000 WTNT42 KNHC 050236 TCDAT2 HURRICANE KATIA DISCUSSION NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011 1100 PM AST SUN SEP 04 2011 AFTER KATIA STRENGTHENED STEADILY EARLIER TODAY...THE INTENSIFICATION PROCESS APPEARS TO HAVE STOPPED FOR NOW. THE CONVECTIVE PATTERN HAS BECOME A LITTLE LESS SYMMETRIC SINCE THE LAST ADVISORY...WITH THE COLDEST CLOUD TOPS LOCATED OVER THE SOUTHERN HALF OF THE CIRCULATION. ALTHOUGH AN EYE IS EASILY SEEN IN MULTI-CHANNEL NIGHT VISIBLE IMAGERY...IT IS ONLY OCCASIONALLY EVIDENT IN INFRARED IMAGES. DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN 90 KT...AND THE INITIAL WIND SPEED IS HELD AT THAT VALUE. THE HURRICANE CONTINUES NORTHWESTWARD AT 11 KT ON THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL HIGH LOCATED OVER THE CENTRAL ATLANTIC. DURING THE NEXT TWO TO THREE DAYS...THE HIGH IS EXPECTED TO BUILD WESTWARD AS A TROUGH BETWEEN BERMUDA AND THE UNITED STATES WEAKENS. THIS PATTERN WILL ALLOW KATIA TO CONTINUE ON THE SAME GENERAL TRACK WITH A SLIGHT DECREASE IN FORWARD SPEED. BEYOND THREE DAYS...KATIA IS FORECAST TO TURN TOWARD THE NORTH AS IT BECOMES EMBEDDED IN THE FLOW BETWEEN THE AFOREMENTIONED HIGH AND A LARGE CUTOFF LOW OVER THE EASTERN UNITED STATES. GLOBAL MODELS SHOW A SERIES OF SHORTWAVES MOVING ACROSS NEW ENGLAND AND ATLANTIC CANADA IN FOUR TO FIVE DAYS...AND THAT COULD CAUSE THE HURRICANE TO TURN NORTHEASTWARD AT THE END OF THE FORECAST PERIOD. THE OFFICIAL FORECAST IS ADJUSTED TO THE EAST THIS CYCLE...ESPECIALLY AT 120 HOURS...BUT LIES WEST OF THE MULTI-MODEL CONSENSUS. IF THE CURRENT TREND TOWARD A FASTER NORTHEASTWARD MOTION CONTINUES IN THE GUIDANCE...FURTHER ADJUSTMENTS IN THAT DIRECTION WOULD BE REQUIRED. ALTHOUGH THE INTENSITY OF KATIA HAS LEVELED OFF THIS EVENING...THE HURRICANE IS FORECAST TO STRENGTHEN SOME DURING THE NEXT COUPLE OF DAYS AS IT REMAINS IN FAVORABLE ATMOSPHERIC AND OCEANIC ENVIRONMENTS. SOME WEAKENING IS FORECAST IN THE THREE TO FIVE DAY RANGE AS THE HURRICANE MOVES INTO A REGION WITH LOWER VALUES OF OCEANIC HEAT CONTENT AND PERHAPS INTO A MORE STABLE ENVIRONMENT. THE OFFICIAL FORECAST FOLLOWS THE TREND IN THE GUIDANCE AND IS NEAR A BLEND OF THE STATISTICAL AND DYNAMICAL MODELS. LONG-PERIOD SWELLS ASSOCIATED WITH KATIA ARE ALREADY APPROACHING PARTS OF THE EAST COAST OF THE UNITED STATES. EVEN IF KATIA DOES NOT DIRECTLY IMPACT THE UNITED STATES...THE THREAT FOR HIGH SURF AND RIP CURRENTS ALONG EAST COAST BEACHES IS EXPECTED TO INCREASE OVER THE NEXT FEW DAYS. PLEASE CONSULT PRODUCTS ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES FOR MORE INFORMATION. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 23.4N 61.0W 90 KT 105 MPH 12H 05/1200Z 24.4N 62.4W 95 KT 110 MPH 24H 06/0000Z 25.7N 64.0W 100 KT 115 MPH 36H 06/1200Z 26.9N 65.5W 100 KT 115 MPH 48H 07/0000Z 28.0N 66.9W 105 KT 120 MPH 72H 08/0000Z 30.3N 69.8W 100 KT 115 MPH 96H 09/0000Z 33.5N 71.0W 95 KT 110 MPH 120H 10/0000Z 36.0N 69.0W 85 KT 100 MPH $$ FORECASTER CANGIALOSI