[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 070228
TCDAT4
TROPICAL DEPRESSION NINE DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SAT AUG 06 2005

THE DEPRESSION CONTINUES TO BE STRONGLY SHEARED. THERE IS A
WELL-DEFINED LOW-LEVEL CIRCULATION AND MOST OF THE CONVECTION IS TO
THE EAST OF THE CENTER. DVORAK CLASSIFICATIONS CAN HARDLY
SUPPORT A T-NUMBER BY USING THE DISTANCE BETWEEN THE CENTER AND THE
CONVECTION.  INITIAL INTENSITY IS KEPT AT 30 KNOTS.  IT IS DIFFICULT
TO VISUALIZE HOW THE CYCLONE WILL SURVIVE WITH THE CURRENT SHEAR
CAUSED BY THE AMPLIFYING UPPER-LOW TO ITS NORTH. THE ATLANTIC IS
PLAGUED WITH UPPER-LOWS...A PATTERN THAT IS UNFAVORABLE FOR
TROPICAL CYCLONES TO INTENSIFY. THE GFS IS KEEPING THE UNFAVORABLE
UPPER-LEVEL WINDS NEAR THE CYCLONE FOR DAYS...AND BOTH THE GFS AND
THE GFDL RELENTLESSLY INSIST ON DISSIPATING THE CYCLONE. IT IS
HARD TO GO AGAINST THESE TWO MODELS. HOWEVER...CONTINUITY FROM
PREVIOUS FORECASTS WILL BE FOLLOWED...AND THE OFFICIAL FORECAST
CALLS FOR SOME STRENGTHENING BY THE END OF THE PERIOD. THIS IS
BASED ON THE OTHER GLOBAL MODELS WHICH HAVE A LESS HOSTILE
ENVIRONMENT ALONG WITH THE SHIPS MODEL GUIDANCE.

THE CENTER HAS BEEN MOVING WESTWARD ABOUT 9 KNOTS DURING THE PAST
FEW HOURS. HOWEVER...MOST OF THE GUIDANCE IS IN FAIRLY GOOD
AGREEMENT MOVING THE CYCLONE TOWARD THE WEST-NORTHWEST OR 285
DEGREES AT 9 KNOTS DURING THE NEXT 2 TO 3 DAYS. THEREAFTER...THE
UK...THE ECMWF AND THE CANADIAN MODELS PREFER A SOUTHERNMOST TRACK
AND THE NOGAPS A NORTHERMOST. THE GFS AND GFDL ARE NOT INCLUDED
SINCE THEY DISSIPATE THE CYCLONE QUITE SOON. THE OFFICIAL FORECAST
TRACK IS IN THE MIDDLE OF THE GUIDANCE ENVELOPE. THERE IS LOW
CONFIDENCE IN THIS FORECAST BECAUSE IF THE SHEAR CONTINUES...THERE
WILL BE NOTHING TO TRACK AS SUGGESTED BY GFS AND GFDL MODELS.

FORECASTER AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL      07/0300Z 18.9N  44.3W    30 KT
 12HR VT     07/1200Z 19.2N  45.6W    30 KT
 24HR VT     08/0000Z 19.7N  47.6W    30 KT
 36HR VT     08/1200Z 20.5N  49.5W    30 KT
 48HR VT     09/0000Z 21.5N  51.0W    30 KT
 72HR VT     10/0000Z 23.0N  54.5W    35 KT
 96HR VT     11/0000Z 25.0N  57.0W    45 KT
120HR VT     12/0000Z 27.0N  59.5W    50 KT


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