Tropical Depression TWENTY

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TROPICAL DEPRESSION TWENTY DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SAT OCT 01 2005
 
SATELLITE DATA AND SURROUNDING SURFACE OBSERVATIONS INDICATE THE
LARGE LOW PRESSURE SYSTEM THAT HAS BEEN SLOWLY FESTERING OVER THE
NORTHWESTERN CARIBBEAN SEA FOR THE PAST 4 DAYS HAS FINALLY
ORGANIZED ENOUGH TO BE CLASSIFIED AS A TROPICAL CYCLONE. THE EXACT
CENTER OF THE DEPRESSION IS DIFFICULT TO DETERMINE... BUT WIND AND
PRESSURE REPORTS FROM NOAA BUOY 42056 SUGGEST THAT THE CENTER IS
LOCATED JUST SOUTH OR SOUTHWEST OF THE BUOY LOCATION. THE INITIAL
INTENSITY OF 25 KT IS BASED ON NOAA BUOY WIND REPORTS RANGING FROM
23 TO 27 KT OVER THE PAST 9 HOURS. TWO SHIPS NEAR THE YUCATAN
CHANNEL AT 01/06Z ALSO REPORTED SUSTAINED WINDS OF 28-32 KT.
HOWEVER... QUALITY CONTROL CHECKS BY THE NOAA OCEAN PREDICTION
CENTER INDICATE THAT THOSE WINDS WERE LIKELY 3-5 KT HIGH.
CONVECTIVE BANDING FEATURES CONTINUE TO IMPROVE... AND SO HAS THE
OUTFLOW PATTERN. AN AIR FORCE RESERVE AIRCRAFT IS ENROUTE TO
INVESTIGATE THE SYSTEM AND SHOULD ARRIVE BY EARLY AFTERNOON.
 
THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 295/05. THE LOW-LEVEL
CIRCULATION CENTER HAS BEEN DIFFICULT TO LOCATE AT BEST... BUT THE
SLOWLY BACKING WIND PROFILE AT NOAA BUOY 42056 SUGGESTS THAT THE
CENTER IS SOMEWHERE NEARBY. THE AVAILABLE NHC MODEL GUIDANCE IS IN
FAIR AGREEMENT ON THE CYCLONE MOVING WEST-NORTHWESTWARD FOR THE
NEXT 72 HOURS AS THE BROAD BUT WEAK SUBTROPICAL RIDGE ALONG THE
NORTHERN GULF COAST REMAINS INTACT THROUGH THE FORECAST PERIOD. THE
FORECAST TRACK IS A BLEND OF THE 3 BAM MODELS... PLUS THE GFS AND
UKMET SOLUTIONS.

THE MAIN INHIBITING FACTOR FOR INTENSIFICATION DURING THE NEXT 4
DAYS IS LAND INTERACTION. AS THE CYCLONE PASSES OVER THE YUCATAN
PENINSULA IN 18-30 HOURS... INCREASED FRICTIONAL CONVERGENCE IS
EXPECTED TO TIGHTEN UP THE RATHER LOOSE LOW-LEVEL WIND FIELD... AND
THIS SHOULD AID IN THE QUICK REDEVELOPMENT OF DEEP CONVECTION ONCE
THE SYSTEM EMERGES OVER THE SOUTHWESTERN GULF OF MEXICO BY 36
HOURS. THE VERTICAL SHEAR IS FORECAST TO DECREASE TO 5 KT OR LESS
WHILE THE CYCLONE IS OVER 29-30C SSTS. WITH A VERY FAVORABLE
OUTFLOW PATTERN FORECAST BY ALL THE GLOBAL MODELS... THIS SYSTEM
COULD EASILY REACH HURRICANE STRENGTH BEFORE IT MAKES A SECOND
LANDFALL OVER NORTHEASTERN MEXICO. EXCLUDING LAND INTERACTION...
THE SHIPS MODEL INCREASES THE INTENSITY TO 88 KT BY 96 HOURS.
 
FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      01/1500Z 19.3N  85.8W    25 KT
 12HR VT     02/0000Z 19.9N  86.9W    35 KT
 24HR VT     02/1200Z 20.8N  88.8W    25 KT...INLAND YUCATAN
 36HR VT     03/0000Z 21.7N  90.7W    30 KT...OVER WATER
 48HR VT     03/1200Z 22.5N  92.5W    45 KT
 72HR VT     04/1200Z 23.4N  95.5W    60 KT
 96HR VT     05/1200Z 23.5N  98.5W    40 KT...INLAND NERN MEXICO
120HR VT     06/1200Z 23.0N 101.5W    20 KT...DISSIPATING INLAND
 
 
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