Hurricane HILARY

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HURRICANE HILARY DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SUN AUG 21 2005
 
TWO MICROWAVE PASSES...A TRMM PASS AT 0950Z AND AN AQUA PASS AT
0907Z...SUGGEST THAT HILARY MAY NOT BE QUIRE AS WELL ORGANIZED AS
IT WAS OVERNIGHT.  THE TRMM PASS IN PARTICULAR SHOWS AN EROSION OF
THE BANDING OR EYEWALL-LOOKING FEATURE WITH A CENTER NORTH OF OUR
PREVIOUS TRACK.  DVORAK CLASSIFICATIONS...WHICH ARE UNCHANGED FROM
6 HOURS AGO...ARE UNCERTAIN DUE TO QUESTIONS ABOUR THE CENTER
LOCATION. THE ADVISORY INTENSITY WILL REMAIN 70 KT PENDING VISIBLE
IMAGERY...AND HOPEFULLY SOME MORE CLARITY ABOUT THE STRUCTURE OF
THE CYCLONE. HILARY IS MAINTAINING VERY COLD CONVECTION AT THIS
TIME AND HAS A LARGE ENVELOPE OF MOISTURE. BOTH THE SHIPS AND GFDL
GUIDANCE SUGGEST ADDITIONAL STRENGTHENING IS LIKELY BEFORE HILARY
REACHES COOLER WATERS IN ABOUT 48 HOURS. THE OFFICIAL FORECAST
DIFFERS FROM THE PREVIOUS ADVISORY WITH A FASTER DECAY OVER THE
COLD WATER...MORE IN LINE WITH THE GFDL GUIDANCE.

THE MICROWAVE PASSES REQUIRE A NORTHWARD ADJUSTMENT IN THE PRIOR
TRACK...WITH AN INITIAL MOTION ESTIMATE OF 295/11.  HILARY IS SOUTH
OF A MINOR WEAKNESS IN THE SUBTROPICAL RIDGE...BUT WILL SHORTLY
BYPASS THIS WEAKNESS.  MODEL GUIDANCE HAS BEEN TOO FAST WITH THE
FORWARD SPEED OF HILARY AND STILL APPEARS TO BE INCONSISTENT WITH
THE PRESENT ESTIMATE OF 11 KT.  A MORE SIGNIFICANT EROSION OF THE
RIDGE IS EXPECTED WITHIN ABOUT 48 HOURS AS A MID-LEVEL TROUGH IS
FORECAST TO BECOME ESTABLISHED OVER SOUTHERN CALIFORNIA IN ABOUT 48
HOURS.  THIS PATTERN SHOULD ALLOW FOR A TEMPORARY INCREASE IN
SPEED OVER THE NEXT 24 HOURS...FOLLOWED BY A SLOWING OF THE MOTION
THEREAFTER.  THE OFFICIAL FORECAST REMAINS SLOWER THAN MOST OF THE
DYNAMICAL GUIDANCE AND IS ALSO SOMEWHAT ON THE RIGHT SIDE OF A
FAIRLY NARROW GUIDANCE ENVELOPE.  
 
RAINBANDS PRODUCING OCCASIONAL GUSTY WINDS AND LOCALLY HEAVY
RAINFALL ARE AFFECTING PORTIONS OF THE SOUTHWESTERN COAST OF MEXICO
WEST OF ACAPULCO.  CONDITIONS THERE SHOULD GRADUALLY IMPROVE AS
HILARY MOVES AWAY FROM THE COAST DURING THE NEXT DAY OR SO.
 
FORECASTER FRANKLIN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/1500Z 15.6N 106.1W    70 KT
 12HR VT     22/0000Z 16.4N 107.9W    80 KT
 24HR VT     22/1200Z 17.3N 110.4W    85 KT
 36HR VT     23/0000Z 18.1N 112.5W    90 KT
 48HR VT     23/1200Z 18.8N 114.2W    90 KT
 72HR VT     24/1200Z 20.0N 116.5W    75 KT
 96HR VT     25/1200Z 21.0N 118.5W    55 KT
120HR VT     26/1200Z 22.5N 120.5W    40 KT
 
 
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