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TROPICAL STORM HUMBERTO DISCUSSION NUMBER 8
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SUN SEP 23 2001
AN AIR FORCE RESERVE HURRICANE HUNTER FOUND A CENTRAL PRESSURE OF
994 MB WITH 65 KT WINDS AT 1500 FT BOTH EAST AND WEST OF A
DEVELOPING 25 NM WIDE EYE. SATELLITE IMAGERY INDICATES THAT
CONVECTION HAS CONSOLIDATED NEAR THE CENTER...AND SATELLITE
INTENSITY ESTIMATES FROM TAFB AND SAB ARE 55 KT. THE MAXIMUM WINDS
ARE INCREASED TO 55 KT FOR THIS ADVISORY.
THE 12 HR MOTION IS 335/8...AND THE SHORT-TERM MOTION MAY BE EVEN
MORE TO THE NORTH. WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW
SOUTHWEST OF HUMBERTO...WITH A SHORTWAVE RIDGE TO THE NORTH OF THE
STORM AND STRONG WESTERLY FLOW OVER THE EASTERN UNITED STATES.
THIS PATTERN...ALONG WITH LARGE-SCALE MODEL FORECASTS OF A STRONG
DEEP-LAYER TROUGH OVER THE EASTERN U.S...FAVORS A GENERALLY
NORTHWARD MOTION FOLLOWED BY ACCELERATION TO THE NORTHEAST. NHC
HURRICANE GUIDANCE GENERALLY AGREES WITH THIS...ALTHOUGH THERE
IS SOME DISAGREEMENT ON HOW SHARPLY TO THE EAST HUMBERTO WILL
TURN. THE AVN...NGPS...AND BAMS TAKE THE STORM NEAR NOVA SCOTIA
IN 72 HR...WHILE THE GFDL...GFDN...AND LBAR TURN IT EASTWARD WELL
AWAY FROM LAND. THE OFFICIAL FORECAST WILL BE A COMPROMISE BETWEEN
THESE EXTREMES AND MORE OR LESS DOWN THE MIDDLE OF THE GUIDANCE.
HUMBERTO IS SHOWING INCREASING ORGANIZATION AND GOOD ANTICYCLONIC
OUTFLOW...SO FURTHER INTENSIFICATION IS POSSIBLE IN THE SHORT
TERM. IN THE LONGER TERM...THE STORM WILL LIKELY ENCOUNTER
STRONG UPPER LEVEL SOUTHWESTERLY FLOW WHICH SHOULD SLOW OR STOP
DEVELOPMENT. THIS SCENARIO IS REFLECTED IN THE INTENSITY
FORECAST...WHICH CALLS FOR HUMBERTO TO STRENGTHEN FOR 24 HR
FOLLOWED BY LITTLE CHANGE. THIS IS IN BEST AGREEMENT WITH THE
SHIPS MODEL.
WHILE HUMBERTO REMAINS SMALL...THE AIRCRAFT DATA INDICATES SOME
EXPANSION OF THE TROPICAL STORM WINDS ON THE EASTERN SIDE.
INTERESTS IN BERMUDA SHOULD MONITOR THE PROGRESS OF HUMBERTO
UNTIL THE SYSTEM IS SAFELY PAST.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 23/0900Z 30.5N 67.5W 55 KTS
12HR VT 23/1800Z 31.6N 68.1W 65 KTS
24HR VT 24/0600Z 33.2N 68.3W 70 KTS
36HR VT 24/1800Z 35.0N 68.3W 70 KTS
48HR VT 25/0600Z 37.0N 67.5W 70 KTS
72HR VT 26/0600Z 42.0N 62.0W 65 KTS
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