000 AXNT20 KNHC 112345 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON MAR 11 2013 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 MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 02N21W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 02N21W TO THE EQUATOR NEAR 26W THEN ALONG THE EQUATOR TO 37W. ISOLATED MODERATE CONVECTION IS FROM 04N-07N BETWEEN 09W-17W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS CENTERED OVER THE GREAT LAKES REGION AND EXTENDS A TROUGH AXIS S- SW OVER THE LOWER MISSISSIPPI RIVER VALLEY AND SW OVER NORTHERN MEXICO. THIS TROUGHING ALOFT SUPPORTS A COLD FRONT ANALYZED INTO THE GULF ACROSS THE FLORIDA PANHANDLE NEAR 31N87W S-SW ALONG 25N93W TO 22N94W TO THE SOUTHERN MEXICO COAST NEAR 18N94W. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF THE FRONT N OF 24N AND WITHIN 90 NM EITHER SIDE OF THE FRONT S OF 24N. WHILE SOUTHERLY LOW-LEVEL RETURN FLOW DOMINATES EAST OF THE FRONT FUELING THE ONGOING CONVECTION... WEST OF THE FRONT...NORTHERLY WINDS IN THE RANGE OF 20 TO 30 KT CONTINUE TO SPREAD EASTWARD WITH THE MOVEMENT OF THE FRONT. GALE FORCE CONDITIONS S OF 26N ARE FORECAST TO OCCUR OVER THE NEXT 6 HOURS. HIGH PRESSURE IS EXPECTED TO BUILD AND LINGER NORTHWEST OF THE GULF OVER THE SOUTHERN PLAINS THROUGH WEDNESDAY WITH STRONG NORTHEASTERLY WINDS PERSISTING GENERALLY E OF 94W. CARIBBEAN SEA... GENERALLY WEST-NORTHWESTERLY MIDDLE TO UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY OVER THE CARIBBEAN BASIN THIS EVENING PROVIDING FOR OVERALL DRY AND STABLE CONDITIONS AT THE SURFACE. EAST-NORTHEASTERLY TRADE PERSIST WITH THE STRONGEST WINDS LOCATED S OF 15N BETWEEN 70W-78W...AND IN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. A FEW ISOLATED LOW-TOPPED ARE NOTED ON SATELLITE IMAGERY OCCURRING OVER CENTRAL PORTIONS OF THE BASIN FROM 13N-17N BETWEEN 66W-76W. THE TRADES ARE EXPECTED TO PERSIST THROUGH WEDNESDAY WITH THE ARRIVAL OF A GULF OF MEXICO COLD FRONT ENTERS THE NW CARIBBEAN LATE WEDNESDAY INTO THURSDAY INTRODUCING STRONG N-NE WINDS N OF 17N W OF 78W. ATLANTIC OCEAN... MIDDLE TO UPPER LEVEL RIDGING EXTENDS FROM THE WESTERN CARIBBEAN NORTHWARD TO BEYOND 32N78W AND COVERS MUCH OF THE SW NORTH ATLC AND SUPPORTS A SURFACE RIDGE ANCHORED BY A 1028 MB HIGH CENTERED WELL NORTH OF THE DISCUSSION AREA NEAR 41N67W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO THE WINDWARD PASSAGE NEAR 20N74W. WEST OF THE RIDGE AXIS...LOW-LEVEL MOISTURE CONTINUES TO MOVE NORTHWARD IN ASSOCIATION WITH AN APPROACHING COLD FRONT ANALYZED OVER THE SE CONUS AND NE GULF OF MEXICO. FARTHER EAST...A DEEP LAYERED LOW CENTERED NEAR 34N49W REFLECTS TO THE SURFACE AS A 992 MB LOW NEARLY COLLOCATED NEAR 35N49W. THE PRIMARY FRONT IS ANALYZED AS A DISSIPATING COLD FRONT FROM 32N38W TO 21N48W AND BECOMES A SURFACE TROUGH AXIS TO 14N57W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF BOTH BOUNDARIES. A SECONDARY WAVE OF ENERGY ALOFT FOLLOWS THE COLD FRONT AND IS ANALYZED AS A SURFACE TROUGH FROM 32N48W SW TO 24N57W. LIFTING DYNAMICS ALOFT ARE PRIMARILY GENERATING ELEVATED ISOLATED SHOWERS AND TSTMS FROM 26N-31N BETWEEN 48W-58W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1019 MB CENTERED NW OF THE CANARY ISLANDS NEAR 29N20W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN