000 AXNT20 KNHC 202318 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN DEC 20 2009 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2230 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N8W 7N21W 5N37W 1N53W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM EQ-6N BETWEEN 31W-42W. ...DISCUSSION... GULF OF MEXICO... SURFACE RIDGING CONTINUES TO DOMINATE THE GULF OF MEXICO ANCHORED BY A 1028 MB SURFACE HIGH OVER NE MEXICO...AND A 1027 MB HIGH NEAR NE LOUISIANA. MAINLY N-NE WINDS ARE ACROSS THE BASIN. IN THE UPPER LEVELS...MOIST SWLY FLOW COVERS THE AREA AROUND THE E SIDE OF AN UPPER LEVEL TROUGH EXTENDING DOWN THE TEXAS COASTLINE INTO CENTRAL MEXICO. THE MID-UPPER LEVEL TROPICAL MOISTURE BEING DRAWN N-NE ACROSS THE BASIN IS SUPPORTING POSSIBLE ISOLATED SHOWERS ACROSS THE SW GULF. EXPECT THE SURFACE RIDGE TO GRADUALLY SHIFT EWD AS RETURN FLOW INCREASES ACROSS THE NW GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO ENTER THE BASIN LATE WED. CARIBBEAN SEA... A STATIONARY FRONT EXTENDS ACROSS THE CARIBBEAN THIS EVENING FROM THE WINDWARD PASSAGE ACROSS JAMAICA INTO THE SW CARIBBEAN TO NRN COSTA RICA. A SURFACE TROUGH IS AHEAD OF THE FRONT EXTENDING ACROSS HAITI TO NRN COLOMBIA. N-NE WINDS UP TO 25 KTS ARE BEHIND THE FRONT. THE FRONT IS SUPPORTED BY AN UPPER LEVEL LOW OFF THE NE UNITED STATES COAST. HOWEVER...MOST OF THE CARIBBEAN IS COVERED BY AN UPPER LEVEL RIDGE WITH AXIS FROM VENEZUELA ACROSS THE LEEWARD ISLANDS. MOIST SWLY FLOW AROUND THE W SIDE OF THE RIDGE IS DRAWING TROPICAL MOISTURE ACROSS THE NW CARIBBEAN AND CENTRAL AMERICA. THIS ALONG WITH SURFACE CONVERGENCE NEAR THE FRONT/TROUGH AXIS ARE SUPPORTING SCATTERED SHOWERS WITHIN 120 NM OF THE FRONT AXIS...AND ISOLATED SHOWERS WITHIN 60 NM OF THE SURFACE TROUGH. POSSIBLE ISOLATED SHOWERS ARE ELSEWHERE W OF 73W. DRY AIR AND SUBSIDENCE COVER THE E CARIBBEAN NOTED IN WATER VAPOR IMAGERY BRINGING GENERALLY FAIR WEATHER TO THAT PORTION OF THE BASIN. EXPECT THE FRONT TO REMAIN STATIONARY OVER THE NEXT 24 HRS WITH CONTINUED PRECIPITATION BECOMING DIFFUSE BY TUE. ATLANTIC OCEAN... AN OCCLUDED 968 MB LOW IS LOCATED OFF THE NEW ENGLAND COAST NEAR 41N66W WITH A COLD FRONT ENTERING INTO THE DISCUSSION AREA NEAR 32N54W CONTINUING ALONG 25N64W TO JUST E OF TURKS AND CAICOS NEAR 21N70W BECOMING STATIONARY TO THE WINDWARD PASSAGE AND INTO THE CARIBBEAN. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE FRONT...AND FARTHER E N OF 26N BETWEEN 41W-58W. A LARGE AREA OF STRATOCUMULUS CLOUDS AND STRONG W-NW WINDS ARE BEHIND THE FRONT. A WEAK 1017 MB HIGH IS LOCATED IN THE CENTRAL ATLC NEAR 21N46W SANDWICHED BETWEEN THE AFOREMENTIONED COLD FRONT AND A SECOND COLD FRONT EXTENDING FROM E OF THE CANARY ISLANDS ALONG 32N16W 23N26W BECOMING A DYING STATIONARY FRONT NEAR 21N35W TO 20N43W. THE WEAK SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE EXTENDING FROM THE CARIBBEAN ACROSS THE LEEWARD ISLANDS TO NEAR 33N50W. THE SECOND COLD FRONT IN THE E ATLC IS SUPPORTED BY AN UPPER LEVEL TROUGH CENTERED NEAR THE AZORES ISLANDS. ISOLATED SHOWERS ARE WITHIN 60 NM OF THE FRONT AXIS..WITH SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS W OF THE FRONT N OF 24N BETWEEN 21W-34W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE. $$ WALTON