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| #49493 (Received by flhurricane at: 11:08 PM 01.Oct.2005) TCDAT4 TROPICAL DEPRESSION NINETEEN DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT SAT OCT 01 2005 TROPICAL DEPRESSION NINETEEN IS FEELING THE EFFECTS OF WESTERLY SHEAR THIS EVENING. THE LOW-LEVEL CENTER IS PARTLY EXPOSED BETWEEN CONVECTIVE CLUSTERS TO THE NORTHEAST AND SOUTHWEST. SATELLITE INTENSITY ESTIMATES REMAIN 35 KT FROM TAFB AND SAB. HOWEVER...A QUIKSCAT OVERPASS SHOW NO WINDS HIGHER THAN 25 KT THAT WERE NOT IN THE CONVECTIVE CLUSTERS. BLENDING THESE DATA PRODUCES AN INITIAL INTENSITY OF 30 KT. THE INITIAL MOTION IS 350/6. A LARGE-DEEP LAYER LOW NORTH OF THE DEPRESSION IS FORECAST TO MOVE WESTWARD FOR THE NEXT 3-4 DAYS... ALLOWING THE DEPRESSION TO MOVE GENERALLY NORTH-NORTHWESTWARD TO NORTHWARD ON THE EAST SIDE OF THE LOW. AFTER THAT...THE FORECAST BECOME MORE UNCERTAIN. MUCH OF THE GUIDANCE WANTS TO TURN THE CYCLONE EASTWARD AFTER 72 HR EVEN THOUGH THE MODEL MASS FIELDS INDICATE RIDGING NORTH OF THE DEPRESSION. BASED ON THE RIDGING... THE FORECAST TRACK WILL CALL FOR A MUCH SLOWER NORTHEASTWARD TURN THAT THAT CURRENTLY CALLED FOR BY THE GUIDANCE. THE BIG QUESTION IS HOW LONG WILL THE SYSTEM SURVIVE? ALL THE LARGE-SCALE MODELS FORECAST SIGNIFICANT SOUTHWESTERLY TO WESTERLY SHEAR THROUGH THE FORECAST PERIOD...PARTICULARLY NORTH OF 20N WHERE IT IS FORECAST TO BE IN EXCESS OF 40 KT AND THE SEA SURFACE TEMPERATURES ARE BARELY 26C. BASED ON THIS...THE INTENSITY FORECAST IS LOWERED SLIGHTLY FROM THE PREVIOUS ADVISORY. THE FORECAST CALLS FOR SOME SLIGHT STRENGTHENING DURING THE NEXT 24 HR IN CASE SOME TEMPORARY DECREASE IN THE SHEAR OCCURS OR A STRONG CONVECTIVE BURST SPINS THE SYSTEM UP. IT THEN CALLS FOR THE SYSTEM TO WEAKEN AS THE SHEAR INCREASES...BECOMING A REMNANT LOW BY 120 HR. IT IS POSSIBLE GIVEN CURRENT TRENDS THAT THE DEPRESSION MAY NOT STRENGTHEN AT ALL...AND DISSIPATE SOONER THAN CURRENTLY FORECAST. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 02/0300Z 15.3N 34.0W 30 KT 12HR VT 02/1200Z 16.6N 34.4W 30 KT 24HR VT 03/0000Z 18.2N 35.3W 35 KT 36HR VT 03/1200Z 19.9N 36.0W 35 KT 48HR VT 04/0000Z 22.0N 36.4W 30 KT 72HR VT 05/0000Z 25.0N 36.5W 25 KT 96HR VT 06/0000Z 27.5N 36.0W 25 KT...DISSIPATING 120HR VT 07/0000Z 29.5N 34.0W 20 KT...REMNANT LOW |
