Tropical Storm COSME

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TROPICAL STORM COSME DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP062007
800 PM PDT SUN JUL 15 2007
 
COSME IS GETTING BETTER ORGANIZED.  AN AMSR-E OVERPASS AT 2200 UTC
SUGGESTED THE DEVELOPMENT OF A TIGHTER INNER CORE...AND SUBSEQUENT
CONVENTIONAL IMAGERY SHOWS A SIGNIFICANT INCREASE IN CONVECTION
NEAR THE CENTER.  SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB
ARE NOW 45 KT...AND THAT IS THE INITIAL INTENSITY.

THE INITIAL MOTION REMAINS 305/7.  LARGE-SCALE MODEL ANALYSES SHOW A
WEAKNESS IN THE MID/UPPER-LEVEL SUBTROPICAL RIDGE NORTH OF
COSME...WITH SATELLITE IMAGERY SHOWING A WELL-DEFINED LOW-LEVEL
RIDGE NORTH OF THE STORM.  THIS PATTERN SHOULD STEER COSME
GENERALLY WEST-NORTHWESTWARD FOR 24 HR OR SO...FOLLOWED BY A MORE
WESTWARD MOTION AS THE MID/UPPER-LEVEL RIDGE STRENGTHENS SOMEWHAT. 
WHILE ALL TRACK GUIDANCE AGREES WITH THIS GENERAL SCENARIO...THE
UKMET...ECMWF...AND BAM MODELS CALL FOR MORE NORTHWARD MOTION IN
THE FIRST 24 HR BEFORE THE WESTWARD TURN.  THE GFS...GFDL...HWRF...
AND CONSENSUS MODELS CALL FOR LESS NORTHWARD MOVEMENT BEFORE THE
TURN...AND THE NEW FORECAST TRACK FOLLOWS THESE MODELS.  ALL THE
GUIDANCE CALLS FOR A FASTER MOTION AFTER 36 HR THAN THE PREVIOUS
RUNS...SO THE FORECAST FORWARD SPEED HAS BEEN INCREASED SOMEWHAT. 
IT SHOULD BE NOTED THAT COSME IS EMBEDDED IN A LARGE CYCLONIC GYRE
THAT INCLUDES THE REMAINS OF TROPICAL DEPRESSION 5-E...AND THIS MAY
PRODUCE SOME TRACK WOBBLES DURING THE FIRST 24-36 HR.

COSME IS IN AN ENVIRONMENT OF LIGHT SOUTHEASTERLY VERTICAL SHEAR...
AND THE CYCLONE SHOULD REMAIN IN A FAVORABLE SHEAR ENVIRONMENT FOR
AT LEAST THE NEXT FOUR DAYS.  THUS...THE INTENSITY WILL BE
CONTROLLED MAINLY BY THE SEA SURFACE TEMPERATURES.  SST ANALYSES
INDICATE THAT THE STORM IS OVER 27C TEMPERATURES...WHICH SHOULD
COOL ALONG THE FORECAST TRACK AFTER 12-24 HR.  THIS SHOULD ALLOW
COSME SOME ADDITIONAL STRENGTHENING BEFORE GRADUAL WEAKENING BEGINS
IN 36 HR OR SO.  SHIPS FORECAST COSME TO BECOME A HURRICANE...WHILE
THE GFDL AND HWRF DO NOT.  THE INTENSITY FORECAST HAS BEEN
INCREASED...NOW CALLING FOR COSME TO PEAK AT 60 KT IN 24 HR AS A
COMPROMISE BETWEEN SHIPS AND THE GFDL/HWRF.  IF THE CURRENT
CONVECTIVE TRENDS CONTINUE...THERE IS A CHANCE COSME COULD BECOME A
HURRICANE BEFORE WEAKENING BEGINS. 

THE FORECAST WIND RADII HAVE BEEN INCREASED BASED ON THE INCREASED
FORECAST INTENSITY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0300Z 13.3N 128.8W    45 KT
 12HR VT     16/1200Z 13.8N 129.9W    55 KT
 24HR VT     17/0000Z 14.5N 131.6W    60 KT
 36HR VT     17/1200Z 14.8N 133.4W    60 KT
 48HR VT     18/0000Z 15.0N 135.5W    55 KT
 72HR VT     19/0000Z 15.5N 140.5W    50 KT
 96HR VT     20/0000Z 16.5N 146.0W    40 KT
120HR VT     21/0000Z 17.5N 151.0W    30 KT
 
$$
FORECASTER BEVEN
 
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