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| #11565 (Received by flhurricane at: 5:17 PM 08.Oct.2004) TCDAT4 TROPICAL STORM MATTHEW DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT FRI OCT 08 2004 THE AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT INVESTIGATING THE AREA OF LOW PRESSURE IN THE WESTERN GULF OF MEXICO FOUND A REASONABLY WELL-DEFINED CIRCULATION WITH STRONG WINDS...48 KT AT A FLIGHT LEVEL OF 600 FT...NEAR THE CENTER. WHILE THE CONVECTIVE ORGANIZATION OF THE SYSTEM IS POOR AND HIGHLY ASYMMETRIC...THE CORE CIRCULATION DICTATES THAT TROPICAL CYCLONE ADVISORIES BE INITIATED AT THIS TIME. ALTHOUGH THE FLIGHT-LEVEL WINDS WOULD SUPPORT AN INTENSITY ESTIMATE OF 40 KT...THESE WINDS WERE OBSERVED OVER A VERY SMALL AREA AND MIGHT NOT BE REPRESENTATIVE. THE INITIAL INTENSITY IS SET TO 35 KT FOR THIS ADVISORY. THE INITIAL MOTION IS 085/9...WITH THE CENTER FOLLOWING THE DEEP CONVECTION THROUGH MUCH OF THE DAY TODAY. THERE IS CONSIDERABLE UNCERTAINTY REGARDING THE FUTURE COURSE AND STRENGTH OF MATTHEW. GLOBAL MODEL GUIDANCE INDICATES THE FORMATION OF A SEPARATE BAROCLINICALLY FORCED LOW CENTER IN THE NORTHWESTERN GULF OF MEXICO...AND THE BEGINNINGS OF THIS LOW ARE ALREADY APPARENT IN THE SURFACE OBSERVATIONS. IF THIS OCCURS...AND MATTHEW SURVIVES AS A SEPARATE ENTITY...IT COULD TAKE A GENTLY CURVING PATH AROUND THE PERIPHERY OF THE NEW LOW. THIS IS THE SCENARIO INDICATED BY THE SIMPLER STEERING MODELS SUCH AS THE BAM FAMILY OF MODELS. THE GFDL SHOWS A MUCH SHARPER TURN TO THE NORTH...WHILE THE GFS...UKMET...AND CANADIAN MODELS SHOW ONLY THE DEVELOPING BAROCLINIC LOW...WHICH SPENDS MOST OF THE NEXT 2-3 DAYS OVER LOUISIANA. THE OFFICIAL FORECAST LEANS TOWARDS THE BAM GUIDANCE...IN PART BECAUSE THIS GUIDANCE APPEARS TO BE MORE CONSISTENT WITH CURRENT TRENDS...BUT I AM NOT REAL COMFORTABLE BEING SO FAR AWAY FROM THE NORMALLY GOOD-PERFORMING GLOBAL GUIDANCE. THERE IS MODERATE SHEAR OVER MATTHEW NOW...AND GLOBAL GUIDANCE INDICATES THAT THIS SHEAR WILL INCREASE...AT LEAST OVER THE WESTERN GULF. IF THE TRACK FORECAST IS WRONG AND MATTHEW ENDS UP MOVING MORE TO THE NORTH...IT WOULD LIKELY FIND ITSELF IN AN ENVIRONMENT UNFAVORABLE FOR STRENGTHENING. A MORE LEISURELY TRACK ACROSS THE CENTRAL OR EASTERN GULF WOULD AFFORD MORE OF AN OPPORTUNITY FOR DEVELOPMENT. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 08/2100Z 24.2N 93.8W 35 KT 12HR VT 09/0600Z 24.6N 92.6W 35 KT 24HR VT 09/1800Z 25.3N 91.1W 35 KT 36HR VT 10/0600Z 26.3N 89.2W 35 KT 48HR VT 10/1800Z 28.0N 87.5W 35 KT 72HR VT 11/1800Z 32.0N 86.0W 20 KT...INLAND 96HR VT 12/1800Z...DISSIPATED |
