000 WTNT42 KNHC 010248 TCDAT2 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