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HURRICANE MICHELLE DISCUSSION NUMBER 23
NATIONAL WEATHER SERVICE MIAMI FL
4 AM EST SUN NOV 04 2001
THE CENTRAL DEEP CONVECTION HAS BECOME DISRUPTED DUE TO INCREASING
UPPER-LEVEL WESTERLY SHEAR. HOWEVER...THE CONVECTION HAS MADE A
RETURN DURING THE PAST 3 HOURS WITH A RING OF -75 TO -80C TOPS
STARTING TO ENCIRCLE THE CLOUD-COVERED EYE. THE INITIAL INTENSITY
OF 115 KT IS BASED ON AN EARLIER RECON REPORT OF STEP-FREQUENCY
MICROWAVE RADIOMETER SURFACE WINDS OF 117 KT. THE NEXT RECON INVEST
FLIGHT WILL BE AROUND 12Z.
THE INITIAL MOTION ETSIMATE IS 040/06. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. WATER VAPOR
IMAGERY INDICATES AN UPPER-LEVEL TROUGH DIGGING SOUTHWARD ACROSS
TEXAS AND THE WESTERN GULF OF MEXICO. AHEAD OF THE TROUGH...THE
UPPER-LEVEL FLOW IS BEGINNING TO BACK AS INDICATED BY THE NORTHWARD
SPREADING OF CIRRUS CLOUDS ACROSS NORTH FLORIDA AND GEORGIA.
HOWEVER...00Z UPPER-AIR AND G-IV DROPSONDE DATA INDICATE THAT THE
700 TO 300 MB RIDGE LOCATED ACROSS THE BAHAMAS AND SOUTHERN FLORIDA
HAS CHANGED LITTLE. VTHE RESULT IS THAT MICHELLE IS EXPECTED TO
SLOWLY MOVE NORTHEAST OR NORTH-NORTHEASTWARD INTO THE MID- AND
UPPER-LEVEL RIDGE POSITION AND BE DEFLECTED SLIGHTLY POLEWARD INTO
THE SOUTHEAST FLORIDA STRAITS BEFORE THE RIDGE ERODES COMPLETELY IN
ABOUT 24 HOURS...WHICH SHOULD ALLOW MICHELLE TO ACCLERATE RAPIDLY
ACROSS THE NORTHERN AND CENTRAL BAHAMAS. A SLIGHT POLEWARD JOG WAS
INDICATED AT 24 HOURS WHEN MICHELLE IS EXPECTED TO EMERGE OFF THE
NORTH COAST OF CUBA. THIS IS DUE TO A POSSIBLE LEESIDE OR INVERTED
TROUGH FORMING ALONG THE NORTH COAST IN RESPONSE TO FAST SOUTHERLY
FLOW COMING ACROSS THE HIGHER TERRAIN OF CUBA. THE OFFICIAL TRACK IS
CLOSE TO THE PREVIOUS FORECAST TRACK AND IS ALSO CLOSE TO THE
UKMET...AVN...AND NOGAPS CONSENSUS.
DUE TO THE INCREASING UPPER-LEVEL WESTERLY SHEAR...MICHELLE HAS
PROBABLY PEAKED IN INTENSITY. THE INTENSITY IS HELD CONSTANT UNTIL
LANDFALL...AND THEN WEAKENING IS EXPECTED BY 24 HOURS DUE TO LAND
INTERACTION WITH CUBA AND STRONG WESTERLY SHEAR AS INDICATED BY THE
AVN AND SHIPS MODELS.
THE HURRICANE WATCH AND TROPICAL STORM WARNING FOR THE FLORIDA KEYS
WAS UPGRADED TO A HURRICANE WARNING DUE TO THE CLOSE PROXIMITY OF
MICHELLE AND THE UNCERTAINTY IN THE FORECAST TRACK. WHILE SUSTAINED
HURRICANE FORCE WINDS MAY NOT OCCUR...GUSTS TO HURRICANE FORCE ARE
POSSIBLE IN STRONG SQUALLS...ESPECIALLY ACROSS THE MIDDLE AND UPPER
KEYS LATER TONIGHT OR MONDAY.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 04/0900Z 20.4N 83.1W 115 KTS
12HR VT 04/1800Z 21.6N 82.2W 115 KTS
24HR VT 05/0600Z 23.4N 80.6W 100 KTS
36HR VT 05/1800Z 25.1N 77.9W 90 KTS
48HR VT 06/0600Z 27.5N 73.5W 75 KTS
72HR VT 07/0600Z 34.0N 62.0W 55 KTS...BECOMING EXTRATROPICAL
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