000
WTNT44 KNHC 192047
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT SUN AUG 19 2007
 
THE RECONNAISSANCE AIRCRAFT COMPLETED ITS MISSION...FINDING PEAK
FLIGHT-LEVEL WINDS OF 144 KT...WITH PEAK SFMR WINDS OF 121 KT.  ONE
OF THE LAST EYEWALL DROPSONDES GAVE A SURFACE ESTIMATE OF 118 KT
DERIVED FROM THE LOWEST 150 METERS OF THE SOUNDING.  IN SPITE OF A
GRADUAL PRESSURE RISE...THESE DATA INDICATE THAT 125 KT IS STILL A
GOOD INTENSITY ESTIMATE.  CONCENTRIC EYEWALLS ARE APPARENT IN
MICROWAVE...CONVENTIONAL SATELLITE...AND AIRCRAFT DATA...WITH THE
STRONGEST WINDS NOW ASSOCIATED WITH THE OUTER EYEWALL.  SHORT-TERM
INTENSITY CHANGES WILL BE GOVERNED BY INNER-CORE PROCESSES THAT ARE
DIFFICULT TO TIME...BUT OVERALL CONDITIONS IN THE WESTERN CARIBBEAN
WOULD FAVOR FURTHER INTENSIFICATION...AND DEAN COULD VERY WELL
BECOME A CATEGORY FIVE HURRICANE DURING THE NEXT DAY OR TWO.
 
THE INITIAL MOTION IS 280/17. THERE IS NO MAJOR CHANGE TO THE
FORECAST THINKING...ALTHOUGH MODEL GUIDANCE HAS BEEN TRENDING
SOUTHWARD...WITH NEARLY ALL OF THE LARGE-SCALE MODELS BUILDING THE
SUBTROPICAL RIDGE WESTWARD IN TANDEM WITH DEAN. THE UPPER LOW IN
THE GULF OF MEXICO CONTINUES WESTWARD AND IS NOT EXPECTED TO BE A
MAJOR PLAYER IN THE FUTURE TRACK OF THE HURRICANE. THE OFFICIAL
FORECAST HAS BEEN SHIFTED A LITTLE TO THE SOUTH...BUT STILL LIES TO
THE NORTH OF ALL THE MAJOR MODELS EXCEPT FOR THE HWRF. ALTHOUGH I
CANNOT EXPLAIN WHY...THE DETERMINISTIC RUN OF THE GFS IS ALONG THE
SOUTHERN END OF THE GUIDANCE ENVELOPE...WHILE THE GFS ENSEMBLE
MEMBERS ARE ALMOST UNIFORMLY ALONG THE NORTHERN EDGE. BECAUSE MOST
OF THE GUIDANCE MODELS LIE TO THE SOUTH OF THE OFFICIAL FORECAST...
SOME ADDITIONAL SOUTHWARD ADJUSTMENTS TO THE TRACK ARE POSSIBLE.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/2100Z 17.3N  76.8W   125 KT
 12HR VT     20/0600Z 17.8N  79.4W   130 KT
 24HR VT     20/1800Z 18.4N  83.0W   135 KT
 36HR VT     21/0600Z 19.0N  86.5W   140 KT
 48HR VT     21/1800Z 19.9N  90.0W    80 KT...INLAND
 72HR VT     22/1800Z 21.5N  96.5W   100 KT
 96HR VT     23/1800Z 23.0N 101.0W    35 KT...INLAND
120HR VT     24/1800Z...DISSIPATED
 
$$
FORECASTER FRANKLIN/RHOME