Flhurricane.com - Central Florida Hurricane Center - Tracking Storms since 1995Hurricanes Without the Hype! Since 1995
The Atlantic is quiet
|
Show Selection: |
| #455126 (Received by flhurricane at: 4:40 AM 31.Aug.2011) TCDAT2 TROPICAL STORM KATIA DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011 500 AM AST WED AUG 31 2011 SATELLITE IMAGERY THIS MORNING INDICATES THAT KATIA IS GRADUALLY BECOMING BETTER ORGANIZED. THE PRIMARY CONVECTIVE BAND HAS WRAPPED FARTHER AROUND THE CENTER...AND THE CLOUD TOPS IN THE BAND HAVE COOLED. SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM SAB AND TAFB...AND THAT IS THE INITIAL INTENSITY FOR THIS ADVISORY. THE CIRRUS OUTFLOW IS FAIR TO GOOD IN ALL DIRECTIONS. THE INITIAL MOTION IS 285/18. KATIA IS ON THE SOUTH SIDE OF A DEEP-LAYER SUBTROPICAL RIDGE...WHILE WATER VAPOR IMAGERY SHOWS A LARGE MID/UPPER-LEVEL LOW...A WEAKNESS IN THE RIDGE...CENTERED NEAR 30N54W AND MOVING WESTWARD. THE TRACK GUIDANCE IS IN VERY GOOD AGREEMENT THAT KATIA SHOULD MOVE GENERALLY WEST-NORTHWARD FOR THE NEXT 48 HR OR SO....THEN GRADUALLY TURN TOWARD THE NORTHWEST AT A SLOWER FORWARD SPEED AS IT APPROACHES THE LOW OR ITS REMNANTS. THE GUIDANCE ENVELOPE HAS SHIFTED A LITTLE TO THE SOUTH DURING THE FIRST 36 HR...AND SHIFTED A LITTLE TO THE NORTH AFTER THAT TIME. THE NEW FORECAST TRACK MAKES SIMILAR SMALL ADJUSTMENTS COMPARED TO THE PREVIOUS FORECAST AND LIES NEAR THE VARIOUS CONSENSUS MODELS. A COUPLE OF ISSUES HAVE APPEARED REGARDING THE INTENSITY FORECAST. FIRST...WATER VAPOR IMAGERY AND MICROWAVE TOTAL PRECIPITABLE WATER DATA SHOW DRY AIR NOT FAR TO THE NORTH AND EAST OF THE CORE OF KATIA. THIS HAS NOT YET AFFECTED DEVELOPMENT...AND THE NEW INTENSITY FORECAST KEEPS THE TREND OF THE PREVIOUS FORECAST FOR THE FIRST 36 HR. HOWEVER...THERE IS A POSSIBILITY THAT INTENSIFICATION COULD BE SLOWER THAN FORECAST IF THE DRY AIR REACHES THE CENTER. SECOND...THE DYNAMICAL MODELS DISAGREE ON THE UPPER-LEVEL WINDS NEAR KATIA FROM 72-120 HR. THE GFS...NOGAPS... AND CANADIAN MODELS SHOW THE UPPER-LEVEL LOW TO THE NORTHWEST WEAKENING TO THE POINT WHERE THE STORM REMAINS IN LIGHT VERTICAL WIND SHEAR CONDITIONS. THE ECMWF AND UKMET KEEP A STRONG ENOUGH UPPER-LEVEL TROUGH FOR KATIA TO EXPERIENCE SIGNIFICANT SOUTHWESTERLY SHEAR. THE FORECAST INTENSITIES HAVE BEEN LOWERED SLIGHTLY AFTER 48 HR DUE TO THE POSSIBILITY OF SHEAR DURING THAT TIME. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 13.9N 39.1W 55 KT 65 MPH 12H 31/1800Z 14.3N 41.7W 65 KT 75 MPH 24H 01/0600Z 15.0N 44.9W 75 KT 85 MPH 36H 01/1800Z 15.8N 47.7W 85 KT 100 MPH 48H 02/0600Z 16.8N 50.2W 90 KT 105 MPH 72H 03/0600Z 19.0N 54.0W 95 KT 110 MPH 96H 04/0600Z 21.0N 57.0W 100 KT 115 MPH 120H 05/0600Z 23.0N 60.0W 105 KT 120 MPH $$ FORECASTER BEVEN |
