000 WTNT42 KNHC 100849 TCDAT2 HURRICANE KATIA DISCUSSION NUMBER 49 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011 500 AM AST SAT SEP 10 2011 KATIA APPEARS TO BE GRADUALLY LOSING ITS TROPICAL CHARACTERISTICS. THE ASSOCIATED CLOUD PATTERN IS BECOMING INCREASINGLY ELONGATED... WITH THE LOW-LEVEL CENTER ON THE SOUTHERN EDGE OF THE CONVECTION. THE LATEST SATELLITE CLASSIFICATIONS SUGGEST THAT KATIA HAS WEAKENED A LITTLE...AND THAT IS THE BASIS FOR THE SLIGHTLY LOWER INITIAL INTENSITY OF 70 KT. STRONG SOUTHWESTERLY SHEAR ASSOCIATED WITH A DEEP-LAYER TROUGH AND SEA SURFACE TEMPERATURES COLDER THAN 20C...SHOULD CAUSE KATIA TO BECOME EXTRATROPICAL IN ABOUT 12 HOURS. HOWEVER...THE CYCLONE IS EXPECTED TO REMAIN QUITE STRONG AS AN EXTRATROPICAL SYSTEM WHILE MOVING QUICKLY ACROSS THE FAR NORTH ATLANTIC....APPROACHING THE BRITISH ISLES AND NORTHERN EUROPE IN A COUPLE OF DAYS. THE HURRICANE IS EMBEDDED IN THE STRONG MID-LATITUDE WESTERLIES... AND THE LATEST INITIAL MOTION ESTIMATE IS 060/38. THE CYCLONE IS EXPECTED TO ACCELERATE DURING THE NEXT 12 TO 24 HOURS WITHIN THE STRONG FLOW TO THE EAST OF A HIGH LATITUDE DEEP-LAYER TROUGH. THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS ONE AND CLOSE TO THE GUIDANCE PROVIDED BY THE OCEAN PREDICTION CENTER. INTERESTS IN AND AROUND THE BRITISH ISLES AND NORTHERN EUROPE SHOULD MONITOR PRODUCTS ISSUED BY THE UKMET OFFICE AT WWW.METOFFICE.GOV.UK/WEATHER NO 96-HOUR FORECAST POINT HAS BEEN PROVIDED DUE TO SOFTWARE ISSUES WHEN SYSTEMS MOVE EAST OF ZERO DEGREES LONGITUDE. THE 34- AND 50-KT WIND RADII WERE EXPANDED OUTWARD OVER THE WESTERN SEMICIRCLE BASED ON A 0144 UTC ASCAT PASS. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 43.3N 53.4W 70 KT 80 MPH 12H 10/1800Z 46.0N 44.7W 65 KT 75 MPH 24H 11/0600Z 50.2N 32.2W 65 KT 75 MPH...POST-TROP/EXTRATROP 36H 11/1800Z 53.9N 21.6W 65 KT 75 MPH...POST-TROP/EXTRATROP 48H 12/0600Z 57.3N 13.7W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 13/0600Z 61.3N 1.3W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 14/0600Z...EAST OF ZERO DEGREES LONGITUDE $$ FORECASTER CANGIALOSI