000 AXNT20 KNHC 300519 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0445 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 9N12W 6N22W 6N33W 3N45W 1N51W. SCATTERED MODERATE CONVECTION IS FROM 2N-7N BETWEEN 14W-28W. SIMILAR CONVECTION IS S OF 10N BETWEEN 32W-43W. ...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 1003 MB SURFACE LOW IN S MISSISSIPPI NEAR 31N89W ACROSS THE NW GULF TO 27N93W TO NE MEXICO NEAR 23N100W. PARTICULARLY STRONG UPPER LEVEL DIVERGENCE IN THE SW QUADRANT OF AN ANTICYCLONICALLY-CURVED 140-150 KT UPPER LEVEL JET MAXIMUM OVER THE E CONUS IS SUPPORTING BANDS OF SHOWERS AND THUNDERSTORMS ALONG AND WITHIN 60 NM E OF THE COLD FRONT. 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 SUNDAY... 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 THE APPROACH OF THE UPPER LEVEL JET MAXIMUM WILL ENHANCE THE STRONG TO SEVERE THUNDERSTORM THREAT. ALSO...GALE CONDITIONS ARE EXPECTED N OF 28N BETWEEN 85W AND 89W FOR SUNDAY EVENING THROUGH EARLY MONDAY MORNING. IN THE WAKE OF THE COLD FRONT... RELATIVELY COOLER AND DRIER CONDITIONS ARE EXPECTED. ALSO... ACROSS THE S GULF...A SURFACE TROUGH EXTENDS FROM A 1003 MB SURFACE LOW IN THE W GULF NEAR 22N97W TO 18N92W TO N HONDURAS NEAR 15N87W...WITH DEEP LAYER DRY AIR CURRENTLY IN PLACE LIMITING DEEP CONVECTION NEAR THESE FEATURES. 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 11N W OF 77W...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 15N81W TO 19N85W. OVER THE N AND E CARIBBEAN...DEEP LAYER SUBSIDENCE AND DEEP LAYER DRY AIR ARE IN PLACE RESULTING IN FAIR WEATHER...WHERE STRONG NORTHWESTERLY FLOW ALOFT IS PRESENT. ALSO...A SURFACE TROUGH EXTENDS FROM A 1003 MB SURFACE LOW IN THE W GULF NEAR 22N97W TO 18N92W ACROSS THE FAR W CARIBBEAN TO N HONDURAS NEAR 15N87W... WITH DEEP LAYER DRY AIR CURRENTLY IN PLACE LIMITING DEEP CONVECTION NEAR THESE FEATURES. ATLANTIC OCEAN... STRONG WESTERLY FLOW ALOFT COVERS MUCH OF THE W AND CENTRAL ATLC. A SURFACE RIDGE EXTENDS ACROSS THE W ATLC FROM A 1019 MB SURFACE HIGH NEAR 27N60W...WITH SUBSIDENCE AND FAIR WEATHER IN THE VICINITY OF THE SURFACE HIGH AND RIDGE. TO THE E...A SURFACE TROUGH EXTENDS FROM 32N45W TO 30N43W TO 28N40W...WITH LOW LEVEL CONVERGENCE RESULTING IN SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS FEATURE. THIS ACTIVITY IS BEING ENHANCED BY ATMOSPHERIC LIFT IN MOIST SOUTHWESTERLY FLOW ALOFT E OF AN UPPER TROUGH AXIS EXTENDING FROM 29N44W TO 32N46W TO N OF THE DISCUSSION AREA. FARTHER TO THE S...A SURFACE TROUGH EXTENDS FROM 23N35W TO 15N47W TO 8N61W...WITH LOW LEVEL CONFLUENCE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THIS FEATURE. THIS ACTIVITY N OF 16N IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE ASSOCIATED WITH A 100-110 KT ANTICYCLONICALLY-CURVED UPPER LEVEL JET MAXIMUM OVER THE E ATLC. ADDITIONALLY...AN UPPER RIDGE IS PRESENT S OF 11N BETWEEN 16W-32W...WITH UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS RIDGE ENHANCING THE CONVECTION IN THE VICINITY OF THE ITCZ BETWEEN 14W-28W. OVER THE NEXT DAY...A SURFACE COLD FRONT WILL MOVE SOUTHEASTWARD ACROSS PORTIONS OF THE W ATLC...WITH SCATTERED 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 DEEP LAYER WIND SHEAR. ADDITIONALLY...GALE CONDITIONS ARE FORECAST FOR SUNDAY AFTERNOON THROUGH MONDAY FOR PORTIONS OF THE W ATLC. ALSO...IN THE WAKE OF THE COLD FRONT...RELATIVELY COOLER AND DRIER CONDITIONS ARE EXPECTED. 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