000
WTNT44 KNHC 210900
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT TUE AUG 21 2007
 
DEAN MADE LANDFALL ON THE EAST COAST OF THE YUCATAN PENINSULA NEAR
THE CRUISE SHIP PORT OF COSTA MAYA AROUND 0830 UTC...AND THE EYE IS
NOW JUST INLAND.  OBSERVATIONS FROM AN AIR FORCE HURRICANE HUNTER
PLANE INDICATE THAT THE HURRICANE WAS INTENSIFYING RIGHT UP TO
LANDFALL.  A PEAK FLIGHT-LEVEL WIND OF 165 KT WAS MEASURED JUST
NORTH OF THE EYE.  MAXIMUM SURFACE WINDS FROM THE SFMR WERE 124
KT...BUT IT IS HIGHLY LIKELY THAT THE MAXIMUM SURFACE WIND SPEED
WAS NOT REPORTED BY THE SFMR INSTRUMENT.  A GPS DROPSONDE IN THE
NORTHERN EYEWALL MEASURED A WIND SPEED OF 178 KT AVERAGED OVER THE
LOWEST 150 METERS OF THE SOUNDING.  BASED ON THE DROPSONDE AND THE
FLIGHT-LEVEL WINDS...THE INTENSITY IS SET AT 145 KT.  A DROPSONDE
IN THE EYE MEASURED A CENTRAL PRESSURE OF 906 MB JUST PRIOR TO
LANDFALL.  SOME HISTORIC NOTES ARE IN ORDER HERE.  THE 906 MB
CENTRAL PRESSURE IS THE NINTH LOWEST ON RECORD FOR AN ATLANTIC
BASIN HURRICANE...AND THE THIRD LOWEST AT LANDFALL BEHIND THE 1935
LABOR DAY HURRICANE IN THE FLORIDA KEYS AND HURRICANE GILBERT OF
1988 IN CANCUN MEXICO.  DEAN IS ALSO THE FIRST CATEGORY FIVE
HURRICANE TO MAKE LANDFALL IN THE ATLANTIC BASIN SINCE ANDREW OF
1992.
 
DEAN WILL WEAKEN AS IT TRAVERSES THE YUCATAN PENINSULA AND
THE AMOUNT OF WEAKENING WILL DEPEND ON HOW LONG THE CENTER REMAINS
OVER LAND.  OUR CURRENT THINKING IS THAT THE CYCLONE WILL STILL BE
A BORDERLINE CAT 1/2 HURRICANE WHEN IT EMERGES OVER THE BAY OF
CAMPECHE...BUT THERE IS CONSIDERABLE UNCERTAINTY IN THIS FORECAST.
ASSUMING THAT THE INNER CORE IS NOT TOO DISRUPTED BY ITS
INTERACTION WITH LAND...DEAN SHOULD REGAIN MAJOR HURRICANE STATUS
BEFORE ITS FINAL LANDFALL IN MAINLAND MEXICO.

INITIAL MOTION IS ESTIMATED TO BE 285/17.  DEEP LAYER HIGH PRESSURE
NEAR THE NORTHERN GULF COAST SHOULD STEER THE HURRICANE ON A
WEST-NORTHWESTWARD TO WESTWARD HEADING FOR THE NEXT COUPLE OF DAYS. 
THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE.

THE HURRICANE WARNING IS EXTENDED WESTWARD ALONG THE BAY OF CAMPECHE
COASTLINE OF MEXICO.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0900Z 18.7N  87.8W   145 KT
 12HR VT     21/1800Z 19.1N  90.4W    85 KT...INLAND
 24HR VT     22/0600Z 19.6N  93.9W    95 KT...OVER BAY OF CAMPECHE
 36HR VT     22/1800Z 20.1N  96.8W   105 KT...INLAND
 48HR VT     23/0600Z 20.5N 100.0W    25 KT...INLAND...DISSIPATING
 72HR VT     24/0600Z...DISSIPATED
 
$$
FORECASTER PASCH/BROWN