HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM BARBARA DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT THU JUN 21 2001
 
BANDING IMPROVED FOR A TIME EARLIER THIS MORNING...AND THE 12Z 
DVORAK CLASSIFICATIONS FROM TAFB AND SAB WERE BOTH 55 KT.  THE 
ESTIMATE FROM KGWC WAS LOWER...35 KT.  SINCE THEN THE CONVECTION HAS 
DECREASED IN EXTENT AND DEPTH...AND THERE APPEARS TO HAVE BEEN AN 
INCREASE IN SOUTHERLY SHEAR OVER THE SYSTEM.  THE OFFICIAL INTENSITY 
IS INCREASED TO 50 KT FOR THIS ADVISORY...BUT I SUSPECT THAT THE 
DECAY STAGE HAS ALREADY BEGUN.  
 
THE PRIMARY ENVIRONMENTAL SYNOPTIC FEATURES CONTINUE TO BE A
MID-LEVEL ANTICYCLONE TO THE NORTH OF THE TROPICAL STORM...AND A
LARGE MID- TO UPPER-LEVEL COLD LOW CURRENTLY CENTERED NEAR 24N/148W.
THE COLD LOW HAS MOVED LITTLE SINCE YESTERDAY...AND IS FORECAST BY
BOTH THE AVN AND UKMET MODELS TO SLOWLY WEAKEN BUT REMAIN NEARLY
STATIONARY OVER THE NEXT THREE DAYS.  WATER VAPOR IMAGERY SHOWS THAT
THE STORM IS NOW ENTERING THE RELATIVELY DRIER ENVIRONMENT SOUTHEAST
OF THE UPPER LOW.  ALTHOUGH WATER TEMPERATURES WILL BE DECREASING 
ONLY SLOWLY...THE SHIPS MODEL FORECASTS A SHARP INCREASE IN VERTICAL 
SHEAR ASSOCIATED WITH THE UPPER LOW.  DISSIPATION OF THE SYSTEM IS 
EXPECTED TO BEGIN WITHIN 72 HOURS.

THE INITIAL MOTION ESTIMATE IS 290/14.  THE FUTURE TRACK OF BARBARA
WILL BE GOVERNED TO SOME EXTENT BY HOW LONG THE SYSTEM MAINTAINS
DEEP CONVECTION AS IT APPROACHES THE UPPER LOW.  IF THE CONVECTION
FADES SOONER RATHER THAN LATER...AS EXPECTED...THEN THE SYSTEM
SHOULD CONTINUE ON A GENERALLY WEST-NORTHWESTERLY TRACK FOR THE
NEXT THREE DAYS.

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     21/1500Z 15.0N 134.9W    50 KTS
12HR VT     22/0000Z 15.7N 137.0W    45 KTS
24HR VT     22/1200Z 16.6N 139.5W    40 KTS
36HR VT     23/0000Z 17.6N 142.0W    35 KTS
48HR VT     23/1200Z 18.5N 144.5W    30 KTS
72HR VT     24/1200Z 19.5N 149.0W    25 KTS...DISSIPATING
 
 
NNNN