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HURRICANE GEORGES DISCUSSION NUMBER  23
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SUN SEP 20 1998
 
THE MET OFFICE IN GUADELOUPE HAS FORWARDED THE 01Z OBSERVATION FROM
DESIRADE WHICH REPORTED SUSTAINED WINDS OF 57 KNOTS WITH A GUSTS TO
76 KNOTS.  THE LATEST DATA RECEIVED FROM THE AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT INDICATES THAT GEORGES HAS CONTINUED TO
WEAKEN THIS EVENING WITH THE CENTRAL PRESSURE HAVING RISEN TO
966 MB. THIS REPRESENTS A 25 MB INCREASE DURING THE LAST 24 HOURS.
THE MAXIMUM FLIGHT LEVEL WINDS DURING THE LAST PASS WAS 114 KNOTS.
SATELLITE IMAGERY CONFIRMS THE WEAKENING TREND WITH THE COLD CLOUD
TOPS REMAINING ASYMMETRIC AND THE STRONGEST CONVECTION IN THE
NORTHWEST QUADRANT OF THE CYCLONE.  BASED ON THIS DATA...THE INITIAL
INTENSITY IS REDUCED TO 100 KNOTS...KEEPING GEORGES A CATEGORY THREE
HURRICANE THAT IS CAPABLE OF PRODUCING EXTENSIVE DAMAGE.
 
SATELLITE IMAGERY SHOWS THAT THE OUTFLOW OVER THE WESTERN SEMICIRCLE
IS RESTRICTED.  EXAMINATION OF WATER VAPOR IMAGERY...ALONG WITH
ANALYSES FROM THE COOPERATIVE INSTITUTE FOR METEOROLOGICAL SATELLITE
STUDIES AT THE UNIVERSITY OF WISCONSIN...SUGGESTS THAT NORTH/
NORTHWESTERLY VERTICAL SHEAR ASSOCIATED WITH AN UPPER-LEVEL
ANTICYCLONE OVER THE EASTERN CARIBBEAN IS ONE OF THE POSSIBLE
CULPRITS RESPONSIBLE FOR GEORGES WEAKENING.  SOME OF THE GLOBAL
MODELS SHOW THAT THE SHEAR SHOULD RELAX SOMEWHAT AS THE SYSTEM MOVES
WEST-NORTHWESTWARD WHICH COULD ALLOW FOR SOME RE-INTENSIFICATION. ON
THE OTHER HAND...THE SYSTEM MAY WEAKEN MORE AS IT INTERACTS WITH THE
LARGER ISLANDS...I.E. PUERTO RICO AND HISPANIOLA. THEREFORE...GIVEN
THIS UNCERTAINTY THE FORECAST MAINTAINS GEORGES INTENSITY AT 100
KNOTS THROUGHOUT THE FORECAST PERIOD.
 
THE INITIAL MOTION ESTIMATE REMAINS UNCHANGED AT 285/14 KNOTS.
THE STEERING OF THIS TROPICAL CYCLONE WILL DEPEND UPON THE STRENGTH
OF THE MID-TO UPPER-TROPOSPHERIC RIDGE CURRENTLY LOCATED BETWEEN
20N-30N NORTH. THE OFFICIAL TRACK FORECAST IS VERY SIMILAR TO THE
PREVIOUS ADVISORY. THE GFDL MODEL IS TO THE LEFT OF OUR TRACK WHILE
THE UKMET IS WELL TO THE RIGHT.  THERE IS STILL CONSIDERABLE
UNCERTAINTY CONCERNING THE THREAT TO THE MAINLAND U.S. AT THIS TIME.
 
GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     21/0300Z 16.9N  61.4W   100 KTS
12HR VT     21/1200Z 17.2N  63.5W   100 KTS
24HR VT     22/0000Z 18.0N  66.0W   100 KTS
36HR VT     22/1200Z 18.8N  68.3W   100 KTS
48HR VT     23/0000Z 19.6N  70.3W   100 KTS
72HR VT     24/0000Z 21.0N  74.0W   100 KTS
 
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