Tropical Storm DEBBY

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TROPICAL STORM DEBBY DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042012
1000 PM CDT MON JUN 25 2012
 
AFTER AN INTENSE BURST OF DEEP CONVECTION NEAR AND NORTH OF THE
LOW-LEVEL CENTER THIS LATE AFTERNOON AND EVENING...THE CONVECTIVE
CLOUD SHIELD IS SHOWING SIGNS OF SLOWLY PULLING AWAY FROM CENTER OF
CIRCULATION DUE TO MODERATE TO STRONG SOUTHWESTERLY VERTICAL WIND
SHEAR. THE HIGHEST RELIABLE SFMR WINDS REPORTED BY AN AIR FORCE
RESERVE RECON AIRCRAFT THIS EVENING HAS BEEN 42 KT TO THE WEST AND
WELL SOUTHEAST OF THE CENTER...ALONG WITH 59-KT AND 56-KT
FLIGHT-LEVEL WINDS...RESPECTIVELY. ALTHOUGH THE TALLAHASSEE DOPPLER
WEATHER RADAR HAS BEEN INDICATING LARGE WINDS OF 60-65 VELOCITIES
BETWEEN 2000 AND 6500 FT IN SOME RATHER VIGOROUS CONVECTION...THOSE
CONDITIONS HAVE BEEN OVER LAND. THEREFORE...THE INITIAL INTENSITY
WILL REMAIN AT 40 KT.

THE MOTION ESTIMATE IS A SLOW DRIFT TO THE NORTHEAST OR 040/02 KT
OVER THE PAST 12 HOURS. THERE IS NO SIGNIFICANT CHANGE TO THE
PREVIOUS TRACK REASONING. UPPER-AIR DATA AT 18Z AND 00Z INDICATE 
DEBBY REMAINS TRAPPED IN A BLOCKING RIDGE PATTERN THAT EXTENDS
ACROSS THE SOUTHEASTERN U.S. AND INTO THE EASTERN GULF OF MEXICO
AND WESTERN ATLANTIC. THE RESULTANT WEAK STEERING FLOW SHOULD KEEP
DEBBY MOVING VERY SLOWLY NORTHEAST OR EASTWARD AT LESS THAN 5 KT
THROUGHOUT THE FORECAST PERIOD. IN FACT...DEBBY WILL LIKELY REMAIN
OVER THE NORTHEASTERN GULF OF MEXICO FOR AT LEAST THE NEXT 2 DAYS
BEFORE IT CREEPS SLOWLY ACROSS NORTH FLORIDA IN DAYS 3-4. IN THE
ABSENCE OF ANY LARGE-SCALE STEERING FLOW...THE LOW-LEVEL CENTER OF
DEBBY WILL CLOSELY FOLLOW ANY DEEP CONVECTION THAT DEVELOPS...WHICH
SHOULD REMAIN PRIMARILY TO NORTHEAST OF THE CENTER.  THE OFFICIAL
FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK THROUGH
DAY 3...AND IS THEN A LITTLE NORTH OF THE PREVIOUS TRACK AND CLOSE
TO THE NHC MODEL CONSENSUS.

THE PRESENCE OF DRY MID-LEVEL AIR WRAPPING INTO THE WESTERN AND
SOUTHERN PORTION OF THE CIRCULATION...ALONG WITH SOUTHWESTERLY
VERTICAL WIND SHEAR OF 20-25 KT FOR THE NEXT 48 HOURS OR SO SHOULD
INHIBIT ANY SIGNIFICANT DEVELOPMENT WHILE DEBBY REMAINS OVER WATER.
THE SHEAR DECREASES SIGNIFICANTLY BY 72 HOURS AND BEYOND...BUT
DEBBY WILL BE OVER OR INTERACTING WITH LAND AT DAYS 3 AND 4...SO
THAT WILL PREVENT THE CYCLONE FROM TAKING ADVANTAGE OF THE
IMPROVING SHEAR CONDITIONS. BY DAY 5...HOWEVER...DEBBY IS EXPECTED
TO BE MOVING OVER THE WARMER WATERS OF THE GULFSTREAM...WHICH MAY
ALLOW FOR SOME MODEST STRENGTHENING TO OCCUR AFTER HAVING WEAKENED
OVER LAND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE
PREVIOUS ADVISORY AND CLOSELY FOLLOWS THE LGEM INTENSITY MODEL.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/0300Z 29.2N  85.1W   40 KT  45 MPH
 12H  26/1200Z 29.3N  84.9W   40 KT  45 MPH
 24H  27/0000Z 29.4N  84.6W   40 KT  45 MPH
 36H  27/1200Z 29.5N  84.2W   40 KT  45 MPH
 48H  28/0000Z 29.6N  83.6W   40 KT  45 MPH
 72H  29/0000Z 29.8N  82.3W   30 KT  35 MPH...INLAND
 96H  30/0000Z 30.1N  80.7W   35 KT  40 MPH...OVER WATER
120H  01/0000Z 30.8N  78.7W   40 KT  45 MPH
 
$$
FORECASTER STEWART
 
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