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Tropical Depression SIX (Text)

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TROPICAL DEPRESSION SIX DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON JUL 21 2003
 
TROPICAL DEPRESSION SIX HAS BECOME BETTER ORGANIZED DURING THE PAST
6 HOURS AND IS PROBABLY CLOSE TO TROPICAL STORM STRENGTH...IF IT
HAS A CLOSED SURFACE CIRCULATION. AN AIR FORCE RESERVE RECON
AIRCRAFT WILL INVESTIGATE THE CYCLONE LATER THIS AFTERNOON. THE
INITIAL INTENSITY REMAINS AT 30 KT BASED ON CONSENSUS T2.0 OR 30 KT
FROM ALL THREE SATELLITE AGENCIES.
 
THE INITIAL MOTION IS 280/20.  THE DEPRESSION REMAINS EMBEDDED IN
DEEP EASTERLY STEERING FLOW ON THE SOUTH SIDE OF A DEEP ANTICYCLONE
THAT IS ANCHORED OVER THE CENTRAL ATLANTIC. A GENERAL WEST TO
WEST-NORTHWESTWARD MOTION SHOULD CONTINUE THROUGH AT LEAST 72
HOURS. AFTER THAT...THE FORECAST IS LESS STRAIGHT-FORWARD. ALL OF
THE GLOBAL MODELS NOW AGREE ON A PORTION THE CURRENT LONGWAVE
TROUGH OVER THE SOUTHEASTERN U.S. LIFTING OUT TO THE NORTHEAST IN
48 TO 72 HOURS WITH ANOTHER SHORTWAVE TROUGH DROPPING DOWN THE BACK
SIDE AND MAINTAINING THE TROUGH AXIS AND AN ASSOCIATED WEAKNESS IN
THE MID-LEVEL SUBTROPICAL RIDGE ACROSS FLORIDA...THE SOUTHEASTERN
U.S.... AND THE CENTRAL AND EASTERN GULF OF MEXICO. THE NOGAPS AND
UKMET MODELS ARE ALMOST IDENTICAL IN BRINGING THE CYCLONE ACROSS
HISPANIOLA AND TO NEAR THE EAST COAST OF FLORIDA BY DAY 5...WHILE
THE GFS AND CANADIAN MODELS DISSIPATE THE CYCLONE BY 72 HOURS.
HOWEVER...THE BAM MODELS ARE CLUSTERED CLOSE TOGETHER AND BRING THE
CYCLONE ACROSS WESTERN CUBA BY DAY 4 AND INTO THE SOUTHEAST GULF OF
MEXICO BY DAY 5. THIS TRACK IS ALSO SIMILAR TO THE RTACK OF THE GFS
AND CANADIAN 500 MB MID-LEVEL CIRCULATION. THEREFORE...THE OFFICIAL
FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS TRACK THROUGH
DAY 4...WITH A SLOWER SPEED AND SLIGHT NORTHWARD SHIFT ON DAY 5.

THERE IS NO CHANGE TO THE PREVIOUS FEW INTENSITY FORECASTS OR
REASONINGS. UPPER-LEVEL CONDITIONS ARE NOT OVERLY FAVORABLE FOR
DEVELOPMENT THROUGH 48 TO 72 HOURS...BUT AFTERWARDS CONDITIONS ARE
FORECAST TO IMPROVE. GIVEN THAT THE CYCLONE WILL BE OVER 29C OR
HIGHER SST WATER...THE INTENSITY FORECASTS AT DAYS 4 AND 5 COULD
EASILY BE TOO LOW. IT SHOULD BE NOTED THAT THE SHIPS INTENSITY
MODEL ONLY BRINGS THE CYCLONE UP TO 47 KT IN 120 HOURS...WHILE
SHIFOR BRINGS IT UP TO 80 KT.

TROPICAL STORM WATCHES ARE NOW IN EFFECT FOR PUERTO RICO AND THE
U.S. VIRGIN ISLANDS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0900Z 14.0N  56.7W    30 KT
 12HR VT     21/1800Z 14.6N  59.7W    35 KT
 24HR VT     22/0600Z 15.5N  63.5W    40 KT
 36HR VT     22/1800Z 16.6N  67.3W    45 KT
 48HR VT     23/0600Z 17.7N  70.8W    50 KT
 72HR VT     24/0600Z 20.0N  77.5W    55 KT
 96HR VT     25/0600Z 22.5N  82.0W    60 KT
120HR VT     26/0600Z 25.5N  85.0W    60 KT
 
 
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