Tropical Storm OMAR

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TROPICAL STORM OMAR DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
500 AM EDT SAT OCT 18 2008
 
CENTRAL CONVECTION...AND I USE THAT TERM QUITE LOOSELY IN THIS
CASE...HAS CONTINUED TO RAPIDLY DECREASE AND INNER-CORE CLOUD TOPS
ARE BARELY -20C...WITH MOST TOPS WARMER THAN -10C. ONE COULD
CERTAINLY ARGUE THAT OMAR MAY NOT EVEN BE A TROPICAL CYCLONE.
HOWEVER...I DON'T LIKE DROPPING SYSTEMS AT NIGHT OVER THE OPEN
OCEAN JUST IN CASE A BRIEF FLARE UP OF CONVECTION REDEVELOPS.
THE INITIAL INTENSITY ESTIMATE OF 50 KT IS BASED THE WELL-DEFINED
EYE-LIKE FEATURE AND A DVORAK CI NUMBER OF T3.0/45 KT FROM TAFB.

THE INITIAL MOTION ESTIMATE IS 045/14. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. OMAR IS
EXPECTED TO CONTINUE TO MOVE NORTHEASTWARD AND EVENTUALLY
EAST-NORTHEASTWARD AROUND THE THE NORTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE LOCATED TO THE EAST OF THE CYCLONE FOR THE NEXT 2
DAYS. BY 48 HOURS...THE STEERING FLOW IS FORECAST TO BECOME MORE
WESTERLY AHEAD OF A LARGE EXTRATROPICAL LOW FORECAST TO DEVELOP OFF
THE U.S.EAST COAST...WHICH IS EXPECTED TO FORCE OMAR ON A MORE
EASTERLY TRACK. BY 72 HOURS...OMAR IS FORECAST BY MOST OF THE
MODELS TO BE PULLED SLOWLY POLEWARD UNDER THE INFLUENCE OF THE
APPROACHING LARGER EXTRATROPICAL TO THE WEST...AND EVENTUALLY BE
ABSORBED BY THE LOW IN 96-120 HOURS. THE OFFICIAL FORECAST TRACK IS
SIMILAR TO THE PREVIOUS ADVISORY AND IS IN THE MIDDLE OF THE NHC
MODEL GUIDANCE SUITE.

OMAR WILL CONTINUE TO MOVE OVER SUB-26C SSTS AND BENEATH INCREASING
SOUTHWESTERLY VERTICAL WIND SHEAR...SO ADDITIONAL WEAKENING APPEARS
LIKELY. IF THE RECENT CONVECTIVE DEGENERATION TREND CONTINUES...
THEN OMAR COULD BECOME EXTRATROPICAL IN 24 HOURS OR LESS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0900Z 32.9N  51.5W    50 KT
 12HR VT     18/1800Z 34.3N  49.8W    45 KT
 24HR VT     19/0600Z 36.1N  47.3W    40 KT
 36HR VT     19/1800Z 37.6N  44.6W    35 KT...BECOMING EXTRATROPICAL
 48HR VT     20/0600Z 38.7N  42.1W    30 KT...EXTRATROPICAL
 72HR VT     21/0600Z 40.3N  38.2W    30 KT...EXTRATROPICAL
 96HR VT     22/0600Z 43.0N  35.4W    30 KT...EXTRATROPICAL
120HR VT     23/0600Z...ABSORBED BY LARGER EXTRATROPICAL LOW
 
$$
FORECASTER STEWART
 
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