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#58536 (Received by flhurricane at: 3:34 AM 26.Nov.2005) TCDAT3 TROPICAL STORM DELTA DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 4 AM EST SAT NOV 26 2005 ANALYSES FROM CIMMS AT THE UNIVERSITY OF WISCONSIN INDICATE THAT THE VERTICAL SHEAR IS NOW 40 KT...AND AS A RESULT THE LOW-LEVEL CENTER IS NOW MOSTLY EXPOSED TO THE WEST OF THE REMAINING DEEP CONVECTION. SATELLITE INTENSITY ESTIMATES ARE 35 KT FROM ALL AGENCIES. THE INITIAL INTENSITY IS REDUCED TO 45 KT...AND THIS COULD BE A BIT GENEROUS. A QUIKSCAT OVERPASS IN THE NEXT HOUR OR SO SHOULD PROVIDE MORE INFORMATION ON THE ACTUAL INTENSITY OF DELTA. DELTA HAS STOPPED ITS SOUTHWARD MOTION AND OVER THE PAST FEW HOURS SEEMS TO BE MOVING DUE EAST. THE INITIAL MOTION IS THUS A SOMEWHAT UNCERTAIN 090/5. WATER VAPOR IMAGERY SHOWS A STRONG MID/UPPER- LEVEL SHORTWAVE TROUGH ALONG 59W FROM 20N-32N...AND AN UPPER-LEVEL LOW NEAR 31N37W. SATELLITE IMAGERY ALSO SHOWS A LARGE AND POWERFUL DEEP-LAYER TROUGH OVER WESTERN EUROPE AND THE ADJACENT ATLANTIC NORTH OF 30N EAST OF 20W. THE LARGE-SCALE MODELS INDICATE THIS TROUGH WILL REMAIN IN PLACE...WHILE THE SHORTWAVE WEST OF DELTA MOVES SOUTHEASTWARD AND INTENSIFIES...CREATING A NEW SURFACE LOW WEST OF THE STORM. THIS COMBINATION SHOULD CAUSE DELTA TO TURN NORTHEASTWARD DURING THE NEXT 12-24 HR WITH SOME ACCELERATION... THEN GRADUALLY TURN MORE EASTWARD AS IT ENCOUNTERS THE FRONTAL SYSTEM ASSOCIATED WITH THE EUROPEAN TROUGH. MOST LARGE-SCALE MODELS SHOW A WEAKENING DELTA NEAR NORTHEASTERN AFRICA IN ABOUT 72 HR. HOWEVER...THERE IS STILL A POSSIBILITY THAT THE NEW SURFACE LOW COULD TRY TO ABSORB DELTA...WHICH WOULD KEEP IT FROM MOVING EASTWARD AS QUICKLY AS THE MODELS ARE FORECASTING. THEREFORE... WHILE THE NEW FORECAST TRACK WILL CALL FOR A FASTER EASTWARD MOTION THAN THE PREVIOUS FORECAST...IT WILL BE SLOWER THAN THE GUIDANCE. THE LARGE-SCALE MODELS FORECAST INCREASING SHEAR OVER DELTA DURING THE NEXT 72 HR...AND THE SEA SURFACE TEMPERATURES DECREASE ALONG THE FORECAST TRACK. THUS...THE CURRENT WEAKENING TREND SHOULD CONTINUE. DELTA SHOULD ENCOUNTER THE FRONTAL ZONE ASSOCIATED WITH THE EUROPEAN TROUGH IN ABOUT 48 HR AND BECOME EXTRATROPICAL...THEN LOSE ITS IDENTITY IN 72-96 HR. EVEN IF DELTA IS SLOWER TO MOVE EASTWARD INTO COLD AIR AND COLD WATER THAN FORECAST...THE STRONG SHEAR SHOULD CONTINUE TO WEAKEN THE STORM. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 26/0900Z 21.9N 39.0W 45 KT 12HR VT 26/1800Z 22.5N 38.3W 40 KT 24HR VT 27/0600Z 24.4N 36.3W 35 KT 36HR VT 27/1800Z 26.7N 33.5W 30 KT 48HR VT 28/0600Z 28.3N 30.2W 30 KT...EXTRATROPICAL 72HR VT 29/0600Z 29.0N 26.0W 30 KT...EXTRATROPICAL 96HR VT 30/0600Z...ABSORBED BY FRONTAL SYSTEM |