Tropical Storm HILARY

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TROPICAL STORM HILARY DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SAT AUG 20 2005
 
HILARY APPEARS TO HAVE STRENGTHENED OVERNIGHT AT A FAIRLY RAPID
PACE. THE LOW LEVEL CENTER IS NOW WELL EMBEDDED BENEATH AN
EXPANDING AREA OF CONVECTIVE CLOUD TOPS COLDER THAN -80C... AND THE
MODERATE TO WEAK NORTHEASTERLY WIND SHEAR SEEMS TO BE GIVING WAY TO
OUTFLOW FROM THE CONVECTION. DVORAK INTENSITY ESTIMATES FROM TAFB
AND SAB... AND RECENT ODT ESTIMATES... HAVE INCREASED TO 55 KT...
WHICH IS THE BASIS FOR THE ADVISORY INTENSITY... AND HILARY MIGHT
HAVE BEEN STRONGER THAN ESTIMATED EARLIER THIS MORNING. LITTLE
SEEMS TO STAND IN THE WAY OF CONTINUED INTENSIFICATION... WITH THE
NORTHEASTERLY SHEAR EXPECTED TO REMAIN FAIRLY WEAK... AND THE OCEAN
IS MORE THAN WARM ENOUGH. COMBINING THESE FORECAST CONDITIONS WITH
THE RECENT INTENSITY TREND... THE NEW OFFICIAL FORECAST IS ADJUSTED
UPWARD FROM THE PREVIOUS ADVISORY. THE SHIPS... GFDL... AND THE
OFFICIAL FORECAST CALL FOR 90 KT BY 48 HOURS. WEAKENING IS EXPECTED
BEYOND 72 HOURS WHEN HILARY SHOULD REACH COOLER WATERS.
 
LACKING ANY RECENT MICROWAVE DATA TO REFINE THE POSITION OF THE LOW
LEVEL CENTER... THE INITIAL POSITION AND MOTION ARE BASED ON
CONTINUITY AND ON FOLLOWING THE CENTROID OF THE DEEP CONVECTION.
THE INITIAL MOTION ESTIMATE REMAINS 275/16. HILARY IS BEING STEERED
WESTWARD ALONG THE SOUTHERN PERIPHERY OF A MID-LEVEL RIDGE CENTERED
OVER THE SOUTHEASTERN UNITED STATES THAT EXTENDS WESTWARD OVER
NORTHERN MEXICO AND THE EXTREME EASTERN PACIFIC. DYNAMICAL MODELS
FORECAST THIS RIDGE TO REMAIN INTACT AND EXPAND WESTWARD DURING THE
NEXT COUPLE OF DAYS. THEREAFTER... A WEAKNESS IN THE RIDGE IS
FORECAST TO DEVELOP JUST WEST OF MEXICO AS A MIDLATITUDE TROUGH
DEEPENS OVER THE WEST COAST OF THE UNITED STATES. THIS FEATURE
SHOULD INDUCE A GRADUAL BEND IN THE TRACK OF HILARY TO THE RIGHT...
EVENTUALLY TOWARD THE NORTHWEST WITH A STEADY DECREASE IN FORWARD
SPEED. THE NEW OFFICIAL FORECAST IS VERY CLOSE TO THE DYNAMICAL
MODEL CONSENSUS... WHICH HAS SHIFTED A LITTLE WESTWARD COMPARED TO
THE PREVIOUS ADVISORY... MAINLY DUE TO THE WESTERNMOST SOLUTIONS
PROVIDED BY THE GFS AND GFDL.
 
RAINBANDS PRODUCING GUSTY WINDS AND LOCALLY HEAVY RAINFALL COULD
AFFECT PORTIONS OF THE SOUTHWESTERN COAST OF MEXICO FROM PUERTO
ESCONDIDO WESTWARD TO ZIHUATANEJO DURING THE NEXT DAY OR SO.
 
FORECASTER KNABB
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/1500Z 13.9N 102.1W    55 KT
 12HR VT     21/0000Z 14.3N 104.1W    65 KT
 24HR VT     21/1200Z 15.1N 106.7W    75 KT
 36HR VT     22/0000Z 15.9N 109.1W    85 KT
 48HR VT     22/1200Z 16.9N 111.3W    90 KT
 72HR VT     23/1200Z 18.5N 114.5W    90 KT
 96HR VT     24/1200Z 20.0N 117.0W    80 KT
120HR VT     25/1200Z 22.0N 118.5W    60 KT
 
 
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