Hurricane HENRIETTE

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HURRICANE HENRIETTE DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP082013
200 AM PDT TUE AUG 06 2013
 
AFTER A BRIEF CONVECTIVE RESPITE...A PRONOUNCED CDO FEATURE WITH
CLOUD TOPS OF -75C TO -80C HAS DEVELOPED OVER THE CENTER DURING THE
PAST 4 HOURS. VARIOUS MICROWAVE DATA DURING THE PAST 6 HOURS
INDICATE THAT A WELL-DEFINED AND VERTICALLY ALIGNED EYE HAS
DEVELOPED THROUGH A DEEP LAYER OF THE TROPICAL CYCLONE...AND WAS
EVEN BRIEFLY EVIDENT IN NIGHT TIME VISIBLE IMAGERY AROUND 0500 UTC.
SATELLITE INTENSITY ESTIMATES ARE T4.4/75 KT FROM UW-CIMSS ADT...
AND T4.0.65 KT FROM BOTH TAFB AND SAB. THEREFORE...HENRIETTE IS
UPGRADED TO A 65-KT HURRICANE...WHICH COULD BE CONSERVATIVE.

MICROWAVE SATELLITE IMAGERY INDICATES HENRIETTE HAS WOBBLED TOWARD
THE WEST-NORTHWEST DURING THE PAST 6 HOURS. HOWEVER...THIS IS
BELIEVED TO BE A TEMPORARY MOTION DUE TO RE-ORGANIZATION OF THE
INNER CORE AND DEVELOPMENT OF THE EYE....AND HENRIETTE IS EXPECTED
TO RESUME A NORTHWESTWARD MOTION LATER TODAY AS IT MOVES TOWARD A
WEAKNESS IN THE MID-PACIFIC SUBTROPICAL RIDGE LOCATED ALONG
136-137W LONGITUDE. BY 48-72 HOURS...THE RIDGE IS FORECAST TO BUILD
BACK WESTWARD AS THE UPPER-LEVEL TROUGH INDUCING THE WEAKNESS LIFTS
OUT TO THE NORTHEAST. AS THE RIDGE BUILDS WESTWARD...HENRIETTE IS
EXPECTED TO TURN WESTWARD OR EVEN WEST-SOUTHWESTWARD ON DAYS 4/5.
THE FORECAST TRACK IS CLOSE TO BOTH THE PREVIOUS ADVISORY TRACK AND
IS SIMILAR TO THE CONSENSUS MODEL TVCE.

ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR ADDITIONAL STRENGTHENING
TO OCCUR FOR AT LEAST THE NEXT 24 HOURS OR SO...ESPECIALLY GIVEN
THE VERY LOW VERTICAL WIND SHEAR CONDITIONS AND IMPRESSIVE OUTFLOW
PATTERN. HOWEVER...NONE OF THE RELIABLE MODEL GUIDANCE BRINGS
HENRIETTE MUCH ABOVE 75 KT...INCLUDING THE SHIPS AND LGEM MODELS.
THESE LOWER INTENSITY VALUES MAY BE THE RESULT OF THOSE MODELS
USING SST VALUES THAT ARE ABOUT 0.5C LOWER THAN WHAT IS NOTED IN
THE MOST RECENT SST ANALYSES. GIVEN THE 20-25 NMI DIAMETER EYE
NOTED IN A RECENT 0555Z AMSU MICROWAVE OVERPASS...THE INTENSITY IS
FORECAST TO INCREASE FOR THE NEXT 12-24 HOURS. BY 36 HOURS...
GRADUAL WEAKENING IS EXPECTED TO BEGIN AS HENRIETTE MOVES OVER OR
NEAR SUB-26C SSTS AND INTO A SLIGHTLY MORE STABLE AIRMASS.
HOWEVER...THE WEAKENING MIGHT NOT OCCUR AS QUICKLY OR AS MUCH AS
FORECAST DUE TO THE VERY LOW SHEAR CONDITIONS THAT ARE EXPECTED TO
EXIST THROUGHOUT THE ENTIRE FORECAST PERIOD. THE OFFICIAL FORECAST
IS SIMILAR TO THE PREVIOUS ONE...AND CLOSELY FOLLOWS THE SHIPS AND
LGEM MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/0900Z 13.8N 130.9W   65 KT  75 MPH
 12H  06/1800Z 14.7N 132.1W   75 KT  85 MPH
 24H  07/0600Z 15.8N 133.7W   75 KT  85 MPH
 36H  07/1800Z 16.7N 135.3W   70 KT  80 MPH
 48H  08/0600Z 17.3N 137.0W   65 KT  75 MPH
 72H  09/0600Z 17.8N 141.1W   55 KT  65 MPH
 96H  10/0600Z 17.0N 145.3W   40 KT  45 MPH
120H  11/0600Z 16.8N 150.3W   30 KT  35 MPH
 
$$
FORECASTER STEWART
 
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