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Tropical Storm DELTA


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TROPICAL STORM DELTA DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
4 AM EST SUN NOV 27 2005
 
DELTA CONTINUES TO PRODUCE DEEP CONVECTION WITH CLOUD TOPS TO -70C
OR COLDER.  IN FACT...THE CONVECTION IS ABOUT AS STRONG AS IT HAS
BEEN DURING THE LIFETIME OF THE SYSTEM.  DVORAK CLASSIFICATIONS
SUGGEST THAT THE STORM MIGHT BE AS STRONGER THAN 35 KT.  DVORAK
INTENSITY ESTIMATES FOR SHEARED TROPICAL CYCLONES ARE HIGHLY
DEPENDENT ON THE LOCATION OF THE CENTER WITH RESPECT TO THE DENSE
OVERCAST...AND THE CENTER IS DIFFICULT TO LOCATE.  GIVEN THE
UNCERTAINTIES...THE WIND SPEED IS KEPT AT 35 KT.  WESTERLY SHEAR...
ASSOCIATED WITH AN UPPER-TROPOSPHERIC TROUGH TO THE WEST OF
DELTA...IS FORECAST TO INCREASE...AND THE CYCLONE WILL BE MOVING
OVER PROGRESSIVELY COOLER SEA SURFACE TEMPERATURES.  IN VIEW OF THE
CURRENT VIGOR OF THE DEEP CONVECTION...HOWEVER...ONLY SLOW
WEAKENING IS FORECAST.  OUTPUT FROM THE NCEP GLOBAL FORECAST
SYSTEM...GFS...SHOWS DELTA INTERACTING WITH A FRONTAL ZONE...AND
BECOMING EXTRATROPICAL IN 24 HOURS AND SO DOES THE OFFICIAL
FORECAST.
 
THE STORM CONTINUES TO GRADUALLY ACCELERATE AND IS NOW MOVING
GENERALLY NORTHEASTWARD NEAR 21 KT.  A FURTHER INCREASE IN FORWARD
SPEED AND A TURN TOWARD THE EAST IS LIKELY AS DELTA OR ITS
EXTRATROPICAL COUNTERPART COMES UNDER THE INFLUENCE OF
THE WESTERLIES ASSOCIATED WITH A LARGE LOW PRESSURE SYSTEM OVER
WESTERN EUROPE.  THE OFFICIAL TRACK FORECAST IS TO THE RIGHT OF THE
MODEL CONSENSUS AND SLIGHTLY FASTER...BUT NOT AS FAST AS THE GFS.

ALTHOUGH DELTA IS FORECAST TO BECOME EXTRATROPICAL IN 24
HOURS...WINDS TO NEAR GALE FORCE COULD SPREAD ACROSS PORTIONS OF
THE CANARY ISLANDS IN 24-36 HOURS.
 
FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/0900Z 25.6N  32.8W    35 KT
 12HR VT     27/1800Z 27.4N  29.6W    35 KT
 24HR VT     28/0600Z 28.8N  24.0W    35 KT...EXTRATROPICAL
 36HR VT     28/1800Z 28.8N  17.5W    30 KT...EXTRATROPICAL
 48HR VT     29/0600Z 28.8N  11.5W    30 KT...EXTRATROPICAL
 72HR VT     30/0600Z...DISSIPATED
 
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