000
WTNT45 KNHC 171505
TCDAT5
TROPICAL STORM OMAR DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
1100 AM EDT FRI OCT 17 2008
 
OMAR HAS RE-INTENSIFIED SOME THIS MORNING AS SHOWN IN THE STRONGLY
CURVED BANDED STRUCTURE FROM GEOSTATIONARY SATELLITE IMAGERY. THE
DVORAK ESTIMATE FROM TAFB SUGGESTED 55 KT AT 12 UTC...THOUGH
IMPROVED DEEP CONVECTION SINCE WOULD INDICATE A STRONGER CYCLONE AT
ADVISORY TIME. ADDITIONALLY...A WELL-PLACED QUIKSCAT OVERPASS AT
0922 UTC SHOWED SEVERAL BELIEVABLE 55-60 KT VECTORS AND TWO
HURRICANE FORCE WINDS...THOUGH THESE MIGHT HAVE SOME RAIN
CONTAMINATION BOOSTING THE VALUES. CURRENT INTENSITY IS SET AT 60
KT...ALTHOUGH OMAR COULD BE A MARGINAL HURRICANE.
 
OMAR HAS ACCELERATED TO ABOUT 30 KT TOWARD THE NORTHEAST UNDER THE
INFLUENCE OF A SHORTWAVE TROUGH JUST TO THE NORTHWEST AND A
DEEP-LAYER RIDGE TO THE EAST. THIS TROUGH ADVECTS ALONG QUICKLY
TOWARD THE EAST-NORTHEAST AND LEAVES OMAR BEHIND...LIKELY CAUSING
THE CYCLONE TO SLOW DOWN SIGNIFICANTLY IN THE NEXT DAY OR SO. THE
EXTRATROPICAL STORM THAT WILL EMERGE OFF OF THE U.S. EAST COAST
EARLY ON SUNDAY IS THE FEATURE THAT IS EXPECTED TO ABSORB OMAR LATE
IN THE FORECAST PERIOD. THIS IS THE SOLUTION FAVORED BY ALL OF THE
GLOBAL AND HURRICANE MODELS...WITH THE EXCEPTION OF NOGAPS WHICH
MAINTAINS OMAR AS A SEPARATE ENTITY AND LOOPS IT BACK TOWARD THE
SOUTH AND WEST. THE TRACK FORECAST IS BASED A BLEND OF A CONSENSUS
OF THESE MODELS...WITH THE EXCEPTION OF NOGAPS...AND THE FASTER
PREVIOUS ADVISORY.

OMAR HAS A SHORT WINDOW OF OPPORTUNITY TO INTENSIFY BEFORE REACHING
COOLER WATERS AND UNDER MUCH STRONGER SHEAR IN ABOUT 24 HOURS. 
CURRENTLY...OMAR IS MOVING IN THE DIRECTION OF...BUT FASTER THAN...
THE SHEAR VECTOR...WHICH MAY HAVE SOMEWHAT COUNTERACTED THE
OTHERWISE LARGE NEGATIVE SHEAR INFLUENCE.  ANOTHER LIMITING FACTOR
IS THAT THE CYCLONE IS NEARLY SURROUNDED BY DRY AIR IN THE MID TO
LOW TROPOSPHERE.  THE FORECAST CALLS FOR NO SIGNIFICANT CHANGE IN
WINDS DURING THE NEXT DAY OR SO WITH GRADUAL WEAKENING THEREAFTER
...IN BEST AGREEMENT WITH THE LGEM STATISTICAL AND HWRF DYNAMICAL
MODELS.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/1500Z 28.9N  55.1W    60 KT
 12HR VT     18/0000Z 31.4N  53.2W    60 KT
 24HR VT     18/1200Z 33.4N  51.3W    55 KT
 36HR VT     19/0000Z 35.1N  49.2W    50 KT
 48HR VT     19/1200Z 36.6N  47.0W    45 KT
 72HR VT     20/1200Z 39.0N  42.0W    40 KT...BECOMING EXTRATROPICAL
 96HR VT     21/1200Z 40.5N  36.0W    35 KT...EXTRATROPICAL
120HR VT     22/1200Z...ABSORBED BY EXTRATROPICAL LOW
 
$$
FORECASTER LANDSEA/STEWART