[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT41 KNHC 272100
TCDAT1
HURRICANE FRANCES DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI AUG 27 2004

FRANCES HAS CONTINUED TO RAPIDLY INTENSIFY AS INDICATED BY A DVORAK
SATELLITE INTENSITY ESTIMATE OF T5.5...OR 102 KT...FROM BOTH TAFB
AND SAB. THE INNER-CORE CONVECTION HAS INCREASED IN VERTICAL DEPTH
AND AREAL COVERAGE...AND THE OUTFLOW IS EXCELLENT AND CONTINUES TO
IMPROVE AND EXPAND OUTWARD.

THE MOTION IS 305/09. FRANCES HAS MADE A SLIGHT NORTHWESTWARD JOG AS
ALLUDED TO IN THE PREVIOUS ADVISORY...BUT THIS IS EXPECTED TO BE
SHORT-LIVED AS THE SHORTWAVE TROUGH LOCATED DUE NORTH OF FRANCES
MOVES EASTWARD AND THE RIDGE BUILDS BACK IN BEHIND THE TROUGH. THIS
SHOULD TURN FRANCES BACK TO THE WEST-NORTHWEST ON SATURDAY. THERE
IS NOW MUCH LESS DIVERGENCE IN THE NHC MODEL SUITE AFTER 48 HOURS
...AND IN THE LONGER TIME PERIODS. ALL OF THE MODELS NOW AGREE THAT
THE HIGH ZONAL FLOW FORECAST TO DEVELOP ACROSS THE NORTHERN U.S.
AND THE NORTH ATLANTIC AFTER 48HR WILL ALLOW FOR A STRONG
SUBTROPICAL RIDGE TO THE SOUTH TO EXTEND EAST-WEST FROM THE AZORES
TO BERMUDA AND INTO THE SOUTHEASTERN U.S.  THE LATEST GFS AND
CANADIAN MODELS HAVE SHIFTED FARTHER NORTH...WHILE THE UKMET AND
GFDL MODELS HAVE SHIFTED A LITTLE MORE TO THE SOUTH AND WEST. ALL
OF THESE MODELS ARE CONVERGING NICELY ABOUT THE PREVIOUS SEVERAL
NHC FORECAST TRACKS...SO I SEE NO REASON AT THIS TIME TO MAKE ANY
SIGNIFICANT CHANGES TO THE PREVIOUS TRACK FORECASTS. THE OFFICIAL
TRACK IS JUST AN EXTENSION OF THE PREVIOUS TRACK AND IS CLOSE TO
THE GUNA MODEL CONSENSUS.

FRANCES IS FORECAST TO REMAIN IN A LOW SHEAR ENVIRONMENT AND OVER
INCREASING SSTS THROUGHOUT THE PERIOD. THE SHIPS INTENSITY MODEL
NOW MAKES FRANCES A 113 KT MAJOR HURRICANE IN 48 HOURS...SINCE THE
'SELF-INDUCED' VERTICAL SHEAR HAS DECREASED OWING TO THE GFS
FORECAST POSITONS BEING CLOSER TO THE OFFICIAL TRACK FORECAST.
THERE WILL LIKELY BE SEVERAL FLUCTUATIONS IN THE INTENSITY OVER THE
NEXT 5 DAYS...BUT CATEGORY FOUR INTENSITY SEEMS LIKELY SOME TIME
DURING THAT PERIOD...AND CATEGORY 5 STRENGTH IS EVEN POSSIBLE.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      27/2100Z 15.7N  49.8W   100 KT
 12HR VT     28/0600Z 16.9N  51.2W   105 KT
 24HR VT     28/1800Z 17.9N  52.8W   110 KT
 36HR VT     29/0600Z 18.9N  54.5W   115 KT
 48HR VT     29/1800Z 19.7N  56.4W   115 KT
 72HR VT     30/1800Z 20.6N  60.0W   115 KT
 96HR VT     31/1800Z 21.5N  64.5W   115 KT
120HR VT     01/1800Z 22.5N  69.0W   115 KT


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