Tropical Storm DEBBY

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TROPICAL STORM DEBBY DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042012
1100 AM EDT TUE JUN 26 2012
 
DEEP CONVECTION HAS BECOME SHEARED AWAY FROM THE CENTER OF DEBBY
AGAIN...WITH THE NEAREST SHOWER ACTIVITY OVER NORTHERN FLORIDA. AN
AMPLIFYING TROUGH OVER THE NORTHEASTERN STATES IS RESPONSIBLE FOR
AN INCREASE IN WESTERLY SHEAR TO 20-25 KT...WELL PREDICTED EARLIER
BY DYNAMICAL MODELS. THE CLOUD LINES IN THE CYCLONE CORE ARE NOT
WELL DEFINED...AND THE CIRCULATION IS BECOMING SLIGHTLY ELONGATED
FROM SOUTHWEST TO NORTHEAST. AIRCRAFT DATA SUGGEST THAT DEBBY IS
WEAKENING...WITH PEAK FLIGHT-LEVEL WINDS OF 51 KT AT 850MB AND
MAXIMUM BIAS-CORRECTED SFMR OBSERVATIONS OF AROUND 30 KT. A
DROPSONDE ABOUT 80 NM SOUTHEAST OF THE CENTER REPORTED SURFACE
WINDS OF 33 KT. BASED ON THESE DATA...THE INITIAL INTENSITY IS
ESTIMATED TO BE 35 KT. DRY AIR CONTINUES TO WRAP AROUND CIRCULATION
OF DEBBY...WITH ADDITIONAL DRY AIR FORECAST BY THE MODELS TO ADVECT
TOWARD THE STORM IN THE NEXT DAY OR SO. DEBBY IS EXPECTED TO WEAKEN
TO A DEPRESSION WHILE THE CENTER MOVES ACROSS FLORIDA...IF NOT
BEFORE. LATER IN THE FORECAST PERIOD...A LESSENING OF THE SHEAR AND
A NEW SUPPLY OF WARM WATER COULD ALLOW DEBBY TO RESTRENGTHEN.
 
AIRCRAFT FIXES AND RADAR IMAGERY INDICATE THAT DEBBY IS DRIFTING
EASTWARD...WITH THE INITIAL MOTION ESTIMATE 090/03.  THE
LARGE-SCALE MODELS ARE IN GOOD AGREEMENT THAT A LONGWAVE TROUGH
DIGGING ALONG 70W WILL HAVE ENOUGH AMPLITUDE TO CARRY DEBBY ACROSS
NORTH-CENTRAL FLORIDA DURING THE NEXT 24-48 HOURS.  EVEN THOUGH THE
WESTERN ATLANTIC TROUGH LIFTS OUT IN ABOUT 2-3 DAYS...AN ABSENCE
OF RIDGING ACROSS THIS REGION MAKES DEBBY SUSCEPTIBLE TO THE
MID-LATITUDE WESTERLY FLOW...AND THE CYCLONE IS NOW EXPECTED TO
CONTINUE MOVING NORTHEASTWARD THROUGH THE FORECAST PERIOD.  THE
GUIDANCE...INCLUDING THE THE 06Z GFS ENSEMBLE MEMBERS...ARE IN
BETTER AGREEMENT ON A FASTER MOTION.  THE LATEST OFFICIAL FORECAST
IS FASTER THAN THE PREVIOUS ONE BUT STILL SLOWER THAN THE BULK OF
THE GUIDANCE.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/1500Z 28.9N  84.2W   35 KT  40 MPH
 12H  27/0000Z 28.9N  83.9W   35 KT  40 MPH
 24H  27/1200Z 29.1N  82.9W   35 KT  40 MPH
 36H  28/0000Z 29.3N  81.7W   30 KT  35 MPH...INLAND
 48H  28/1200Z 29.6N  80.0W   30 KT  35 MPH
 72H  29/1200Z 30.3N  77.5W   35 KT  40 MPH
 96H  30/1200Z 31.5N  74.5W   40 KT  45 MPH
120H  01/1200Z 33.5N  72.0W   45 KT  50 MPH
 
$$
FORECASTER KIMBERLAIN/FRANKLIN
 
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