000 AXNT20 KNHC 042343 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT MAY 04 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 08N13W TO 05N15W TO 03N21W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 03N21W TO THE EQUATOR NEAR 37W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 04N-11N BETWEEN THE PRIME MERIDIAN AND 12W. ISOLATED MODERATE CONVECTION IS S OF 06N BETWEEN 11W- 31W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL CUT-OFF LOW IS CENTERED OVER ARKANSAS AND CONTINUES TO SUPPORT A COMPLEX AREA OF LOW PRESSURE OVER THE EASTERN GULF AND FLORIDA PENINSULA THIS EVENING. TROUGHING ALOFT EXTENDS SE FROM THE CUT-OFF LOW AND INTO THE SW NORTH ATLC SUPPORTING A 1005 MB LOW CENTERED NEAR 29N81W WITH A SECONDARY 1007 MB LOW CENTERED IN THE NE GULF NEAR 28N84W. A COLD FRONT IS ANALYZED ACROSS THE FLORIDA PANHANDLE NEAR 30N84W INTO THE 1007 MB LOW THEN CONTINUES SW ALONG 25N85W TO 21N92W. WHILE WATER VAPOR IMAGERY INDICATES VERY DRY AIR S OF 30N E OF 90W THE COLD FRONT IS ONLY GENERATING A FEW ISOLATED SHOWERS N OF 28 WITHIN 30 NM EITHER SIDE OF THE BOUNDARY. MOSAIC DOPPLER RADAR IMAGERY SHOWS THIS ACTIVTY STRETCHES NE OVER THE NORTHERN FLORIDA PENINSULA AND EASTERN PORTIONS OF THE FLORIDA PANHANDLE. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF DRY WESTERLY FLOW ALOFT AND A SURFACE RIDGE ANCHORED BY A 1018 MB HIGH CENTERED NEAR 27N95W. WHILE STRONG NORTHERLY WINDS ASSOCIATED WITH THE FRONTAL PASSAGE ARE GENERALLY E OF 90W...10 TO 15 KT ANTICYCLONIC WINDS ARE NOTED W OF 90W IN ASSOCIATION WITH THE HIGH PRESSURE OVER THE WESTERN GULF. A WEAK COLD FRONT...ANOTHER WAVE OF MIDDLE TO UPPER LEVEL ENERGY ASSOCIATED WITH THE CUT-OFF UPPER LEVEL LOW...WILL SKIRT THE NW AND NORTH- CENTRAL GULF WATERS THROUGH THE OVERNIGHT HOURS INTO SUNDAY INITIATING ANOTHER ROUND OF NW WINDS. CARIBBEAN SEA... WEST-SOUTHWESTERLY MIDDLE TO UPPER LEVEL FLOW IS OVER MUCH OF THE CARIBBEAN THIS EVENING AS THE OVERALL SURFACE PRESSURE PATTERN REMAINS RELAXED AND SLIGHTLY MODIFIED FROM THE USUAL E- NE TRADE WIND FLOW. A LARGE AREA OF SURFACE TROUGHING IS ESTABLISHED OVER THE EASTERN GULF...FLORIDA PENINSULA...AND SW NORTH ATLC WHICH STRETCHES SOUTHWARD AND COVERS THE BASIN BETWEEN 64W-80W. WEAK SOUTHERLY WINDS ARE NOTED E OF 74W AS ISOLATED SHOWERS REMAIN POSSIBLE THROUGH THE OVERNIGHT HOURS. A SURFACE TROUGH EXTENDS FROM WESTERN HISPANIOLA NEAR 19N74W TO 13N76W AND IS PROVIDING FOCUS FOR SOME OF THIS ACTIVITY ACROSS HISPANIOLA AND OVER THE CENTRAL CARIBBEAN. W OF 74W...N-NW WINDS IN THE RANGE OF 10 TO 20 KT CONTINUE TO FILTER IN ACROSS THE WESTERN CARIBBEAN AND ARE FORECAST TO PERSIST THROUGH LATE MONDAY. MEANWHILE WEAK SURFACE RIDGING WILL MAINTAIN ITS POSITION OVER THE EASTERN CARIBBEAN AND LESSER ANTILLES E OF 64W. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL CUT-OFF LOW IS CENTERED OVER ARKANSAS THIS EVENING AND SUPPORTS A BROAD AREA OF LOWER PRESSURE ACROSS THE SW NORTH ATLC. THE CUT-OFF LOW SUPPORTS A 1005 MB SURFACE LOW CENTERED NEAR 29N81W WITH A STATIONARY FRONT EXTENDING SE ALONG 26N75W TO A 1008 MB LOW CENTERED NEAR 24N64W. THE STATIONARY FRONT CONTINUES EAST...BUT BECOMES SUPPORTED BY A CENTRAL ATLC FEATURE ALOFT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING GENERALLY ALONG AND WITHIN 180 NM NORTH OF THE FRONT. ANOTHER STREAM OF MID-LEVEL MOISTURE AND CLOUDINESS IS NOTED N OF 18N BETWEEN 60W-70W. WITH THE STATIONARY FRONT IN PLACE...SCATTERED SHOWERS AND ISOLATED TSTMS ARE ALSO OCCURRING OVER THIS AREA AND NORTH TO 28N. FARTHER EAST...WATER VAPOR IMAGERY INDICATES A COMPLEX MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 41N43W WITH A SHORTWAVE TROUGH ROTATING AROUND THE SOUTHERN PERIPHERY NEAR 34N50W. LOWER PRESSURE RESULTS AT THE SURFACE WITH A 1004 MB LOW CENTERED NEAR 39N34W AND A SECONDARY 1007 MB LOW CENTERED W-SW NEAR 35N52W. FROM THE MAIN LOW...A COLD FRONT EXTENDS FROM THE LOW CENTER TO NEAR 31N42W WITH A SURFACE TROUGH CONTINUING FROM 30N41W TO 26N51W. FROM THERE THE BOUNDARY BECOMES A STATIONARY FRONT AND CONNECTS UP WITH THE 1008 MB LOW MENTIONED ABOVE CENTERED NEAR 24N64W. WITH AMPLE DIFFLUENCE ALOFT SOUTH OF THE CENTRAL ATLC UPPER LEVEL DYNAMICS AND SURFACE BOUNDARIES ABLE TO AID IN GENERATING CONVECTION...ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER A LARGE AREA OF THE CENTRAL ATLC FROM 20N-32N BETWEEN 32W-66W. FINALLY...A SURFACE RIDGE IS MAINTAINING CONTROL OVER THE EASTERN ATLC ANCHORED BY A 1021 MB HIGH CENTERED NEAR 38N15W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO 29N21W TO 20N38W TO 14N64W IN THE EASTERN CARIBBEAN SEA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE AT THE REQUEST OF METEO-FRANCE AND THE METEROLOGICAL SERVICES OF HAITI AND THE DOMINICAN REPUBLIC...THE TROPICAL ANALYSIS AND FORECAST BRANCH (TAFB) WILL BEGIN PROVIDING...ON A TEMPORARY BASIS...A SEPARATE DETAILED SECTION WITHIN THE ATLANTIC TROPICAL WEATHER DISCUSSION (TWDAT). IT WILL COVER BOTH HAITI AND THE DOMINICAN REPUBLIC DUE TO THE SHARED GEOGRAPHY OF BOTH COUNTRIES ON THE ISLAND OF HISPANIOLA. THE SECTION BEGINS ON MAY 15 2013 AT 1800 UTC...2 PM EDT. IT WILL PROVIDE GUIDANCE FOR SIGNIFICANT WEATHER EVENTS THAT ARE EXPECTED TO IMPACT THE REGION THROUGH 48 HOURS...WITH THE FOCUS ON ASSESSING THE POTENTIAL FOR HEAVY RAINFALL. $$ HUFFMAN