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TROPICAL STORM BRET DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU AUG 19 1999
 
THE LATEST DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTER PLANE
INDICATE A SIGNIFICANT DROP IN THE CENTRAL PRESSURE...DOWN 6 MB
OVER 6 HOURS.   THE AIRCRAFT CREW REPORTS A CLOSED RING OF CENTRAL
CONVECTION AND FLIGHT LEVEL WINDS OF 45 KT.  THEREFORE THE INTENSITY
IS INCREASED TO 40 KT FOR THIS ADVISORY.  ALTHOUGH BRET DOES NOT
HAVE MUCH DEEP CONVECTION...WHAT CONVECTION THERE IS IS WELL
ORGANIZED WITH THE SUGGESTION OF SOME BANDING DEVELOPING.
 
BRET IS EMBEDDED IN A WEAK STEERING FLOW AND HAS BEEN NEARLY
STATIONARY OVER THE PAST SEVERAL HOURS.  THE AVN...GFDL...UKMET...
AND DEEP BAM NOW KEEP BRET OFFSHORE THROUGH THE FORECAST PERIOD.
THE OFFICIAL FORECAST IS AGAIN SHIFTED TO THE RIGHT OF THE PREVIOUS
PACKAGE...WITH A SLOW NORTHWESTWARD MOTION EXPECTED TO RESUME
TOMORROW.  THE CENTER IS EXPECTED TO BE VERY CLOSE TO THE MEXICAN
COAST IN 72 HOURS.
 
WATER VAPOR IMAGERY SHOWS THAT THE UPPER-LEVEL TROUGH IN THE
NORTHWESTERN GULF IS MOVING WESTWARD AND IS BEING REPLACED BY
ANTICYCLONIC FLOW.  GIVEN THE IMPROVED ORGANIZATION OF THE
SYSTEM...THE PRESSURE FALL...AND THE MORE FAVORABLE UPPER
FLOW...BRET IS EXPECTED TO STRENGTHEN.  THE SHIPS INTENSITY FORECAST
MODEL BRINGS BRET TO HURRICANE STRENGTH BY 48 H AND THE OFFICIAL
FORECAST IS SIMILAR.
 
FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     20/0300Z 19.8N  94.7W    40 KTS
12HR VT     20/1200Z 19.8N  94.7W    45 KTS
24HR VT     21/0000Z 20.0N  95.0W    50 KTS
36HR VT     21/1200Z 20.3N  95.4W    60 KTS
48HR VT     22/0000Z 21.0N  96.0W    65 KTS
72HR VT     23/0000Z 22.0N  97.5W    70 KTS
 
 
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