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| #355928 (Received by flhurricane at: 10:52 PM 28.Jun.2010) TCDAT1 TROPICAL STORM ALEX DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010 1000 PM CDT MON JUN 28 2010 ALTHOUGH THE SATELLITE PRESENTATION OF ALEX CONTINUES TO BE A LITTLE RAGGED-LOOKING...DATA FROM THE AIR FORCE HURRICANE HUNTERS INDICATE THAT THE STORM IS GRADUALLY STRENGTHENING. PEAK 925 MB FLIGHT-LEVEL WINDS WERE 68 KT AND MAXIMUM SFMR-MEASURED WINDS WERE 53 KT. AIRCRAFT OBSERVATIONS ALSO SHOWED THAT THE MINIMUM CENTRAL PRESSURE HAS DROPPED TO 985 MB...A RATHER LOW VALUE FOR A TROPICAL STORM. BASED ON THE WIND MEASUREMENTS...THE INITIAL INTENSITY IS SET TO 55 KT FOR THIS ADVISORY. CENTER FIXES FROM THE RECONNAISSANCE AIRCRAFT INDICATE THAT THE STORM HAS DRIFTED MOSTLY NORTHWARD OVER THE PAST SEVERAL HOURS...AND THE INITIAL MOTION ESTIMATE IS 360/4. THIS MOTION IS BELIEVED TO BE TEMPORARY BECAUSE THE GLOBAL MODELS ARE FORECASTING A MID-LEVEL RIDGE TO BUILD TO THE NORTH OF ALEX OVER THE NEXT COUPLE OF DAYS...WHICH SHOULD INDUCE A GRADUAL BEND OF THE TRACK TO THE LEFT. THE TRACK MODEL CONSENSUS HAS SHIFTED ABOUT A HALF DEGREE TO THE NORTH DUE TO THE RECENT NORTHWARD MOTION...AND THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY NORTHWARD AS WELL. ONE SHOULD NOT FOCUS ON THE EXACT LANDFALL POINT...HOWEVER...SINCE THE AVERAGE TRACK FORECAST ERROR IN THE 48- TO 72-HOUR TIME FRAME IS 100-150 NAUTICAL MILES. THE WESTERLY SHEAR THAT WAS AFFECTING ALEX HAS ABATED AND THE SHIPS MODEL DIAGNOSES A FURTHER DECREASE IN SHEAR...TO BELOW 10 KT IN 24 HOURS. AS ALEX MOVES AWAY FROM THE SHELF WATERS NEAR THE NORTHWEST COAST OF THE YUCATAN...IT SHOULD PASS OVER WARMER SEA SURFACE TEMPERATURES DURING THE NEXT 48 HOURS OR SO...ALTHOUGH THE PROJECTED TRACK IS NOW A LITTLE TO THE NORTH OF A WARM EDDY OVER THE SOUTHWEST GULF. IT IS STILL SOMEWHAT PUZZLING THAT THE GFDL AND HWRF MODELS STILL DO NOT FORECAST ALEX TO BECOME A HURRICANE...PARTICULARLY SINCE THE CYCLONE IS APPROACHING HURRICANE STRENGTH AS WE SPEAK. THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE STATISTICAL LGEM GUIDANCE...AND IS ESSENTIALLY THE SAME AS THE PREVIOUS NHC FORECAST. GIVEN THE LATEST 36-HR FORECAST POINT AND THE EXTENT OF TROPICAL-STORM FORCE WINDS IN THE FORECAST...IT IS TIME TO UPGRADE THE HURRICANE WATCH FOR TO A HURRICANE WARNING FOR THE SOUTH TEXAS AND NORTHEAST MEXICAN COASTS. FORECAST POSITIONS AND MAX WINDS INITIAL 29/0300Z 21.0N 91.6W 55 KT 12HR VT 29/1200Z 22.2N 92.3W 65 KT 24HR VT 30/0000Z 23.6N 93.5W 70 KT 36HR VT 30/1200Z 24.5N 95.2W 75 KT 48HR VT 01/0000Z 25.2N 96.9W 80 KT 72HR VT 02/0000Z 25.7N 99.6W 45 KT...INLAND 96HR VT 03/0000Z 27.0N 102.0W 20 KT...INLAND 120HR VT 04/0000Z...DISSIPATED $$ FORECASTER PASCH/KIMBERLAIN |
