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| #58389 (Received by flhurricane at: 3:34 AM 25.Nov.2005) TCDAT3 TROPICAL STORM DELTA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 4 AM EST FRI NOV 25 2005 INFRARED SATELLITE IMAGERY THIS MORNING SHOWS THAT DELTA HAS BECOME LESS ORGANIZED DURING THE PAST 6 HR...WITH THE MAIN CONVECTION CURRENTLY CONFINED TO RAGGED BANDS OVER THE EASTERN SEMICIRCLE. THE CIRRUS OUTFLOW IS FAIR OVER THE EASTERN SEMICIRCLE AND NON-EXISTENT ELSEWHERE. SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM TAFB AND SAB...AND 35 KT FROM AFWA. BASED ON THIS...THE INITIAL INTENSITY IS REDUCED TO 55 KT. THE INITIAL MOTION IS 220/3...BASED ON A 6 HR MOTION. AT THIS TIME...DELTA IS IN WEAK STEERING CURRENTS EAST OF A WEAKENING DEEP-LAYER RIDGE OVER THE MID-ATLANTIC. THIS SHOULD RESULT IN ERRATIC MOTION...AND LITTLE OVERALL MOTION IS EXPECTED TODAY. AFTER 24 HR...FALLING PRESSURES WEST OF DELTA ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH AND DEVELOPING SURFACE LOW SHOULD MOVE THE STORM NORTH-NORTHEASTWARD OR NORTHWARD. THE VARIOUS TRACK GUIDANCE MODELS AGREE ON THIS THROUGH 48 HR...THEN ARE EVEN MORE AGGRESSIVE IN TURNING DELTA EASTWARD IN WESTERLY FLOW SOUTH OF A DEVELOPING TROUGH OVER WESTERN EUROPE THAN THEY WERE 6 HR AGO. WHILE THE MODELS AGREE WELL ON THE EASTWARD MOTION...THIS WAS NOT THE CASE 12 HR AGO...AND IT WILL TAKE A RUN OR TWO MORE SHOWING THIS MOTION BEFORE THE FORECAST TRACK CAN FULLY FOLLOW IT. THE NEW FORECAST TRACK IS SHIFTED EAST OF THE PREVIOUS TRACK AFTER 24 HR... AND SIGNIFICANTLY CHANGED TO A MORE EASTWARD MOTION AFTER 72 HR. HOWEVER...THE TRACK IS ALONG THE NORTH SIDE OF THE GUIDANCE ENVELOPE AND IS SLOWER THAN ALL THE MODELS SAVE THE UKMET. IF SUBSEQUENT MODEL RUNS CONTINUE FORECASTING A FASTER EASTWARD MOTION...AND IT CONTINUES TO APPEAR THAT DELTA WILL NOT BE ABSORBED INTO THE NEW LOW TO THE WEST...ADDITIONAL REVISIONS TO THE TRACK FORECAST MAY BE NECESSARY IN LATER ADVISORIES. THE TREND OF DECREASING ORGANIZATION REDUCES THE CHANCE THAT DELTA WILL BECOME A HURRICANE. THE LARGE-SCALE MODELS AND THE SHIPS MODEL FORECAST VERTICAL SHEAR TO INCREASE AS THE UPPER-LEVEL CYCLONIC SHEAR AXIS CURRENTLY NEAR THE STORM WEAKENS AND MOVES EASTWARD...AND THIS MAY ALREADY BE UNDERWAY. THE INTENSITY FORECAST IS THUS CHANGED TO SLOW WEAKENING DURING THE NEXT 48 HR AS DELTA MOVES NORTH-NORTHEASTWARD...FOLLOWED BY EXTRATROPICAL TRANSITION AS THE STORM TURNS EASTWARD SOUTH OF THE EUROPEAN TROUGH. IF THE SHEAR INCREASES AS MUCH AS THE MODELS ARE SUGGESTING...DELTA COULD WEAKEN FASTER THAN CURRENTLY FORECAST. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 25/0900Z 23.7N 39.3W 55 KT 12HR VT 25/1800Z 23.6N 39.4W 55 KT 24HR VT 26/0600Z 24.0N 39.0W 55 KT 36HR VT 26/1800Z 25.0N 38.3W 50 KT 48HR VT 27/0600Z 26.8N 37.1W 50 KT 72HR VT 28/0600Z 31.0N 34.0W 45 KT...BECOMING EXTRATROPICAL 96HR VT 29/0600Z 32.0N 28.0W 45 KT...EXTRATROPICAL 120HR VT 30/0600Z 32.0N 21.0W 45 KT...EXTRATROPICAL |
