Tropical Storm CALVIN

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TROPICAL STORM CALVIN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT MON JUN 27 2005
 
THE SATELLITE AND RADAR PRESENTATIONS OF CALVIN HAVE DETERIORATED
DRAMATICALLY THIS EVENING.  ON SATELLITE IMAGERY...CLOUD TOPS HAVE
WARMED AND THE BANDING SEEN EARLIER HAS ALL BUT DISAPPEARED.  TWO
MICROWAVE PASSES NEAR 01Z INDICATE THAT THE LOW-LEVEL CIRCULATION
CENTER IS ABOUT 50 NMI TO THE SOUTHEAST OF WHAT ROTATION CAN BE
SEEN ALOFT.  DVORAK CLASSIFICATIONS SUGGEST THAT CALVIN IS NEAR
MINIMAL TROPICAL STORM STRENGTH...AND THE INITIAL INTENSITY IS
LOWERED TO 35 KT FOR THIS ADVISORY.  CALVIN STILL HAS 24-36 HOURS
OVER WARM WATER...SO THE CONVECTION COULD WELL RETURN...BUT GLOBAL
MODEL GUIDANCE DOES NOT SUGGEST THAT THE SHEAR WILL LESSEN ANYTIME
SOON...AND CALVIN IS LIKELY TO STRUGGLE IN A MARGINAL ENVIRONMENT
UNTIL ITS INEVITABLE DEMISE.  BOTH THE SHIPS AND GFDL INTENSITY
GUIDANCE SUGGEST LITTLE OVERALL CHANGE IN STRENGTH UNTIL CALVIN
REACHES COOLER WATERS.  

CALVIN REMAINS BASICALLY ON TRACK...295/9.  THE OFFICIAL FORECAST
HAS BEEN ADJUSTED TO BE A LITTLE SLOWER THAN THE PREVIOUS
PACKAGE...BASED ON THE DETERIORATING STRUCTURE OF THE CYCLONE IN AN
EASTERLY SHEARING FLOW...AND IS IN BEST AGREEMENT WITH THE GFDL
MODEL.  A MID-LEVEL RIDGE IS EXPECTED TO MAINTAIN CALVIN ON A
WEST-NORTHWEST TRACK THAT WILL GRADUALLY EDGE AWAY FROM THE MEXICAN
COAST...AND THE TROPICAL STORM WATCH WILL LIKELY BE LOWERED SOON.
 
FORECASTER FRANKLIN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/0300Z 15.8N 101.6W    35 KT
 12HR VT     28/1200Z 16.2N 103.0W    35 KT
 24HR VT     29/0000Z 16.7N 105.0W    35 KT
 36HR VT     29/1200Z 17.1N 107.0W    30 KT
 48HR VT     30/0000Z 17.5N 109.0W    25 KT...DISSIPATING
 72HR VT     01/0000Z 17.5N 112.0W    25 KT...REMNANT LOW
 96HR VT     02/0000Z 17.5N 115.0W    20 KT...REMNANT LOW
120HR VT     03/0000Z 17.5N 117.0W    20 KT...REMNANT LOW
 
 
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