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| #376283 (Received by flhurricane at: 4:35 PM 15.Sep.2010) TCDAT3 TROPICAL STORM KARL DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL132010 400 PM CDT WED SEP 15 2010 KARL IS SLOWLY WEAKENING AS THE CENTER CROSSES THE YUCATAN PENINSULA. SATELLITE IMAGERY AND DATA FROM THE BELIZE CITY RADAR INDICATE THE CYCLONE CONTINUES TO PRODUCE STRONG CONVECTION...BUT THIS IS CURRENTLY CONFINED TO THE SOUTHWESTERN QUADRANT. THERE ARE NO OBSERVATION AVAILABLE NEAR THE CORE...AND THUS THE INITIAL INTENSITY OF 40 KT IS SOMEWHAT UNCERTAIN. THE INITIAL MOTION IS NOW 285/13. THE CYCLONE REMAINS ON THE SOUTH SIDE OF A LOW/MID-LEVEL RIDGE CENTERED OVER THE NORTHERN GULF COAST...AND THIS FEATURE SHOULD STEER THE CYCLONE GENERALLY WEST-NORTHWESTWARD OR WESTWARD ACROSS THE SOUTHWESTERN GULF OF MEXICO INTO MAINLAND MEXICO. THERE REMAINS SOME SPREAD IN THE GUIDANCE...WITH THE HWRF INDICATING A MORE NORTHWARD MOTION ON THE RIGHT SIDE OF THE GUIDANCE ENVELOPE AND THE GFDN A MORE WESTWARD MOTION ON THE LEFT. SEVERAL OF THE OTHER DYNAMICAL MODELS NOW FORECAST KARL TO SLOW ITS FORWARD MOTION BEFORE REACHING THE COAST OF MAINLAND MEXICO...AND ALSO FORECAST A TURN TO SOUTH OF WEST MOTION NEAR OR JUST AFTER LANDFALL. THE NEW FORECAST TRACK REFLECTS BOTH OF THESE POSSIBILITIES...WITH THE NEW TRACK BEING SIMILAR TO...BUT A LITTLE SLOWER THAN...THE PREVIOUS TRACK AFTER 36 HR. KARL IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION BY THE TIME IT REACHES THE WEST COAST OF THE YUCATAN PENINSULA IN ABOUT 12 HR. ONCE THE CENTER REACHES WATER...THE COMBINATION OF WARM SEA SURFACE TEMPERATURES AND LIGHT VERTICAL WIND SHEAR SHOULD ALLOW RE-INTENSIFICATION AS FORECAST BY ALL GUIDANCE. IT SHOULD BE NOTED THAT THE HWRF...WHILE FORECASTING STRENGTHENING...HAS CONSISTENTLY KEPT KARL AT LESS THAN HURRICANE STRENGTH. GIVEN THE SEEMINGLY FAVORABLE ENVIRONMENT...THE INTENSITY FORECAST CALLS FOR KARL TO REACH HURRICANE STRENGTH OVER THE GULF OF MEXICO IN AGREEMENT WITH THE SHIPS AND LGEM MODELS. THE FORECAST SHOWS A PEAK INTENSITY OF 70 KT...BUT KARL COULD BECOME STRONGER THAN THAT BETWEEN THE 48 AND 72 HR FORECAST POINTS. FORECAST POSITIONS AND MAX WINDS INITIAL 15/2100Z 19.0N 89.4W 40 KT...INLAND 12HR VT 16/0600Z 19.6N 90.9W 30 KT...OVER WATER 24HR VT 16/1800Z 20.5N 92.7W 35 KT 36HR VT 17/0600Z 21.1N 94.4W 50 KT 48HR VT 17/1800Z 21.3N 95.7W 65 KT 72HR VT 18/1800Z 21.5N 98.5W 70 KT...INLAND 96HR VT 19/1800Z 21.0N 101.5W 25 KT...INLAND 120HR VT 20/1800Z...DISSIPATED $$ FORECASTER BEVEN |
