[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 202033
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  31
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT MON AUG 20 2007

COMMUNICATIONS PROBLEMS ARE PREVENTING THE RECEIPT OF MOST DATA FROM
THE AIR FORCE RECONNAISSANCE AIRCRAFT THIS AFTERNOON...ALTHOUGH A
1930Z VORTEX FIX WAS RECEIVED. AT THAT TIME THE MINIMUM PRESSURE
WAS 918 MB...WITH MAXIMUM FLIGHT-LEVEL WINDS OF 151 KT. EARLIER IN
THE FLIGHT...A PEAK SFMR WIND OF 123 KT WAS OBSERVED.  DVORAK
CLASSIFICATIONS FROM TAFB AND SAB WERE 127 KT AT 18Z.  BASED ON
THESE DATA...THE INITIAL INTENSITY IS HELD AT 130 KT. ALL OBJECTIVE
GUIDANCE SHOWS ADDITIONAL INTENSIFICATION OVER THE DEEP WARM WATERS
OF THE WESTERN CARIBBEAN...AND DEAN COULD REACH CATEGORY FIVE
STATUS BEFORE MAKING LANDFALL. A 15Z MICROWAVE PASS SHOWS A PARTIAL
OUTER EYEWALL...BUT THIS WILL PROBABLY NOT HAVE ENOUGH TIME TO
INDUCE ANY WEAKENING BEFORE LANDFALL.  DEAN IS EXPECTED TO MAINTAIN
HURRICANE STRENGTH AS IT TRAVERSES THE YUCATAN PENINSULA...AND
APPROACH MAJOR HURRICANE STRENGTH AGAIN BEFORE ITS FINAL LANDFALL.

THE INITIAL MOTION IS 275/17.  DEAN IN EXPECTED TO MAINTAIN A TRACK
BETWEEN WEST AND WEST-NORTHWEST TO THE SOUTH OF THE WESTWARD-
BUILDING SUBTROPICAL RIDGE.  MOST OF THE DYNAMICAL MODEL GUIDANCE
HAS TRENDED SOUTH AND THE OFFICIAL FORECAST HAS BEEN NUDGED
SOUTHWARD.  ALL THE LARGE-SCALE MODELS TAKE THE MID-LEVEL VORTICITY
OF DEAN WEST-SOUTHWESTWARD ACROSS THE MOUNTAINS OF CENTRAL
MEXICO...AND THE OFFICIAL FORECAST NOW SHOWS A LEFTWARD BEND OF THE
TRACK AFTER FINAL LANDFALL.  I DO NOT ACTUALLY EXPECT A WELL-
DEFINED SURFACE CIRCULATION TO EXIST AT 72 HOURS...BUT A POINT IS
PROVIDED SO THAT IT DOESN'T APPEAR THAT THE TRACK ENDS IN THE GULF
OF MEXICO.


FORECAST POSITIONS AND MAX WINDS

INITIAL      20/2100Z 18.2N  84.2W   130 KT
 12HR VT     21/0600Z 18.5N  86.7W   140 KT
 24HR VT     21/1800Z 19.3N  90.2W    75 KT...INLAND
 36HR VT     22/0600Z 20.2N  93.6W    85 KT
 48HR VT     22/1800Z 21.0N  97.0W    95 KT
 72HR VT     23/1800Z 21.5N 103.0W    30 KT...INLAND
 96HR VT     24/1800Z...DISSIPATED

$$
FORECASTER FRANKLIN

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