Tropical Storm ERIKA

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TROPICAL STORM ERIKA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062009
1100 PM AST TUE SEP 01 2009
 
AN AIR FORCE RECONNAISSANCE PLANE HAS BEEN TRAVERSING ERIKA AND
FOUND THAT THE CENTER HAS MOVED VERY LITTLE DURING THE PAST SEVERAL
HOURS. THE CIRCULATION HAS BECOME BETTER ESTABLISHED AND THE
MINIMUM CENTRAL PRESSURE FROM A DROP WAS 1004 MB. THIS VALUE COULD
BE A LITTLE BIT LOWER SINCE THE DROP MEASURED 19 KNOTS AT THE
SURFACE. THE SFMR AND THE PLANE MEASURED 55 AND 50 KNOTS...
RESPECTIVELY...TO THE NORTHEAST OF THE CENTER. THEREFORE...THE
INITIAL INTENSITY IS SET AT 50 KNOTS. THERE HAS BEEN AN INCREASE IN
CONVECTION NEAR THE CENTER AND THERE ARE SOME INDICATIONS FROM THE
HIGH-CLOUD MOTION THAT THE SHEAR HAS LESSENED A LITTLE BIT. ERIKA
COULD STRENGTHEN SOME DURING THE NEXT DAY OR TWO. THEREAFTER...MOST
OF THE GLOBAL MODELS HAVE STRONG UPPER-LEVEL WESTERLY WINDS OVER
ERIKA...A PATTERN THAT IS NOT FAVORABLE FOR STRENGTHENING. IN
FACT...THE OFFICIAL FORECAST CALLS FOR WEAKENING DURING THAT PERIOD
AS OPPOSED TO THE GFDL AND HWRF THAT BOTH MAKE ERIKA A STRONG
HURRICANE.  

ERIKA HAS BEEN MOVING VERY LITTLE DURING THE PAST FEW HOURS...BUT
THIS COULD BE THE RESULT OF THE CYCLONE BEING IN ITS FORMATIVE
STAGE. ERIKA IS LOCATED ON THE SOUTHWESTERN EDGE OF THE
AZORES-BERMUDA HIGH AND THE CYCLONE SHOULD BEGIN TO MOVE TOWARD THE
WEST-NORTHWEST OR 300 DEGREES AT 7 KNOTS ON WEDNESDAY. BECAUSE THE
AZORES-BERMUDA HIGH IS FORECAST TO EXPAND WESTWARD A LITTLE
BIT...ERIKA SHOULD MAINTAIN THIS WEST-NORTHWEST TO NORTHWEST TRACK.
SINCE THE STEERING CURRENTS ARE NOT VERY STRONG....ERIKA SHOULD
MOVE SLOWLY. GUIDANCE IS NOT IN GOOD AGREEMENT AND THE CONFIDENCE
IN THE FORECAST TRACK IS LOW. BOTH THE UK AND THE GFS TAKE A MORE
WESTWARD TRACK WHILE THE OTHER MODELS SHOW A MORE NORTHWESTERLY
COMPONENT. THE OFFICIAL FORECAST IS VERY CLOSE TO THE CONSENSUS
WHICH IS CENTERED BETWEEN THESE TWO MODEL OPTIONS. 

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/0300Z 17.5N  57.6W    50 KT
 12HR VT     02/1200Z 18.0N  58.7W    55 KT
 24HR VT     03/0000Z 18.5N  60.2W    60 KT
 36HR VT     03/1200Z 19.0N  61.8W    60 KT
 48HR VT     04/0000Z 19.5N  63.2W    55 KT
 72HR VT     05/0000Z 21.0N  66.0W    50 KT
 96HR VT     06/0000Z 22.6N  68.4W    45 KT
120HR VT     07/0000Z 24.5N  71.0W    45 KT
 
$$
FORECASTER AVILA
 
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