[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 240857
TCDAT2
TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED AUG 24 2005

SATELLITE IMAGERY DURING THE NIGHT INDICATES THAT TROPICAL
DEPRESSION TWELVE IS GRADUALLY BECOME BETTER ORGANIZED...WITH AN
INCREASE IN THE CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE.
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT SHOW
THAT OVERALL THE CIRCULATION IS BETTER DEFINED THAT IT WAS 12 HR
AGO...ALTHOUGH THE MAXIMUM WINDS ARE 75-90 N MI EAST OF THE CENTER.
THE AIRCRAFT FOUND 45 KT FLIGHT-LEVEL WINDS AT 925 MB IN THAT
AREA...WHICH WOULD NORMALLY SUPPORT TROPICAL STORM SURFACE WINDS.
HOWEVER...SINCE THE WINDS ARE SO FAR REMOVED FROM THE CENTER...AND
NONE OF THE BAHAMAS STATIONS ARE REPORTING MORE THAN 20 KT WINDS...
IT IS UNCLEAR HOW MUCH OF THE FLIGHT-LEVEL WINDS ARE REACHING THE
SURFACE.  THUS...THE CYCLONE REMAINS A 30 KT DEPRESSION FOR THIS
ADVISORY.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 310/6.  THE DEPRESSION IS
ON THE SOUTHWEST SIDE OF THE BERMUDA HIGH...WITH A WEAKNESS IN THE
HIGH NEAR THE SOUTHEAST U.S. COAST.  LARGE-SCALE MODELS...EXCEPT
FOR THE GFS...FORECAST THE WEAKNESS TO FILL AND BE REPLACED BY A
RIDGE AS A MID/UPPER-LEVEL TROUGH OVER THE NORTHEASTERN U. S. MOVES
EASTWARD.  THIS SHOULD CAUSE THE CYCLONE TO TURN MORE WESTWARD IN
24-48 HR...TRACKING ACROSS SOUTHERN FLORIDA INTO THE EASTERN GULF
OF MEXICO.  ALL TRACK GUIDANCE EXCEPT FOR THE GFS AGREES WITH THIS
SCENARIO.  THE GFS KEEPS A WEAKNESS IN PLACE THROUGH THE FORECAST
PERIOD...AND CALLS FOR THE CYCLONE TO STALL OVER FLORIDA AND THEN
MOVE NORTHWARD BY 120 HR.  THE OFFICIAL FORECAST DISREGARDS THE GFS
SOLUTION AND CALLS FOR THE CYCLONE TO CROSS FLORIDA INTO THE GULF.
THE NEW TRACK IS AN UPDATE OF THE OLD TRACK AND IS JUST TO THE
RIGHT OF THE MODEL CONSENSUS.

THE INTENSITY FORECAST REMAINS PROBLEMATIC.  IN THE SHORT TERM...THE
BROAD NATURE OF THE SYSTEM AND A POCKET OF MID/UPPER-LEVEL DRY AIR
SEEN IN WATER VAPOR IMAGERY JUST WEST OF THE SYSTEM SHOULD SLOW
DEVELOPMENT.  ONCE THE CYCLONE CONSOLIDATES...IT SHOULD STRENGTHEN
MORE QUICKLY AS THE UPPER-LEVEL WINDS BECOME MORE FAVORABLE.  THE
SHIPS MODEL BRINGS THE SYSTEM TO 55-65 KT AS IT REACHES FLORIDA.
ON THE OTHER HAND...THE GFDL BRINGS IT TO FLORIDA AS A DEPRESSION.
THIS APPEARS UNLIKELY GIVEN THE REASONABLY FAVORABLE ENVIRONMENT
ALONG THE FORECAST TRACK.  THE INTENSITY FORECAST LEANS TOWARDS THE
SHIPS MODEL...CALLING FOR A 60 KT INTENSITY IN 48 HR.  THE CYCLONE
SHOULD WEAKEN WHILE OVER FLORIDA...THE RE-INTENSIFY OVER THE
EASTERN GULF OF MEXICO.

A TROPICAL STORM WARNING COULD BE ISSUED FOR PORTIONS OF THE
TROPICAL STORM WATCH AREA IN FLORIDA LATER TODAY... POSSIBLY
INCLUDING A HURRICANE WATCH IF THE DEPRESSION STRENGTHENS MORE
RAPIDLY THAN CURRENTLY FORECAST.

THE UNCERTAINTY IN THIS FORECAST...AND THE POTENTIAL IMPACTS OF
THIS TROPICAL CYCLONE... ARE QUANTIFIED IN AN EXPERIMENTAL NHC TEXT
PRODUCT ISSUED WITH THIS AND EVERY ADVISORY PACKAGE DURING 2005.
THIS PRODUCT PROVIDES WIND SPEED PROBABILITIES AT SPECIFIC
LOCATIONS. THE PROBABILITIES OF EXPERIENCING TROPICAL STORM FORCE
WINDS FROM THIS SYSTEM DURING THE NEXT FIVE DAYS ARE SIMILAR AT
EACH INDIVIDUAL LOCATION THROUGHOUT THE TROPICAL STORM WATCH AREA.


FORECASTER BEVEN


FORECAST POSITIONS AND MAX WINDS

INITIAL      24/0900Z 24.0N  76.4W    30 KT
 12HR VT     24/1800Z 24.7N  77.1W    40 KT
 24HR VT     25/0600Z 25.5N  78.0W    45 KT
 36HR VT     25/1800Z 25.9N  78.9W    50 KT
 48HR VT     26/0600Z 26.1N  80.0W    60 KT
 72HR VT     27/0600Z 26.5N  82.0W    40 KT...INLAND
 96HR VT     28/0600Z 27.0N  84.0W    55 KT...OVER WATER
120HR VT     29/0600Z 28.0N  86.5W    65 KT


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