000 WTNT42 KNHC 021454 TCDAT2 HURRICANE KATIA DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011 1100 AM AST FRI SEP 02 2011 THE CONVECTIVE DEPICTION OF KATIA HAS IMPROVED THIS MORNING AS BOTH MICROWAVE IMAGERY FROM SSMIS AND CONVENTIONAL VISIBLE SATELLITE IMAGERY INDICATE THAT AN EYE MAY BE FORMING. BECAUSE OF THE IMPROVED STRUCTURE...BOTH TAFB AND SAB DVORAK CLASSIFICATIONS CAME IN AT A 4.0...OR 65 KT...AS DID A 1053Z CIMSS AMSU INTENSITY ESTIMATE. THUS KATIA HAS REGAINED HURRICANE STATUS. THE HURRICANE IS MOVING TOWARD THE WEST-NORTHWEST AT ABOUT 12 KT...AS IT IS BEING ADVECTED AROUND THE SOUTHWEST PERIPHERY OF A DEEP-LAYER RIDGE. KATIA SHOULD MOVE TOWARD THE WEST-NORTHWEST OR NORTHWEST FOR THE NEXT FEW DAYS AT A SLIGHTLY SLOWER RATE OF SPEED. ALL OF THE RELIABLE GUIDANCE...WITH THE EXCEPTION OF THE UKMET WHICH HAS A MUCH MORE EQUATORWARD SOLUTION DUE TO A SHORT-WAVE TROUGH OFF OF THE U.S. EAST COAST LIFTING OUT TO THE NORTHEAST MORE QUICKLY... IS IN EXCELLENT AGREEMENT. THE TRACK FORECAST IS VERY SIMILAR TO THE PREVIOUS ADVISORY AND THE CONSENSUS OF THE GLOBAL AND HURRICANE MODELS LESS THE UKMET MODEL. DESPITE BECOMING A HURRICANE AGAIN...KATIA FACES A RELATIVELY HOSTILE ENVIRONMENT WITH SOUTHWEST VERTICAL SHEAR OF 15-20 KT SUGGESTED FOR THE NEXT DAY OR TWO. BEYOND 48 HOURS...THE SHEAR FROM THE GLOBAL MODELS IS ANTICIPATED TO DECREASE...BUT THE THERMODYNAMICS MAY NOT BE IDEAL WITH LOW HUMIDITIES AND A MORE STABLE ENVIRONMENT ANTICIPATED. SOME OF THE UPPER-LEVEL TEMPERATURE INCREASES ANALYZED IN THE SHIPS/LGEM STATISTICAL MODELS...HOWEVER...MAY BE SPURIOUS...AS THE STRONGER VORTEX FROM THE GFS MAY BE THE CAUSE OF THESE VALUES RATHER THAN THE ENVIRONMENT. THUS THE SHIPS/LGEM GUIDANCE MAY BE TOO LOW AT DAYS THREE TO FIVE. THE INTENSITY PREDICTION IS SLIGHTLY LOWER THAN A SHIPS/LGEM/HWRF BLEND BUT HIGHER THAN THE PREVIOUS ADVISORY DURING THE NEXT TWO DAYS. FORECAST POSITIONS AND MAX WINDS INIT 02/1500Z 17.5N 52.4W 65 KT 75 MPH 12H 03/0000Z 18.6N 53.8W 65 KT 75 MPH 24H 03/1200Z 19.6N 55.2W 70 KT 80 MPH 36H 04/0000Z 20.6N 56.4W 75 KT 85 MPH 48H 04/1200Z 21.7N 57.9W 80 KT 90 MPH 72H 05/1200Z 24.0N 61.0W 90 KT 105 MPH 96H 06/1200Z 26.0N 64.0W 95 KT 110 MPH 120H 07/1200Z 27.0N 67.0W 100 KT 115 MPH $$ FORECASTER LANDSEA/STEWART