Tropical Storm ERIKA

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TROPICAL STORM ERIKA DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062009
500 PM AST WED SEP 02 2009
 
SATELLITE IMAGES SHOW THAT THE CIRCULATION OF ERIKA IS ELONGATED
FROM SOUTHWEST TO NORTHEAST...IN AGREEMENT WITH SURFACE OBSERVATIONS
FROM THE LESSER ANTILLES AND REPORTS FROM AN AIR FORCE HURRICANE
HUNTER AIRCRAFT.  THE SWIRL SOUTHWEST OF GUADELOUPE APPEARS TO BE
PART OF THIS ELONGATED CIRCULATION...BUT IS NOT THE MEAN CENTER OF
THE OVERALL CYCLONIC ENVELOPE.  AIRCRAFT DATA ALSO INDICATE THAT
ERIKA IS STILL A TROPICAL STORM.  PEAK FLIGHT LEVEL WINDS WERE 44
KT AND SFMR DATA WERE BETWEEN 35-40 KT.  HOWEVER THE STRONGEST
WINDS WERE NEAR A LARGE THUNDERSTORM COMPLEX WELL SOUTHEAST OF THE
CENTER AND NOT DIRECTLY ASSOCIATED WITH THE STORM CIRCULATION.  THE
INITIAL INTENSITY WILL BE HELD AT 35 KT FOR THIS ADVISORY.
 
ERIKA HAS A DIFFICULT ROAD AHEAD WITH INCREASING SHEAR LIKELY AS THE
STORM NEARS THE GREATER ANTILLES.  WHILE SOME INTENSIFICATION CAN
NOT BE RULED OUT IN THE NEXT DAY OR SO...ALL OF THE GLOBAL MODELS
SHOW A VERY HOSTILE ENVIRONMENT WITH 20-30 KT SOUTHWESTERLY WINDS
AT 250 MB OVER ERIKA.  THESE WINDS ARE FORECAST TO CONTINUE...OR
INCREASE...AS THE STORM MOVES NEAR HISPANIOLA.  ALTHOUGH MOST OF THE
INTENSITY GUIDANCE STILL SHOWS RESTRENGTHENING OF ERIKA...THE
GUIDANCE HAS COME DOWN QUITE A BIT FROM THIS MORNING.  THE NHC
FORECAST IS LOWER THAN THE PREVIOUS ONE...AND SHOWS DISSIPATION OF
THE TROPICAL CYCLONE BY 5 DAYS.  ONE ALTERNATIVE SOLUTION IS THAT
INTERACTION WITH HISPANIOLA CAUSES AN EVEN FASTER DEMISE OF ERIKA.
 
THE LONG-TERM MOTION OF THIS SYSTEM IS ABOUT 275/9.  DURING THE
NEXT SEVERAL DAYS...THE STORM SHOULD BE STEERED TO THE WEST OR
WEST-NORTHWEST PRIMARILY BY A RIDGE OVER THE WESTERN ATLANTIC.  THE
GLOBAL MODELS HAVE SHIFTED SOUTHWARD WITH THE TRACK FORECAST SINCE
THIS MORNING...PERHAPS DUE TO THE WEAKER INITIAL STATE OF ERIKA.
THE NHC FORECAST IS SHIFTED SOUTHWARD AS WELL...REMAINING WEST OF
THE MODEL CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/2100Z 16.4N  61.7W    35 KT
 12HR VT     03/0600Z 16.8N  62.9W    35 KT
 24HR VT     03/1800Z 17.4N  64.6W    35 KT
 36HR VT     04/0600Z 18.0N  66.4W    30 KT...INLAND
 48HR VT     04/1800Z 18.7N  67.9W    30 KT
 72HR VT     05/1800Z 20.0N  70.5W    25 KT
 96HR VT     06/1800Z 21.5N  73.5W    20 KT...REMNANT LOW
120HR VT     07/1800Z...DISSIPATED
 
$$
FORECASTER BLAKE/FRANKLIN
 
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