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TROPICAL DEPRESSION SEVENTEEN-E DISCUSSION NUMBER 1
NATIONAL WEATHER SERVICE MIAMI FL
7 PM PST TUE OCT 30 2001
THE AREA OF DISTURBED WEATHER LOCATED SEVERAL HUNDRED MILES
SOUTHWEST OF BAJA CALIFORNIA HAS BECOME BETTER ORGANIZED THIS
EVENING AND HAS DEVELOPED INTO TROPICAL DEPRESSION SEVENTEEN-E.
CONVECTIVE BANDING HAS INCREASED SIGNIFICANTLY DURING THE PAST 6
HOURS AND THE INITIAL INTENSITY OF 30 KT IS BASED ON A BLEND OF
DVORAK SATELLITE INTENSITY ESTIMATES OF 35 KT FROM TAFB AND 25 KT
FROM SAB. OUTFLOW IS GOOD TO THE WEST BUT RESTRICTED TO THE EAST DUE
TO EASTERLY UPPER-LEVEL SHEAR.
THE INITIAL MOTION ESTIMATE IS 290/14. TD-17E IS EXPECTED TO TRACK
IN A GENERAL WEST-NORTHWESTWARD DIRECTION THROUGH 24 HOURS AND THEN
GRADUALLY TURN TO THE NORTH BY 36 HOURS AS THE CYCLONE COMES UNDER
THE INFLUENCE OF SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING
MID-LEVEL TROUGH...WHICH IS EXPECTED TO WEAKEN THE SUBTROPICAL RIDGE
CURRENTLY LOCATED TO THE NORTH OF THE DEPRESSION. RECURVATURE TO THE
NORTHEAST IS EXPECTED FROM 48 TO 72 HOURS AHEAD OF THE APPROACHING
MID-LATITUDE TROUGH. THE OFFICIAL FORECAST TRACK IS CLOSE TO THE
MEDIUM AND DEEP BAM MODELS...EXCEPT SLOWER LIKE THE AVN MODEL
SOLUTION.
THE EAST TO SOUTHEASTERLY VERTICAL SHEAR CURRENTLY IMPINGING ON THE
DEPRESSION IS FORECAST TO WEAKEN TO AROUND 5 KT IN 24 TO 36 HOURS AS
THE CYCLONE MOVES INTO A WEAKNESS OR COL REGION IN THE SUBTROPICAL
RIDGE. THIS SHOULD ALLOW FOR STEADY STRENGTHENING THROUGH ABOUT 48
HOURS...AFTER WHICH STRONG SOUTHWESTERLY UPPER-LEVEL SHEAR IS
EXPECTED TO KICK IN. WATER TEMPERATURES ARE SUFFICIENTLY WARM
ENOUGH TO SUPPORT MINIMAL HURRICANE STRENGTH AND THIS COULD OCCUR BY
AROUND 48 HOURS. THE SHIPS INTENSITY MODEL ONLY STRENGTHENS THE
CYCLONE TO 49 KT IN 36 HOURS...BUT THIS OUTPUT WAS BASED ON THE LBAR
MODEL WHICH MAINTAINS A WEST-NORTHWEST TO NORTHWESTWARD TRACK
THROUGHOUT THE PERIOD...RIGHT INTO THE UPPER-LEVEL TROUGH AND 30 TO
40 KT OF SHEAR...WHICH SEEMS UNLIKELY AT THIS TIME.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 31/0300Z 12.5N 123.5W 30 KTS
12HR VT 31/1200Z 13.1N 125.2W 35 KTS
24HR VT 01/0000Z 14.4N 126.9W 40 KTS
36HR VT 01/1200Z 15.8N 127.5W 45 KTS
48HR VT 02/0000Z 17.3N 127.3W 55 KTS
72HR VT 03/0000Z 20.0N 125.5W 45 KTS
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