Hurricane HILARY

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HURRICANE HILARY DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092011
200 PM PDT SAT SEP 24 2011
 
HILARY STILL IS EXHIBITING THE CLASSIC SIGNATURE OF A VERY
INTENSE...BUT TINY...HURRICANE.  AS SEEN IN THE INFRARED
IMAGERY...VERY COLD SYMMETRIC CLOUD TOPS ARE SURROUNDING A 10 NM
WIDE WARM EYE.  THE TAFB/SAB SUBJECTIVE DVORAK AND THE CIMSS
ADVANCED DVORAK TECHNIQUE CLASSIFICATIONS HAVE DROPPED
SLIGHTLY...BUT ARE STILL SUPPORTING AN INTENSITY OF 115 KT.  A
1457Z CIRA AMSU PASS PROVIDED GUIDANCE FOR THE WIND RADII ANALYSIS.
 
HILARY CONTINUES TO SHOW SHORT-TERM TROCHOIDAL MOTION OVER THE LAST
SEVERAL HOURS...BUT A LONGER TERM DIRECTION AND SPEED OF 270/9 IS
ESTIMATED. A MOTION TOWARD THE WEST OR WEST-NORTHWEST AT ABOUT THE
SAME SPEED IS EXPECTED DURING THE NEXT THREE DAYS AS HILARY IS
STEERED ALONG THE SOUTH SIDE OF A DEEP-LAYER RIDGE. BY DAYS 4 AND
5...A WEAKNESS DEVELOPS IN THE RIDGE DUE TO A MID- TO UPPER-LEVEL
LOW MOVING IN FROM THE NORTHWEST. HILARY SHOULD RESPOND BY TURNING
SLOWLY NORTHWARD NEAR 115W ON THOSE DAYS. ALL OF THE RELIABLE TRACK
MODELS REMAIN IN EXCELLENT AGREEMENT WITH THIS SCENARIO. IN
FACT...SOME OF THE GUIDANCE SUGGESTS THAT HILARY WILL UNDERGO A
FUJIWARA-TYPE OF INTERACTION WITH THE UPPER-LOW WITH A MUTUAL
COUNTER-CLOCKWISE ROTATION OF THE TWO SYSTEMS.  THE TRACK FORECAST
IS VERY SIMILAR TO THE PREVIOUS ADVISORY AND THE MULTI-MODEL
CONSENSUS.
 
THE HURRICANE IS CURRENTLY IN A QUITE CONDUCIVE ENVIRONMENT OF LOW
VERTICAL SHEAR...WARM WATERS...AND ABUNDANT MOISTURE.  THE CYCLONE
IS EXPECTED TO REMAIN A MAJOR HURRICANE FOR THE NEXT TWO DAYS.
AFTER WHICH...A DRIER AND MORE STABLE ATMOSPHERE MAY BEGIN SOME
SIGNIFICANT WEAKENING OF HILARY.  BY THE END OF THE FORECAST
PERIOD...STRONG VERTICAL SHEAR AND COOL SSTS SHOULD CAUSE AN EVEN
QUICKER DECAY.  THE INTENSITY PREDICTION IS BASED UPON THE
SHIPS/LGEM/GFDL MODEL CONSENSUS AND IS VERY SIMILAR TO THE PREVIOUS
ADVISORY.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/2100Z 16.9N 106.8W  115 KT 135 MPH
 12H  25/0600Z 17.0N 107.9W  115 KT 135 MPH
 24H  25/1800Z 17.1N 109.5W  110 KT 125 MPH
 36H  26/0600Z 17.2N 111.3W  110 KT 125 MPH
 48H  26/1800Z 17.3N 113.0W  105 KT 120 MPH
 72H  27/1800Z 18.0N 115.5W   95 KT 110 MPH
 96H  28/1800Z 19.5N 116.0W   80 KT  90 MPH
120H  29/1800Z 22.0N 116.0W   60 KT  70 MPH
 
$$
FORECASTER LANDSEA/STEWART
 
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