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HURRICANE MICHAEL DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT WED OCT 18 2000
 
THE AIR FORCE RESERVE HURRICANE HUNTER FOUND A MINIMUM CENTRAL
PRESSURE OF 984 MB AND MAXIMUM 850 MB WINDS OF 73 KT IN THE
SOUTHEAST QUADRANT NEAR 06Z.  A SECOND FIX NEAR 08Z SHOWED 986 MB. 
WHILE THE SATELLITE APPEARANCE HAS BECOME A LITTLE RAGGED...A FAINT
EYE IS STILL PRESENT AND SATELLITE INTENSITY ESTIMATES RANGE FROM 65
TO 77 KT.  THE MAXIMUM WINDS REMAIN AT 65 KT FOR THIS ADVISORY.

MICHAEL IS MOVING A LITTLE FASTER AND THE INITIAL MOTION IS NOW
015/6.  WATER VAPOR IMAGERY SHOWS A STRONG DEEP LAYER TROUGH
DEVELOPING OVER THE NORTHEASTERN UNITED STATES...WITH RIDGING EAST
OF MICHAEL.  INFRARED IMAGERY AND SURFACE ANALYSES INDICATE A STRONG
LOW/MID LEVEL RIDGE NORTH AND EAST OF THE HURRICANE.  THE TROUGH AND
THE ASSOCIATED SOUTHWESTERLIES SHOULD MOVE MICHAEL NORTHEASTWARD...
HOWEVER THE LOW LEVEL RIDGE IS CURRENTLY PREVENTING SIGNIFICANT
EASTWARD MOTION.  THE RIDGE WILL WEAKEN AS A SURFACE LOW DEVELOPS
NEAR NEW ENGLAND OR THE CANADIAN MARITIMES...AND MICHAEL SHOULD TURN
NORTHEASTWARD AND ACCELERATE AS THAT HAPPENS.  ALL MODEL GUIDANCE
AGREES WITH THIS SCENARIO...WITH THE MAIN DIFFERENCES BEING IN HOW
FAST MICHAEL WILL MOVE.  THE OFFICIAL FORECAST IS TO THE LEFT AND
SOMEWHAT FASTER THAN THE PREVIOUS PACKAGE...ACCELERATING MICHAEL TO
MORE THAN 30 KT BY 48 HR.

WATER VAPOR IMAGERY SHOWS WESTERLIES ENCROACHING ON MICHAEL...AND
BOTH SATELLITE AND AIRCRAFT DATA HINT THAT SHEARING IS BEGINNING. 
LARGE-SCALE MODELS INDICATE THAT THE SHEAR SHOULD STEADILY INCREASE
AS MICHAEL MOVES NORTHEASTWARD INTO COOLER WATER.  THIS SHOULD CAUSE
THE STORM TO WEAKEN...AND THIS IS REFLECTED IN THE INTENSITY
FORECAST.  MICHAEL SHOULD LOSE TROPICAL CHARACTERISTICS BY 48 HR AND
MERGE WITH THE BAROCLINIC LOW BY 72 HR.  WHILE SOME STORMS THAT
INTERACT WITH THE WESTERLIES STRENGTHEN AS THEY ACCELERATE...THE
GUIDANCE SUGGESTS THESE WESTERLIES SHOULD PRODUCE TOO MUCH SHEAR TO
ALLOW MICHAEL TO DO THAT.

34 KT AND 50 KT WIND RADII HAVE BEEN EXPANDED IN THE EASTERN
SEMICIRCLE BASED ON AIRCRAFT FLIGHT LEVEL WINDS OF 60 KT 75 NM EAST
OF THE CENTER.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     18/0900Z 31.1N  70.8W    65 KTS
12HR VT     18/1800Z 32.1N  70.4W    65 KTS
24HR VT     19/0600Z 34.7N  68.5W    60 KTS
36HR VT     19/1800Z 38.7N  64.5W    55 KTS
48HR VT     20/0600Z 44.0N  58.5W    50 KTS...EXTRATROPICAL
72HR VT     21/0600Z...ABSORBED BY EXTRATROPICAL LOW...
 
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