000 AXNT20 KNHC 191200 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... TROPICAL STORM NADINE IS CENTERED NEAR 36.7N 31.7W AT 19/1200 UTC OR ABOUT 161 NM S OF FLORES IN THE AZORES MOVING NE AT 4 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-42N BETWEEN 29W-37W. 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 14N19W TO 19N18W MOVING W AT 10-15 KT. EXAMINING THE DAKAR UPPER AIR TIME-SECTION ANALYSES...THE WAVE PASSED DAKAR AROUND 18/0000 UTC AND HAS SINCE MOVED OFF THE W AFRICAN COAST. A 1010 MB LOW IS CENTERED AT THE SOUTHERN EXTENT OF THE WAVE AND REMAINS EMBEDDED WITHIN LOW-LEVEL MONSOONAL FLOW. ISOLATED MODERATE CONVECTION IS FROM 12N-15N BETWEEN 18W-20W. TROPICAL WAVE EXTENDS FROM 07N50W TO 17N44W MOVING W AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN BROAD LOW-LEVEL CYCLONIC FLOW FROM 07N-18N BETWEEN 44W-52W AND WITHIN A SURGE OF DEEP LAYER MOISTURE AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 12N-18N BETWEEN 44W-49W. TROPICAL WAVE EXTENDS FROM 12N68W TO 19N65W MOVING W AT 10-15 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 15N-19N BETWEEN 60W-75W. ISOLATED MODERATE CONVECTION IS FROM 15N-19N BETWEEN 64W-71W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 13N19W TO 04N34W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N34W TO 05N42W TO 07N47W. ISOLATED MODERATE CONVECTION IS FROM 03N-09N BETWEEN 12W-45W. ...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 19/0900 UTC FROM NORTHERN FLORIDA NEAR 30N82W TO 25N87W 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 AND PORTIONS OF THE SW GULF S OF 22N. THE FRONT IS FORECAST TO BECOME STATIONARY DRAPED FROM NORTHERN FLORIDA TO 25N90W LATE WEDNESDAY INTO THURSDAY AND THEN 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 MORNING 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 20N78W TO 18N88W...INCLUDING THE YUCATAN CHANNEL...AND THE ADJACENT COASTAL WATERS OF 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. A FEW ISOLATED SHOWERS ARE HOWEVER NOTED WITHIN 75 NM EITHER SIDE OF A LINE FROM 16N78W TO 13N83W. TO THE EAST OF THIS UPPER LEVEL TROUGH... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER HISPANIOLA NEAR 19N70W. WHILE PROVIDING AN OVERALL DIFFLUENT ATMOSPHERE BENEATH THIS FEATURE...A WEAK 850 MB TO 700 MB TROUGH IS LOCATED ALOFT OVER THE TROPICAL WAVE ALONG 72W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 15N-20N BETWEEN 64W-76W. THE PRESENCE OF THE TROPICAL WAVE IS LIKELY ENHANCING LOW-LEVEL MOISTURE CONVERGENCE AND WILL CONTINUE TO PROVIDE A HIGHER LIKELIHOOD OF PRECIPITATION 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 AND SW GULF OF MEXICO. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING W OF 76W WITH MORE INTENSE CONVECTION LOCATED ACROSS THE FLORIDA STRAITS FROM 23N-26N BETWEEN 79W-81W. SE OF THIS AREA...AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER HISPANIOLA NEAR 19N70W AND EXTENDS A RIDGE AXIS NORTHWARD TO ANOTHER ANTICYCLONIC CIRCULATION NEAR 35N67W. WATER VAPOR IMAGERY INDICATES MOST MIDDLE TO UPPER LEVEL MOISTURE IS CENTERED OVER HISPANIOLA WITH ISOLATED SHOWERS AND TSTMS OCCURRING FROM 18N-22N BETWEEN 65W-75W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 30N53W AND EXTENDS A TROUGH AXIS SOUTHWARD TO A BASE NEAR 21N56W. THIS TROUGHING SUPPORTS A 1012 MB SURFACE LOW CENTERED NEAR 30N53W. A SURFACE TROUGH EXTENDS SW FROM THE LOW TO 26N62W WITH SCATTERED SHOWERS AND TSTMS OCCURRING OVER AN AREA EAST OF THE LOW CENTER FROM 26N-35N BETWEEN 45W-54W. ASIDE FROM THE CYCLONIC WINDS ASSOCIATED WITH TROPICAL STORM NADINE N OF 27N BETWEEN 24W-42W...THE REMAINDER OF THE EASTERN AND CENTRAL ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1017 MB HIGH CENTERED NEAR 25N44W WITH A RIDGE AXIS EXTENDING EASTWARD FROM THE HIGH CENTER ALONG 24N33W TO 32N19W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN