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| #156892 (Received by flhurricane at: 11:03 AM 28.Oct.2007) TCDAT1 TROPICAL DEPRESSION SIXTEEN DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL162007 1100 AM EDT SUN OCT 28 2007 THE APPEARANCE OF THE CYCLONE ON SATELLITE IMAGERY HAS BECOME FAIRLY IMPRESSIVE...FOR A TROPICAL DEPRESSION. INFRARED CLOUD TOP TEMPERATURES ARE QUITE COLD OVER A LARGE AREA...AND THERE IS EVEN A BAND EXTENDING SOUTHWARD...GIVING THE SYSTEM A COMMA SHAPE. THE DEPRESSION CERTAINLY SEEMS ON THE VERGE OF BECOMING A TROPICAL STORM...BUT THE AVAILABLE DATA AT THE MOMENT ARE INCONCLUSIVE AS TO WHETHER OR NOT THIS HAS YET OCCURRED. THE EASTERN EDGE OF A QUIKSCAT PASS FROM ABOUT 1115Z ONLY CAUGHT A PORTION OF THE CIRCULATION AND DID NOT RETRIEVE ANY RELIABLE WINDS OF TROPICAL STORM FORCE. DVORAK INTENSITY ESTIMATES ARE UNCHANGED SINCE 06Z AND THE ADVISORY INTENSITY REMAINS 30 KT. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO DEPART SHORTLY TO INVESTIGATE THE DEPRESSION AND GIVE US A BETTER HANDLE ON THE INTENSITY. THE DEPRESSION CONTINUES WEST-NORTHWESTWARD TO THE SOUTH OF A LOW- TO MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC. ALL OF THE MODELS FORECAST THE MID-LEVEL RIDGE TO WEAKEN DURING THE NEXT DAY OR TWO AS A SHORT WAVE TROUGH MOVES INTO THE SOUTHEASTERN UNITED STATES AND HEIGHTS RISE FARTHER TO THE EAST. SOME OF THE TRACK MODELS...IN PARTICULAR THE GFDL AND HWRF...RESPOND TO THIS PATTERN CHANGE BY FORECASTING A RELATIVELY QUICK RECURVATURE OUT OF THE CARIBBEAN VIA EASTERN CUBA. MOST OF THE GLOBAL MODELS...HOWEVER...FORECAST A SLOWER MOTION GENERALLY TOWARD THE WEST-NORTHWEST AND KEEP THE CYCLONE SOUTH OF CUBA BETWEEN 3 AND 5 DAYS. THE NEW OFFICIAL TRACK FORECAST FOLLOWS THE SAME PATH AS IN THE PREVIOUS ADVISORY...BUT AT A SLIGHTLY SLOWER PACE IN DEFERENCE TO THE GLOBAL MODELS. THE HUGE UNCERTAINTIES IN THE TRACK FORECAST ALSO TRANSLATE INTO A VERY CHALLENGING INTENSITY PROGNOSIS. IF THE OFFICIAL TRACK WERE TO VERIFY PERFECTLY...THE CIRCULATION CENTER WOULD REMAIN OVER WATER FOR ABOUT FOUR MORE DAYS BEFORE CROSSING CUBA. SINCE THE UPPER-LEVEL LOW CURRENTLY NEAR THE DEPRESSION IS FORECAST TO DISSIPATE WITHIN A DAY OR TWO...THE RESULTING DECREASE IN WIND SHEAR WOULD PROBABLY ALLOW FOR SOME STRENGTHENING. IF...HOWEVER... THE CYCLONE GOES FARTHER NORTH AND EAST...LAND INTERACTION WOULD OCCUR SOONER AND PERHAPS FOR A LONGER PERIOD AND COULD LIMIT STRENGTHENING. FINALLY...A TRACK FARTHER SOUTH AND WEST COULD PLACE THE CYCLONE WITHIN A WEAKER-SHEAR ENVIRONMENT AND ALLOW FOR MORE STRENGTHENING THAN FORECAST. IF THE CYCLONE DOES RECURVE TOWARD THE WESTERN ATLANTIC IN A FEW DAYS...THE UPPER-LEVEL WESTERLIES NORTH OF CUBA ARE FORECAST BY THE GLOBAL MODELS TO BE STRONG AND NOT CONDUCIVE FOR THE CYCLONE TO STRENGTHEN...AT LEAST NOT AS A TROPICAL CYCLONE. THE NEW OFFICIAL INTENSITY FORECAST PEAKS JUST A LITTLE HIGHER THAN THE PREVIOUS ADVISORY AND IS BETWEEN THE LGEM AND SHIPS SOLUTIONS...AND MUCH LESS THAN THE GFDL AND HWRF FORECASTS. FORECAST POSITIONS AND MAX WINDS INITIAL 28/1500Z 16.5N 72.5W 30 KT 12HR VT 29/0000Z 17.0N 73.4W 35 KT 24HR VT 29/1200Z 18.0N 75.0W 40 KT 36HR VT 30/0000Z 19.0N 76.5W 45 KT 48HR VT 30/1200Z 20.0N 78.0W 50 KT 72HR VT 31/1200Z 21.0N 79.5W 55 KT 96HR VT 01/1200Z 22.0N 80.0W 50 KT...INLAND OVER CUBA 120HR VT 02/1200Z 24.0N 78.0W 45 KT...OVER WATER $$ FORECASTER KNABB |
