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Tropical Storm DELTA


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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
 
 
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