000 AXNT20 KNHC 242350 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT DEC 24 2011 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N11W TO 07N14W TO 04N29W TO 06N41W. A SURFACE TROUGH IS ANALYZED ON THE WESTERN EXTENT OF THE ITCZ AXIS FROM 07N44W TO 14N42W LARGELY AS A REFLECTION OF AN UPPER LEVEL LOW CENTERED NEAR 23N44W AND THE ASSOCIATED TROUGH AXIS WHICH EXTENDS SOUTHWARD TO 12N50W. LOW-LEVEL CONVERGENCE EAST OF THE SURFACE TROUGH AND ENHANCEMENT DUE TO STRONG UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL TROUGH AXIS IS GENERATING A LARGE AREA OF SCATTERED MODERATE CONVECTION NORTH OF THE ITCZ FROM 05N-22N BETWEEN 27W-43W. ...DISCUSSION... GULF OF MEXICO... SOUTHWESTERLY UPPER LEVEL FLOW IS NOTED ACROSS THE ENTIRE GULF THIS EVENING ON THE WESTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE BAHAMAS NEAR 25N77W. THE INFLUENCE OF THE UPPER LEVEL RIDGE EXTENDS WESTWARD TO 92W WHERE UPPER LEVEL MOISTURE INCREASES TO THE WEST OVER THE NW GULF AND MOST OF TEXAS AND LOUISIANA. THIS MOISTURE IS LOCATED EAST OF AN UPPER LEVEL LOW CENTERED OVER NEW MEXICO WITH THE ASSOCIATED HEIGHT FALLS SUPPORTING CYCLOGENESIS OVER THE NW GULF. AS OF 24/2100 UTC...A 1017 MB LOW IS CENTERED NEAR 27N96W WITH A STATIONARY FRONT EXTENDING ALONG 27N TO THE EAST...AND A STATIONARY FRONT EXTENDING SOUTHWARD TO SOUTHERN MEXICO NEAR 20N93W. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE NUMEROUS SHOWERS N OF 26N W OF 93W AND ISOLATED SHOWERS AND TSTMS WITHIN 90 NM EITHER SIDE OF THE FRONT S OF 27N. ASIDE FROM PRECIPITATION IMPACTS...WINDS IN THE VICINITY OF THE SURFACE LOW REMAIN STRONG IN THE RANGE OF 20 TO 30 KT AS THE PRESSURE GRADIENT CONTINUES TO STRENGTHEN AS THE UPPER LEVEL FEATURE APPROACHES FROM THE WEST. THESE WINDS ARE EXPECTED TO REACH GALE FORCE W OF 95W THROUGH THE OVERNIGHT HOURS INTO SUNDAY AS STRONG HIGH PRESSURE BUILDS IN ACROSS THE SOUTHERN PLAINS AND NE MEXICO. CARIBBEAN SEA... AN UPPER LEVEL RIDGE EXTENDS ACROSS THE CARIBBEAN SEA WITH AXIS FROM THE SE CARIBBEAN NEAR 10N66W N-NW TO EASTERN CUBA THEN TO AN ANTICYCLONIC CIRCULATION CENTERED OVER THE BAHAMAS NEAR 25N77W. WATER VAPOR IMAGERY INDICATES DRY AIR AND SUBSIDENCE OVER MUCH OF THE BASIN E OF 82W THIS EVENING IN THE MIDDLE AND UPPER LEVELS. HOWEVER...AT THE SURFACE A STRONG PRESSURE GRADIENT CONTINUES ACROSS THE CENTRAL CARIBBEAN AND A PORTION OF THE WESTERN CARIBBEAN AS A 1024 MB HIGH IS CENTERED IN THE SW NORTH ATLC NEAR 28N65W AND LOWER PRESSURE LOCATED OVER NORTHERN SOUTH AMERICA. AS A RESULT...EAST-NORTHEAST TRADES REMAIN STRONG IN THE RANGE OF 20 TO 30 KT AS DEPICTED BY AN EARLIER ASCAT PASS AROUND 24/1438 UTC. ELSEWHERE...MOST LOW-LEVEL MOISTURE IS NOTED ALONG THE CENTRAL AMERICA COAST WITH CONVERGENCE OF THE TRADES GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS WEST OF A LINE FROM 10N76W TO 20N87W. THE SURFACE HIGH OVER THE SW NORTH ATLC IS FORECAST TO DISSIPATE SLIGHTLY THROUGH THE OVERNIGHT HOURS AND RE-ESTABLISH ITSELF THROUGH MONDAY WITH FRESH TO STRONG E-NE TRADES EXPECTED TO PERSIST BETWEEN 65W-82W THROUGH TUESDAY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH LOCATED WELL NORTH OF THE DISCUSSION AREA OFF THE NEW ENGLAND COAST EXTENDS A COLD FRONT S OF 32N ALONG 32N70W TO THE FLORIDA PENINSULA NEAR 28N81W. THE ENERGY ASSOCIATED WITH THE FRONT CONTINUES TO BECOME MORE DIFFUSE AS AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE BAHAMAS NEAR 25N77W AND INFLUENCES MUCH OF THE SW NORTH ATLC. LOW-LEVEL MOISTURE ASSOCIATED WITH THE FRONT CONTINUES TO GENERATE ISOLATED SHOWERS WITHIN 75 NM EITHER SIDE OF THE BOUNDARY. TO THE SE OF THE FRONT...THE UPPER LEVEL RIDGING SUPPORTS A 1024 MB HIGH CENTERED NEAR 28N65W WHICH IS EXPECTED TO DISSIPATE SLIGHTLY THROUGH THE OVERNIGHT HOURS AND RE-ESTABLISH ITSELF THROUGH MONDAY. FARTHER EAST...AN UPPER LEVEL LOW CENTERED NEAR 23N44W AND ASSOCIATED TROUGHING WITH AXIS ALONG 45W SUPPORTS A SURFACE TROUGH ANALYZED FROM 23N45W TO 30N44W. LOW-LEVEL CONVERGENCE EAST OF THE SURFACE TROUGH AXIS AND MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL LOW IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 22N-29N BETWEEN 36W-45W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1038 MB HIGH CENTERED NE OF THE AZORES NEAR 43N15W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN