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NHC Forecast Discussion


TCDAT5
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

Last updated: 03/22/14