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TROPICAL STORM ERIN DISCUSSION NUMBER 23
NATIONAL WEATHER SERVICE MIAMI FL
11 PM AST FRI SEP 07 2001
ERIN IS SHOWING SIGNS OF CONSOLIDATING THIS EVENING...WITH
CONVECTION INCREASING NEAR THE CENTER AND IN BANDS OVER THE
NORTHEAST QUADRANT. SATELLITE INTENSITY ESTIMATES ARE 35 KT
FROM TAFB AND 30 KT FROM SAB AND AFWA...SO THE INITIAL INTENSITY
REMAINS 35 KT. AN AIR FORCE RESERVE HURRICANE HUNTER WILL
INVESTIGATE THE STORM AROUND 06Z TO SEE IF THE CONVECTIVE INCREASE
ACTUALLY INDICATES STRENGTHENING.
THE INITIAL MOTION IS 360/5. WATER VAPOR IMAGERY INDICATES THAT
DEEP LAYER RIDGING IS DEVELOPING NORTH OF ERIN...AND LARGE SCALE
MODELS SUGGEST THIS RIDGING WILL BUILD EAST OF THE STORM DURING
THE FORECAST PERIOD. THIS SUGGESTS THAT ERIN SHOULD TURN MORE
TOWARD THE NORTHWEST WITH TIME...AND NHC HURRICANE GUIDANCE
GENERALLY AGREES WITH THIS SCENARIO. THE OFFICIAL FORECAST TRACK
IS BASICALLY AN UPDATE OF THE PREVIOUS PACKAGE...CALLING FOR A
GRADUAL TURN TO THE NORTHWEST OVER THE NEXT 72 HR.
WHILE ERIN IS GETTING BETTER ORGANIZED...LARGE SCALE MODELS SUGGEST
THAT SOUTHEASTERLY OR SOUTHERLY SHEAR MAY DEVELOP OVER THE SYSTEM
DURING THE NEXT 24 HR DUE TO AN UPPER LEVEL LOW DEVELOPING TO THE
SOUTHWEST. THERE ARE SOME HINTS THIS PROCESS MAY BE STARTING IN
WATER VAPOR IMAGERY AND IN THE DECREASE IN CLOUDINESS IN THE
SOUTHEAST QUADRANT. WHILE THE ENVIRONMENT DOES NOT LOOK TOO
HOSTILE...GIVEN ERIN'S TRACK RECORD OF RESPONDING BADLY TO SHEAR
THE INTENSITY FORECAST WILL CALL FOR ONLY SLOW DEVELOPMENT.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 08/0300Z 26.3N 58.1W 35 KTS
12HR VT 08/1200Z 27.2N 58.3W 40 KTS
24HR VT 09/0000Z 28.8N 58.8W 45 KTS
36HR VT 09/1200Z 30.5N 60.0W 50 KTS
48HR VT 10/0000Z 32.0N 61.5W 55 KTS
72HR VT 11/0000Z 34.5N 64.5W 65 KTS
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