HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL STORM GERT DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT MON SEP 13 1999
 
INFRARED SATELLITE IMAGERY INDICATES THAT GERT IS NEAR HURRICANE
STRENGTH. SATELLITE INTENSITY ESTIMATES FROM SAB...TAFB...AND AFWA
ARE 65 KT...55 KT...AND 55 KT RESPECTIVELY. A WARM SPOT IS PRESENT
NEAR THE CENTER...BUT IS NOT YET GOOD ENOUGH LOOKING TO CALL AN EYE.
THE MAXIMUM SUSTAINED WINDS REMAIN AT 60 KT FOR THIS PACKAGE.

THE INITIAL MOTION REMAINS 275/17. THE SYNOPTIC SITUATION IS
STRAIGHT FORWARD...WITH A STRONG SUBTROPICAL RIDGE NORTH OF THE
STORM THROUGH THE FORECAST PERIOD. NHC HURRICANE GUIDANCE IS SPLIT
INTO TWO CAMPS...WITH THE UKMET...BAMM...BAMS...AVN...AND CLIPER
BEING FASTER AND A LITTLE FARTHER NORTH. THE GFDL...BAMD...AND LBAR
ARE SLOWER AND FURTHER SOUTH. THE FORECAST TRACK FOLLOWS THE FIRST
GROUP AND IS AN UPDATE OF THE PREVIOUS PACKAGE.

GERT HAS STRONG CONVECTION AND GOOD OUTFLOW OVER THE WESTERN
SEMICIRCLE. FURTHER STRENGTHENING IS LIKELY ALONG THE LINES OF THE
SHIPS MODEL...WITH THE SYSTEM BECOMING A HURRICANE LATER TODAY AND
NEAR MAJOR HURRICANE INTENSITY BY THE END OF THE FORECAST PERIOD.
ONE POSSIBLE INHIBITING FACTOR IS THAT THE AVN AND NOGAPS DEVELOP A
STRONG UPPER LEVEL TROUGH OVER THE CENTRAL AND EASTERN TROPICAL
ATLANTIC THAT COULD CREATE NORTHERLY SHEAR. THE INTENSITY FORECAST
IS THE SAME AS THE PREVIOUS PACKAGE BASED ON THE PREMISES THAT GERT
IS LIKELY TO BECOME A HURRICANE BEFORE THIS HAPPENS...AND COULD WELL
BE FAR ENOUGH WEST TO ESCAPE THE WORST OF THE SHEAR. 

BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/0900Z 15.3N  38.1W    60 KTS
12HR VT     13/1800Z 15.6N  40.7W    65 KTS
24HR VT     14/0600Z 16.0N  43.9W    75 KTS
36HR VT     14/1800Z 16.5N  47.3W    85 KTS
48HR VT     15/0600Z 17.0N  50.0W    90 KTS
72HR VT     16/0600Z 17.5N  55.0W    95 KTS
 
 
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