LOW-LEVEL CENTER OF 1800DEBBY WILL CLOSELY FOLLOW ANY DEEP CONVECTION THAT DEVELOPS...WHICH 1801SHOULD REMAIN PRIMARILY TO NORTHEAST OF THE CENTER. THE OFFICIAL 1802FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK THROUGH 1803DAY 3...AND IS THEN A LITTLE NORTH OF THE PREVIOUS TRACK AND CLOSE 1804TO THE NHC MODEL CONSENSUS. 1805 1806THE PRESENCE OF DRY MID-LEVEL AIR WRAPPING INTO THE WESTERN AND 1807SOUTHERN PORTION OF THE CIRCULATION...ALONG WITH SOUTHWESTERLY 1808VERTICAL WIND SHEAR OF 20-25 KT FOR THE NEXT 48 HOURS OR SO SHOULD 1809INHIBIT ANY SIGNIFICANT DEVELOPMENT WHILE DEBBY REMAINS OVER WATER. 1810THE SHEAR DECREASES SIGNIFICANTLY BY 72 HOURS AND BEYOND...BUT 1811DEBBY WILL BE OVER OR INTERACTING WITH LAND AT DAYS 3 AND 4...SO 1812THAT WILL PREVENT THE CYCLONE FROM TAKING ADVANTAGE OF THE 1813IMPROVING SHEAR CONDITIONS. BY DAY 5...HOWEVER...DEBBY IS EXPECTED 1814TO BE MOVING OVER THE WARMER WATERS OF THE GULFSTREAM...WHICH MAY 1815ALLOW FOR SOME MODEST STRENGTHENING TO OCCUR AFTER HAVING WEAKENED 1816OVER LAND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE 1817PREVIOUS ADVISORY AND CLOSELY FOLLOWS THE LGEM INTENSITY MODEL. 1818 1819 1820FORECAST POSITIONS AND MAX WINDS 1821 1822INIT 26/0300Z 29.2N 85.1W 40 KT 45 MPH 1823 12H 26/1200Z 29.3N 84.9W 40 KT 45 MPH 1824 24H 27/0000Z 29.4N 84.6W 40 KT 45 MPH 1825 36H 27/1200Z 29.5N 84.2W 40 KT 45 MPH 1826 48H 28/0000Z 29.6N 83.6W 40 KT 45 MPH 1827 72H 29/0000Z 29.8N 82.3W 30 KT 35 MPH...INLAND 1828 96H 30/0000Z 30.1N 80.7W 35 KT 40 MPH...OVER WATER 1829120H 01/0000Z 30.8N 78.7W 40 KT 45 MPH 1830 1831$$ 1832FORECASTER STEWART 1833 1834 1835WTNT44 KNHC 260841 1836TCDAT4 1837 1838TROPICAL STORM DEBBY DISCUSSION NUMBER 12 1839NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1840500 AM EDT TUE JUN 26 2012 1841 1842DEBBY REMAINS A SHEARED TROPICAL STORM WITH MOST OF THE DEEP 1843CONVECTION OVER NORTHERN FLORIDA AND SOUTHEASTERN GEORGIA...I.E. 1844DISPLACED WELL TO THE NORTHEAST OF THE CENTER. IN SPITE OF ITS 1845DISORGANIZED APPEARANCE...OBSERVATIONS FROM A C-MAN STATION NEAR 1846APALACHICOLA AND AN ASCAT OVERPASS INDICATE THAT THE CYCLONE IS 1847MAINTAINING AN INTENSITY OF ABOUT 40 KT. GIVEN THE MARGINAL 1848ATMOSPHERIC AND OCEANIC ENVIRONMENT FOR THE NEXT COUPLE OF 1849DAYS...NO SIGNIFICANT CHANGE IN STRENGTH IS LIKELY UNTIL THE CENTER 1850MOVES OVER LAND. DEBBY IS LIKELY TO WEAKEN IF AND WHEN IT MOVES 1851OVER LAND AND...BASED ON THIS OFFICIAL FORECAST...IT COULD BECOME A 1852DEPRESSION IN A COUPLE OF DAYS. ASSUMING THAT THE CYCLONE WILL 1853EMERGE OVER THE ATLANTIC...SOME RE-INTENSIFICATION IS EXPECTED. 1854THE OFFICIAL INTENSITY FORECAST IN THE 3 TO 5 DAY TIME RANGE IS 1855CLOSE TO THE MODEL CONSENSUS...BUT COULD BE CONSERVATIVE GIVEN THE 1856POTENTIAL INFLUENCE OF THE GULF STREAM. 1857 1858SURFACE SYNOPTIC DATA AND RADAR IMAGERY SUGGEST THAT DEBBY HAS 1859TURNED TOWARD THE EAST OVER THE PAST FEW HOURS. THE INITIAL MOTION 1860ESTIMATE IS 090/3...AS THE STORM IS APPARENTLY BEGINNING TO RESPOND 1861TO A MID-LEVEL TROUGH OVER THE EASTERN UNITED STATES. SOME OF THE 1862DYNAMICAL MODEL GUIDANCE...IN PARTICULAR THE TYPICALLY 1863BEST-PERFORMING GFS AND ECMWF GLOBAL MODELS...ARE NOW TAKING DEBBY 1864SIGNIFICANTLY FASTER TO THE EAST AND NORTHEAST OVER THE FORECAST 1865PERIOD. IT IS WORTH NOTING THAT THE TRACK FORECASTS FROM THESE TWO 1866MODELS HAVE NOW COME INTO RATHER CLOSE AGREEMENT. THE U.K. MET. 1867OFFICE GLOBAL MODEL IS BY THE FAR THE FASTEST AND SHOWS THE CYCLONE 1868NEAR THE CANADIAN MARITIMES IN 4 DAYS OR LESS. WHEREAS THE LATTER 1869SCENARIO SEEMS UNREALISTIC...THE OVERALL CHANGE IN THE GUIDANCE 1870SUPPORTS A FASTER TRACK ACROSS FLORIDA AND INTO THE ATLANTIC THAN 1871THE PREVIOUS NHC PREDICTIONS. THE NEW OFFICIAL FORECAST TRACK LIES 1872BETWEEN THE PREVIOUS NHC TRACK AND THE ECMWF AND GFS SOLUTIONS. 1873 1874FORECAST POSITIONS AND MAX WINDS 1875 1876INIT 26/0900Z 29.0N 84.5W 40 KT 45 MPH 1877 12H 26/1800Z 29.0N 84.2W 40 KT 45 MPH 1878 24H 27/0600Z 29.0N 83.8W 40 KT 45 MPH 1879 36H 27/1800Z 29.1N 83.1W 40 KT 45 MPH 1880 48H 28/0600Z 29.3N 82.2W 30 KT 35 MPH...INLAND 1881 72H 29/0600Z 29.9N 80.4W 35 KT 40 MPH 1882 96H 30/0600Z 30.5N 78.5W 40 KT 45 MPH 1883120H 01/0600Z 31.5N 76.5W 45 KT 50 MPH 1884 1885$$ 1886FORECASTER PASCH 1887 1888 1889WTNT44 KNHC 261452 1890TCDAT4 1891 1892TROPICAL STORM DEBBY DISCUSSION NUMBER 13 1893NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 18941100 AM EDT TUE JUN 26 2012 1895 1896DEEP CONVECTION HAS BECOME SHEARED AWAY FROM THE CENTER OF DEBBY 1897AGAIN...WITH THE NEAREST SHOWER ACTIVITY OVER NORTHERN FLORIDA. AN 1898AMPLIFYING TROUGH OVER THE NORTHEASTERN STATES IS RESPONSIBLE FOR 1899AN INCREASE IN WESTERLY SHEAR TO 20-25 KT...WELL PREDICTED EARLIER 1900BY DYNAMICAL MODELS. THE CLOUD LINES IN THE CYCLONE CORE ARE NOT 1901WELL DEFINED...AND THE CIRCULATION IS BECOMING SLIGHTLY ELONGATED 1902FROM SOUTHWEST TO NORTHEAST. AIRCRAFT DATA SUGGEST THAT DEBBY IS 1903WEAKENING...WITH PEAK FLIGHT-LEVEL WINDS OF 51 KT AT 850MB AND 1904MAXIMUM BIAS-CORRECTED SFMR OBSERVATIONS OF AROUND 30 KT. A 1905DROPSONDE ABOUT 80 NM SOUTHEAST OF THE CENTER REPORTED SURFACE 1906WINDS OF 33 KT. BASED ON THESE DATA...THE INITIAL INTENSITY IS 1907ESTIMATED TO BE 35 KT. DRY AIR CONTINUES TO WRAP AROUND CIRCULATION 1908OF DEBBY...WITH ADDITIONAL DRY AIR FORECAST BY THE MODELS TO ADVECT 1909TOWARD THE STORM IN THE NEXT DAY OR SO. DEBBY IS EXPECTED TO WEAKEN 1910TO A DEPRESSION WHILE THE CENTER MOVES ACROSS FLORIDA...IF NOT 1911BEFORE. LATER IN THE FORECAST PERIOD...A LESSENING OF THE SHEAR AND 1912A NEW SUPPLY OF WARM WATER COULD ALLOW DEBBY TO RESTRENGTHEN. 1913 1914AIRCRAFT FIXES AND RADAR IMAGERY INDICATE THAT DEBBY IS DRIFTING 1915EASTWARD...WITH THE INITIAL MOTION ESTIMATE 090/03. THE 1916LARGE-SCALE MODELS ARE IN GOOD AGREEMENT THAT A LONGWAVE TROUGH 1917DIGGING ALONG 70W WILL HAVE ENOUGH AMPLITUDE TO CARRY DEBBY ACROSS 1918NORTH-CENTRAL FLORIDA DURING THE NEXT 24-48 HOURS. EVEN THOUGH THE 1919WESTERN ATLANTIC TROUGH LIFTS OUT IN ABOUT 2-3 DAYS...AN ABSENCE 1920OF RIDGING ACROSS THIS REGION MAKES DEBBY SUSCEPTIBLE TO THE 1921MID-LATITUDE WESTERLY FLOW...AND THE CYCLONE IS NOW EXPECTED TO 1922CONTINUE MOVING NORTHEASTWARD THROUGH THE FORECAST PERIOD. THE 1923GUIDANCE...INCLUDING THE THE 06Z GFS ENSEMBLE MEMBERS...ARE IN 1924BETTER AGREEMENT ON A FASTER MOTION. THE LATEST OFFICIAL FORECAST 1925IS FASTER THAN THE PREVIOUS ONE BUT STILL SLOWER THAN THE BULK OF 1926THE GUIDANCE. 1927 1928 1929FORECAST POSITIONS AND MAX WINDS 1930 1931INIT 26/1500Z 28.9N 84.2W 35 KT 40 MPH 1932 12H 27/0000Z 28.9N 83.9W 35 KT 40 MPH 1933 24H 27/1200Z 29.1N 82.9W 35 KT 40 MPH 1934 36H 28/0000Z 29.3N 81.7W 30 KT 35 MPH...INLAND 1935 48H 28/1200Z 29.6N 80.0W 30 KT 35 MPH 1936 72H 29/1200Z 30.3N 77.5W 35 KT 40 MPH 1937 96H 30/1200Z 31.5N 74.5W 40 KT 45 MPH 1938120H 01/1200Z 33.5N 72.0W 45 KT 50 MPH 1939 1940$$ 1941FORECASTER KIMBERLAIN/FRANKLIN 1942 1943 1944WTNT44 KNHC 262059 1945TCDAT4 1946 1947TROPICAL STORM DEBBY DISCUSSION NUMBER 14 1948NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1949500 PM EDT TUE JUN 26 2012 1950 1951AN AIR FORCE MISSION THAT ENDED EARLY THIS AFTERNOON MEASURED 1952BIAS-CORRECTED SFMR WINDS JUST BELOW TROPICAL STORM STRENGTH. BASED 1953ON THOSE DATA...IT IS ASSUMED THAT THERE ARE STILL A FEW SPOTS OF 1954TROPICAL-STORM-FORCE WINDS REMAINING IN BANDS TO THE SOUTHEAST OF 1955THE CENTER. IN THE FACE OF STRONG WESTERLY VERTICAL WIND 1956SHEAR...DEBBY IS GENERATING ONLY LIMITED DEEP CONVECTION TO THE 1957NORTHEAST OF THE CENTER OVER NORTHERN FLORIDA...AND HAS LESS THAN A 1958FULLY TROPICAL APPEARANCE. THE CYCLONE IS ALSO BEING OVERTAKEN BY A 1959LARGE REGION OF DRY AIR OVER THE SOUTHERN UNITED STATES AND GULF OF 1960MEXICO. THE PASSAGE OF DEBBY OVER LAND...IN ADDITION TO THE 1961NEGATIVE FACTORS CITED ABOVE...WILL LIKELY CAUSE DEBBY TO WEAKEN TO 1962A DEPRESSION WITHIN 12 HOURS. AFTER THE CENTER EMERGES OVER THE 1963WESTERN ATLANTIC...SUBSTANTIALLY LOWER SHEAR AND WARMER WATERS 1964FAVOR SOME RE-INTENSIFICATION OF THE CYCLONE LATER IN THE FORECAST 1965PERIOD. THE NEW NHC FORECAST IS CLOSE TO THE SHIPS/LGEM GUIDANCE 1966AND IS BASICALLY AN UPDATE OF THE PREVIOUS ONE. 1967 1968AS ADVERTISED BY DYNAMICAL MODELS...DEBBY IS MOVING FASTER TOWARD 1969THE EAST-NORTHEAST AND THE INITIAL MOTION ESTIMATE IS 070/05. THE 1970INCREASE IN FORWARD SPEED IS RELATED TO AN INCREASING WESTERLY MID- 1971TO UPPER-TROPOSPHERIC FLOW ASSOCIATED WITH AN UNUSUALLY DEEP 1972LONGWAVE TROUGH DIGGING OFFSHORE THE ATLANTIC SEABOARD. THE GFS 1973BRIEFLY SLOWS THE CYCLONE MOTION IN THE FIRST 12-24 HOURS OF THE 1974FORECAST...AND PERHAPS AS A RESULT THE WESTERN ATLANTIC TROUGH 1975FAILS TO CAPTURE DEBBY AS STRONGLY AS SHOWN BY THE ECMWF AND UKMET. 1976THE NEW NHC FORECAST IS FASTER THAN THE PREVIOUS ONE BUT IS NOT AS 1977QUICK AS THE ECMWF/UKMET/MULTI-MODEL CONSENSUS...BOTH BECAUSE OF 1978CONTINUITY AND RESPECT FOR THE GFS. 1979 1980FORECAST POSITIONS AND MAX WINDS 1981 1982INIT 26/2100Z 29.5N 83.4W 35 KT 40 MPH...ON THE COAST 1983 12H 27/0600Z 29.5N 82.5W 30 KT 35 MPH...INLAND 1984 24H 27/1800Z 29.7N 81.4W 30 KT 35 MPH...INLAND 1985 36H 28/0600Z 30.0N 79.7W 30 KT 35 MPH...OVER WATER 1986 48H 28/1800Z 30.3N 77.7W 35 KT 40 MPH 1987 72H 29/1800Z 31.4N 74.1W 35 KT 40 MPH 1988 96H 30/1800Z 33.5N 71.0W 40 KT 45 MPH 1989120H 01/1800Z 36.6N 66.0W 45 KT 50 MPH 1990 1991$$ 1992FORECASTER KIMBERLAIN/FRANKLIN 1993 1994 1995WTNT44 KNHC 270301 1996TCDAT4 1997 1998TROPICAL DEPRESSION DEBBY DISCUSSION NUMBER 15 1999NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 20001100 PM EDT TUE JUN 26 2012 2001 2002THE CENTER OF DEBBY MADE LANDFALL IN THE FLORIDA BIG BEND 2003REGION AT AROUND 2100 UTC. SINCE THAT TIME...THE CENTER HAS TURNED 2004SOUTHEASTWARD...POSSIBLY DUE TO INTERACTION WITH A GUST FRONT FROM 2005THE MOST RECENT CONVECTIVE BURST AND A MESOSCALE VORTICITY CENTER 2006OVER NORTHEASTERN FLORIDA. THE CIRCULATION HAS ALSO BECOME 2007ELONGATED WITH THE CENTRAL PRESSURE RISING TO AROUND 1000 MB. THE 2008INITIAL INTENSITY OF 30 KT IS BASED ON COASTAL OBSERVATIONS AND THE 2009CHANCE THAT SOME STRONGER WINDS MAY EXIST OVER THE WATER. 2010 2011THE INITIAL MOTION IS 125/6. A DEEP-LAYER TROUGH IS NORTH AND 2012NORTHEAST OF DEBBY...AND AN ASSOCIATED SURFACE FRONTAL ZONE EXTENDS 2013FROM SOUTHERN GEORGIA EAST-NORTHEASTWARD INTO THE ATLANTIC. WHILE 2014THE LARGE-SCALE MODELS FORECAST THESE FEATURES TO WEAKEN DURING THE 2015NEXT 72 HR...THEY AGREE THAT THERE WILL BE ENOUGH WESTERLY STEERING 2016FLOW TO ALLOW THE CENTER TO CROSS FLORIDA AND REACH THE ATLANTIC 2017DURING THE NEXT 24 HR OR SO. THE MODELS DIVERGE AFTER THAT. THE 2018NOGAPS AND CANADIAN MODELS SHOW THE CENTER STALLING OFF THE U. S. 2019COAST...WHILE THE GFS...UKMET...ECMWF...GFDL...AND HWRF MOVE IT 2020EAST-NORTHEASTWARD INTO THE ATLANTIC AT VARYING SPEEDS. THE 2021FORECAST TRACK GOES WITH THE LATTER SCENARIO. THE NEW FORECAST IS 2022ADJUSTED SOUTH OF THE PREVIOUS TRACK BASED ON THE INITIAL POSITION 2023AND MOTION...AND IS A BIT FASTER. IT SHOULD BE NOTED THAT 2024ADDITIONAL ADJUSTMENTS TO THE TRACK FORECAST MAY BE NECESSARY IF 2025THE CENTER RE-FORMS WHILE CROSSING FLORIDA. 2026 2027DEBBY IS CURRENTLY EXPERIENCING MODERATE VERTICAL WIND SHEAR...DRY 2028AIR ENTRAINMENT...AND LAND INTERACTION. THIS COMBINATION SHOULD 2029PERSIST UNTIL THE CENTER REACHES THE ATLANTIC. IN 36-48 HR...THE 2030GFS...UKMET...AND ECMWF FORECAST AN UPPER-LEVEL TROUGH TO INTERACT 2031WITH THE CYCLONE...WHICH COULD REDUCE THE SHEAR AND PROVIDE 2032FAVORABLE UPPER-LEVEL DIVERGENCE. HOWEVER...DEEP-LAYER DRY AIR 2033SHOULD STILL BE NEAR DEBBY AT THAT TIME...WHICH COULD PREVENT THE 2034MORE FAVORABLE DYNAMICS FROM STRENGTHENING THE SYSTEM. THUS...THE 2035NEW INTENSITY FORECAST IS ALMOST IDENTICAL TO THE PREVIOUS 2036FORECAST. 2037 2038 2039FORECAST POSITIONS AND MAX WINDS 2040 2041INIT 27/0300Z 29.0N 82.8W 30 KT 35 MPH 2042 12H 27/1200Z 29.3N 81.7W 30 KT 35 MPH...INLAND 2043 24H 28/0000Z 29.7N 80.0W 30 KT 35 MPH...OVER WATER 2044 36H 28/1200Z 30.3N 77.8W 30 KT 35 MPH 2045 48H 29/0000Z 30.7N 75.6W 35 KT 40 MPH 2046 72H 30/0000Z 32.0N 72.5W 40 KT 45 MPH 2047 96H 01/0000Z 35.0N 69.0W 45 KT 50 MPH 2048120H 02/0000Z 39.0N 62.0W 45 KT 50 MPH 2049 2050$$ 2051FORECASTER BEVEN 2052 2053 2054WTNT44 KNHC 270832 2055TCDAT4 2056 2057TROPICAL DEPRESSION DEBBY DISCUSSION NUMBER 16 2058NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 2059500 AM EDT WED JUN 27 2012 2060 2061SATELLITE...RADAR AND SURFACE OBSERVATIONS INDICATE THAT THE 2062CIRCULATION OF DEBBY IS INCREASINGLY BECOMING ELONGATED. THE CENTER 2063IS DIFFICULT TO LOCATE GIVEN THE LACK OF ORGANIZATION...BUT THE AREA 2064OF MINIMUM PRESSURE HAS BEEN MOVING EAST-NORTHEASTWARD OR 075 2065DEGREES AT 9 KNOTS ACROSS NORTH-CENTRAL FLORIDA. MOST OF THE DEEP 2066CONVECTION IS IN A FRONTAL-TYPE BAND EXTENDING NORTHEASTWARD FROM 2067FLORIDA ACROSS THE ADJACENT ATLANTIC. THE MAXIMUM WINDS ARE STILL 2068PROBABLY 30 KNOTS IN A FEW SQUALLS MAINLY OVER WATER. 2069 2070NONE OF THE INTENSITY GUIDANCE SHOW A SIGNIFICANT INCREASE IN 2071STRENGTH...AND IN FACT...BOTH THE GFS AND THE ECMWF SUGGEST 2072WEAKENING IN THE 00 UTC RUN. THE OFFICIAL FORECAST KEEPS DEBBY AS A 2073TROPICAL DEPRESSION AND ALLOWS SOME SLIGHT STRENGTHENING BEYOND 3 2074DAYS. 2075 2076DEBBY IS EMBEDDED IN WESTERLY FLOW WITHIN THE BASE OF A MID-LATITUDE 2077TROUGH...AND IT SHOULD CONTINUE TO MOVE TOWARD THE EAST-NORTHEAST OR 2078NORTHEAST AS INDICATED BY GLOBAL MODELS. THE OFFICIAL FORECAST IS 2079IN BETWEEN THE GFS AND ECMWF MODELS. 2080 2081 2082FORECAST POSITIONS AND MAX WINDS 2083 2084INIT 27/0900Z 29.6N 81.0W 30 KT 35 MPH...OVER WATER 2085 12H 27/1800Z 30.0N 79.4W 30 KT 35 MPH 2086 24H 28/0600Z 30.5N 76.5W 30 KT 35 MPH 2087 36H 28/1800Z 31.0N 73.0W 30 KT 35 MPH 2088 48H 29/0600Z 32.0N 70.5W 30 KT 35 MPH 2089 72H 30/0600Z 35.0N 66.5W 35 KT 40 MPH 2090 96H 01/0600Z 38.0N 62.0W 40 KT 45 MPH 2091120H 02/0600Z 45.5N 50.0W 40 KT 45 MPH 2092 2093$$ 2094FORECASTER AVILA 2095 2096 2097WTNT44 KNHC 271438 2098TCDAT4 2099 2100TROPICAL DEPRESSION DEBBY DISCUSSION NUMBER 17 2101NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 21021100 AM EDT WED JUN 27 2012 2103 2104DEBBY IS STRUGGLING TO SURVIVE AS A TROPICAL CYCLONE. OCCASIONAL 2105BURSTS OF CONVECTION CONTINUE TO FORM NEAR THE CENTER...BUT ARE 2106IMMEDIATELY BEING PUSHED TO THE EAST BY STRONG WESTERLY SHEAR. IN 2107FACT...AT 12Z...THE CONVECTION WAS TOO DISORGANIZED TO WARRANT A 2108DVORAK CLASSIFICATION. THE LOW-LEVEL CENTER HAS BECOME INCREASINGLY 2109DISTORTED...WITH AN ELONGATED NORTHEAST-TO-SOUTHWEST APPEARANCE. A 2110LOW-LEVEL BAROCLINIC ZONE IS ALSO IMPINGING ON THE CYCLONE BUT HAS 2111NOT YET BECOME INVOLVED WITH THE CIRCULATION CENTER. BUOY REPORTS 2112NEAR THE CENTER SHOW 1-MINUTE WINDS OF AROUND 25 KT. IT IS ASSUMED 2113THAT STRONGER WINDS ARE OCCURING IN THE CONVECTION TO THE EAST...SO 2114THE INITIAL INTENSITY IS KEPT AT 30 KT. 2115 2116SATELLITE...RADAR...AND SYNOPTIC DATA INDICATE THAT THE CENTER OF 2117DEBBY MOVED INTO THE WESTERN ATLANTIC AROUND 8Z. USING THESE DATA 2118SOURCES...THE INITIAL MOTION ESTIMATE IS 085/09. ALTHOUGH A DEEP 2119TROUGH OVER THE WESTERN ATLANTIC WILL BE IN THE PROCESS OF LIFTING 2120OUT OVER THE NEXT COUPLE OF DAYS...GLOBAL MODELS SHOW IT HAVING 2121SUFFICIENT AMPLITUDE TO DRAW DEBBY EAST-NORTHEASTWARD. HAVING 2122GAINED ENOUGH LATITUDE...STRONGER MID-LATITUDE WESTERLY FLOW SHOULD 2123THEN CAUSE DEBBY TO ACCELERATE NORTHEASTWARD FOR THE REMAINDER OF 2124THE FORECAST PERIOD. THE ECMWF/GFS/UKMET ARE IN GOOD AGREEMENT ON 2125THIS SCENARIO...BUT THE REGIONAL DYNAMICAL MODELS SHOW DEBBY BEING 2126LEFT BEHIND BY THE WESTERN ATLANTIC TROUGH. ASSUMING THAT DEBBY 2127REMAINS A DISTINCT ENTITY...THE FORMER CAMP OF MODELS FAVORS THIS 2128SCENARIO AND SO DOES THIS OFFICIAL FORECAST. 2129 2130ALTHOUGH THERE SHOULD BE A RELATIVE DECREASE IN THE SHEAR OVER THE 2131CYCLONE AFTER 24 HOURS...DEBBY WILL REMAIN SURROUNDED BY A LARGE 2132POOL OF VERY DRY AND STABLE AIR OVER THE WESTERN ATLANTIC EVEN 2133AFTER THE FRONTAL BOUNDARY RETREATS. THESE FACTORS SHOULD TEMPER 2134ANY SIGNIFICANT RE-INTENSIFICATION. THE SHIPS/LGEM GENERALLY AGREE 2135WITH THIS IDEA...NO LONGER SHOWING MUCH STRENGTHENING. IT SHOULD BE 2136NOTED THAT THE GFS SHOWS DEBBY LOSING ORGANIZATION DURING THE NEXT 213748 HOURS AND BECOMING AN OPEN WAVE OVER THE CENTRAL ATLANTIC. IN 2138THE FACE OF THESE NEGATIVE ENVIRONMENTAL FACTORS...THERE IS A 2139POSSIBILITY THAT DEBBY WILL DISSIPATE SOON. 2140 2141 2142FORECAST POSITIONS AND MAX WINDS 2143 2144INIT 27/1500Z 29.7N 79.8W 30 KT 35 MPH 2145 12H 28/0000Z 30.1N 77.5W 30 KT 35 MPH 2146 24H 28/1200Z 30.5N 74.8W 30 KT 35 MPH 2147 36H 29/0000Z 31.3N 71.8W 30 KT 35 MPH 2148 48H 29/1200Z 32.3N 69.5W 30 KT 35 MPH 2149 72H 30/1200Z 35.5N 65.3W 30 KT 35 MPH 2150 96H 01/1200Z 40.0N 60.0W 35 KT 40 MPH 2151120H 02/1200Z 46.0N 48.0W 35 KT 40 MPH 2152 2153$$ 2154FORECASTER KIMBERLAIN 2155 2156 2157