Hurricane GORDON

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HURRICANE GORDON DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072006
1100 PM EDT MON SEP 18 2006
 
GORDON IS AN IMPRESSIVE HIGH-LATITUDE HURRICANE. IT HAS BEEN
MAINTAINING A MOSTLY SOLID RING OF DEEP CONVECTION AROUND THE
CENTER... WHILE THE EYE RECENTLY HAS BEEN CONTRACTING. SUBJECTIVE
DVORAK ESTIMATES ARE AT LEAST 77 KT... WHILE IN-HOUSE OBJECTIVE
ESTIMATES ARE NEAR 93 KT. A WELL-TIMED HIGH-RESOLUTION QUIKSCAT
MICROWAVE OVER THE HURRICANE AT 2215 UTC SHOWED MAXIMUM WINDS OF 85
KT. THUS THE INTENSITY IS BUMPED UP TO 85 KT IN ACCORDANCE WITH THE
ABOVE ESTIMATES. THE ONLY FACTOR THAT WOULD SUPPORT THE HURRICANE
MAINTAINING ITS INTENSITY IS COOLING UPPER-LEVEL TEMPERATURES...
WHICH WOULD GENERALLY KEEP A MORE UNSTABLE ENVIRONMENT THAN
NORMAL... AS DIAGNOSED BY SHIPS GUIDANCE. HOWEVER... IT DOESN'T
SEEM LIKE GORDON CAN KEEP UP THIS INTENSITY FOR TOO MUCH LONGER
BEFORE INCREASING SHEAR... COOLER SSTS... AND AN APPROACHING COLD
FRONT TAKE THEIR TOLL. ALL OF THESE EFFECTS WILL PROBABLY NOT
WEAKEN GORDON VERY QUICKLY... AND IT IS BECOMING MORE AND MORE
LIKELY THAT THE SYSTEM WILL BE A HURRICANE AS IT MOVES CLOSE TO THE
AZORES. THEREFORE... A HURRICANE WARNING HAS BEEN ISSUED FOR THOSE
ISLANDS. HURRICANES ARE RARE BUT NOT UNPRECEDENTED IN THE AZORES. A
QUICK CHECK OF THE 1851-2005 BEST TRACK DATABASE SHOWS THAT NINE
HURRICANES HAVE IMPACTED THE AZORES DURING THIS TIME... THE MOST
RECENT BEING CHARLEY OF 1992.
 
GORDON IS ZIPPING EASTWARD TONIGHT... 085/24.  TRACK MODELS ARE
TIGHTLY CLUSTERED ON THIS GENERAL MOTION CONTINUING WITH SOME
ACCELERATION FOR THE FIRST 24 HOURS.  THIS INCREASE IN FORWARD
SPEED APPEARS TO BE DUE TO THE HURRICANE BECOMING EMBEDDED IN FAST
ZONAL FLOW BETWEEN A DEEP-LAYERED TROUGH OVER THE NORTH ATLANTIC
OCEAN AND THE SUBTROPICAL RIDGE TO THE SOUTH.  EXTRATROPICAL
TRANSITION SHOULD BEGIN IN ABOUT 24 HOURS AS A COLD FRONT CATCHES
UP TO GORDON AND WIND SHEAR INCREASES ABOVE 40 KT.  THE TRACK
FORECAST IS SHIFTED A BIT SOUTHWARD FROM THE PREVIOUS FORECAST AS
THE GLOBAL MODELS MAINTAIN GORDON AS A SEPARATE ENTITY FROM THE
ONCOMING TROUGH FOR A LITTLE LONGER THAN EARLIER.  THESE MODELS ALSO
ARE IN GOOD AGREEMENT ON GORDON BECOMING ABSORBED IN THIS TROUGH BY
72 HOURS.  

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0300Z 38.0N  41.6W    85 KT
 12HR VT     19/1200Z 38.2N  37.0W    75 KT
 24HR VT     20/0000Z 38.3N  30.2W    65 KT
 36HR VT     20/1200Z 39.5N  22.0W    55 KT...EXTRATROPICAL
 48HR VT     21/0000Z 42.0N  13.5W    50 KT...EXTRATROPICAL
 72HR VT     22/0000Z...ABSORBED
 
$$
FORECASTER BLAKE/PASCH

 
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