000 WTNT41 KNHC 051505 TCDAT1 HURRICANE TOMAS DISCUSSION NUMBER 30 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL212010 1100 AM EDT FRI NOV 05 2010 BEFORE IT DEPARTED TOMAS...THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT REPORTED THAT THE CENTRAL PRESSURE HAD RISEN SLIGHTLY TO 987 MB. HOWEVER...THE FLIGHT-LEVEL AND SFMR WINDS STILL SUPPORTED AN INTENSITY OF 75 KT...WHICH IS THE INITIAL INTENSITY FOR THIS ADVISORY. THE CENTRAL CONVECTION IS CURRENTLY LOOKING A LITTLE RAGGED IN SATELLITE IMAGERY AND RADAR DATA FROM CUBA...POSSIBLY DUE TO THE CIRCULATION OF TOMAS INTERACTING WITH THE MOUNTAINS OF HISPANIOLA. THE CIRRUS OUTFLOW IS GOOD TO EXCELLENT OVER THE NORTHERN SEMICIRCLE AND POOR ELSEWHERE. THE INITIAL MOTION IS 030/10. TOMAS IS TO THE EAST OF A STRONG DEEP-LAYER TROUGH AND ASSOCIATED SURFACE FRONTAL SYSTEM OVER THE EASTERN UNITED STATES AND THE WESTERN ATLANTIC. FOR THE NEXT 36-48 HR...THIS FEATURE SHOULD STEER THE HURRICANE GENERALLY NORTH-NORTHEASTWARD. THE TRACK GUIDANCE IS IN GOOD AGREEMENT WITH THE DIRECTION OF MOTION...BUT THERE ARE DIFFERENCES IN SPEED BETWEEN THE FASTER GFS/GFDL/HWRF AND THE SLOWER UKMET/ECMWF/NOGAPS. THIS PART OF THE FORECAST TRACK IS SIMILAR TO...BUT A LITTLE TO THE LEFT OF...THE PREVIOUS TRACK...AND IN THE MIDDLE OF THE GUIDANCE ENVELOPE. AFTER 36-48 HR...THE GUIDANCE SHOWS SIGNIFICANT SPREAD IN BOTH DIRECTION AND SPEED. THE UKMET AND NOGAPS...WHICH APPEAR TO SHEAR TOMAS APART...SHOW A SLOW EASTWARD MOTION SOUTH OF 25N. THE GFS/GFDL/HWRF MOVE TOMAS MUCH MORE QUICKLY TO THE NORTH OR NORTHEAST AND ABSORB IT INTO THE BAROCLINIC SYSTEMS OVER THE WESTERN ATLANTIC. THE ECMWF IS IN BETWEEN...SHOWING AN EASTWARD TURN FOLLOWED BY AN EAST-NORTHEASTWARD MOTION BY THE END OF THE FORECAST PERIOD. THIS PART OF THE NEW FORECAST TRACK LIES SOUTH OF THE CENTER OF THE GUIDANCE ENVELOPE BETWEEN THE CONSENSUS MODELS AND THE ECMWF...AND SHOWS A SLOWER FORWARD SPEED THE THE ECMWF. THIS PORTION OF THE TRACK FORECAST REMAINS LOW CONFIDENCE. TOMAS STILL HAS ABOUT 24 HR IN WHICH TO STRENGTHEN BEFORE ENCOUNTERING INCREASING VERTICAL WIND SHEAR AND DRIER AIR ASSOCIATED WITH THE TROUGH...WITH THE CAVEAT THAT INTERACTION WITH HISPANIOLA COULD SLOW OR HALT DEVELOPMENT. THE SHIPS...LGEM...AND GFDL MODELS NOW SHOW THE CYCLONE BECOMING A CATEGORY 2 HURRICANE IN 24 HR...AND THE NEW INTENSITY FORECAST WILL FOLLOW SUIT. AFTER THAT...THE CYCLONE IS EXPECTED TO ENCOUNTER HOSTILE ENOUGH CONDITIONS TO CAUSE WEAKENING REGARDLESS OF THE EXACT TRACK IT TAKES...AND THE FORECAST FOLLOWS THE TREND OF THE PREVIOUS ADVISORY IN SHOWING A QUICK WEAKENING. THE FINAL DEMISE OF TOMAS IS DEPENDENT UPON ITS TRACK...AS A MORE NORTHWARD MOTION WOULD LIKELY LEAD TO EXTRATROPICAL TRANSITION AND A MORE EASTWARD MOTION TO DEGENERATION INTO A REMNANT LOW. THE FORECAST WILL CONTINUE TO USE THE LATTER SCENARIO FOR THE TIME BEING. REGARDLESS OF THE EXACT TRACK AND INTENSITY OF TOMAS...THE MOST SIGNIFICANT THREAT FROM THIS TROPICAL CYCLONE SHOULD CONTINUE TO BE HEAVY RAINFALL...WHICH COULD PRODUCE FLASH FLOODING AND LIFE- THREATENING MUD SLIDES OVER PORTIONS OF HAITI AND THE DOMINICAN REPUBLIC DURING THE NEXT COUPLE OF DAYS. FORECAST POSITIONS AND MAX WINDS INITIAL 05/1500Z 19.1N 74.4W 75 KT 12HR VT 06/0000Z 20.8N 73.4W 80 KT 24HR VT 06/1200Z 23.1N 72.1W 90 KT 36HR VT 07/0000Z 25.1N 71.0W 80 KT 48HR VT 07/1200Z 26.0N 69.9W 65 KT 72HR VT 08/1200Z 27.5N 67.5W 40 KT 96HR VT 09/1200Z 28.0N 64.5W 25 KT...POST-TROP/REMNT LOW 120HR VT 10/1200Z 29.0N 62.5W 25 KT...POST-TROP/REMNT LOW $$ FORECASTER BEVEN