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Tropical Depression TWENTY-FOUR (Text)

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TROPICAL DEPRESSION TWENTY-FOUR DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SUN OCT 16 2005
 
THE CONVECTIVE STRUCTURE OF THE DEPRESSION HAS CERTAINLY CHANGED
DURING THE PAST 24 HOURS.  WHILE OUTER BANDS HAVE DISSIPATED...
SOME VERY DEEP CONVECTION HAS ERUPTED NEAR AND ESPECIALLY TO THE
SOUTH OF THE CIRCULATION CENTER TONIGHT... ALTHOUGH THE CONVECTION
HAS BEEN PERCOLATING RATHER THAN MAINTAINING CONSISTENCY NEAR THE
CENTER.  DVORAK INTENSITY ESTIMATES AT 00Z WERE T2.5/35 KT FROM
TAFB AND SAB AND T2.0/30 KT FROM AFWA.  WIND OBSERVATIONS FROM NOAA
BUOY 42057 ABOUT 60 MILES WEST OF THE CENTER AND OUTSIDE OF THE
CONVECTION HAVE BEEN NO STRONGER THAN 19 KT DURING THE EVENING...
AND IT IS NOT CERTAIN THAT THE WINDS ARE TWICE THAT STRONG BENEATH
THE DEEP CONVECTION.  EVEN THOUGH THE ADVISORY INTENSITY IS HELD AT
30 KT... THE DEPRESSION APPEARS VERY CLOSE TO TROPICAL STORM STATUS
AND WILL LIKELY REACH IT ON MONDAY MORNING.
 
THE INITIAL MOTION REMAINS ALMOST NON-EXISTENT BUT IS ESTIMATED TO
BE 275/2. THE VARIOUS DYNAMICAL MODELS AGREE ON A GENERAL WESTWARD
TRACK FOR THE NEXT 2-3 DAYS WITH PERHAPS A SLIGHT INCREASE IN
FORWARD SPEED. THE WESTWARD TREND CONTINUES IN THE 18Z RUNS OF THE
GFS AND GFDL WHICH NOW FORECAST THE TROPICAL CYCLONE TO REACH THE
YUCATAN PENINSULA IN ABOUT FOUR DAYS. THE LAST FEW GFS RUNS HAVE
BEEN HANGING ON TO PROGRESSIVELY MORE MID-LEVEL RIDGING FOR THE
NEXT THREE DAYS OR SO OVER THE WESTERN GULF OF MEXICO... AND
SLIGHTLY MORE ZONAL FLOW OVER THE SOUTHEASTERN UNITED STATES ON
DAYS 4-5. THE NEW GFS AND GFDL SOLUTIONS ARE NOW MUCH CLOSER TO THE
NOGAPS... WHICH IS STILL ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE
BUT HAS NUDGED A LITTLE BACK TO THE NORTH. THE FORECAST PATTERN NOW
ANTICIPATED BY MOST OF THE MODELS WOULD DELAY A TURN OF THE
TROPICAL CYCLONE NORTHWARD TO VERY LATE IN THE FIVE DAY FORECAST
PERIOD. THE NEW OFFICIAL FORECAST IS AGAIN ADJUSTED SOUTHWESTWARD
TOWARD... BUT NOT AS FAR AS... THE DYNAMICAL CONSENSUS. DUE TO THE
LARGE SPREAD OF THE MODELS... ESPECIALLY AT DAYS 3-5... THE
UNCERTAINTY IN THIS TRACK FORECAST IS FAIRLY SIGNIFICANT.
 
THERE IS NO CHANGE TO THE INTENSITY FORECAST OR SUPPORTING
REASONING.  AN ENVIRONMENT OF WEAK VERTICAL WIND SHEAR PROVIDED BY
A LARGE UPPER-LEVEL ANTICYCLONE OVER THE WESTERN CARIBBEAN... AND
WATERS WITH LARGE UPPER OCEANIC HEAT CONTENT... SHOULD LEAD TO
STEADY STRENGTHENING DURING THE NEXT FEW DAYS.  THIS APPEARS EVEN
MORE LIKELY NOW GIVEN THE MORE CONCENTRATED CONVECTION NEAR THE
CIRCULATION CENTER THIS EVENING.  THE LATEST GFDL FORECASTS MORE
STRENGTHENING... AND MORE RAPIDLY... THAN IN THE PREVIOUS FEW
RUNS... WITH AN INTENSITY NEAR 115 KT IN ABOUT 36 HOURS.  MEANWHILE
THE SHIPS GUIDANCE REMAINS MORE CONSERVATIVE IN FORECASTING A
HURRICANE IN 48-72 HOURS.  THE NEW OFFICIAL FORECAST REMAINS IN
BETWEEN AND IS ESSENTIALLY AN UPDATE OF THE PREVIOUS ADVISORY.


FORECASTER KNABB
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 17.6N  79.7W    30 KT
 12HR VT     17/1200Z 17.7N  80.2W    40 KT
 24HR VT     18/0000Z 17.8N  80.9W    50 KT
 36HR VT     18/1200Z 18.0N  81.9W    60 KT
 48HR VT     19/0000Z 18.3N  83.0W    70 KT
 72HR VT     20/0000Z 19.0N  85.0W    80 KT
 96HR VT     21/0000Z 20.5N  86.5W    90 KT
120HR VT     22/0000Z 22.5N  87.5W    90 KT
 
 
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