Hurricane KATIA

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HURRICANE KATIA DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
1100 PM AST WED AUG 31 2011
 
THE CLOUD PATTERN ASSOCIATED WITH KATIA CONTINUES TO GRADUALLY
IMPROVE.  THE CENTER IS LOCATED NEAR THE MIDDLE OF AN EXPANDING
CENTRAL DENSE OVERCAST AND THERE IS A LARGE CURVED BAND OF DEEP
CONVECTION OVER THE SOUTHERN SEMICIRCLE OF THE CYCLONE.  RECENT
SSMIS MICROWAVE DATA SHOWED THE BEGINNINGS OF A BANDING EYE
FEATURE...HOWEVER THE CONVECTION OVER THE SOUTHERN PORTION OF THE
EYE IS STILL A BIT THIN.  SUBJECTIVE AND OBJECTIVE DVORAK SATELLITE
INTENSITY ESTIMATES HAVE INCREASED TO 65 KT...AND THE INITIAL
INTENSITY HAS BEEN RAISED ACCORDINGLY.  KATIA IS THE SECOND
HURRICANE OF THE 2011 ATLANTIC HURRICANE SEASON.

THE HURRICANE IS EXPECTED TO REMAIN IN A LOW SHEAR ENVIRONMENT
AND OVER WARM WATER DURING THE NEXT DAY OR SO...WHICH SHOULD FAVOR
ADDITIONAL STRENGTHENING.  AFTER THAT TIME...A MID- TO UPPER-LEVEL
TROUGH SEEN IN WATER VAPOR IMAGERY BETWEEN 50W AND 60W IS FORECAST
BY THE GLOBAL MODELS TO WEAKEN.  THIS SHOULD KEEP THE HURRICANE IN
A FAVORABLE UPPER-LEVEL WIND PATTERN AND KATIA IS FORECAST TO
BECOME A MAJOR HURRICANE WITHIN 72 HOURS.  THE NEW NHC INTENSITY
FORECAST SHOWS A SLIGHTLY FASTER RATE OF INTENSIFICATION DURING THE
FIRST 2-3 DAYS THAN INDICATED IN THE PREVIOUS ADVISORY...AND IS A
BLEND OF THE STATISTICAL AND DYNAMICAL GUIDANCE.

THE INITIAL MOTION ESTIMATE IS 285/17 KT.   THE HURRICANE IS
EXPECTED TO CONTINUE MOVING WEST-NORTHWESTWARD TO THE SOUTH OF A
SUBTROPICAL RIDGE DURING THE NEXT 2-3 DAYS.  AFTER 72 HOURS...
KATIA WILL BE NEARING THE SOUTHWESTERN PORTION OF THE RIDGE.  THIS
SHOULD RESULT IN A REDUCTION IN FORWARD SPEED AND A GRADUAL TURN
TOWARD THE NORTHWEST.  THE NEW TRACK FORECAST IS ESSENTIALLY AN
UPDATE OF THE PREVIOUS NHC FORECAST AND LIES BETWEEN THE
MULTI-MODEL CONSENSUS AND THE RELIABLE GFS AND ECMWF MODELS.

THE WIND RADII HAVE BEEN ADJUSTED SLIGHTLY ON THE BASIS OF RECENT
ASCAT DATA.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0300Z 15.0N  44.4W   65 KT  75 MPH
 12H  01/1200Z 15.6N  46.7W   75 KT  85 MPH
 24H  02/0000Z 16.3N  49.1W   85 KT 100 MPH
 36H  02/1200Z 17.3N  51.3W   90 KT 105 MPH
 48H  03/0000Z 18.4N  53.1W   95 KT 110 MPH
 72H  04/0000Z 20.5N  56.0W  100 KT 115 MPH
 96H  05/0000Z 22.5N  59.0W  105 KT 120 MPH
120H  06/0000Z 24.0N  61.5W  105 KT 120 MPH
 
$$
FORECASTER BROWN
 
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