000 AXNT20 KNHC 171138 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT MON SEP 17 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 32.0N 36.4W AT 17/0900 UTC OR ABOUT 585 NM SW OF THE AZORES MOVING ENE AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 985 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SCATTERED MODERATE CONVECTION IS FROM 32N-37N BETWEEN 31W-40W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N37W TO 17N33W MOVING W AT 10-15 KT THE WAVE REMAINS EMBEDDED WITHIN BROAD CYCLONIC FLOW S OF 17N BETWEEN 31W-40W AND WITHIN A SURGE OF DEEP LAYER MOISTURE AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 13N-16N BETWEEN 32W-38W. TROPICAL WAVE EXTENDS FROM 11N59W TO 19N55W MOVING W AT 10 KT. EXAMINING SHORTWAVE INFRARED SATELLITE IMAGERY...A VERY WEAK 1010 MB AREA OF LOW PRESSURE IS ALONG THE WAVE AXIS NEAR 14N58W. THE WAVE REMAINS VERY SHALLOW AND EXHIBITS A LACK OF SIGNIFICANT DEEP CONVECTION WITH GLOBAL MODEL DATA INDICATING A 700 MB TROUGH AXIS FARTHER TO THE WEST OF THE WAVE AXIS ACROSS THE EASTERN CARIBBEAN SEA. GIVEN THE LOW-LEVEL CONVERGENCE SURROUNDING THE WAVE AND LOW TO MIDDLE LEVEL LIFT ASSOCIATED WITH THE 700 MB TROUGHING...WIDELY SCATTERED SHOWERS AND ISOLATED MODERATE CONVECTION IS OCCURRING FROM 13N-18N BETWEEN 57W-67W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 09N22W TO 11N29W TO 09N40W TO 09N47W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N47W TO 14N54W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 03N-09N BETWEEN 14W-23W. ISOLATED MODERATE CONVECTION IS FROM 04N-08N BETWEEN 24W-34W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL TROUGH IS LOCATED OVER EASTERN TEXAS WITH AXIS EXTENDING FROM 33N97W TO 23N104W. WITH MUCH OF THE LIFTING DYNAMICS MOVING OVER EASTERN TEXAS INTO THE LOWER MISSISSIPPI RIVER VALLEY THIS MORNING...THE TROUGH SUPPORTS A SURFACE TROUGH ANALYZED OVER THE WESTERN GULF FROM VERMILION BAY NEAR 30N92W INTO A 1011 MB LOW CENTERED NEAR 27N96W THEN SOUTHWARD TO 23N97W. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE W OF 90W IS GENERATING SCATTERED SHOWERS AND TSTMS NW OF A LINE FROM 29N90W TO THE SURFACE TROUGH NEAR 25N96W...AND ALSO WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH S OF 25N. GLOBAL MODELS ALL SUGGEST THE NEWLY FORMED SURFACE LOW PRESSURE AREA WILL QUICKLY MOVE NE AND BECOME EMBEDDED WITHIN THE NEXT COLD FRONT TO SWEEP FROM THE CENTRAL PLAINS INTO THE SE CONUS BY EARLY TUESDAY. THIS WILL RESULT IS GENERAL SURFACE TROUGHING ACROSS MUCH OF THE GULF AND PLACE IT UNDER 10 TO 20 KT S TO SW WINDS E OF THE LOW TODAY AND GENERALLY 10 TO 15 KT WEST WINDS W OF THE SURFACE TROUGH AXIS. ELSEWHERE...A WEAK UPPER LEVEL SHORTWAVE IS CENTERED OVER THE MIDDLE FLORIDA KEYS NEAR 25N81W AND IS PROVIDING ENOUGH MIDDLE TO UPPER LEVEL LIFT TO GENERATE ISOLATED SHOWERS AND TSTMS FROM 23N-27N E OF 85W...INCLUDING THE FLORIDA STRAITS. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER BELIZE NEAR 17N89W THAT EXTENDS INFLUENCE AS FAR EAST AS 79W. A DIFFLUENT ENVIRONMENT REMAINS MAXIMIZED OVER PORTIONS OF THE NW CARIBBEAN AND CENTRAL AMERICA GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 15N-21N BETWEEN 82W-89W... INCLUDING THE GULF OF HONDURAS. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 14N75W AND EXTENDS AN INVERTED UPPER LEVEL TROUGH AXIS NORTHWARD FROM THE UPPER LEVEL LOW CENTER TO OVER EASTERN CUBA NEAR 20N76W. WATER VAPOR IMAGERY INDICATES THAT MOSTLY DRY AIR IS ASSOCIATED WITH THIS FEATURE ACROSS THE CENTRAL CARIBBEAN BETWEEN 68W-81W. FINALLY...ACROSS THE EASTERN CARIBBEAN...AS MENTIONED ABOVE...A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES ANALYZED IN THE VICINITY OF 58W. A WEAK 700 MB TROUGH IS ALSO NOTED WEST OF THE WAVE AXIS AND THIS IS PROVIDING FOR AN OVERALL UNSTABLE ATMOSPHERE WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 13N-18N BETWEEN 55W-67W. OTHERWISE...EASTERLY TRADES ARE EXPECTED TO PERSIST IN THE RANGE OF 10 TO 20 KT THROUGH TUESDAY. ATLANTIC OCEAN... A WEAK UPPER LEVEL SHORTWAVE IS CENTERED OVER THE MIDDLE FLORIDA KEYS 25N81W AND CONTINUES TO PROVIDE ENOUGH MIDDLE TO UPPER LEVEL LIFT IN THE ATMOSPHERE TO GENERATE ISOLATED SHOWERS ACROSS THE NW BAHAMAS AND FLORIDA STRAITS THIS MORNING. MOSTLY EMBEDDED WITHIN EASTERLY FLOW AND LOCATED ON THE SOUTHERN PERIPHERY OF A RIDGE ANCHORED TO THE NORTH NEAR THE OUTER BANKS...THE SHOWER ACTIVITY REMAINS FROM 22N-28N W OF 75W. FARTHER NORTHEAST...A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 36N54W INTO THE DISCUSSION AREA TO A BASE NEAR 25N60W. THIS TROUGH SUPPORTS A DISSIPATED COLD FRONT FROM 31N58W TO 26N65W...AND A PAIR OF PRE- FRONTAL SURFACE TROUGHS FROM 27N56W TO 32N54W AND FROM 24N62W TO 29N58W. NO SIGNIFICANT DEEP CONVECTION IS NOTED WITH EITHER FEATURE...HOWEVER ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF BOTH SURFACE TROUGHS. FINALLY...WHILE TROPICAL STORM NADINE TRACKS TO THE EAST-NORTHEAST AND NORTH OF THE DISCUSSION AREA...A SURFACE RIDGE IS ESTABLISHED FROM THE CANARY ISLANDS SOUTHWESTWARD TO 20N45W ANCHORED BY A 1017 MB HIGH CENTERED NEAR 25N24W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN