000 AXNT20 KNHC 272351 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU SEP 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL STORM NADINE IS CENTERED NEAR 28.6N 32.8W AT 27/2100 UTC OR ABOUT 635 NM SSW OF THE AZORES MOVING WSW AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 992 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SCATTERED MODERATE CONVECTION IS FROM 27N-31N BETWEEN 31W-34W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 09N34W TO 17N31W MOVING W AT 10 KT. THE WAVE COINCIDES WITH A 700 MB TROUGH NOTED IN GLOBAL MODEL GUIDANCE BETWEEN 28W-35W. TOTAL PRECIPITABLE WATER IMAGERY ALSO INDICATES THE WAVE LIES WITHIN A DEEP LAYER MOISTURE MAXIMUM FROM 12N-18N BETWEEN 22W-33W. ISOLATED MODERATE CONVECTION IS FROM 14N-18N BETWEEN 24W-30W. TROPICAL WAVE EXTENDS FROM 11N78W TO 21N75W MOVING W AT 5-10 KT. THIS WAVE ALSO COINCIDES WITH A SHARPER...MORE DEFINED 700 MB TROUGH OVER THE WESTERN CARIBBEAN ALONG 78W AND IS EXPECTED TO MOVE WESTWARD ON THE SOUTHEASTERN PERIPHERY OF A MID-LEVEL RIDGE ANCHORED OVER THE SOUTHERN FLORIDA PENINSULA NEAR 27N81W. TOTAL PRECIPITABLE WATER VALUES REMAIN ELEVATED ACROSS THE WESTERN CARIBBEAN AS THE WAVE MOVES THROUGH THE REGION WITH RESULTANT SCATTERED MODERATE CONVECTION FROM 17N-22N BETWEEN 74W-79W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 13N25W TO 08N37W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N37W TO 07N41W TO 10N46W TO 10N50W. ISOLATED MODERATE CONVECTION IS FROM 04N-09N BETWEEN 10W-35W...AND FROM 05N-13N BETWEEN 38W-46W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM 30N84W TO A BASE OVER WESTERN CUBA NEAR 22N83W. WHILE WATER VAPOR IMAGERY INDICATES FAIRLY DRY AIR ALOFT OVER THE NE GULF...THE REMAINDER OF THE GULF IS UNDER NORTH-NORTHWESTERLY FLOW ALOFT DUE TO BROAD UPPER LEVEL RIDGING OVER MUCH OF MEXICO AND THE SOUTH-CENTRAL CONUS. MIDDLE TO UPPER LEVEL MOISTURE CONTINUES TO SPILL OVER THE TOP OF THE RIDGE PROVIDING THE GULF WITH BROKEN TO OVERCAST CLOUDINESS THIS EVENING. AT THE SURFACE...A RIDGE EXTENDS FROM THE SE CONUS ANCHORED BY A 1022 MB HIGH CENTERED OVER NORTHERN GEORGIA TO THE WESTERN GULF NEAR 21N98W WITH PRIMARILY LIGHT EAST TO SOUTHEASTERLY SURFACE FLOW. WITH THE MIDDLE TO UPPER LEVEL MOISTURE IN PLACE...A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING THIS EVENING W OF 87W. OTHERWISE...PEAK DAYTIME HEATING AND INSTABILITY IS RESPONSIBLE FOR SCATTERED SHOWERS AND TSTMS OCCURRING OVER INLAND PORTIONS OF THE SOUTHERN FLORIDA PENINSULA...CUBA...AND THE YUCATAN CHANNEL. LOOKING AHEAD...THE REMAINDER OF THE WEEK HOLDS RELATIVELY BENIGN CONDITIONS FOR THE GULF WITH SURFACE RIDGING FORECAST TO HOLD THROUGH SATURDAY. GLOBAL MODELS ARE THEN SUGGESTING A SURFACE LOW TO DEVELOP OVER SOUTHERN TEXAS ALONG THE GULF COAST AND MOVE E-NE INTO THE NW GULF EARLY SUNDAY. CARIBBEAN SEA... AN UPPER LEVEL TROUGH EXTENDS FROM THE EASTERN GULF OF MEXICO INTO THE NW CARIBBEAN AND WHILE SKY CONDITIONS THROUGH THE YUCATAN CHANNEL REMAIN CLEAR THIS EVENING...EAST OF THE UPPER LEVEL TROUGH AXIS...MOIST SOUTHWESTERLY FLOW ALONG WITH PEAK DAYTIME HEATING AND INSTABILITY IS ENHANCING SCATTERED SHOWERS AND TSTMS OVER CUBA...JAMAICA...AND THE ADJACENT COASTAL WATERS FROM 17N-23N BETWEEN 75W-83W. THE PRESENCE OF A TROPICAL WAVE ALONG 77W IS ALSO PROVIDING LOW TO MID-LEVEL LIFT TO SUPPORT THE CONVECTION. SOUTH OF THIS AREA OVER THE SW CARIBBEAN AND CENTRAL AMERICA...AN UPPER LEVEL RIDGE REMAINS S OF 16N W OF 79W WHICH CONTINUES TO GENERATE SCATTERED SHOWERS AND TSTMS MAINLY OVER INLAND AREAS OF PANAMA...COSTA RICA...NICARAGUA...AND HONDURAS. AS MOISTURE AND PRECIPITATION ASSOCIATED WITH THE TROPICAL WAVE MOVES WESTWARD DURING THE WEEKEND...PRECIPITATION PROBABILITIES WILL REMAIN HIGH ACROSS CENTRAL AMERICA WITH THE INCREASED CHANCE OF LOCALIZED FLOODING AND MUDSLIDES OVER THE HIGHER TERRAIN. LASTLY...THE EASTERN CARIBBEAN REMAINS UNDER FAIRLY TRANQUIL CONDITIONS THIS EVENING WITH ONLY A FEW EARLY EVENING SCATTERED SHOWERS AND TSTMS OCCURRING OVER HISPANIOLA AND PUERTO RICO. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS LOCATED OVER THE EASTERN GULF OF MEXICO AND PORTIONS OF THE FLORIDA PENINSULA PROVIDING THE MUCH OF THE SW NORTH ATLC WITH MOIST SOUTHWESTERLY UPPER LEVEL FLOW BETWEEN 70W-82W. WHILE NO SPECIFIC SURFACE FRONTAL BOUNDARIES ARE PRESENT...SCATTERED SHOWERS AND TSTMS ARE OCCURRING W OF 74W. ANOTHER AREA OF ENHANCED SHOWERS AND POSSIBLE ISOLATED TSTMS IS LOCATED FROM 26N-32N BETWEEN 58W-70W. ALL OF THIS MOISTURE CONTINUES TO RIDE OVER THE NORTHERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NORTH OF PUERTO RICO NEAR 20N67W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 30N48W AND EXTENDS A TROUGH AXIS S-SW TO A BROAD BASE NEAR 14N59W. ANALYZED WITHIN THE INFLUENCE OF THE UPPER LEVEL TROUGHING...A SURFACE TROUGH EXTENDS FROM 19N61W TO 24N55W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 20N-23N BETWEEN 53W-57W WITH ISOLATED SHOWERS AND TSTMS OCCURRING ELSEWHERE IN ASSOCIATION WITH THE UPPER LEVEL TROUGH FROM 14N-25N BETWEEN 43W-55W. OTHERWISE THE REMAINDER OF THE EASTERN ATLC CONTAINS TROPICAL STORM NADINE IN THE VICINITY OF 29N33W. IT REMAINS A FAIRLY SMALL SYSTEM WITH INFLUENCE FROM 24N-34N BETWEEN 27W-38W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN