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| #378288 (Received by flhurricane at: 4:53 PM 23.Sep.2010) TCDAT5 TROPICAL STORM MATTHEW DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 500 PM EDT THU SEP 23 2010 AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING THE CYCLONE FOUND 42-KT FLIGHT-LEVEL WINDS AT ABOUT 1500 FT IN THE NORTHEAST QUADRANT ON ITS OUTBOUND LEG. THAT WIND SPEED WOULD NORMALLY EQUATE TO ABOUT 34 KT AT THE SURFACE. ALSO...THERE WERE SEVERAL BELIEVABLE SFMR SURFACE WINDS OF 35-37 KT IN THAT AREA. SINCE THOSE WIND REPORTS...CONVECTIVE BANDING HAS CONTINUED TO INCREASE AND BECOME BETTER ORGANIZED..AND THE DEPRESSION HAS BEEN UPGRADED TO TROPICAL STORM MATTHEW. THE INITIAL MOTION ESTIMATE IS 280/14. TROPICAL STORM MATTHEW IS EXPECTED TO MOVE WEST TO WEST-NORTHWESTWARD FOR THE NEXT 48 HOURS OR SO...AND PASS OVER OR NEAR THE NORTHERN COASTS OF NICARAGUA AND HONDURAS IN 36-48 HOURS. AFTER THAT...THE GLOBAL MODELS DIFFER ON THE TIMING OF THE WEAKENING OF THE SUBTROPICAL RIDGE OVER THE NORTHWESTERN CARIBBEAN SEA AND THE GULF OF MEXICO. A STRONG MID-LATITUDE TROUGH CURRENTLY OFF THE U.S. WEST COAST IS FORECAST TO MOVE QUICKLY EASTWARD INTO THE CENTRAL U.S. BY DAY 3...THE TROUGH IS FORECAST TO DIG SOUTHEASTWARD AND AMPLIFY INTO A LOW PRESSURE SYSTEM OVER THE SOUTHEASTERN U.S. AND THE GULF OF MEXICO. EROSION OF THE SUBTROPICAL RIDGE TO THE NORTH OF MATTHEW IS EXPECTED TO CAUSE THE STEERING CURRENTS TO COLLAPSE ACROSS THE NORTHWESTERN CARIBBEAN SEA AND THE YUCATAN PENINSULA. ALL OF THE NHC MODELS ARE CONSISTENT ON THE EVOLUTION OF THIS SYNOPTIC SCALE PATTERN...EXCEPT FOR THE TIMING. THE GFS...ECMWF...NOGAPS... HWRF...AND GFDL MODELS KEEP THE LOW WEST OF 85W LONGITUDE BY 120 HOURS...WHEREAS THE UKMET IS MUCH MORE PROGRESSIVE AND MOVES THE LARGE TROUGH EAST OF 80W. GIVEN THE USUAL SLOW MOVEMENT OF SUCH A HIGH AMPLITUDE TROUGH...THE UKMET IS CONSIDERED AN OUTLIER MODEL AT THIS TIME. AS A RESULT...THE OFFICIAL FORECAST TRACK IS A BLEND OF THE GLOBAL AND REGIONAL MODELS...EXCLUDING THE UKMET SOLUTION... AND IS JUST AN UPDATE OF THE PREVIOUS FORECAST TRACK. STEADY INTENSIFICATION IS EXPECTED THROUGH 72 HOURS SINCE MATTHEW WILL BE MOVING OVER 30C SSTS AND BENEATH A REGION OF UPPER-LEVEL ANTICYCLONIC FLOW. MATTHEW IS EXPECTED TO MOVE OVER OR NEAR THE NORTH COAST OF HONDURAS IN 36-48 HOURS...AND MOVE INLAND NEAR BELIZE BY DAY 4. LAND INTERACTION WOULD DISRUPT THE INTENSIFICATION PROCESS DESPITE THE OTHERWISE FAVORABLE ENVIRONMENTAL CONDITIONS. HOWEVER...IF THE CYCLONE REMAINS OVER WATER...THEN MATTHEW COULD EASILY REACH HURRICANE STRENGTH DURING THE NEXT 48 HOURS AND BEYOND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND THE SHIPS/LGEM MODELS...AND IS BASED ON THE ASSUMPTION THAT MATTHEW WILL MOVE INLAND AFTER 72 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 23/2100Z 14.0N 76.9W 35 KT 12HR VT 24/0600Z 14.4N 78.9W 40 KT 24HR VT 24/1800Z 15.1N 81.7W 50 KT 36HR VT 25/0600Z 15.6N 84.0W 60 KT...INLAND 48HR VT 25/1800Z 16.2N 85.8W 60 KT...OVER WATER 72HR VT 26/1800Z 17.1N 88.0W 70 KT 96HR VT 27/1800Z 18.3N 88.4W 70 KT...INLAND 120HR VT 28/1800Z 19.5N 87.5W 70 KT...INLAND $$ FORECASTER STEWART |
