TROPICAL STORM GUSTAV DISCUSSION NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072008
1100 AM EDT FRI AUG 29 2008
SINCE THE LAST AIRCRAFT FIX OVER WESTERN JAMAICA AT ABOUT 1100
UTC...WHICH INCLUDED A CENTRAL PRESSURE ESTIMATE OF 988 MB...GOES
VISIBLE IMAGERY SUGGESTS THAT GUSTAV IS REGAINING ORGANIZATION NOW
THAT ITS CENTER HAS EMERGED OVER WATER WEST OF JAMAICA. THE
ADVISORY INTENSITY IS MAINTAINED AT 55 KT UNTIL WE RECEIVE NEW DATA
FROM THE NEXT AIRCRAFT THIS AFTERNOON...ALTHOUGH IT IS POSSIBLE
THAT GUSTAV IS ALREADY A LITTLE STRONGER. THE CYCLONE WILL HAVE
MORE THAN 24 HOURS OVER THE VERY WARM WATERS OF THE NORTHWESTERN
CARIBBEAN...AND BENEATH AN UPPER-LEVEL ANTICYCLONE...SO
STRENGTHENING SEEMS IMMINENT AND COULD EVEN BE RAPID. THE RAPID
INTENSIFICATION INDEX BASED ON THE SHIPS MODEL INDICATES A 28
PERCENT CHANCE OF AN INTENSITY INCREASE OF 30 KT OR MORE DURING THE
NEXT 24 HOURS. SINCE THERE IS ABOUT 36 HOURS LEFT BEFORE GUSTAV
CROSSES CUBA...THERE REMAINS SOME POSSIBILITY THAT GUSTAV COULD
BECOME A MAJOR HURRICANE BEFORE CROSSING THE WESTERN PORTIONS OF
THAT ISLAND. CONDITIONS OVER THE GULF OF MEXICO APPEAR TO SUPPORT A
MAJOR HURRICANE AS WELL...ALTHOUGH WIND SHEAR COULD INCREASE A
LITTLE. THE NEW OFFICIAL INTENSITY FORECAST IS VERY SIMILAR TO THE
PREVIOUS ONE AND IS A LITTLE HIGHER THAN THE INTENSITY CONSENSUS.
GUSTAV IS MOVING AT ABOUT 295/7 BUT IS IN THE PROCESS OF TURNING TO
THE RIGHT IN RESPONSE TO THE RIDGE TO ITS NORTH...AND IS HEADED FOR
A WEAKNESS IN THE RIDGE THAT IS FORECAST BY ALL MODELS TO DEVELOP
OVER THE EASTERN GULF OF MEXICO DURING THE NEXT COUPLE OF DAYS.
THE GUIDANCE IS IN VERY GOOD AGREEMENT ON A PATH OVER THE WESTERN
PORTIONS OF CUBA IN ROUGHLY 36 HOURS...FOLLOWED BY A TRACK INTO THE
SOUTH-CENTRAL GULF OF MEXICO. THEREAFTER...THE MODELS DIVERGE
TREMENDOUSLY OVER THE NORTHERN GULF DUE TO DIFFERENCES IN HOW THEY
HANDLE THE HIGH MOVING EASTWARD ACROSS THE GREAT LAKES REGION. THE
MODELS THAT SHOW A SLOWER AND MORE WESTWARD MOTION ACROSS THE
NORTHERN GULF SHOW A LITTLE MORE RIDGING EXTENDING SOUTHWESTWARD
FROM THE GREAT LAKES HIGH...WHILE THOSE THAT ARE FASTER AND
STRAIGHT NORTHWESTWARD TOWARD THE NORTH-CENTRAL GULF COAST SHOW
LESS OF THAT RIDGING. THE NEW OFFICIAL TRACK FORECAST IS ADJUSTED
ONLY SLIGHTLY RIGHT OF THE PREVIOUS ADVISORY AND THE
CONSENSUS...GIVING RESPECT TO THE NWS MODELS GFS...GFDL...AND
HWRF...WHICH ALSO SEEM TO DEPICT A SLIGHTLY DEEPER SYSTEM THAT WE
EXPECT GUSTAV TO BE. NEEDLESS TO SAY...DUE TO THE MODEL SPREAD THE
TRACK FORECAST IS RATHER UNCERTAIN...AND FINAL LANDFALL REMAINS
POSSIBLE THROUGHOUT THE NORTHERN GULF COAST.
