000 AXNT20 KNHC 190550 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED SEP 19 2012 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... TROPICAL STORM NADINE IS CENTERED NEAR 36.2N 32.1W AT 19/0600 UTC OR ABOUT 195 NM SSW OF FLORES IN THE AZORES MOVING NNE AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SCATTERED MODERATE CONVECTION IS FROM 36N-41N BETWEEN 28W-36W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 07N48W TO 18N41W MOVING W AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN BROAD CYCLONIC FLOW FROM 08N-17N BETWEEN 41W-50W AND WITHIN A SURGE OF DEEP LAYER MOISTURE AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF A LINE FROM 10N50W TO 18N44W. TROPICAL WAVE EXTENDS FROM 12N68W TO 19N65W MOVING W AT 10 KT. THE WAVE REMAINS DIFFICULT TO TRACK WITH LOW-LEVEL CYCLONIC FLOW EVIDENT ACROSS THE LESSER ANTILLES ON INFRARED SATELLITE IMAGERY...HOWEVER MOST OF THE ACTIVE CONVECTION IS LOCATED FARTHER W-NW ACROSS THE NORTH-CENTRAL CARIBBEAN SEA AND PORTIONS OF PUERTO RICO AND HISPANIOLA. TOTAL PRECIPITABLE WATER IMAGERY INDICATES MAXIMIZED VALUES OVER THE AREA FROM 14N-19N BETWEEN 60W-74W. ISOLATED MODERATE CONVECTION IS FROM 15N-21N BETWEEN 64W-75W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO 05N29W TO 05N36W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N36W TO 08N44W THEN RESUMES AT 08N51W TO 08N59W. ISOLATED MODERATE CONVECTION IS FROM 04N-08N BETWEEN 25W-44W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE UPPER GREAT LAKES REGION S-SW TO THE LOWER MISSISSIPPI RIVER VALLEY AND OVER PORTIONS OF THE NW GULF. THE TROUGHING SUPPORTS A COLD FRONT ANALYZED AT 19/0300 UTC FROM NORTHERN FLORIDA NEAR 31N83W TO 25N88W BECOMING STATIONARY INTO THE SW GULF TO NEAR 19N93W. LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE FRONT ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND TSTMS ALONG AND EAST OF THE FRONT WITH THE MOST INTENSE CONVECTION OCCURRING OVER THE FLORIDA STRAITS...YUCATAN CHANNEL...AND PORTIONS OF THE YUCATAN PENINSULA. THE FRONT IS FORECAST TO BECOME STATIONARY DRAPED FROM NORTHERN FLORIDA TO 25N90W WEDNESDAY INTO THURSDAY AND EVENTUALLY BECOME ABSORBED INTO A SECONDARY COLD FRONT CURRENTLY EXTENDING FROM THE WESTERN FLORIDA PANHANDLE TO THE TEXAS AND LOUISIANA BORDER. THE FRONT IS EXPECTED TO GRADUALLY DISSIPATE OVER THE EASTERN GULF WATERS AND LINGER ACROSS THE FLORIDA PENINSULA THURSDAY INTO FRIDAY. CARIBBEAN SEA... AN APPROACHING MIDDLE TO UPPER LEVEL TROUGH IS OVER THE GULF OF MEXICO THIS EVENING AND THE ASSOCIATED DIFFLUENCE EAST OF THE TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND TSTMS OVER PORTIONS OF THE NW CARIBBEAN NORTH OF A LINE FROM 22N80W TO 17N88W...INCLUDING THE YUCATAN CHANNEL...YUCATAN PENINSULA...AND WESTERN CUBA. ELSEWHERE OVER THE WESTERN CARIBBEAN...MOSTLY CLEAR SKIES PREVAIL W OF 76W AS AN INVERTED UPPER LEVEL TROUGH WITH AXIS ALONG 80W REMAINS EMBEDDED WITHIN DRY AIR ALOFT AS NOTED ON WATER VAPOR IMAGERY. TO THE EAST OF THIS UPPER LEVEL TROUGH AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NORTH OF HISPANIOLA NEAR 21N69W. WHILE PROVIDING AN OVERALL DIFFLUENT ATMOSPHERE BENEATH THIS FEATURE...A WEAK 850 MB TO 700 MB TROUGH IS LOCATED BETWEEN THE TROPICAL WAVE ALONG 68W AND 76W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 15N-20N BETWEEN 64W-75W. THE PRESENCE OF THE TROPICAL WAVE IS LIKELY ENHANCING LOW-LEVEL MOISTURE CONVERGENCE AND WILL CONTINUE TO PROVIDE A HIGHER LIKELIHOOD OF PRECIPITATION THROUGH THE OVERNIGHT HOURS INTO WEDNESDAY FOR PUERTO RICO AND HISPANIOLA. ATLANTIC OCEAN... WITH THE APPROACH OF AN MIDDLE TO UPPER LEVEL TROUGH ACROSS THE SE CONUS...THE SW NORTH ATLC IS UNDER THE INFLUENCE OF MAXIMIZED DIFFLUENCE ALOFT AHEAD OF A FRONTAL BOUNDARY EXTENDING FROM NORTHERN FLORIDA INTO THE SOUTH-CENTRAL GULF OF MEXICO. SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 29N-33N BETWEEN 73W-76W...FROM 25N-29N W OF 77W...AND W OF 80W...INCLUDING THE FLORIDA STRAITS. SE OF THIS AREA...AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED N OF HISPANIOLA NEAR 21N69W AND EXTENDS A RIDGE AXIS NORTHWARD TO ANOTHER ANTICYCLONIC CIRCULATION NEAR 34N68W. WATER VAPOR IMAGERY INDICATES MOST MIDDLE TO UPPER LEVEL MOISTURE IS CENTERED OVER HISPANIOLA WITH ISOLATED SHOWERS AND TSTMS OCCURRING FROM 18N-23N BETWEEN 65W-76W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 33N53W AND EXTENDS A TROUGH AXIS SOUTHWARD TO A BASE NEAR 22N57W. THIS TROUGHING SUPPORTS A 1014 SURFACE LOW CENTERED NEAR 31N50W. A SURFACE TROUGH EXTENDS SW FROM THE LOW TO 25N55W WITH SCATTERED SHOWERS AND TSTMS OCCURRING OVER THE AREA FROM 26N-33N BETWEEN 45W-55W. ASIDE FROM THE CYCLONIC WINDS ASSOCIATED WITH TROPICAL STORM NADINE N OF 28N BETWEEN 24W-44W...THE REMAINDER OF THE EASTERN AND CENTRAL ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1019 MB HIGH CENTERED NEAR 29N20W WITH A RIDGE AXIS EXTENDING SW FROM THE HIGH CENTER TO 22N40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN