172
WTNT41 KNHC 310847
TCDAT1
TROPICAL STORM NOEL DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL162007
500 AM EDT WED OCT 31 2007
SURFACE AND RADAR OBSERVATIONS INDICATE THAT THE CENTER OF NOEL IS
APPROACHING THE NORTHERN COAST OF CUBA NEAR CAYO COCO. RADAR AND
SATELLITE IMAGERY SHOW A LARGE AREA OF STRONG CONVECTIVE BANDS
NORTH AND EAST OF THE CENTER...ALTHOUGH THERE IS LITTLE CONVECTION
NEAR THE CENTER AT THIS TIME. A SURFACE OBSERVATION AT CAYO COCO
SUGGESTS THE CENTRAL PRESSURE IS NEAR 1000 MB...AND AN EARLIER
ASCAT OVERPASS SUGGESTS THE MAXIMUM WINDS REMAIN NEAR 35 KT.
NOEL HAS TURNED TO THE RIGHT OVER THE PAST SEVERAL HOURS. THE 12 HR
MOTION IS 330/6...AND THE SHORT-TERM MOTION MAY EVEN BE MORE TOWARD
THE NORTH. IT IS UNCLEAR WHETHER THIS IS AN EARLY START OF THE
FORECAST NORTHWARD TURN...OR IF IT IS A RE-FORMATION OF THE CENTER.
THE DYNAMICAL MODELS SHOW FOUR POSSIBLE SCENARIOS FOR NOEL BASED ON
INTERACTIONS WITH A MID/UPPER-LEVEL TROUGH MOVING EASTWARD ACROSS
THE GULF OF MEXICO AND A DEEP-LAYER TROUGH MOVING INTO THE EASTERN
UNITED STATES. THE FIRST...SUPPORTED BY THE NOGAPS...THE GFDL...
AND THE HWRF...IS FOR NOEL TO RECURVE INTO THE WESTERLIES AND
BECOME A STRONG EXTRATROPICAL LOW OVER THE NORTHWESTERN ATLANTIC.
THE SECOND...SUPPORTED BY THE GFS...IS FOR AN EXTRATROPICAL LOW TO
FORM OFF THE FLORIDA COAST WHICH ABSORBS NOEL. THE THIRD...
SUPPORTED BY THE UKMET...IS FOR AN EXTRATROPICAL LOW TO FORM OFF
THE FLORIDA COAST WITH IT AND NOEL MOVING NORTHEASTWARD IN TANDEM.
THE FOURTH...SUPPORTED BY THE ECMWF...IS FOR AN EXTRATROPICAL LOW
TO FORM OFF THE FLORIDA COAST AND A WEAKENING NOEL BEING DRIVEN
SOUTHWESTWARD INTO THE CARIBBEAN BY THE ASSOCIATED COLD FRONT. THE
OFFICIAL FORECAST WILL FOLLOW THE FIRST SCENARIO...WITH NOEL
RECURVING INTO THE WESTERLIES DURING THE NEXT 24-36 HR AND THEN
ACCELERATING NORTHEASTWARD. THE TRACK FORECAST IS IN GOOD OVERALL
AGREEMENT WITH THE VARIOUS CONSENSUS MODELS.
ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE NOEL IS
EXPERIENCING 20-25 KT OF WESTERLY VERTICAL WIND SHEAR...MUCH OF IT
DUE TO STRONG LOW-LEVEL EASTERLY FLOW. AS NOEL MOVES OFF CUBA...
THERE WILL BE A 24 HR OR SO PERIOD OF DECREASED SHEAR THAT COULD
ALLOW SOME STRENGTHENING. AFTER THAT...INTENSIFICATION AS A
TROPICAL CYCLONE SHOULD STOP AS NOEL ENCOUNTERS STRONGER SHEAR AND
BEGINS EXTRATROPICAL TRANSITION. THE CYCLONE IS FORECAST TO
STRENGTHEN FURTHER AFTER BECOMING EXTRATROPICAL...WITH A PEAK
INTENSITY OF 60 KT.
THE STRONG GUSTY WINDS THAT CONTINUE TO AFFECT PORTIONS OF FLORIDA
ARE ASSOCIATED WITH THE PRESSURE GRADIENT BETWEEN A STRONG HIGH
OVER THE U.S. EAST COAST AND NOEL...BUT ARE NOT DIRECTLY ASSOCIATED
WITH THE CIRCULATION OF THE TROPICAL STORM. SEE STATEMENTS FROM
NWS LOCAL FORECAST OFFICES.
FORECAST POSITIONS AND MAX WINDS
INITIAL 31/0900Z 22.1N 78.2W 35 KT...INLAND
12HR VT 31/1800Z 22.9N 78.7W 40 KT...OVER WATER
24HR VT 01/0600Z 23.9N 78.7W 45 KT
36HR VT 01/1800Z 25.6N 77.8W 45 KT
48HR VT 02/0600Z 28.0N 75.7W 45 KT...BECOMING EXTRATROPICAL
72HR VT 03/0600Z 35.0N 69.0W 50 KT...EXTRATROPICAL
96HR VT 04/0600Z 44.0N 61.5W 60 KT...EXTRATROPICAL
120HR VT 05/0600Z 54.0N 53.0W 60 KT...EXTRATROPICAL
FORECASTER BEVEN
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