HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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HURRICANE GERT DISCUSSION NUMBER  15
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT TUE SEP 14 1999
 
THE APPEARANCE OF GERT HAS CONTINUED TO IMPROVE THIS EVENING. 
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 102 AND 115 KT. 
IN FACT...THE PAST FEW ESTIMATES FROM THE UNIVERSITY OF WISCONSIN
OBJECTIVE TECHNIQUE ARE UP TO 120 KT OR MORE.  THE INTENSITY IS
INCREASED TO 110 KT FOR THIS ADVISORY.  IF GERT CAN MAINTAIN ITS
CURRENT STRUCTURE FOR A FEW MORE HOURS IT WILL PROBABLY BE ASSIGNED 
CATEGORY FOUR STATUS.  OUTFLOW CONTINUES TO LOOK OUTSTANDING IN
ALL QUADS.   THERE IS SOME INDICATION OF INCREASED SHEAR AT THE END
OF THE FORECAST PERIOD...ASSOCIATED WITH AN UPPER LOW TO THE
NORTHWEST OF THE CYCLONE...AND THE INTENSITY FORECAST CALLS FOR ONLY
MODEST ADDITIONAL STRENGTHENING.  

THERE HAVE BEEN SOME FLUCTUATIONS IN FORWARD SPEED OVER THE PAST FEW
HOURS BUT THE INITIAL MOTION IS ESTIMATED AS 280/12.  THE SYNOPTIC
REASONING IS UNCHANGED FROM THE PREVIOUS ADVISORY.  RIDGING NORTH OF
GERT SHOULD KEEP GERT ON A WEST/WEST-NORTHWEST TRACK FOR 36 HOURS. 
BEYOND THAT...THE MAIN LOBE OF THE RIDGE RETREATS EASTWARD AS FLOYD
INTERACTS WITH AN APPROACHING SHORT WAVE ALONG THE U.S. EAST COAST. 
MOST GUIDANCE MODELS TAKE GERT ON A MORE NORTHWESTERLY TRACK BY 72
HOURS.  THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO THE RIGHT OF
THE PREVIOUS ADVISORY...BUT IT IS STILL ON THE LEFT SIDE OF
VIRTUALLY ALL OF THE GUIDANCE.  IF GERT IS KIND ENOUGH TO FOLLOW
EVEN THE OFFICIAL TRACK IT WILL PASS SAFELY NORTH OF THE LESSER
ANTILLES.

TWO NOAA AIRCRAFT ARE CURRENTLY FLYING IN THE ENVIRONMENTS OF
HURRICANES FLOYD AND GERT TO PROVIDE ENHANCED SOUNDING COVERAGE FOR
THE 00Z GLOBAL MODELS.  THESE DATA WILL BE INCLUDED IN THE GUIDANCE
FOR THE NEXT ADVISORY PACKAGE.
 
FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     15/0300Z 17.3N  47.3W   110 KTS
12HR VT     15/1200Z 17.6N  49.1W   115 KTS
24HR VT     16/0000Z 18.0N  51.5W   120 KTS
36HR VT     16/1200Z 18.6N  53.8W   120 KTS
48HR VT     17/0000Z 19.5N  56.0W   115 KTS
72HR VT     18/0000Z 22.0N  60.0W   115 KTS
 
 
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