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Tropical Storm BARBARA


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TROPICAL STORM BARBARA DISCUSSION NUMBER   4...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022007
800 AM PDT WED MAY 30 2007

...CORRECTED DEPRESSION TO TROPICAL CYCLONE IN 2ND PARAGRAPH
 
THE SATELLITE PRESENTATION OF THE TROPICAL CYCLONE HAS BECOME A
LITTLE STRONGER...WITH A RAGGED BAND IN THE SOUTHEASTERN QUADRANT
OF THE CIRCULATION.  SATELLITE INTENSITY ESTIMATES FROM TAFB AND
SAB ARE 35 AND 30 KT...RESPECTIVELY...WHILE THE CIMSS ADT GIVES 41
KT.  ON THIS BASIS...THE DEPRESSION IS UPGRADED TO A 35 KT TROPICAL
STORM.  ONLY TWICE BEFORE...IN 1956 AND 1984...HAVE THERE BEEN TWO
EASTERN NORTH PACIFIC NAMED STORMS IN MAY.
 
THE TROPICAL CYCLONE REMAINS NEARLY STATIONARY.  WATER VAPOR IMAGERY
INDICATES THAT A LARGE MID- TO UPPER-LEVEL TROUGH IS DEVELOPING OVER
MEXICO AND THE WESTERN GULF OF MEXICO...WITH A LARGE MID/UPPER-
LEVEL RIDGE OVER THE PACIFIC WEST OF THE TROUGH.  THE IMAGERY ALSO
SHOWS MID-LEVEL NORTHERLIES ABOUT TO IMPINGE ON THE CIRCULATION. 
IN THE SHORT TERM...THIS SHOULD RESULT IN A SOUTHWARD DRIFT AWAY
FROM THE MEXICAN COASTLINE...AND MODEL GUIDANCE IS IN GOOD
AGREEMENT ON THIS FOR THE FIRST DAY OR TWO OF THE FORECAST.  AFTER
THAT...HOWEVER...THERE IS A GREAT DEAL OF UNCERTAINTY AS TO WHETHER
BARBARA WILL BE STEERED NORTHEASTWARD AHEAD OF THE GULF TROUGH OR
SLIDE WESTWARD AS THE TROUGH LIFTS OUT AND RIDGING BUILDS BEHIND
IT.  IN THE FORMER CAMP ARE THE GFS AND ECMWF...WHILE A MORE
WESTWARD TRACK IS INDICATED BY THE GFDL...UKMET...AND NOGAPS. 
INTERESTINGLY...THE ECMWF ENSEMBLES ARE PRETTY MUCH SPLIT BETWEEN
THESE TWO OPTIONS.  THE OFFICIAL FORECAST...ADMITTEDLY LOW
CONFIDENCE...CONTINUES TO FAVOR THE MORE WESTWARD SCENARIO.  

THE INTENSITY FORECAST IS DIFFICULT AS WELL.  THE MID-LEVEL
NORTHERLIES APPROACHING THE CYCLONE WILL ADVECT SOME DRY AIR INTO
THE CIRCULATION AND INCREASE THE VERTICAL SHEAR.  CONSEQUENTLY...
BARBARA COULD STRUGGLE IN THE SHORT RUN.  OVERALL...HOWEVER...
CONDITIONS APPEAR FAVORABLE FOR DEVELOPMENT...WITH VERY WARM WATERS
AND GOOD UPPER OUTFLOW.  THE SHIPS AND GFDL MODELS CONTINUE TO
FORECAST BARBARA TO REACH HURRICANE STRENGTH IN 48-72 HOURS.  THE
OFFICIAL FORECAST ENDS UP IN ABOUT THE SAME PLACE BUT WITH LESS
DEVELOPMENT INITIALLY. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/1500Z 14.2N  97.3W    35 KT
 12HR VT     31/0000Z 13.9N  97.2W    35 KT
 24HR VT     31/1200Z 13.4N  97.1W    40 KT
 36HR VT     01/0000Z 13.0N  97.0W    50 KT
 48HR VT     01/1200Z 13.0N  96.8W    60 KT
 72HR VT     02/1200Z 13.5N  96.5W    70 KT
 96HR VT     03/1200Z 15.0N  97.5W    75 KT
120HR VT     04/1200Z 16.5N 100.0W    70 KT
 
$$
FORECASTER FRANKLIN
 
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