Tropical Storm ERIKA

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TROPICAL STORM ERIKA DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062009
1100 PM AST WED SEP 02 2009
 
ERIKA IS BARELY A TROPICAL STORM. DATA FROM A RECONNAISSANCE PLANE A
FEW HOURS AGO AND OBSERVATIONS FROM THE LESSER ANTILLES INDICATE
THAT ERIKA IS VERY DISORGANIZED AND CONSISTS OF A BROAD ELONGATED
CYCLONIC CIRCULATION WITH TROPICAL STORM FORCE WINDS IN
SQUALLS...LIMITED TO A FEW SPOTS OVER THE EASTERN SEMICIRCLE. A NEW
CENTER COULD REFORM AT ANY TIME WITHIN THE LARGE GYRE. INFRARED
PICTURES SUGGEST THAT THERE IS UPPER-LEVEL OUTFLOW IN ALL
QUADRANTS...BUT THERE IS ALSO SHEAR CAUSED BY WINDS BELOW THE
CIRRUS CANOPY BECAUSE THE CENTER CONTINUES TO BE LOCATED ON THE
WESTERN EDGE OF A STRONG AREA OF CONVECTION. IT APPEARS THAT ERIKA
IS ON ITS WAY TO DEGENERATE INTO A TROUGH OF LOW PRESSURE OR REFORM
SOMEWHERE WITHIN THE CIRCULATION. GLOBAL MODELS ARE FORECASTING A
LITTLE MORE FAVORABLE ENVIRONMENT IN 12 TO 24 HOURS AND THAT IS THE
REASON THE OFFICIAL FORECAST CALLS FOR NO CHANGE IN INTENSITY
DURING THE NEXT 12 HOURS. THEREAFTER...THE COMBINATION OF VERY
HOSTILE UPPER-LEVEL WESTERLIES AND THE LAND MASS OF HISPANIOLA
ALONG THE PATH OF THE CYCLONE...WOULD RESULT IN WEAKENING. THE HWRF
IS THE ONLY MODEL THAT FORECAST ERIKA TO BECOME A STRONG HURRICANE
AND THIS IS HIGHLY UNLIKELY TO OCCUR.           

THE CENTER OF THE LARGE CIRCULATION ENVELOPE HAS BEEN MOVING
WESTWARD AT 7 KNOTS. THE CYCLONE SHOULD BE STEERED TOWARD THE
WEST-NORTHWEST DURING THE NEXT FEW DAYS AROUND THE SUBTROPICAL
RIDGE WHICH IS FORECAST TO BUILD WESTWARD BY THE GLOBAL MODELS.
THE TRACK GUIDANCE IS LIMITED SINCE VARIOUS MODELS WEAKEN THE
CYCLONE WITH TIME AND THE TRACKERS NO LONGER FOLLOW THE CENTER.
HOWEVER...THE AVAILABLE CONSENSUS ALSO SUGGESTS THAT ERIKA OR ITS
REMNANTS SHOULD MOVE TOWARD THE WEST-NORTHWEST UNTIL DISSIPATION
AND SO DOES THE OFFICIAL FORECAST.  
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      03/0300Z 16.1N  62.4W    35 KT
 12HR VT     03/1200Z 16.4N  63.8W    35 KT
 24HR VT     04/0000Z 17.0N  65.5W    30 KT
 36HR VT     04/1200Z 18.0N  67.0W    30 KT
 48HR VT     05/0000Z 18.5N  68.5W    30 KT...INLAND
 72HR VT     06/0000Z 20.0N  71.0W    25 KT...REMNANT LOW
 96HR VT     07/0000Z 22.0N  73.0W    20 KT...REMNANT LOW
120HR VT     08/0000Z...DISSIPATED
 
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FORECASTER AVILA
 
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