Tropical Storm OMAR

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TROPICAL STORM OMAR DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
500 PM EDT TUE OCT 14 2008
 
SATELLITE...RADAR...AND AIR FORCE RECON DATA INDICATE THAT OMAR HAS
RAPIDLY INTENSIFIED THIS AFTERNOON. ALTHOUGH MAXIMUM 850 MB
FLIGHT-LEVEL WINDS OBSERVED HAVE ONLY BEEN 63 KT...RELIABLE SFMR
SURFACE WIND DATA HAVE BEEN AS HIGH 57-60 KT ON THE SOUTH SIDE OF
THE CIRCULATION CENTER. THE LOWEST CENTRAL PRESSURE MEASURED BY A
DROPSONDE WAS 986 MB...BUT THE SURFACE WIND WAS 46 KT. THEREFORE...
THE PRESSURE IS ESTIMATED TO BE 982 MB AND THE INTENSITY HAS BEEN
INCREASED TO A CONSERVATIVE 60 KT. OMAR CONTINUES TO GET BETTER
ORGANIZED IN BOTH RADAR AND SATELLITE IMAGERY...AND VERY COLD CLOUD
TOPS OF -80C TO -87C PERSIST OVER AND NEAR THE CIRCULATION CENTER.
ON THE LAST PASS THROUGH THE CENTER OF OMAR...THE FLIGHT CREW
REPORTED A 10-15 NMI DIAMETER EYE WAS FORMING. OUTFLOW ALSO
CONTINUES TO IMPROVE AND EXPAND IN ALL QUADRANTS...EXCEPT TO THE
NORTHWEST WHERE IT IS SLIGHTLY RESTRICTED.
 
THE INITIAL MOTION ESTIMATE IS NOW 060/06. THE THREE RECON FIXES
THIS AFTERNOON SUGGEST THAT OMAR MAY BE FINALLY MAKING THE TURN TO
THE NORTHEAST THAT THE MODELS HAVE BEEN FORECASTING FOR THE PAST
SEVERAL CYCLES. ALL OF THE AVAILABLE MODEL GUIDANCE IS TIGHTLY
CLUSTERED ON A TRACK THROUGH THE NORTHERN LEEWARD ISLANDS IN ABOUT
36 HOURS...WITH SIGNIFICANT ACCELERATION EXPECTED AFTER THAT AS
OMAR GETS LIFTED RAPIDLY NORTHEASTWARD AHEAD OF A DIGGING
MID-TROPOSPHERIC TROUGH THAT COVERS MOST OF THE CENTRAL AND WESTERN
ATLANTIC. THE MAIN DIFFERENCE BETWEEN THE MODELS IS IN THE FORWARD
SPEED OF OMAR AFTER 24 HOURS. THE GFS...GFDL...AND HWRF MODELS RACE
OMAR QUICKLY TO THE NORTHEAST...WHEREAS THE UKMET AND ECMWF MODELS
ARE NOTICEABLY SLOWER. THE OFFICIAL FORECAST TRACK HAS BEEN SHIFTED
SLIGHTLY TO THE EAST OF THE PREVIOUS TRACK THROUGH 36 HOURS...BUT
REMAINS JUST TO THE WEST OF AND SLOWER THAN THE MODEL CONSENSUS.
 
ADDITIONAL STRENGTHENING...POSSIBLY EVEN RAPID INTENSIFICATION... IS
EXPECTED SINCE THE ENVIRONMENT IS NOT FORECAST TO CHANGE MUCH IN
THE NEXT DAY OR SO. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF
THE SHIPS...GFDL... AND HWRF MODELS...AND OMAR IS EXPECTED TO
OBTAIN CATEGORY 2 STRENGTH BY THE TIME IT REACHES THE NORTHERN
LEEWARD ISLANDS IN ABOUT 36 HOURS. IT IS WORTH NOTING THAT THE
SHIPS MODEL BRINGS OMAR TO 104 KT BY 48 HOURS. HOWEVER...THE 12Z
HWRF MODEL ONLY BRINGS OMAR TO 88 KT AND THE GFDL ONLY STRENGTHENS
THE CYCLONE TO 62 KT. BASED ON A STRONGER VORTEX INITIALIZED BY THE
MODELS FOR THE 18Z CYCLE...OUTPUT FROM THOSE MODELS DUE OUT IN A
FEW HOURS MAY BE QUITE DIFFERENT AND MUCH STRONGER. AS A RESULT...
SUBSEQUENT NHC INTENSITY FORECASTS MAY HAVE TO BE ADJUSTED UPWARD.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/2100Z 14.0N  68.5W    60 KT
 12HR VT     15/0600Z 14.6N  68.0W    70 KT
 24HR VT     15/1800Z 15.9N  66.4W    80 KT
 36HR VT     16/0600Z 18.0N  64.3W    85 KT
 48HR VT     16/1800Z 20.6N  62.1W    85 KT
 72HR VT     17/1800Z 26.0N  58.4W    80 KT
 96HR VT     18/1800Z 31.1N  55.5W    70 KT
120HR VT     19/1800Z 38.0N  49.0W    60 KT
 
$$
FORECASTER STEWART
 
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