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Tropical Storm DEBBY (Text)

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TROPICAL STORM DEBBY DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042006
500 AM EDT WED AUG 23 2006

THE SATELLITE APPEARANCE OF DEBBY CONTINUES TO IMPROVE AND A 
0331 UTC AQUA MICROWAVE OVERPASS DETECTED A FAIRLY WELL ORGANIZED
SYSTEM...WITH WELL DEFINED BANDS AROUND THE CENTER.  DVORAK
INTENSITY ESTIMATES ARE 45 KT FROM SAB...AND 35 KT FROM TAFB AND
AFWA. THEREFORE...THE INITIAL INTENSITY IS INCREASED TO 40 KT. 
 
THE INITIAL MOTION ESTIMATE IS 295/14. DEBBY IS CURRENTLY BEING
STEERED WEST-NORTHWEST TO NORTHWESTWARD AROUND THE SOUTHWESTERN
PERIPHERY OF A MID-TO UPPER-LEVEL RIDGE CENTERED NEAR THE AZORES.
THE RELIABLE TRACK MODELS ARE TIGHTLY CLUSTERED...MAINTAINING 
THIS MOTION THROUGH THE NEXT 48 TO 72 HOURS. AT DAYS 4 AND
5...GLOBAL MODELS DEVELOP A SIGNIFICANT WEAKNESS IN THE
RIDGE AS A MID- TO UPPER-LEVEL TROUGH AMPLIFIES OVER THE CENTRAL
ATLANTIC.  THE TRACK DIFFERENCES SEEN IN THE THE GLOBAL MODELS
APPEAR TO BE THE RESULT OF DIFFERENCES IN THE FORECAST STRENGTH OF
THE TROPICAL CYCLONE.  THE UMKET MODEL DEPICTS A MUCH WEAKER SYSTEM
AND IN TURN TRACKS IT MORE WESTWARD...WHILE THE GFS AND GFDL MODELS
HAVE A STRONGER CYCLONE WHICH FEELS THE EFFECTS OF THE TROUGH AND
TURNS NORTHWARD NEAR THE END OF THE PERIOD.  THE NOGAPS TRACK SEEMS
UNREASONABLE BECAUSE IT RESULTS FROM AN UNREALISTIC DISSIPATION OF
THE LOW-LEVEL CIRCULATION AND REFORMATION OF THE SYSTEM FROM A MID-
TO UPPER-LEVEL LOW TO THE WEST.  THE OFFICIAL TRACK FORECAST IS
VERY CLOSE TO THE PREVIOUS ADVISORY THROUGH 72 HOURS. THEREAFTER...
IT HAS BEEN SHIFTED SLIGHTLY TO THE RIGHT IN GENERAL AGREEMENT WITH
THE GFS...GFDL...AND THE FSU SUPERENSEMBLE SOLUTIONS.

DEBBY WILL BE ENCOUNTERING DRIER MID-LEVEL AIR AND SLIGHTLY COOLER
SSTS OVER THE NEXT 36 HOURS OR SO...WHICH SHOULD KEEP 
INTENSIFICATION SLOW IN THE NEAR TERM.  THEREAFTER... THE CYCLONE
WILL BE PASSING OVER WARMER SSTS...BUT SHEAR IS FORECAST TO
STRENGTHEN WHICH MAKES FOR A DIFFICULT INTENSITY PREDICTION.  THE
NHC FORECAST BRINGS DEBBY TO HURRICANE STRENGTH IN 4 DAYS...WHICH
IS VERY CLOSE TO THE CONSENSUS OF THE GFDL AND SHIPS...BUT IS
LEVELED OFF IN DEFERENCE TO THE POSSIBILITY OF INCREASING SHEAR.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0900Z 15.9N  30.1W    40 KT
 12HR VT     23/1800Z 16.9N  32.2W    45 KT
 24HR VT     24/0600Z 18.2N  35.0W    50 KT
 36HR VT     24/1800Z 19.6N  37.9W    50 KT
 48HR VT     25/0600Z 21.0N  40.8W    50 KT
 72HR VT     26/0600Z 24.0N  46.5W    60 KT
 96HR VT     27/0600Z 27.5N  51.0W    65 KT
120HR VT     28/0600Z 30.0N  53.0W    65 KT
 
$$
FORECASTER BROWN
 
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