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#457629 (Received by flhurricane at: 10:54 PM 07.Sep.2011) TCDAT2 HURRICANE KATIA DISCUSSION NUMBER 40 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011 1100 PM AST WED SEP 07 2011 CONVENTIONAL SATELLITE AND MICROWAVE IMAGES INDICATE THAT KATIA IS AN ASYMMETRIC HURRICANE. DEEP CONVECTION IS LIMITED TO THE EASTERN HALF OF THE CIRCULATION...WITH THE LOW-LEVEL CENTER ESTIMATED TO BE ON THE WESTERN EDGE OF THE INNER-MOST CONVECTIVE BAND. THIS PATTERN IS THE RESULT OF MODERATE WESTERLY SHEAR AND DRY AIR ENTRAINING INTO THE CIRCULATION. NOAA BUOY 41048...LOCATED ABOUT 90 N MI NORTH OF THE CENTER OF KATIA...RECENTLY REPORTED A MAXIMUM 1-MINUTE WIND OF 58 KT WITH A GUST TO 72 KT. ALTHOUGH THE LATEST DVORAK CLASSIFICATIONS SUGGEST THAT KATIA MAY HAVE WEAKENED A LITTLE...I PREFER TO KEEP THE INITIAL INTENSITY AT 70 KT GIVEN THE BUOY OBSERVATION. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT SEVERAL DAYS...AND ALL OF THE GLOBAL MODELS SHOW KATIA BECOMING A LARGE EXTRATROPICAL STORM OVER THE NORTH ATLANTIC. KATIA IS NOW BEGINNING THE ANTICIPATED NORTHWARD TURN AS IT MOVES BETWEEN THE SUBTROPICAL RIDGE AND A LARGE MID- TO UPPER-LEVEL LOW OVER THE OHIO VALLEY OF THE UNITED STATES. A PRONOUNCED INCREASE IN FORWARD SPEED AND A TURN TO THE NORTHEAST AND EAST-NORTHEAST IS FORECAST TO OCCUR ON FRIDAY AS THE CYCLONE BECOMES EMBEDDED IN THE MID-LATITUDE FLOW. THE MODELS REMAIN IN VERY GOOD AGREEMENT...AND THE OFFICIAL FORECAST IS AN UPDATE OF THE PREVIOUS ONE. THE EXTRATROPICAL FORECAST POINTS ARE VERY CLOSE TO THE GUIDANCE PROVIDED BY THE OCEAN PREDICTION CENTER. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 30.8N 70.0W 70 KT 80 MPH 12H 08/1200Z 32.5N 70.2W 70 KT 80 MPH 24H 09/0000Z 35.2N 69.5W 70 KT 80 MPH 36H 09/1200Z 37.9N 67.0W 70 KT 80 MPH 48H 10/0000Z 40.4N 61.0W 70 KT 80 MPH 72H 11/0000Z 46.6N 40.6W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 12/0000Z 55.0N 22.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 120H 13/0000Z 60.0N 6.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ FORECASTER CANGIALOSI/BEVEN |