Hurricane HILARY
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HURRICANE HILARY DISCUSSION NUMBER 13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT MON AUG 22 2005
INFRARED SATELLITE IMAGERY INDICATES THAT HILARY HAS FORMED A POORLY
DEFINED EYE DURING THE PAST FEW HOURS. THIS FORMATION HAS BEEN
ACCOMPANIED BY A WARMING OF THE CLOUD TOPS NEAR THE EYE...SO THAT
THE SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN 90 KT.
THAT WILL BE THE INITIAL INTENSITY. THE HURRICANE CURRENTLY HAS
GOOD CIRRUS OUTFLOW IN THE WESTERN SEMICIRCLE AND POOR IN THE
EASTERN SEMICIRCLE.
THE INITIAL MOTION IS 295/16. HILARY IS ON THE SOUTH SIDE OF A
MID-LEVEL RIDGE THAT EXTENDS FROM NORTHERN MEXICO WESTWARD INTO THE
PACIFIC. LARGE-SCALE MODELS ALL AGREE THAT A WEAKNESS WILL FORM IN
THE RIDGE NORTH OF HILARY AS A DEEP LAYER TROUGH MOVES ACROSS
CALIFORNIA IN 24-48 HR. HOWEVER...THE MODELS ALL AGREE THAT THE
TROUGH WILL NOT EXTEND FAR ENOUGH SOUTHWARD TO TURN HILARY TO THE
NORTH...WITH THE FORECAST TRACK GUIDANCE CALLING FOR A CONTINUED
WEST-NORTHWESTWARD MOTION WITH A DECREASE IN FORWARD SPEED AS
HILARY PASSES SOUTH OF THE WEAKNESS. THE OFFICIAL FORECAST
TRACK FOLLOWS THIS SCENARIO...CALLING FOR HILARY TO CONTINUE
WEST-NORTHWESTWARD WITH GRADUAL DECELERATION THROUGH 72 HR. AFTER
THAT...THE GUIDANCE CALLS FOR A MORE WESTWARD MOTION UNDER A RIDGE
WEST OF THE WEAKNESS...AND THIS IS REFLECTED IN A WESTWARD BEND OF
THE OFFICIAL TRACK. THE NEW FORECAST TRACK IS NUDGED SOMEWHAT TO
THE SOUTH OF THE PREVIOUS TRACK.
SEA SURFACE TEMPERATURES UNDER THE CORE OF HILARY ARE STARTING TO
COOL...ALTHOUGH AT THIS TIME THEY ARE STILL 28C-29C. THE HURRICANE
WILL BE MOVING OVER PROGRESSIVELY COOLER WATER DURING THE FORECAST
PERIOD...AND THIS WILL ALLOW WEAKENING EVEN THOUGH THE UPPER-LEVEL
WINDS ARE FAVORABLE. THE INTENSITY FORECAST WILL CALL FOR SOME
ADDITIONAL STRENGTHENING DURING THE NEXT 12 HR FOLLOWED BY A
WEAKENING TREND. THE FORECAST IS IN BEST AGREEMENT WITH THE SHIPS
MODEL...ALTHOUGH IT IS WEAKER THAN SHIPS BY 96-120 HR.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 22/0900Z 18.1N 110.7W 90 KT
12HR VT 22/1800Z 18.9N 112.6W 100 KT
24HR VT 23/0600Z 19.7N 114.7W 95 KT
36HR VT 23/1800Z 20.2N 116.3W 90 KT
48HR VT 24/0600Z 20.6N 117.7W 80 KT
72HR VT 25/0600Z 21.5N 120.0W 60 KT
96HR VT 26/0600Z 22.5N 122.5W 40 KT
120HR VT 27/0600Z 23.0N 126.0W 25 KT
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