000 AXNT20 KNHC 301149 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SUN NOV 30 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 10N13W 6N22W 4N33W 4N41W 2N51W. SCATTERED MODERATE CONVECTION IS FROM 5N-9N BETWEEN 11W-16W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 2N-6N BETWEEN 17W-29W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 32W-41W. ...DISCUSSION... GULF OF MEXICO... A VIGOROUS DEEP TROUGH OVER THE CENTRAL CONUS EXTENDS INTO N MEXICO...WITH AN ASSOCIATED SURFACE COLD FRONT EXTENDING FROM A 1000 MB SURFACE LOW OVER W ALABAMA NEAR 34N88W TO THE ALABAMA COAST NEAR 30N89W ACROSS THE NW GULF TO 26N93W TO NE MEXICO NEAR 24N99W. ADDITIONALLY...A SURFACE TROUGH IS LOCATED TO THE E OF THIS COLD FRONT. THIS SURFACE TROUGH EXTENDS FROM THE FLORIDA PANHANDLE NEAR 31N85W TO 27N90W TO A 1005 MB SURFACE LOW IN THE SW GULF NEAR 20N96W TO S MEXICO NEAR 18N95W. STRONG UPPER LEVEL DIVERGENCE IN THE SE QUADRANT OF AN ANTICYCLONICALLY-CURVED 140-150 KT UPPER LEVEL JET MAXIMUM ORIENTED FROM SOUTH-SOUTHWEST TO NORTH-NORTHEAST OVER THE SE CONUS IS SUPPORTING NUMEROUS STRONG THUNDERSTORMS ALONG AND WITHIN 120 NM E OF THE COLD FRONT N OF 23N. THIS ACTIVITY IS RESULTING IN THE DEVELOPMENT OF A WEAK 1004 MB SURFACE HIGH OVER SE ALABAMA NEAR 31N86W. AT THE SAME TIME...SOUTHERLY SURFACE WINDS CONTINUE TO ADVECT LOW LEVEL MOISTURE AHEAD OF THE COLD FRONT...WITH INSTABILITY FORECAST TO CONTINUE INCREASING AHEAD OF THE FRONT. THIS FRONT IS FORECAST TO CONTINUE MOVING SOUTHEASTWARD ACROSS THE GULF THROUGH TONIGHT...WITH INCREASING CHANCES FOR STRONG TO SEVERE THUNDERSTORMS ALONG AND AHEAD OF THE FRONT AS IT ENCOUNTERS THE INCREASINGLY MOIST AND UNSTABLE AIRMASS. THE INCREASING DEEP LAYER SHEAR ASSOCIATED WITH PARTICULARLY STRONG SOUTHWESTERLY FLOW ALOFT WILL ENHANCE THE STRONG TO SEVERE THUNDERSTORM THREAT. AT PRESENT...A TORNADO WATCH IS IN EFFECT FOR PORTIONS OF N FLORIDA AND THE ADJACENT COASTAL WATERS UNTIL NOON EST TODAY. ALSO...GALE CONDITIONS ARE FORECAST TO OCCUR FOR PORTIONS OF THE MIDDLE AND EAST GULF DURING THE NEXT DAY. IN THE WAKE OF THE COLD FRONT...RELATIVELY COOLER AND DRIER CONDITIONS ARE PRESENT. CARIBBEAN SEA... IN THE SW CARIBBEAN...A 1010 MB SURFACE LOW IS CENTERED N OF PANAMA NEAR 10N81W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE LOW IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS S OF 12N W OF 78W...INCLUDING PORTIONS OF PANAMA AND COSTA RICA. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER RIDGE PRESENT OVER THE W CARIBBEAN...WITH THE AXIS OF THIS UPPER RIDGE EXTENDING FROM N COLOMBIA NEAR 10N75W TO 17N81W TO 20N84W. OVER THE N AND E CARIBBEAN...DEEP LAYER SUBSIDENCE AND DEEP LAYER DRY AIR ARE IN PLACE RESULTING IN FAIR WEATHER...WHERE NORTHWESTERLY FLOW ALOFT IS PRESENT. THE SURFACE COLD FRONT OVER THE GULF OF MEXICO IS EXPECTED TO APPROACH THE NW CARIBBEAN OVER THE NEXT DAY...ENTERING THE NW CARIBBEAN ON MONDAY. ATLANTIC OCEAN... A VIGOROUS DEEP LAYER TROUGH OVER THE CENTRAL CONUS CONTINUES APPROACHING THE W ATLC. OVER THE NEXT DAY...THE ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD ACROSS PORTIONS OF THE W ATLC... WITH NUMEROUS SHOWERS AND THUNDERSTORMS ACCOMPANYING THE FRONT. THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS WILL EXIST ACROSS THE W ATLC ALONG AND AHEAD OF THE FRONT...ESPECIALLY GIVEN THE PRESENCE OF STRONG DEEP LAYER WIND SHEAR. AT PRESENT...A TORNADO WATCH IN EFFECT FOR PORTIONS OF N FLORIDA AND THE ADJACENT COASTAL WATERS UNTIL NOON EST TODAY. ALSO...IN THE WAKE OF THE COLD FRONT...RELATIVELY COOLER AND DRIER CONDITIONS ARE PRESENT. FARTHER TO THE E...A SURFACE RIDGE IS PRESENT ACROSS PORTIONS OF THE W ATLC...WHICH IS ASSOCIATED WITH A 1021 MB SURFACE HIGH NEAR 29N59W...WITH SUBSIDENCE AND FAIR WEATHER IN THE VICINITY OF THE SURFACE HIGH AND RIDGE. TO THE E...A SURFACE TROUGH EXTENDS FROM 31N42W TO 29N39W TO 28N38W...WITH LOW LEVEL CONVERGENCE RESULTING IN SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS FEATURE. THIS ACTIVITY IS BEING ENHANCED BY ATMOSPHERIC INSTABILITY IN THE VICINITY OF AN UPPER TROUGH WITH AN AXIS EXTENDING FROM 19N53W TO 26N48W TO 32N44W TO NW OF THE DISCUSSION AREA. FARTHER TO THE S...A SURFACE TROUGH EXTENDS FROM 22N35W TO 17N42W TO 13N52W TO 9N60W...WITH LOW LEVEL CONFLUENCE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 90 NM EITHER SIDE OF THIS FEATURE. THIS ACTIVITY N OF 15N IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE IN THE SW QUADRANT OF A 110-120 KT ANTICYCLONICALLY-CURVED UPPER LEVEL JET MAXIMUM OVER THE E ATLC. ADDITIONALLY...AN UPPER RIDGE IS S OF 16N BETWEEN THE AFRICAN COAST AND 42W...WITH AN UPPER HIGH NEAR 8N24W. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS UPPER RIDGE AND UPPER HIGH IS ENHANCING THE CONVECTION IN THE VICINITY OF THE ITCZ BETWEEN 14W-28W. ADDITIONALLY...GALE CONDITIONS ARE FORECAST DURING THE NEXT DAY FOR PORTIONS OF THE W ATLC. OF NOTE...NOVEMBER 30 MARKS THE CONCLUSION OF THE 2008 ATLANTIC HURRICANE SEASON. DURING THIS SEASON...SIXTEEN NAMED TROPICAL CYCLONES OCCURRED. OF THESE SIXTEEN...EIGHT WERE HURRICANES...OF WHICH FIVE WERE MAJOR HURRICANES OF SAFFIR-SIMPSON CATEGORY THREE STRENGTH OF STRONGER. THIS SEASON WAS THE FIRST EVER WHEN SIX CONSECUTIVE TROPICAL CYCLONES MADE LANDFALL ON THE CONUS MAINLAND. OVERALL...THE 2008 HURRICANE SEASON IS TIED AS THE FOURTH MOST ACTIVE IN TERMS OF NUMBER OF NAMED STORMS AND MAJOR HURRICANES...AND IS ALSO TIED AS FIFTH MOST ACTIVE IN TERMS OF NUMBER OF HURRICANES SINCE 1944...THE BEGINNING OF THE AERIAL RECONNAISSANCE ERA. FINALLY...THIS IS THE TENTH SEASON TO PRODUCE ABOVE-NORMAL TROPICAL CYCLONE ACTIVITY SINCE 1995 WHEN THE CURRENT ACTIVE HURRICANE ERA BEGAN. ADDITIONALLY...A TOTAL OF 64 TROPICAL WAVES MOVED OFF THE COAST OF AFRICA THIS SEASON WHICH IS NEAR THE SEASONAL AVERAGE. $$ COHEN/GR