Tropical Storm DELTA

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TROPICAL STORM DELTA DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 AM EST FRI NOV 25 2005
 
THUNDERSTORM ACTIVITY HAS BEEN ON THE DECREASE THE PAST 6 HOURS...
WITH ONLY A NARROW BAND OF MODERATE CONVECTION NOTED IN THE EASTERN
SEMICIRCLE. DELTA HAS MOVED WEST OF AN UPPER-LEVEL SHEAR AXIS AND
IS NOW UNDERNEATH 30-40 KT NORTHERLY WINDS... WITH 50-70 KT WINDS
LOCATED 60 NMI TO THE WEST AS INDICATED IN A 25/1200Z UW-CIMSS
WATER VAPOR WIND ANALYSIS. THE INTENSITY IS BEING MAINTAINED AT 55
KT BASED ON A 25/0800Z HI-RES QUIKSCAT OVERPASS THAT STILL SHOWED A
FEW 55-KT WIND VECTORS NORTHWEST THROUGH NORTH OF THE CENTER.
 
THE INITIAL MOTION IS 210/4...BASED ON A 12-HR AVERAGE. MOST OF THE
NHC MODEL GUIDANCE INDICATES THAT DELTA SHOULD SLOW ITS SOUTHERLY
COMPONENT OF MOTION DURING THE NEXT 12 HOURS... AND THEN TURN BACK
TOWARD THE NORTH OR NORTH-NORTHEAST. WITH THE LONE EXCEPTION OF THE
CLIPER AND SHALLOW BAM MODELS... THE REMAINDER OF THE NHC GUIDANCE
MODELS TAKE DELTA NORTHEAST AND THEN RAPIDLY EASTWARD AFTER 72
HOURS TO NEAR THE CANARY ISLANDS OR MOROCCO. HOWEVER... THERE IS A
BIG QUESTION AS TO JUST HOW VERTICALLY DEEP DELTA WILL BE IN THE
LATER PERIODS. THE SHIPS MODEL AND OTHER MODELS INDICATE THAT
VERTICAL SHEAR WILL GRADUALLY INCREASE TO 40-50 KT FROM THE
NORTHWEST AND EVENTUALLY THE WEST. THOSE HOSTILE SHEAR CONDITIONS
...COUPLED WITH THE PRESENCE OF VERY DRY AIR LOCATED JUST WEST OF
THE CYCLONE...MAY RESULT IN A DECOUPLING OF THE LOW- AND MID/UPPER-
LEVEL CIRCULATIONS... WITH THE LARGE LOW-LEVEL CIRCULATION
REMAINING BEHIND TO INTERACT WITH AN EXTRATROPICAL LOW THAT IS
FORECAST TO DEVELOP TO THE WEST OF DELTA IN 72 HOURS. THE OFFICIAL
FORECAST TRACK IS SIMILAR TO BUT SLOWER THAN THE PREVIOUS TRACK AND
IS A BLEND OF THE NHC MODEL CONSENSUS AND THE SLOWER BAMS MODEL.
 
ALTHOUGH DELTA CONTINUES TO MOVE SOUTHWESTWARD OVER SLIGHTLY WARMER
WATER... THE INFLUENCE OF STRONG NORTHERLY UPPER-LEVEL WINDS AND
VERY DRY AIR SHOULD INHIBIT THE DEVELOPMENT AND PERSISTENCE OF ANY
SIGNIFICANT DEEP CONVECTION NEAR THE CENTER... RESULTING IN A
GRADUAL SPINDOWN OF THE WIND FIELD. THIS IS CONSISTENT WITH THE
SHIPS MODEL... WHICH EVEN DISSIPATES THE CYCLONE BY 96 HOURS.
 
FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/1500Z 23.2N  39.7W    55 KT
 12HR VT     26/0000Z 23.3N  39.5W    50 KT
 24HR VT     26/1200Z 24.0N  38.9W    50 KT
 36HR VT     27/0000Z 25.5N  38.0W    45 KT
 48HR VT     27/1200Z 27.1N  36.9W    45 KT...BECOMING EXTRATROPICAL
 72HR VT     28/1200Z 30.5N  34.5W    40 KT...EXTRATROPICAL
 96HR VT     29/1200Z 31.0N  29.0W    35 KT...EXTRATROPICAL
120HR VT     30/1200Z 30.0N  24.0W    35 KT...EXTRATROPICAL

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