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TROPICAL STORM FAY DISCUSSION NUMBER   3
NATIONAL WEATHER SERVICE MIAMI FL
4 AM CDT FRI SEP 06 2002
 
WHILE IT IS DEVELOPING...FAY REMAINS A POORLY-ORGANIZED TROPICAL
CYCLONE THIS MORNING.  IR SATELLITE IMAGERY SUGGESTS THAT AN EXPOSED
LOW-LEVEL CENTER IS LOCATED NEAR 27.3N 95.2W...WHILE WSR-88D DATA
FROM HOUSTON SUGGESTS THAT THE CENTER COULD BE TRYING TO RE-FORM
FURTHER TO THE NORTHEAST CLOSER TO THE CONCENTRATED STRONG
CONVECTION.  THE ADVISORY POSITION IS A COMPROMISE BETWEEN THESE
EXTREMES.  REPORTS FROM BUOY 42019 INDICATE THE CENTRAL PRESSURE
HAS DROPPED TO AT LEAST 1005 MB...SO FAY IS MAINTAINING AT LEAST
35 KT WINDS.

THE POORLY-DEFINED CENTER MAKES THE INITIAL MOTION VERY 
PROBLEMATIC...WITH THE BEST ESTIMATE BEING STATIONARY.  FAY IS
SOUTH OF A WEAK LOW/MID LEVEL RIDGE...WHICH LARGE SCALE MODELS 
SUGGEST COULD BECOME WEAKER AS A TROUGH MOVES ACROSS THE CENTRAL
U. S.  NHC TRACK GUIDANCE RESPONDS TO THIS PATTERN BY FORECASTING
A SLOW EITHER NORTHWESTERLY OR WESTERLY MOTION.  THE BAM MODELS
AND LBAR SUPPORT THE NORTHWEST SCENARIO...WHILE THE AVN...GFDL...
AND UKMET SUPPORT THE MORE WESTERLY SCENARIO.  THE NOGAPS HAS THE
MOST EXTREME SOLUTION...MEANDERING FAY AROUND THE WESTERN GULF
OF MEXICO FOR 6 DAYS.  RIGHT NOW...THE POOR CENTER DEFINITION AND
THE POSSIBILITY OF RE-FORMATIONS MAKE IT VERY DIFFICULT TO CHOOSE
WHICH GUIDANCE SET MAY BE CORRECT.  THUS...THE OFFICIAL TRACK
FORECAST WILL CALL FOR A NORTHWESTWARD MOTION SIMILAR TO THE
PREVIOUS PACKAGE...EXCEPTED SHIFTED SOMEWHAT SOUTHWESTWARD FOR THE
INITIAL POSITION.  NOTE THAT SIGNIFICANT CHANGES TO THE TRACK
FORECAST AND THE WARNINGS MAY BE REQUIRED LATER TODAY DEPENDING
ON WHEN AND WHERE THE CENTER FINALLY CONSOLIDATES.
 
FAY IS CURRENTLY IN A LIGHT SOUTHERLY OR SOUTHWESTERLY SHEAR
ENVIRONMENT.  LARGE-SCALE GUIDANCE SUGGESTS THE SHEAR SHOULD
DIMINISH AS A LARGE UPPER-LEVEL ANTICYCLONE BUILDS OVER THE STORM.
THE INTENSITY FORECAST THUS CALLS FOR FAY TO STRENGTHEN UNTIL
LANDFALL.  THE CURRENT LARGE CENTER SUGGESTS THE STRENGTHENING
SHOULD BE SLOW AT FIRST...THEN FASTER AS THE SYSTEM CONSOLIDATES.

FAY SHOWS SOME SIMILARITIES IN SIZE AND STRUCTURE TO TROPICAL
STORM FRANCES IN THE NORTHWESTERN GULF IN SEPTEMBER 1998.  AS IN
FRANCES...THE EFFECTS OF FAY EXTEND FAR FROM THE POORLY-DEFINED
CENTER...SO THERE SHOULD NOT BE OVER-EMPHASIS ON THE EXACT CENTER
POINT OF THE CYCLONE.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     06/0900Z 27.6N  94.1W    35 KTS
12HR VT     06/1800Z 28.0N  94.6W    40 KTS
24HR VT     07/0600Z 28.7N  95.4W    50 KTS
36HR VT     07/1800Z 29.3N  96.2W    45 KTS...INLAND
48HR VT     08/0600Z 29.9N  97.2W    30 KTS...INLAND
72HR VT     09/0600Z 30.5N  99.0W    25 KTS...INLAND AND DISSIPATING
 
 
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