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#376071 (Received by flhurricane at: 4:55 PM 14.Sep.2010) TCDAT3 TROPICAL STORM KARL DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL132010 500 PM EDT TUE SEP 14 2010 AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE LOW PRESSURE AREA IN THE NORTHWESTERN CARIBBEAN SEA FOUND A SMALL AND VIGOROUS WIND/PRESSURE CENTER INSIDE THE LARGER CYCLONIC ENVELOPE. THE MAXIMUM FLIGHT-LEVEL WINDS WERE 41 KT AT LESS THAN 1500 FT JUST EAST OF THE CENTER...AND THE SFMR ESTIMATED RELIABLE-LOOKING WINDS OF 35 KT OUTSIDE OF THE HEAVY RAIN AREAS. THE MINIMUM CENTRAL PRESSURE WAS 1001 MB. BASED ON THESE DATA...THE SYSTEM IS UPGRADED STRAIGHT TO TROPICAL STORM KARL WITH AN INITIAL INTENSITY OF 35 KT. THE INITIAL MOTION IS 295/13. KARL IS LOCATED ON THE SOUTH SIDE OF A DEEP-LAYER RIDGE CENTERED ALONG THE NORTHERN GULF COAST. THE TRACK GUIDANCE IS IN GOOD AGREEMENT THAT THE RIDGE SHOULD STEER KARL GENERALLY WEST-NORTHWESTWARD ACROSS THE YUCATAN PENINSULA INTO THE SOUTHWESTERN GULF OF MEXICO...FOLLOWED BY A GENERAL WESTWARD MOTION TOWARD MAINLAND MEXICO. THERE IS SOME SPREAD IN THE TRACK GUIDANCE OVER THE GULF OF MEXICO...WITH SOME OF THE DYNAMICAL MODELS FORECASTING A SOUTH-OF-WEST MOTION BEFORE KARL REACHES THE COAST OF MAINLAND MEXICO. THE FORECAST TRACK WILL SHOW A WESTWARD MOTION AFTER 72 HR...AND OVERALL IT LIES DOWN THE CENTER OF THE GUIDANCE ENVELOPE. KARL IS IN AN ENVIRONMENT OF LIGHT EASTERLY VERTICAL WIND SHEAR... AND THIS IS FORECAST TO PERSIST FOR THE NEXT 4-5 DAYS. THE MAJOR INFLUENCE ON THE INTENSITY WILL BE LAND INTERACTION. WHILE THE INTENSITY FORECAST SHOWS KARL WITH 45-KT WINDS OVER EASTERN YUCATAN...THE STORM COULD REACH A HIGHER INTENSITY BETWEEN THE 12 AND 24 HR FORECAST POINTS. OVER THE GULF OF MEXICO...KARL SHOULD RE-INTENSIFY...WITH THE SHIPS AND GFDL MODELS CALLING FOR IT TO BECOME A HURRICANE. THE INTENSITY FORECAST IS A BIT MORE CONSERVATIVE DUE TO UNCERTAINTY ABOUT WHAT KIND OF STRUCTURE KARL WILL HAVE AFTER CROSSING THE YUCATAN PENINSULA. AFTER FINAL LANDFALL IN MEXICO...KARL SHOULD EVENTUALLY DISSIPATE OVER THE MOUNTAINS OF CENTRAL MEXICO. FORECAST POSITIONS AND MAX WINDS INITIAL 14/2100Z 18.3N 84.2W 35 KT 12HR VT 15/0600Z 18.9N 86.0W 40 KT 24HR VT 15/1800Z 19.6N 88.1W 45 KT...INLAND 36HR VT 16/0600Z 20.4N 90.3W 30 KT...INLAND 48HR VT 16/1800Z 21.0N 92.6W 35 KT...OVER WATER 72HR VT 17/1800Z 21.5N 96.0W 55 KT 96HR VT 18/1800Z 21.5N 99.5W 30 KT...INLAND 120HR VT 19/1800Z...DISSIPATED $$ FORECASTER BEVEN |