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TROPICAL STORM MICHELLE DISCUSSION NUMBER  10
NATIONAL WEATHER SERVICE MIAMI FL
10 PM EST WED OCT 31 2001
 
AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT FOUND 1500 FT
FLIGHT-LEVEL WINDS OF 42 KT LOCATED NORTHWEST AND SOUTHEAST OF THE
CENTER OF THE BROAD CIRCULATION.  THIS EQUATES TO ABOUT 36 KT AT THE
SURFACE...SO TROPICAL DEPRESSION FIFTEEN HAS BEEN UPGRADED TO
TROPICAL STORM MICHELLE.  THE LOW-LEVEL CENTER IS LOCATED ALONG THE
SOUTHERN EDGE OF THE DEEP CONVECTION OWING TO THE SOUTHERLY
UPPER-LEVEL SHEAR.  HOWEVER...THE CENTRAL DEEP CONVECTION AND
ASSOCIATED BANDING FEATURES HAVE CONTINUED TO IMPROVE OVER THE PAST
4 HOURS SINCE THE LAST RECON FLIGHT.  UPPER-LEVEL OUTFLOW REMAINS
QUITE IMPRESSIVE IN THE NORTHERN SEMICIRCLE AND IS ALSO SHOWING 
SIGNS OF BECOMING LESS RESTRICTED TO THE SOUTH.

THE INITIAL MOTION ESTIMATE IS 350/5.  THE APPARENT NORTHWARD JUMP
IN THE CENTER POSITION IS PRIMARILY DUE TO REFORMATION FARTHER NORTH
NEAR THE DEEP CONVECTION...WHICH HAS BEEN THE HISTORY OF THIS
CYCLONE DURING THE PAST 48 HOURS.  HOWEVER...DROPSONDE DATA FROM THE 
GULFSTREAM-IV AIRCRAFT INDICATES THAT THERE IS A NARROW BREAK IN THE 
SUBTROPICAL RIDGE...BASED ON A TROUGH AXIS THAT EXTENDS FROM 
MICHELLE NORTH-NORTHWESTWARD TO WESTERN CUBA.  ONLY THE 18Z AVN 
MODEL PICKED UP ON THIS SUBTLE FEATURE.  THE CURRENT POSITION AND 
STRENGTH OF THE RIDGE TO THE EAST OF THE CYCLONE IS FORECAST TO 
REMAIN STEADY THROUGHOUT THE PERIOD.  THEREFORE...MICHELLE IS 
EXPECTED TO TRACK SLOWLY UP THE TROUGH IN A NORTHWARD OR 
NORTH-NORTHWESTWARD DIRECTION TOWARD WESTERN CUBA.  THE OFFICIAL 
FORECAST IS A LITTLE TO THE RIGHT OF THE PREVIOUS FORECAST 
TRACK...BUT ONLY DUE TO THE MORE EASTWARD POSITION OF THE CENTER 
BASED ON THE RECON DATA.  THIS SCENARIO IS ALSO CONSISTENT WITH THE 
18Z AVN MODEL.  THE UKMET AND NOGAPS MODEL SOLUTIONS OF TAKING 
MICHELLE WEST-NORTHWESTWARD INTO THE YUCATAN PENINSULA WERE NOT 
CONSIDERED SINCE THEY KEEP THE CYCLONE VERY WEAK...WHICH ALLOWS THE 
LOW-LEVEL STEERING FLOW TO DRIVE THE STORM MORE WESTWARD.

NOW THAT THE CENTER OF MICHELLE IS FINALLY OVER WARM WATER...STEADY 
INTENSIFICATION SHOULD OCCUR IN SPITE OF THE SOUTHERLY SHEAR ON THE 
SYSTEM. THE SHIPS INTENSITY MODEL WAS FOLLOWED CLOSELY...WHICH 
BRINGS MICHELLE TO HURRICANE STRENGTH IN 48 HOURS.  HOWEVER...MY 
BIGGEST CONCERN IS THAT THE LOW-LEVEL CENTER MAY TUCK IN UNDERNEATH 
THE DEEP CONVECTION SOONER THAN EXPECTED...WHICH IS WHAT THE LATEST 
SATELLITE DATA SUGGESTS MAY BE HAPPENING. THIS WOULD ALLOW FOR MORE 
STRENGTHENING THAN IS CURRENTLY INDICATED.  RAPID INTENSIFICATION IS 
ALSO A DISTINCT POSSIBILITY GIVEN THE FAVORABLE UPPER-LEVEL OUTFLOW 
PATTERN AND VERY WARM SSTS CURRENTLY EXISTING ACROSS THE NORTHWEST 
CARIBBEAN SEA.  RECENT HISTORY INDICATES THAT THIS IS THE SAME 
PATTERN THAT PRODUCED HURRICANES MITCH AND LENNY IN THIS SAME AREA.
 
THERE CONTINUES TO BE A MAJOR DISAGREEMENT BETWEEN MODEL TRACK
FORECASTS AFTER 72 HR...THEREFORE IT IS TOO EARLY TO SPECULATE IF
ANY PORTION OF THE UNITED STATES WILL BE THREATENED BY THIS SYSTEM.
STAY TUNED.  HOWEVER...IF MICHELLE TRACKS SLIGHTLY FASTER THAN 
FORECAST...THEN IT COULD REACH THE SOUTHEAST GULF OF MEXICO BEFORE 
THE NEXT BLOCKING SURFACE HIGH PRESSURE SYSTEM CAN TURN TO THE EAST 
LIKE THE AVN MODEL IS INDICATING BY AROUND 72 HOURS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/0300Z 16.1N  83.2W    35 KTS
12HR VT     01/1200Z 16.8N  83.4W    40 KTS
24HR VT     02/0000Z 18.0N  83.8W    45 KTS
36HR VT     02/1200Z 18.9N  84.1W    55 KTS
48HR VT     03/0000Z 20.0N  84.4W    65 KTS
72HR VT     04/0000Z 22.0N  84.5W    75 KTS
 
 
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