1WTNT43 KNHC 190257 2TCDAT3 3TROPICAL DEPRESSION THREE DISCUSSION NUMBER 1 4NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032008 51100 PM EDT FRI JUL 18 2008 6 7OVER THE PAST SEVERAL HOURS...CONVECTION ASSOCIATED WITH THE AREA OF 8LOW PRESSURE OFF THE GEORGIA COAST HAS BECOME MORE CONCENTRATED 9WITH AMPLE MID-LEVEL ROTATION. PERSISTENT NORTHWESTERLY WINDS FROM 10A SKIDAWAY INSTITUTE OF OCEANOGRAPHY 50 METER TOWER A SHORT 11DISTANCE WEST OF THE MAIN AREA OF CONVECTION INDICATE THAT THE 12CIRCULATION HAS BECOME BETTER DEFINED SINCE THIS AFTERNOON. 13CONSEQUENTLY...ADVISORIES ARE INITIATED ON TROPICAL DEPRESSION 14THREE. THERE ARE NO INDICATIONS...EITHER FROM COASTAL RADAR OR 15SURFACE OBSERVATIONS...THAT THE SYSTEM HAS ACQUIRED MUCH IN THE WAY 16OF STRONG WINDS YET...AND THE INITIAL INTENSITY IS SET AT 25 KT. 17 18THE INITIAL MOTION IS ESTIMATED TO BE 040/5. STEERING CURRENTS ARE 19WEAK...WITH THE DEPRESSION SITTING BETWEEN A MID-LEVEL RIDGE EAST 20OF THE BAHAMAS AND A WEAKER ONE OVER THE TENNESSEE VALLEY. MODEL 21GUIDANCE IS IN PRETTY GOOD AGREEMENT THAT A SLOW NORTHEASTWARD 22MOTION WILL CONTINUE...VERY CLOSE TO THE COAST OF THE CAROLINAS... 23FOR THE NEXT DAY OR TWO...WITH A GRADUAL ACCELERATION INTO THE 24WESTERLIES BEFORE THE SYSTEM BECOMES ABSORBED BY THE NEXT 25MID-LATITUDE SHORT WAVE. THE OFFICIAL FORECAST IS NEAR THE 26CONSENSUS OF THE TIGHTLY PACKED GUIDANCE...ALTHOUGH I'LL NOTE THAT 27BOTH THE GFDL AND HWRF HAVE TRACKS THAT ESSENTIALLY STRADDLE THE 28COASTLINE. BECAUSE THE FORECAST TRACK IS NEARLY PARALLEL TO THE 29ORIENTATION OF THE COASTLINE...IT IS IMPOSSIBLE TO PINPOINT A 30POSSIBLE LANDFALL LOCATION AT THIS TIME. 31 32THE ENVIRONMENT DOES NOT SEEM CONDUCIVE TO RAPID DEVELOPMENT. THE 33UPPER-LEVEL WINDS ARE SOMEWHAT DIVERGENT...BUT THERE IS A LOT OF 34DRY AIR NEARBY OVER THE SOUTHEASTERN UNITED STATES. EXCEPT FOR THE 35CLIMATOLOGY AND PERSISTENCE MODEL SHIFOR...NONE OF THE INTENSITY 36GUIDANCE MAKES THE SYSTEM A TROPICAL STORM. HOWEVER...THE SHIPS 37FORECAST SEEMS TO BE BASED ON SSTS THAT LOOK AT LEAST 1C COOLER 38THAN WHAT THE COASTAL BUOYS ARE REPORTING RIGHT NOW...SO I'M GOING 39TO GO A LITTLE ABOVE THAT GUIDANCE AND SHOW JUST ENOUGH 40STRENGTHENING TO MAKE THE SYSTEM A TROPICAL STORM. THE FORECAST 41TRACK AND INTENSITIES REQUIRE THE ISSUANCE OF TROPICAL STORM 42WATCHES AND WARNINGS. 43 44 45FORECAST POSITIONS AND MAX WINDS 46 47INITIAL 19/0300Z 31.9N 79.6W 25 KT 48 12HR VT 19/1200Z 32.4N 79.1W 30 KT 49 24HR VT 20/0000Z 33.4N 78.0W 35 KT 50 36HR VT 20/1200Z 34.4N 76.6W 35 KT 51 48HR VT 21/0000Z 35.5N 75.0W 35 KT 52 72HR VT 22/0000Z 38.0N 70.5W 35 KT 53 96HR VT 23/0000Z...ABSORBED 54 55$$ 56FORECASTER FRANKLIN 57 58 59WTNT43 KNHC 190833 60TCDAT3 61TROPICAL DEPRESSION THREE DISCUSSION NUMBER 2 62NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032008 63500 AM EDT SAT JUL 19 2008 64 65SATELLITE...RADAR AND SURFACE OBSERVATIONS INDICATE THAT THERE HAS 66BEEN LITTLE CHANGE IN THE STRUCTURE OF THE DEPRESSION DURING THE 67PAST FEW HOURS. THE CENTER IS DIFFICULT TO LOCATE BUT APPEARS TO BE 68ON THE NORTHWESTERN EDGE OF A CYCLONICALLY CURVED CONVECTIVE BAND. 69INITIAL INTENSITY REMAINS AT 25 KNOTS. THE ENVIRONMENT IS 70MARGINALLY FAVORABLE FOR DEVELOPMENT AND ONLY A SLIGHT INCREASE IN 71INTENSITY IS INDICATED IN THE FORECAST. NEVERTHERELESS...THE SYSTEM 72COLD BECOME A 35-KNOT TROPICAL STORM. AN AIR FORCE PLANE WILL CHECK 73THE DEPRESSION LATER TODAY. 74 75THE BEST ESTIMATE OF THE INITIAL MOTION IS 035 DEGREES AT 4 KNOTS 76AND THIS MOTION IS UNCERTAIN SINCE THE CENTER IS DIFFICULT TO 77LOCATE. THE DEPRESSION IS EXPECTED TO BE EMBEDDED WITHIN THE 78MID-LATITUDE WESTERLIES AND THIS PATTERN SHOULD CONTINUE TO STEER 79THE CYCLONE TOWARD THE NORTHEAST WITH A SLIGHT INCREASE IN FORWARD 80SPEED UNTIL ABSORBED BY A SHORT WAVE. THE OFFICIAL FORECAST IS IN 81THE MIDDLE OF THE GUIDANCE ENVELOPE...VERY CLOSE TO THE MODEL 82CONSENSUS. 83 84 85FORECAST POSITIONS AND MAX WINDS 86 87INITIAL 19/0900Z 32.4N 79.4W 25 KT 88 12HR VT 19/1800Z 33.0N 78.7W 30 KT 89 24HR VT 20/0600Z 34.0N 77.3W 35 KT 90 36HR VT 20/1800Z 35.0N 76.0W 35 KT 91 48HR VT 21/0600Z 36.5N 73.5W 35 KT 92 72HR VT 22/0600Z 39.0N 69.0W 35 KT 93 96HR VT 23/0600Z...ABSORBED 94 95$$ 96FORECASTER AVILA 97 98 99WTNT43 KNHC 191447 100TCDAT3 101TROPICAL DEPRESSION THREE DISCUSSION NUMBER 3 102NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032008 1031100 AM EDT SAT JUL 19 2008 104 105THE TROPICAL DEPRESSION IS CONTINUING TO ORGANIZE AND IS NEARING 106TROPICAL STORM STRENGTH. RADAR VELOCITY DATA FROM CHARLESTON AND 107WILMINGTON SHOW THAT THE WIND FIELDS ALOFT ARE BECOMING BETTER- 108DEFINED AND INCREASING. IN ADDITION...SHIP PDNN REPORTED 30 KT TO 109THE SOUTHEAST OF THE CENTER AT 1200 UTC. THE MAXIMUM WINDS ARE 110KEPT AT 30 KT IN THIS ADVISORY AND AN AIR FORCE RESERVE 111RECONNAISSANCE PLANE WILL BE IN THE AREA AROUND 1700 UTC TO 112DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL STORM. 113 114ALTHOUGH THERE IS SOME DRY AIR TO THE NORTH...VERTICAL WIND SHEAR IS 115FORECAST TO BE LOW FOR THE NEXT COUPLE OF DAYS AND THE SYSTEM IS 116EXPECTED TO BE NEAR THE WARM GULF STREAM WATERS. SURPRISINGLY... 117NEITHER THE GFDL NOR THE HWRF SHOW MUCH STRENGTHENING WITH THE 118DEPRESSION. WE'RE INCLINED TO THINK THAT SLOW INTENSIFICATION IS 119LIKELY GIVEN THE ENVIRONMENTAL CONDITIONS...SO A SLOW INCREASE IN 120WINDS IS INDICATED...CLOSE TO A BLEND OF THE SHIPS/SHIFOR GUIDANCE. 121 122DATA FROM BUOY 41004 HAS BEEN HELPFUL IN TRACKING THE DEPRESSION... 123WHICH APPEARS TO HAVE REFORMED A LITTLE TO THE EAST. BEST ESTIMATE 124OF INITIAL MOTION IS 050/6. A WEAK MID-TROPOSPHERIC RIDGE TO THE 125SOUTHEAST OF THE STORM SHOULD CONTINUE TO MOVE THE SYSTEM IN THIS 126GENERAL DIRECTION AND AT A SIMILAR SPEED FOR THE NEXT DAY OR SO. 127THEREAFTER... THE DEPRESSION WILL BE CAUGHT UP IN A STRONGER 128STEERING CURRENT BETWEEN A BUILDING RIDGE TO THE EAST AND A 129DEEPENING MIDDLE-LATITUDE TROUGH. MODEL GUIDANCE IS IN GOOD 130AGREEMENT ON TAKING THE SYSTEM NEAR THE SOUTH AND NORTH CAROLINA 131COASTS DURING THE NEXT COUPLE OF DAYS. THE OFFICIAL FORECAST IS 132SHIFTED A LITTLE TO THE EAST OF THE PREVIOUS ONE...MOSTLY DUE TO 133THE CENTER REFORMATION...AND LIES ON THE WESTERN SIDE OF THE 134GUIDANCE ENVELOPE. 135 136 137FORECAST POSITIONS AND MAX WINDS 138 139INITIAL 19/1500Z 32.6N 78.5W 30 KT 140 12HR VT 20/0000Z 33.3N 77.6W 35 KT 141 24HR VT 20/1200Z 34.2N 76.3W 40 KT 142 36HR VT 21/0000Z 35.1N 75.0W 45 KT 143 48HR VT 21/1200Z 36.5N 73.0W 45 KT 144 72HR VT 22/1200Z 40.5N 68.0W 45 KT 145 96HR VT 23/1200Z...ABSORBED 146 147$$ 148FORECASTER BLAKE/KNABB 149 150 151