Hurricane HILARY

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HURRICANE HILARY DISCUSSION NUMBER  25
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092011
200 AM PDT TUE SEP 27 2011
 
HILARY IS GRADUALLY WEAKENING. WHILE THE CENTRAL CONVECTION HAS BEEN
PULSING...THE EYE OF THE HURRICANE HAS RECENTLY DISAPPEARED AND THE
ORGANIZATION OF THE INNER CORE CONVECTION HAS DECREASED. ALTHOUGH
THE EXACT CAUSE IS UNCLEAR...INNER CORE STRUCTURAL CHANGES MAY BE
RESPONSIBLE FOR RECENT DEGRADATION OF SATELLITE APPEARANCE.
SUBJECTIVE INTENSITY ESTIMATES AND ADT VALUES HAVE DECREASED
FURTHER SINCE 0000 UTC...AND A BLEND OF T AND CI NUMBERS IS THE
BASIS FOR LOWERING THE INITIAL INTENSITY TO 100 KT. EVEN THOUGH THE
VERTICAL SHEAR IS FORECAST TO REMAIN LOW THROUGH ABOUT 48
HOURS...HILARY IS ALREADY DEPARTING THE WARMEST WATERS OF THE
BASIN. IN FACT...ACCORDING TO THE SHIPS MODEL...THE OCEANIC
HEAT CONTENT WILL BE ABOUT HALF OF ITS CURRENT VALUE A DAY FROM
NOW. INNER CORE DYNAMICS NOTWITHSTANDING...A STEADY WEAKENING IS
LIKELY DURING THIS TIME. AFTER THAT...HILARY SHOULD ENCOUNTER
INCREASING SOUTHWESTERLY SHEAR AND DRAMATICALLY COOLER WATERS...
BOTH OF WHICH WILL RESULT IN A RAPID WEAKENING. THE OFFICIAL
INTENSITY FORECAST HAS BEEN LOWERED RELATIVE TO THE PREVIOUS
ONE...WITH HILARY NOW FORECAST TO BECOME A REMNANT LOW A DAY
SOONER.
 
HILARY HAS BEEN WOBBLING...BUT A SMOOTHING OF CENTER FIXES YIELDS A
LONGER-TERM MOTION JUST SOUTH OF DUE WEST...265/09. GLOBAL MODELS
FORECAST THE MID-LEVEL RIDGE GUIDING HILARY WESTWARD TO BREAK DOWN
DURING THE NEXT 12-24 HOURS IN RESPONSE TO A TROUGH OVER THE
SOUTHWESTERN UNITED STATES AND BAJA CALIFORNIA. THE MODEL
GUIDANCE AGREES THAT THIS SHOULD CAUSE HILARY TO TURN SHARPLY
NORTHWARD WITH A DECREASE IN FORWARD SPEED BUT DIFFERS ON HOW SOON
THE TURN WILL OCCUR.  THE GFS SOLUTION...AS IT HAS IN PREVIOUS
CYCLES...LIES ON THE EASTERN EDGE OF THE MODEL SUITE SINCE IT
BREAKS DOWN THE RIDGE SOONER.  WHILE THIS OUTCOME CANNOT BE
COMPLETELY DISCREDITED...IT SEEMS SOMEWHAT UNREALISTIC GIVEN THE
CONTINUED STEADY MOTION TOWARD THE WEST. THE OFFICIAL FORECAST
PLACES GREATER WEIGHT ON THE REMAINDER OF THE GUIDANCE WHICH DELAYS
THE TURN.  LATER IN THE PERIOD...LARGE-SCALE MODELS ARE IN GOOD
AGREEMENT THAT HILARY WILL ROTATE AROUND AN UPPER-LEVEL LOW
CURRENTLY SLIDING EASTWARD FROM 28N129W. THE DEGREE OF INTERACTION
WITH THIS FEATURE WILL AT LEAST BE PARTLY DEPENDENT ON WHERE HILARY
ULTIMATELY TURNS NORTHWARD.  THE OFFICIAL NHC TRACK FORECAST HAS
BEEN NUDGED SLIGHTLY TO THE LEFT AND IS NEAR BUT TO THE RIGHT OF
THE MULTI-MODEL AND HFIP CONSENSUS AIDS.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  27/0900Z 16.6N 115.7W  100 KT 115 MPH
 12H  27/1800Z 16.8N 116.5W  100 KT 115 MPH
 24H  28/0600Z 17.4N 117.1W   90 KT 105 MPH
 36H  28/1800Z 18.4N 117.4W   80 KT  90 MPH
 48H  29/0600Z 19.6N 117.4W   70 KT  80 MPH
 72H  30/0600Z 22.1N 117.4W   50 KT  60 MPH
 96H  01/0600Z 24.5N 117.9W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  02/0600Z 27.0N 118.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER KIMBERLAIN
 
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