Tropical Storm HILARY

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TROPICAL STORM HILARY DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT FRI AUG 19 2005
 
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE 30 KT AT 0000Z. 
SINCE THEN...THE CLOUD PATTERN ASSOCIATED WITH TROPICAL DEPRESSION
EIGHT-E HAS INCREASED IN ORGANIZATION...WITH INCREASING CONVECTIVE
BANDING AROUND THE CENTER AND CLOUD TOPS COLDER THAN -80C IN A
CLUSTER SOUTH OF THE CENTER.  THERE IS ALSO A WARM SPOT IN INFRARED
IMAGERY NEAR THE CENTER...ALTHOUGH AT THIS STAGE OF DEVELOPMENT IT
IS TOO EARLY TO CALL THIS AN EYE.  BASED ON THIS...THE DEPRESSION
IS UPGRADED TO TROPICAL STORM HILARY WITH 35 KT WINDS.

HILARY IS MOVING BETWEEN 280-285 DEGREES AT 13-14 KT ON THE SOUTH
SIDE OF A DEEP-LAYER RIDGE EXTENDING FROM MEXICO WESTWARD OVER THE
PACIFIC.  LARGE-SCALE MODELS FORECAST THIS RIDGE TO PERSIST FOR
48-72 HR...THEN RAPIDLY WEAKEN AS AN UNSEASONABLY STRONG DEEP-LAYER
TROUGH DEVELOPS OVER CALIFORNIA AND THE ADJACENT PACIFIC WATERS. 
THIS TROUGH SHOULD HILARY TO TURN NORTHWESTWARD OR POSSIBLY EVEN
NORTHWARD.  THE TRACK MODELS ARE IN GOOD AGREEMENT ON A WESTWARD TO
WEST-NORTHWESTWARD MOTION THROUGH 48-72 HR...AND THE NEW FORECAST
TRACK IS ON THE SOUTH SIDE OF THE MAIN CLUSTER OF TRACK MODELS
DURING THIS TIME.  AFTER 72 HR...THE FORECAST TRACK CALLS FOR A
NORTHWESTWARD TURN IN RESPONSE TO THE CALIFORNIA TROUGH.  THE 120
HR POSITION IS A COMPROMISE BETWEEN THE MORE WESTWARD GFS AND THE
MORE EASTWARD UKMET AND ECMWF.

CONDITIONS APPEAR FAVORABLE FOR ADDITIONAL STRENGTHENING...AS THE
STORM IS EMBEDDED IN DEEP EASTERLY FLOW WITH LIGHT TO MODERATE
VERTICAL SHEAR.  THE GFDL AND SHIPS MODELS CALL FOR HILARY TO
BECOME A HURRICANE IN 36 HR...AND THE INTENSITY FORECAST HAS BEEN
INCREASED TO REFLECT THIS.  THE CYCLONE SHOULD REMAIN OVER WARM
WATER FOR 48-72 HR...FOLLOWED BY MOTION OVER COLDER WATER AND
GRADUAL WEAKENING.  WHILE THE CURRENT FORECAST CALLS FOR A PEAK
INTENSITY OF 80 KT IN GENERAL AGREEMENT WITH THE SHIPS AND GFDL...AN
EXPERIMENTAL RAPID INTENSIFICATION INDEX SHOWS A BETTER THAN 70%
CHANCE OF RAPID STRENGTHENING DURING AT LEAST THE NEXT 24 HR. 
SHOULD THIS OCCUR...HILARY COULD GET MUCH STRONGER THAN CURRENTLY
FORECAST.
 
WIND RADII FORECASTS HAVE BEEN EXPANDED BASED ON A STRONGER
SYSTEM...CLIMATOLOGY...AND THE LARGE-SCALE MODELS SHOWING A LARGE
ENVELOPE ASSOCIATED WITH HILARY.  SOME RAINBANDS WITH GUSTY WINDS
COULD AFFECT PORTIONS OF THE SOUTHWEST COAST OF MEXICO DURING THE
NEXT COUPLE OF DAYS.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0300Z 13.7N  98.9W    35 KT
 12HR VT     20/1200Z 14.0N 100.9W    45 KT
 24HR VT     21/0000Z 14.5N 103.7W    55 KT
 36HR VT     21/1200Z 15.4N 106.3W    65 KT
 48HR VT     22/0000Z 16.4N 108.5W    75 KT
 72HR VT     23/0000Z 18.5N 112.5W    80 KT
 96HR VT     24/0000Z 20.0N 115.0W    75 KT
120HR VT     25/0000Z 21.5N 117.0W    60 KT
 
 
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