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TROPICAL STORM MANUEL DISCUSSION NUMBER 25
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT TUE OCT 16 2001
MANUEL MOST LIKELY PEAKED PRIOR TO 12Z BASED ON 16/1009Z AMSU-B AND
16/1424Z SSMI MICROWAVE DATA WHICH SHOWED AN EYE-LIKE FEATURE.
SINCE THEN...DEEP CONVECTION HAS DECREASED AND IS LIMITED TO THE
SOUTHEAST SEMICIRCLE. THE INITIAL INTENSITY REMAINS AT 45 KT BASED
ON SATELLITE INTENSITY ESTIMATES OF 45 KT FROM BOTH TAFB AND
SAB...AND THE PREVIOUSLY MENTIONED MICROWAVE DATA.
THE INITIAL MOTION ESTIMATE IS 295/14. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK REASONING. VISIBLE SATELLITE
IMAGERY INDICATES MANUEL HAS BEEN MOVING MORE WEST-NORTHWESTWARD AND
FASTER...SO THE OFFICIAL FORECAST HAS BEEN ADJUSTED A LITTLE TO THE
LEFT OF THE PREVIOUS FORECAST TRACK. IT APPEARS THAT THE LOW-LEVEL
RIDGE TO THE NORTH IS NOW EXERTING MORE OF A WESTERLY INFLUENCE ON
MANUEL. MOST OF THE NHC MODEL GUIDANCE MAINTAINS A WEST-NORTHWEST
TO NORTHWESTWARD MOTION THROUGH 48 HOURS. THE BAM MODELS CONTINUE
TO INDICATE NORTHWARD MOTION AT 72 HOURS...BUT THIS SCENARIO HAS
BEEN IGNORED DUE TO THE STRONG RIDGE TO THE NORTH. THE OFFICIAL
FORECAST IS ALONG THE SOUTHERN EDGE OF THE MODEL ENVELOPE...AND IS
BETWEEN THE GFDL AND UKMET SOLUTIONS. HOWEVER...IF A MORE WESTWARD
TREND CONTINUES...THEN THE FORECAST TRACK WILL HAVE TO BE ADJUSTED A
LITTLE FARTHER SOUTH ON THE NEXT ADVISORY.
THERE IS STILL THE POSSIBILITY OF SOME INTENSIFICATION AS MANUEL
GOES THROUGH THE DIURNAL CONVECTIVE MAXIMUM PERIOD TONIGHT.
AFTERWARDS...INCREASING VERTICAL SHEAR...DECREASING SSTS...AND THE
EXPECTED ENTRAINMENT OF COOL STABLE AIR TO THE WEST SHOULD BEGIN TO
RAPIDLY WEAKEN THE CYCLONE BY 36 HOURS. THE SHIPS INTENSITY MODEL
MAINTAINS THE CURRENT INTENSITY THROUGH 36 HOURS...THEN DISSIPATES
THE SYSTEM IN 60 TO 72 HOURS. HOWEVER...IF MANUEL TAKES MORE OF A
WESTWARD TRACK AND REMAINS OVER WARMER SSTS...WEAKENING AND
DISSIPATION COULD BE DELAYED.
FORECASTER STEWART/BROWN
FORECAST POSITIONS AND MAX WINDS
INITIAL 16/2100Z 18.8N 120.0W 45 KTS
12HR VT 17/0600Z 19.7N 121.7W 55 KTS
24HR VT 17/1800Z 20.8N 123.4W 50 KTS
36HR VT 18/0600Z 21.9N 125.0W 40 KTS
48HR VT 18/1800Z 22.7N 126.8W 30 KTS...DISSIPATING
72HR VT 19/1800Z 23.5N 129.5W 25 KTS...REMNANT LOW
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