1WTNT45 KNHC 232051 2TCDAT5 3TROPICAL STORM MATTHEW DISCUSSION NUMBER 2 4NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 5500 PM EDT THU SEP 23 2010 6 7AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING THE 8CYCLONE FOUND 42-KT FLIGHT-LEVEL WINDS AT ABOUT 1500 FT IN THE 9NORTHEAST QUADRANT ON ITS OUTBOUND LEG. THAT WIND SPEED WOULD 10NORMALLY EQUATE TO ABOUT 34 KT AT THE SURFACE. ALSO...THERE WERE 11SEVERAL BELIEVABLE SFMR SURFACE WINDS OF 35-37 KT IN THAT AREA. 12SINCE THOSE WIND REPORTS...CONVECTIVE BANDING HAS CONTINUED TO 13INCREASE AND BECOME BETTER ORGANIZED..AND THE DEPRESSION HAS BEEN 14UPGRADED TO TROPICAL STORM MATTHEW. 15 16THE INITIAL MOTION ESTIMATE IS 280/14. TROPICAL STORM MATTHEW IS 17EXPECTED TO MOVE WEST TO WEST-NORTHWESTWARD FOR THE NEXT 48 HOURS 18OR SO...AND PASS OVER OR NEAR THE NORTHERN COASTS OF NICARAGUA AND 19HONDURAS IN 36-48 HOURS. AFTER THAT...THE GLOBAL MODELS DIFFER ON 20THE TIMING OF THE WEAKENING OF THE SUBTROPICAL RIDGE OVER THE 21NORTHWESTERN CARIBBEAN SEA AND THE GULF OF MEXICO. A STRONG 22MID-LATITUDE TROUGH CURRENTLY OFF THE U.S. WEST COAST IS FORECAST 23TO MOVE QUICKLY EASTWARD INTO THE CENTRAL U.S. BY DAY 3...THE 24TROUGH IS FORECAST TO DIG SOUTHEASTWARD AND AMPLIFY INTO A LOW 25PRESSURE SYSTEM OVER THE SOUTHEASTERN U.S. AND THE GULF OF MEXICO. 26EROSION OF THE SUBTROPICAL RIDGE TO THE NORTH OF MATTHEW IS 27EXPECTED TO CAUSE THE STEERING CURRENTS TO COLLAPSE ACROSS THE 28NORTHWESTERN CARIBBEAN SEA AND THE YUCATAN PENINSULA. ALL OF THE 29NHC MODELS ARE CONSISTENT ON THE EVOLUTION OF THIS SYNOPTIC 30SCALE PATTERN...EXCEPT FOR THE TIMING. THE GFS...ECMWF...NOGAPS... 31HWRF...AND GFDL MODELS KEEP THE LOW WEST OF 85W LONGITUDE BY 120 32HOURS...WHEREAS THE UKMET IS MUCH MORE PROGRESSIVE AND MOVES THE 33LARGE TROUGH EAST OF 80W. GIVEN THE USUAL SLOW MOVEMENT OF SUCH 34A HIGH AMPLITUDE TROUGH...THE UKMET IS CONSIDERED AN OUTLIER MODEL 35AT THIS TIME. AS A RESULT...THE OFFICIAL FORECAST TRACK IS A BLEND 36OF THE GLOBAL AND REGIONAL MODELS...EXCLUDING THE UKMET SOLUTION... 37AND IS JUST AN UPDATE OF THE PREVIOUS FORECAST TRACK. 38 39STEADY INTENSIFICATION IS EXPECTED THROUGH 72 HOURS SINCE MATTHEW 40WILL BE MOVING OVER 30C SSTS AND BENEATH A REGION OF UPPER-LEVEL 41ANTICYCLONIC FLOW. MATTHEW IS EXPECTED TO MOVE OVER OR NEAR THE 42NORTH COAST OF HONDURAS IN 36-48 HOURS...AND MOVE INLAND NEAR 43BELIZE BY DAY 4. LAND INTERACTION WOULD DISRUPT THE INTENSIFICATION 44PROCESS DESPITE THE OTHERWISE FAVORABLE ENVIRONMENTAL CONDITIONS. 45HOWEVER...IF THE CYCLONE REMAINS OVER WATER...THEN MATTHEW COULD 46EASILY REACH HURRICANE STRENGTH DURING THE NEXT 48 HOURS AND 47BEYOND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS 48ADVISORY AND THE SHIPS/LGEM MODELS...AND IS BASED ON THE ASSUMPTION 49THAT MATTHEW WILL MOVE INLAND AFTER 72 HOURS. 50 51 52FORECAST POSITIONS AND MAX WINDS 53 54INITIAL 23/2100Z 14.0N 76.9W 35 KT 55 12HR VT 24/0600Z 14.4N 78.9W 40 KT 56 24HR VT 24/1800Z 15.1N 81.7W 50 KT 57 36HR VT 25/0600Z 15.6N 84.0W 60 KT...INLAND 58 48HR VT 25/1800Z 16.2N 85.8W 60 KT...OVER WATER 59 72HR VT 26/1800Z 17.1N 88.0W 70 KT 60 96HR VT 27/1800Z 18.3N 88.4W 70 KT...INLAND 61120HR VT 28/1800Z 19.5N 87.5W 70 KT...INLAND 62 63$$ 64FORECASTER STEWART 65 66 67 68WTNT45 KNHC 240258 69TCDAT5 70TROPICAL STORM MATTHEW DISCUSSION NUMBER 3 71NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 721100 PM EDT THU SEP 23 2010 73 74THE OVERALL ORGANIZATION OF MATTHEW HAS CONTINUED TO GRADUALLY 75IMPROVE THIS EVENING. A BURST OF DEEP CONVECTION HAS RECENTLY 76DEVELOPED OVER THE CENTER AND SEVERAL BROKEN BANDS OF THUNDERSTORMS 77ARE SEEN AROUND THE PERIPHERY OF THE CIRCULATION. THE LATEST 78SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 AND 35 79KT...RESPECTIVELY. BASED ON THESE ESTIMATES THE INITIAL INTENSITY 80IS SET AT 40 KT. 81 82THE INITIAL MOTION ESTIMATE IS 275/15. FOR THE NEXT 36-48 HOURS... 83MATTHEW IS EXPECTED TO CONTINUE IN A WEST TO WEST-NORTHWEST 84DIRECTION TO THE SOUTH OF A SUBTROPICAL RIDGE THAT EXTENDS FROM THE 85ATLANTIC WESTWARD INTO THE SOUTHEASTERN UNITED STATES. THE TRACK 86GUIDANCE IS IN GOOD AGREEMENT DURING THAT TIME AND THERE IS FAIRLY 87HIGH CONFIDENCE IN THAT PART OF THE FORECAST. IN 2-3 DAYS... 88THE WESTERN PORTION OF THE RIDGE IS EXPECTED TO WEAKEN AS A STRONG 89MID-LATITUDE TROUGH MOVES INTO THE CENTRAL UNITED STATES. THIS 90SHOULD RESULT IN A WEAKENING OF THE STEERING CURRENTS AND A 91DECELERATION OF THE CYCLONE. THEREAFTER...THE MODEL SOLUTIONS 92DIVERGE SIGNIFICANTLY...WITH SEVERAL OF THEM SHOWING RATHER 93COMPLEX SCENARIOS. THE GFS...UKMET...AND ECMWF ALL MOVE MATTHEW 94WELL INLAND OVER THE SOUTHERN PORTION OF THE YUCATAN PENINSULA IN 952-3 DAYS. AFTER THAT TIME...THE GFS AND ECMWF ACTUALLY WEAKEN 96MATTHEW...THEN DEVELOP A SECOND CYCLONE OVER THE NORTHWEST 97CARIBBEAN SEA. ON THE OTHER HAND...THE NOGAPS...GFDL....AND HWRF 98KEEP MATTHEW AS THE PRIMARY SYSTEM AND SHOW IT TURNING NORTHWARD 99ALONG THE CARIBBEAN COAST OF THE YUCATAN PENINSULA AT DAYS 4 AND 5. 100NEEDLESS TO SAY...THERE IS A MUCH HIGHER DEGREE OF UNCERTAINTY IN 101THE 4 AND 5 DAY FORECASTS THAN NORMAL. FOR NOW THE OFFICIAL 102FORECAST HAS BEEN ADJUSTED CLOSER TO THE MULTI-MODEL 103CONSENSUS...TVCN...AND IS WEST OF THE PREVIOUS FORECAST BEYOND 72 104HOURS. 105 106MATTHEW WILL BE IN AN ENVIRONMENT OF LIGHT TO MODERATE EASTERLY 107SHEAR OVER WARM WATER DURING THE NEXT DAY OR SO. THEREFORE... 108STEADY STRENGTHENING IS PREDICTED AND THE OFFICIAL FORECAST IS 109CLOSE TO THE SHIPS/LGEM GUIDANCE DURING THAT TIME. AFTER 24 110HOURS...THE INTENSITY FORECAST IS HIGHLY DEPENDENT ON LAND 111INTERACTION. THE NEW OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS 112ADVISORY THROUGH 48 HOURS...ASSUMING THE CENTER STAYS OFFSHORE OF 113HONDURAS. THEREAFTER...THE INTENSITY FORECAST HAS BEEN ADJUSTED 114DOWNWARD SINCE THE NEW TRACK FORECAST SHOWS MATTHEW OVER THE 115YUCATAN PENINSULA AT 72-120 HOURS. 116 117BASED ON THE NEW TRACK AND INTENSITY FORECAST...SOME CHANGES WERE 118REQUIRED TO THE WATCHES AND WARNINGS. 119 120 121FORECAST POSITIONS AND MAX WINDS 122 123INITIAL 24/0300Z 14.0N 78.4W 40 KT 124 12HR VT 24/1200Z 14.5N 80.5W 50 KT 125 24HR VT 25/0000Z 15.1N 82.9W 65 KT 126 36HR VT 25/1200Z 15.9N 85.1W 60 KT...INLAND 127 48HR VT 26/0000Z 16.6N 87.1W 65 KT...OVER WATER 128 72HR VT 27/0000Z 17.9N 89.2W 50 KT...INLAND 129 96HR VT 28/0000Z 18.5N 89.5W 40 KT...INLAND 130120HR VT 29/0000Z 19.0N 89.5W 35 KT...INLAND 131 132$$ 133FORECASTER BROWN 134 135 136 137WTNT45 KNHC 241457 138TCDAT5 139TROPICAL STORM MATTHEW DISCUSSION NUMBER 5 140NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 1411100 AM EDT FRI SEP 24 2010 142 143AN AIR FORCE PLANE INVESTIGATING MATTHEW THIS MORNING FOUND THAT THE 144TROPICAL CYCLONE HAS NOT BECOME ANY STRONGER. EASTERLY SHEAR HAS 145KEPT THE LOW-LEVEL CENTER NEAR THE NORTHEAST EDGE OF A ROUND BLOB 146OF VERY DEEP CONVECTION AS INDICATED BY THE AIR FORCE PLANE AND 147MICROWAVE DATA. SATELLITE INTENSITY ESTIMATES SUPPORT AN INITIAL 148INTENSITY OF 45 KNOTS...BUT DATA FROM THE RECONNAISSANCE PLANE SO 149FAR SUGGEST THAT THIS ESTIMATE COULD BE GENEROUS. MATTHEW ONLY HAS 15012 HOURS OR LESS TO STRENGTHEN BEFORE LANDFALL...AND GIVEN THAT THE 151ENVIRONMENT IS ONLY MARGINALLY FAVORABLE FOR INTENSIFICATION DUE TO 152SHEAR...THE OFFICIAL FORECAST NO LONGER FORECAST MATTHEW TO BECOME 153A HURRICANE. 154 155THE CYCLONE HAS INCREASED ITS FORWARD SPEED AND THE BEST ESTIMATE OF 156THE INITIAL MOTION IS TOWARD THE WEST OR 275 DEGREES AT 17 KNOTS. 157MATTHEW IS EMBEDDED WITHIN A STRONG DEEP EASTERLY FLOW AND THERE IS 158HIGH CONFIDENCE IN THE FORECAST THAT THE CYCLONE WILL CONTINUE 159WESTWARD OVER CENTRAL AMERICA FOR THE NEXT DAY OR TWO. BEYOND TWO 160DAYS...MODELS SHOW DIFFERENT SCENARIOS AND THE FORECAST BECOMES 161HIGHLY UNCERTAIN. THE MOST LIKELY SCENARIO IS THAT THE MID-LEVEL 162CENTER CONTINUES WESTWARD AND DISSIPATES...WHILE THE LOW-LEVEL 163CIRCULATION WEAKENS AND BECOMES PART OF A NEARLY STATIONARY BROAD 164AREA OF LOW PRESSURE OVER CENTRAL AMERICA. SUCH A WEATHER PATTERN 165WOULD LIKELY PRODUCE DANGEROUS TORRENTIAL RAINS IN CENTRAL AMERICA 166OVER THE NEXT FEW DAYS. 167 168 169FORECAST POSITIONS AND MAX WINDS 170 171INITIAL 24/1500Z 14.4N 82.2W 45 KT 172 12HR VT 25/0000Z 14.6N 84.2W 35 KT...INLAND 173 24HR VT 25/1200Z 15.4N 86.5W 30 KT...INLAND 174 36HR VT 26/0000Z 16.0N 89.0W 30 KT...INLAND 175 48HR VT 26/1200Z 17.0N 90.0W 25 KT...INLAND 176 72HR VT 27/1200Z 18.0N 90.5W 20 KT...POST-TROP/REMNT LOW 177 96HR VT 28/1200Z 18.5N 90.5W 20 KT...POST-TROP/REMNT LOW 178120HR VT 29/1200Z 18.5N 90.5W 20 KT...POST-TROP/REMNT LOW 179 180$$ 181FORECASTER AVILA 182 183 184 185WTNT45 KNHC 242036 186TCDAT5 187TROPICAL STORM MATTHEW DISCUSSION NUMBER 6 188NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 189500 PM EDT FRI SEP 24 2010 190 191THE LATEST AIR FORCE RECONNAISSANCE PLANE IN THE AREA FIXED THE 192CENTER OF MATTHEW AT 1717 UTC ABOUT 30 NMI EAST OF THE NORTHEAST 193COAST OF NICARAGUA WITH A MINIMUM PRESSURE OF 998 MB AND WINDS 194SUPPORTING AN INTENSITY OF 45 KNOTS. SINCE THEN...MATTHEW MOVED 195WESTWARD AND THE CENTER CROSSED THE COAST OF NORTHEASTERN NICARAGUA 196AND IS NOW LOCATED INLAND SOUTH OF PUERTO LEMPIRA HONDURAS. THE 197CLOUD PATTERN IS STILL WELL ORGANIZED WITH NUMEROUS CYCLONICALLY 198CURVED RAINBANDS TO THE NORTH AND VERY DEEP CONVECTION NEAR THE 199CENTER. SINCE THE CENTER IS ALREADY OVER LAND...GRADUAL WEAKENING 200SHOULD BEGIN. 201 202AS THE CENTER OF THE CYCLONE MOVES WESTWARD OVER HONDURAS DURING THE 203NEXT 12 TO 24 HOURS...A LARGE PORTION OF THE CIRCULATION WILL BE 204OVER THE GULF OF HONDURAS...AND TROPICAL STORM FORCE WINDS THERE 205WILL BE SLOW TO SUBSIDE. THE WIND RADII HAVE BEEN EXPANDED IN THE 206NORTHERN SEMICIRCLE BASED ON AIRCRAFT AND NOAA BUOY DATA. 207 208MATTHEW HAS DECREASED SOME IN FORWARD SPEED AND IS MOVING WESTWARD 209ABOUT 13 KNOTS...WELL EMBEDDED IN THE EASTERLY FLOW SOUTH OF A 210SUBTROPICAL HIGH. THIS PATTERN IS NOT EXPECTED TO CHANGE MUCH IN 211THE SHORT TERM...SO THIS GENERAL MOTION WITH A DECREASE IN FORWARD 212SPEED IS EXPECTED TO CONTINUE UNTIL DISSIPATION IN ABOUT 2 TO 3 213DAYS. 214 215FOR THE PAST FEW DAYS GLOBAL MODELS HAVE BEEN CONSISTENTLY DEPICTING 216A TROPICAL CYCLONE IN THE NORTHWESTERN CARIBBEAN SEA TOWARD THE 217MIDDLE OF NEXT WEEK. THE MOST RECENT RUNS INDICATE THAT ANY 218DEVELOPMENT THERE WOULD LIKELY NOT HAVE CONTINUITY WITH MATTHEW... 219BUT RATHER REPRESENT THE FORMATION A NEW TROPICAL CYCLONE. 220 221FORECAST POSITIONS AND MAX WINDS 222 223INITIAL 24/2100Z 14.7N 83.7W 40 KT 224 12HR VT 25/0600Z 15.2N 85.6W 35 KT...INLAND 225 24HR VT 25/1800Z 15.8N 88.0W 30 KT...INLAND 226 36HR VT 26/0600Z 16.5N 90.0W 25 KT...INLAND 227 48HR VT 26/1800Z 17.0N 91.0W 20 KT...POST-TROP/REMNT LOW 228 72HR VT 27/1800Z 17.0N 91.0W 20 KT...POST-TROP/REMNT LOW 229 96HR VT 28/1800Z...DISSIPATED 230 231$$ 232FORECASTER AVILA 233 234 235 236WTNT45 KNHC 250832 237TCDAT5 238TROPICAL STORM MATTHEW DISCUSSION NUMBER 8 239NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 240500 AM EDT SAT SEP 25 2010 241 242SATELLITE IMAGERY SHOWS LITTLE CHANGE IN THE STRUCTURE OF MATTHEW 243DURING THE PAST SEVERAL HOURS...WITH A LARGE AREA OF CONVECTION 244WITH TOPS COLDER THAN -80C CONTINUING TO THE WEST AND SOUTHWEST OF 245THE CENTER. LA CEIBA HONDURAS RECENTLY REPORTED A PRESSURE OF 2461002.7 MB...SUGGESTING THAT THE CENTRAL PRESSURE IS STILL BELOW 2471000 MB. BASED ON THESE FACTORS...THE INITIAL INTENSITY IS HELD AT 24845 KT...WITH THOSE WINDS LIKELY OCCURRING OVER WATER TO THE NORTH 249OF THE CENTER. 250 251THE CENTER IS NOT EASY TO FIND...AND THE INITIAL MOTION IS A 252SOMEWHAT UNCERTAIN 285/14. THE TRACK FORECAST REASONING AGAIN 253REMAINS UNCHANGED...AS A STRONG MID-LEVEL RIDGE OVER THE GULF OF 254MEXICO WILL GENERALLY STEER MATTHEW WEST-NORTHWESTWARD FOR THE NEXT 25536 HOURS OR SO. BY THE TIME MATTHEW MOVES INTO GUATEMALA AND 256EASTERN MEXICO...THE STEERING FLOW WILL WEAKEN AS THE RIDGE BREAKS 257DOWN...AND A SLOW MOTION TOWARD THE WEST-NORTHWEST OR NORTHWEST IS 258EXPECTED UNTIL DISSIPATION. THE NEW TRACK FORECAST IS AGAIN SHIFTED 259A LITTLE TO THE NORTH AND NOW LIES NEAR THE MIDDLE OF THE 260GUIDANCE ENVELOPE. 261 262MATTHEW COULD STRENGTHEN A LITTLE AS THE CENTER CROSSES THE GULF OF 263HONDURAS...BUT IT IS UNLIKELY TO BE OVER WATER LONG ENOUGH FOR 264SIGNIFICANT STRENGTHENING. THE CYCLONE SHOULD WEAKEN STEADILY 265AFTER LANDFALL IN BELIZE AND BECOME A REMNANT LOW BY 48 HR. AFTER 26672 HR...THE REMNANTS ARE EXPECTED TO BE ABSORBED INTO A LARGE 267MONSOON LOW PRESSURE AREA FORECAST TO FORM OVER CENTRAL AMERICA AND 268THE ADJACENT WATERS. 269 270THE LARGEST THREAT FROM MATTHEW IS HEAVY RAINS. IT SHOULD BE NOTED 271THAT A HEAVY RAIN THREAT WILL CONTINUE AFTER MATTHEW DISSIPATES DUE 272TO THE MONSOONAL FLOW ACROSS CENTRAL AMERICA. 273 274FORECAST POSITIONS AND MAX WINDS 275 276INITIAL 25/0900Z 15.7N 86.3W 45 KT 277 12HR VT 25/1800Z 16.2N 88.0W 45 KT...OVER WATER 278 24HR VT 26/0600Z 16.8N 89.8W 35 KT...INLAND 279 36HR VT 26/1800Z 17.2N 90.8W 30 KT...INLAND 280 48HR VT 27/0600Z 17.5N 91.4W 25 KT...POST-TROP/REMNT LOW 281 72HR VT 28/0600Z 18.0N 92.0W 20 KT...POST-TROP/REMNT LOW 282 96HR VT 29/0600Z...DISSIPATED 283 284$$ 285FORECASTER BEVEN 286 287 288 289WTNT45 KNHC 251444 290TCDAT5 291TROPICAL STORM MATTHEW DISCUSSION NUMBER 9 292NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 2931100 AM EDT SAT SEP 25 2010 294 295THE INNER CORE OF MATTHEW HAS BECOME DISRUPTED WHILE MOVING OVER THE 296HIGH TERRAIN OF CENTRAL AMERICA. HOWEVER...THE CYCLONE HAS A BROAD 297CIRCULATION WITH PLENTY OF DEEP CONVECTION. THE AREA OF STRONGEST 298THUNDERSTORMS IS CURRENTLY OVER GUATEMALA AND SOUTHERN BELIZE. THE 299LOW LEVEL CENTER...OR WHAT IS LEFT OF IT...IS VERY DIFFICULT TO 300LOCATE...BUT SURFACE OBSERVATIONS FROM HONDURAS AND BELIZE INDICATE 301THAT THE BROAD AREA OF LOW PRESSURE IS CENTERED JUST OFF THE NORTH 302COAST OF WESTERN HONDURAS. MATTHEW IS STILL GENERATING TROPICAL 303STORM FORCE WINDS NORTH OF THE CENTER...AS INDICATED BY THE STRONG 304EASTERLY WINDS JUST ABOVE THE SURFACE REPORTED BY THE BELIZE RAOB 305THIS MORNING. INITIAL INTENSITY IS 35 KNOTS BUT GIVEN THAT MOST OF 306THE CIRCULATION IS EXPECTED TO REMAIN OVER LAND...WEAKENING IS 307FORECAST. 308 309THERE ARE NO INDICATIONS THAT MATTHEW IS SLOWING DOWN YET. THE 310INITIAL MOTION IS TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 13 311KNOTS. HOWEVER STEERING CURRENTS ARE FORECAST TO COLLAPSE AND THE 312ENTIRE CIRCULATION SHOULD BEGIN TO DRIFT TOWARD THE WEST-NORTHWEST 313DURING THE NEXT 12 TO 24 HOURS UNTIL DISSIPATION. MANY OF THE TRACK 314MODELS KEEP MATTHEW OVER NORTHERN GUATEMALA OR EASTERN MEXICO WHERE 315THE OFFICIAL FORECAST HAS MATTHEW DISSIPATING OR BECOMING A REMNANT 316LOW. 317 318WE MUST EMPHASIZE THAT THE LARGEST THREAT FROM MATTHEW IS HEAVY 319RAINS. TORRENTIAL RAINS WILL CONTINUE AFTER MATTHEW DISSIPATES DUE 320TO MOIST SOUTHWESTERLY FLOW SPREADING ACROSS CENTRAL AMERICA...WHICH 321IS FORECAST TO PREVAIL FOR THE NEXT SEVERAL DAYS. 322 323 324FORECAST POSITIONS AND MAX WINDS 325 326INITIAL 25/1500Z 16.2N 87.8W 35 KT 327 12HR VT 26/0000Z 16.5N 89.5W 30 KT...INLAND 328 24HR VT 26/1200Z 17.0N 90.5W 25 KT...INLAND 329 36HR VT 27/0000Z 17.5N 91.5W 25 KT...INLAND 330 48HR VT 27/1200Z 17.5N 91.5W 20 KT...POST-TROP/REMNT LOW 331 72HR VT 28/1200Z...POST-TROP/REMNT LOW 332 333$$ 334FORECASTER AVILA 335 336 337 338WTNT45 KNHC 260233 339TCDAT5 340TROPICAL DEPRESSION MATTHEW DISCUSSION NUMBER 11 341NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 3421000 PM CDT SAT SEP 25 2010 343 344INFRARED IMAGERY SHOWS DEEP CONVECTION INCREASING AGAIN NEAR THE 345CENTER OF MATTHEW TONIGHT. THE INTENSITY IS HELD AT 30 KT BASED ON 346A 25-KT 10-MINUTE WIND FROM CIUDAD DEL CARMEN MEXICO NORTH OF THE 347CENTER AROUND 0000 UTC...AND THE CENTRAL PRESSURE OF 1001 MB IS 348BASED ON AN OBSERVATION FROM TIKAL GUATEMALA AS THE CENTER PASSED 349NEARBY. GRADUAL WEAKENING IS EXPECTED AS THE CYCLONE WILL REMAIN 350OVER LAND...WITH DISSIPATION EXPECTED BY 72 HOURS. 351 352SATELLITE IMAGERY AND SURFACE OBSERVATIONS SUGGEST THAT MATTHEW IS 353LOCATED FARTHER SOUTH AND WEST THAN PREVIOUSLY ESTIMATED...AND THE 354INITIAL MOTION IS 285/12. MATTHEW CONTINUES TO HAVE A LARGE 355CIRCULATION EMBEDDED WITHIN A LARGER REGION OF CYCLONIC FLOW THAT 356EXTENDS FROM THE EASTERN PACIFIC TO THE WESTERN CARIBBEAN. THE 357CYCLONE WILL BE MOVING INTO A REGION OF WEAK STEERING FLOW IN 358THE NEXT 12 TO 24 HOURS...AND THE FORWARD SPEED SHOULD SLOW 359DRAMATICALLY. BEYOND THAT TIME...A VERY SLOW SOUTHWARD OR 360SOUTHEASTWARD DRIFT SEEMS LIKELY AS WHAT IS LEFT OF MATTHEW ROTATES 361WITHIN THE LARGER CYCLONIC GYRE. THE OFFICIAL FORECAST HAS BEEN 362SHIFTED SOUTH AND WEST OF THE PREVIOUS ONE DUE TO THE INITIAL 363POSITION AND MOTION AND A SOUTHWARD TREND IN MUCH OF THE GUIDANCE 364FROM 24 TO 48 HOURS. 365 366TORRENTIAL RAINS WILL CONTINUE WITH MATTHEW AND ITS REMNANTS OVER 367THE NEXT SEVERAL DAYS. THERE WERE THREE OBSERVING SITES IN HONDURAS 368AND GUATEMALA THAT REPORTED BETWEEN 6.1 AND 7.3 INCHES OF RAIN IN 369THE 24-HOUR PERIOD ENDING AT 0000 UTC. 370 371FORECAST POSITIONS AND MAX WINDS 372 373INITIAL 26/0300Z 17.0N 91.0W 30 KT...INLAND 374 12HR VT 26/1200Z 17.4N 92.1W 25 KT...INLAND 375 24HR VT 27/0000Z 17.7N 92.6W 25 KT...POST-TROP/REMNT LOW 376 36HR VT 27/1200Z 17.5N 92.6W 20 KT...POST-TROP/REMNT LOW 377 48HR VT 28/0000Z 17.4N 92.5W 20 KT...POST-TROP/REMNT LOW 378 72HR VT 29/0000Z...DISSIPATED 379 380$$ 381FORECASTER BRENNAN 382 383 384 385WTNT45 KNHC 260841 386TCDAT5 387TROPICAL DEPRESSION MATTHEW DISCUSSION NUMBER 12 388NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 389400 AM CDT SUN SEP 26 2010 390 391SURFACE OBSERVATIONS AND SATELLITE IMAGERY INDICATE THAT THE CENTER 392OF MATTHEW HAS MOVED INTO EXTREME SOUTHEASTERN MEXICO...AND DEEP 393CONVECTION HAS CONTINUED TO DEVELOP ACROSS SOUTHEASTERN MEXICO AND 394NORTHERN PORTIONS OF CENTRAL AMERICA DURING THE PAST SEVERAL HOURS. 395NO WINDS HIGHER THAN ABOUT 15 KT HAVE BEEN REPORTED OVER LAND 396RECENTLY...AND AN ASCAT PASS FROM AROUND 0340 UTC INDICATED WINDS 397OF 20-25 KT OVER THE SOUTHEASTERN BAY OF CAMPECHE. THE INTENSITY 398IS THEREFORE LOWERED TO 25 KT. VERY FEW OF THE DYNAMICAL MODELS 399KEEP MATTHEW AS A DISTINCT AREA OF LOW PRESSURE FOR MUCH 400LONGER...AND DISSIPATION IS EXPECTED BY 48 HOURS...IF NOT SOONER. 401 402THE DEPRESSION IS SLOWING DOWN AND IS NOW MOVING 285 DEGREES AT 9 403KT. MATTHEW...OR WHAT IS LEFT OF IT...IS EXPECTED TO BECOME NEARLY 404STATIONARY OVER THE ISTHMUS OF TEHUANTEPEC IN ABOUT 24-36 HOURS AS 405IT BECOMES EMBEDDED WITHIN THE MIDDLE OF A MUCH LARGER CYCLONIC GYRE 406THAT WILL EXTEND ACROSS THE NORTHWESTERN CARIBBEAN AND NORTHERN 407CENTRAL AMERICA FOR THE NEXT FEW DAYS. THE NEW TRACK FORECAST IS 408AN UPDATE OF THE PREVIOUS ONE AND LIES NEAR THE CONSENSUS OF THE 409GFS...ECMWF...GFDL...HWRF...AND NOGAPS. 410 411EVEN THOUGH MATTHEW CONTINUES TO WEAKEN...TORRENTIAL RAINS WILL 412CONTINUE WITH THE DEPRESSION AND ITS REMNANTS OVER THE NEXT SEVERAL 413DAYS. 414 415FORECAST POSITIONS AND MAX WINDS 416 417INITIAL 26/0900Z 17.3N 91.8W 25 KT 418 12HR VT 26/1800Z 17.5N 92.7W 25 KT...INLAND 419 24HR VT 27/0600Z 17.5N 93.1W 20 KT...POST-TROP/REMNT LOW 420 36HR VT 27/1800Z 17.4N 93.0W 20 KT...POST-TROP/REMNT LOW 421 48HR VT 28/0600Z...DISSIPATED 422 423$$ 424FORECASTER BERG 425 426 427 428WTNT45 KNHC 261435 429TCDAT5 430TROPICAL DEPRESSION MATTHEW DISCUSSION NUMBER 13 431NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 4321000 AM CDT SUN SEP 26 2010 433 434VISIBLE/INFRARED SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE 435THAT THE DEEP CONVECTION ASSOCIATED WITH THE SYSTEM HAS BECOME 436DISORGANIZED AND THE MAXIMUM SUSTAINED WINDS ARE NO MORE THAN 20 437KT. MATTHEW HAS WEAKENED TO A REMNANT LOW AND THIS WILL BE THE 438LAST ADVISORY. THE SYSTEM HAS BEEN MOVING WESTWARD WITH A GRADUALLY 439DECREASING FORWARD SPEED. OVER THE NEXT DAY OR TWO...THE REMNANT 440OF MATTHEW WILL LIKELY BECOME EMBEDDED WITHIN A BROAD CYCLONIC GYRE 441EXTENDING FROM THE NORTHWESTERN CARIBBEAN WESTWARD ACROSS NORTHERN 442CENTRAL AMERICA. THE REMNANT IS EXPECTED TO TURN SLOWLY CLOCKWISE 443WITHIN THE LARGER CYCLONIC CIRCULATION UNTIL DISSIPATION BY 36 TO 44448 HOURS OR SOONER. 445 446EVEN THOUGH THE LOW IS NO LONGER A TROPICAL CYCLONE THE SYSTEM...IN 447CONJUNCTION WITH THE BROAD CYCLONIC GYRE...WILL CONTINUE TO PRODUCE 448TORRENTIAL RAINS OVER PORTIONS OF EASTERN MEXICO AND CENTRAL 449AMERICA OVER THE NEXT SEVERAL DAYS. 450 451FORECAST POSITIONS AND MAX WINDS 452 453INITIAL 26/1500Z 17.4N 92.9W 20 KT 454 12HR VT 27/0000Z 17.4N 93.4W 20 KT...POST-TROP/REMNT LOW 455 24HR VT 27/1200Z 17.2N 93.5W 20 KT...POST-TROP/REMNT LOW 456 36HR VT 28/0000Z 17.1N 93.3W 20 KT...POST-TROP/REMNT LOW 457 48HR VT 28/1200Z...DISSIPATED 458 459$$ 460FORECASTER PASCH 461 462 463 464