000
WTNT45 KNHC 162059
TCDAT5
HURRICANE OMAR DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
500 PM EDT THU OCT 16 2008
 
OMAR'S CENTRAL CONVECTION HAS DIMINISHED CONSIDERABLY...WHILE THE
PRINCIPAL BAND TO ITS SOUTHEAST AND SOUTH STILL CONTAINS VIGOROUS
DEEP CONVECTION.  CONSTRAINTS ON THE DVORAK TECHNIQUE ARE STILL
FORCING TAFB AND SAB TO INDICATE ABOUT A 90 KT HURRICANE. 
HOWEVER...BASED ON THE CONTINUING DETERIORATION OF THE CENTRAL
FEATURES...THE INTENSITY IS REDUCED TO 65 KT.

THE TROPICAL CYCLONE IS MOVING QUICKLY TOWARD THE NORTH-NORTHEAST...
30 DEGREES AT 23 KT...UNDER THE INFLUENCE OF A DEEP-LAYER LOW TO
ITS NORTH AND MID TO LOW LEVEL RIDGE TO ITS NORTHEAST. THE TRACK
GUIDANCE IS TIGHTLY CLUSTERED THROUGH 72 HR ALONG A TRACK TOWARD
THE NORTHEAST. BUT AS EXTRATROPICAL TRANSITION BEGINS...THE VARIOUS
MODELS SPLIT INTO TWO DIFFERENT SOLUTIONS. THE NOGAPS...UKMET...AND
GFDL MODELS SUGGEST THAT THE CYCLONE WILL UNDERGO SIGNIFICANT
RE-INTENSIFICATION AND EXPANSION IN SIZE NEAR THE AZORES. IN
CONTRAST...THE ECMWF...GFS...AND HWRF MODELS INDICATE THAT THE
CYCLONE WILL CONTINUE TO WEAKEN...BE MUCH FARTHER TO THE WEST...AND
EVENTUALLY BE ABSORBED BY A LARGE EXTRATROPICAL CYCLONE OFF OF
SOUTHEASTERN CANADA. THE SOLUTION FAVORED BY THIS ADVISORY IS THE
LATTER SCENARIO...THOUGH IT IS DIFFICULT THIS FAR IN ADVANCE
EXACTLY WHEN AND HOW EXTRATROPICAL TRANSITION WILL OCCUR. THE
FORECAST TRACK IS SLOWER THAN THE PREVIOUS ADVISORY AND WEST OF THE
CORRECTED MODEL CONSENSUS.
 
DESPITE BEING OVER VERY WARM WATER...THE STRONG SOUTHWESTERLY
VERTICAL SHEAR AND DRY AIR BEING WRAPPED INTO THE INNER CORE
SHOULD CONTINUE TO WEAKEN OMAR.  HOWEVER...THE RAPID MOTION OF THE
CYCLONE TO THE NORTHEAST MAY SOMEWHAT OFFSET THE NEGATIVE IMPACT OF
THE SHEAR.  THE FAST FORWARD MOTION MAY ALSO CONTRIBUTE TOWARD THE
WINDS ON THE RIGHT SIDE OF THE VORTEX.  THUS ONLY GRADUAL WEAKENING
IS INDICATED IN THE NEXT COUPLE OF DAYS.  THE SHIPS AND LGEM
STATISTICAL MODELS SUGGEST MORE RAPID WEAKENING TO A TROPICAL
DEPRESSION...THOUGH THESE TECHNIQUES ARE HEAVILY WEIGHTING THE
LARGE NEGATIVE PERSISTENCE FACTOR.  THE INTENSITY FORECAST IS CLOSE
TO THE GFDL AND HWRF SOLUTIONS AND IS SLIGHTLY LESS THAN INDICATED
IN THE PREVIOUS ADVISORY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 22.1N  59.7W    65 KT
 12HR VT     17/0600Z 25.0N  57.6W    65 KT
 24HR VT     17/1800Z 28.2N  55.1W    60 KT
 36HR VT     18/0600Z 30.1N  53.2W    55 KT
 48HR VT     18/1800Z 32.2N  50.9W    50 KT
 72HR VT     19/1800Z 36.0N  46.0W    45 KT...BECOMING EXTRATROPICAL
 96HR VT     20/1800Z 38.0N  39.0W    40 KT...EXTRATROPICAL
120HR VT     21/1800Z 38.0N  31.0W    35 KT...EXTRATROPICAL
 
$$
FORECASTER LANDSEA/STEWART