000 AXNT20 KNHC 251730 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED SEP 25 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N36W TO 19N38W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A SURFACE TO 700 MB TROUGH WITH A 30 TO 35 KT AFRICAN EASTERLY JET CORE EXTENDING FROM WEST AFRICA NEAR 11N10W TO 12N33W EAST OF THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS FROM 15N-17N BETWEEN 33W-40W. CONVECTION WITH THIS WAVE REMAINS LIMITED DUE TO INCREASED SOUTHWESTERLY SHEAR ALOFT AND SAHARAN DUST SURROUNDING THE WAVE AND ENCOMPASSING A LARGE AREA OF THE EASTERN ATLC. TROPICAL WAVE EXTENDS FROM 09N45W TO 17N49W MOVING W AT 10-15 KT. THE WAVE REMAINS ASSOCIATED WITH WEAK LOW-LEVEL TROUGHING WITH LOW-LEVEL MOISTURE CONVERGENCE MAINLY EAST OF THE WAVE AXIS GENERATING SCATTERED MODERATE CONVECTION FROM 120 NM EITHER SIDE OF A LINE FROM 09N39W TO 16N48W. THIS CONVECTION IS LIKELY ENHANCED DUE TO AN UPPER LEVEL LOW CENTERED NEAR 20N51W THAT IS PROVIDING AN OVERALL DIFFLUENT ENVIRONMENT ON THE UPPER LOW'S EASTERN PERIPHERY. TROPICAL WAVE EXTENDS FROM 13N59W TO 21N57W MOVING W AT 15 KT. THE WAVE CONTINUES TO EXHIBIT A WEAK SATELLITE SIGNATURE AND IS LIKELY BEGINNING TO STRETCH ANY ENERGY REMAINING TO THE N-NW WHILE A WEAK PORTION CONTINUES W-NW. WATER VAPOR IMAGERY INDICATES THE WAVE IS EMBEDDED WITHIN A VERY DRY AIRMASS ALOFT WITH ONLY POSSIBLE ISOLATED SHOWERS OCCURRING WITHIN 90 NM EITHER SIDE OF THE WAVE AXIS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO 08N26W. THE INTERTROPICAL CONVERGENGE ZONE AXIS EXTENDS FROM 08N26W TO 09N34W TO A 1013 MB LOW CENTERED NEAR 08N36W TO 09N44W TO 05N50W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS FROM 04N-10N BETWEEN 14W-20W...AND FROM 08N-10N BETWEEN 34W-38W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE SE CONUS NEAR 34N85W SW TO A BROAD BASE OVER THE WESTERN GULF NEAR 25N94W. WATER VAPOR IMAGERY INDICATES THIS TROUGH AXIS DELINEATES A MOIST AND DIFFLUENT ATMOSPHERE TO THE EAST AND VERY DRY AND SUBSIDENT ATMOSPHERE TO THE WEST. AT THE SURFACE...UPPER LEVEL SUPPORT WANES FOR A 1008 MB LOW CENTERED NEAR 27N92W WITH A SURFACE TROUGH ANALYZED SW TO 25N96W. A STATIONARY FRONT EXTENDS E-NE TO 29N90W AND INTO A 1008 MB LOW CENTERED OVER THE FLORIDA PANHANDLE...THEN CONTINUES DUE EASTWARD ALONG 30N/31N INTO THE SW NORTH ATLC REGION. ISOLATED SHOWERS ARE OCCURRING ALONG THE BOUNDARY W OF 88W AS THE DRY AIR ALOFT IS LIMITING ANY SIGNIFICANT DEEP CONVECTION. E OF 88W CLOSER TO THE MAXIMUM UPPER LEVEL DYNAMICS...SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE EASTERN GULF WATERS AND PORTIONS OF THE FLORIDA PENINSULA FROM 26N-30N BETWEEN 80W-87W. THE CONVECTION TAILS OFF TO THE SW WITH A FEW ISOLATED SHOWERS AND TSTMS OCCURRING IN THE VICINITY OF 24N89W AND THEN FOCUSING AROUND A SURFACE TROUGH ANALYZED ACROSS THE SW GULF FROM 22N92W TO THE MEXICO COAST NEAR 19N96W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS REMAIN GENERALLY S OF 21N ACROSS THIS AREA. FINALLY...THE OVERALL OUTLOOK FOR THE NEXT FEW DAYS IS THAT A COLD FRONT CURRENTLY ANALYZED FROM THE TEXAS AND LOUISIANA BORDER NEAR 30N94W TO MATAGORDA BAY NEAR 28N96W WILL SWEEP EASTWARD ACROSS THE NORTHERN GULF WATERS AND BECOME DIFFUSE BY EARLY FRIDAY OVER THE EASTERN GULF AND FLORIDA PENINSULA. THEREAFTER SOUTHEASTERLY RETURN FLOW WILL RE-ESTABLISH W OF 90W THROUGH THE WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE BAHAMAS IN THE SW NORTH ATLC AND IS PROVIDING MUCH OF THE CENTRAL AND WESTERN CARIBBEAN WITH NORTHEASTERLY FLOW ALOFT. WATER VAPOR IMAGERY INDICATES MUCH OF THIS AREA REMAINS UNDER MODERATELY DRY AIR AND MOSTLY CLEAR SKIES N OF 13N W OF 70W. FARTHER SOUTH ACROSS THE SW CARIBBEAN HOWEVER...AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY NEAR 11N81W. GIVEN THE LOW-LEVEL MOISTURE CONVERGENCE DUE TO EASTERLY TRADES AND THE UPPER LEVEL LIFTING DYNAMICS PROVIDED BY THE UPPER LEVEL LOW...SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 13N BETWEEN 78W-85W...INCLUDING PORTIONS OF EXTREME WESTERN PANAMA...COSTA RICA...AND SOUTHERN NICARAGUA. THIS CONVECTION IS LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS ANALYZED FROM NORTHERN COLOMBIA NEAR 10N75W TO 08N83W IN THE EAST PACIFIC REGION. OTHERWISE...THE REMAINDER OF THE EASTERN CARIBBEAN E OF 70W IS DOMINATED BY FAIR WEATHER AND VERY STABLE CONDITIONS DUE TO A DRY AIRMASS ALOFT. HISPANIOLA... CURRENTLY SKIES CONTINUE AS MOSTLY CLEAR WITH FAIR CONDITIONS AS MANY WEATHER OBSERVATIONS PRIMARILY LOCATED AT COASTAL LOCATIONS AROUND THE ISLAND ARE REPORTING FEW LOW-LEVEL CLOUDS AND UNLIMITED VISIBILITIES. THIS OVERALL TREND SHOULD CONTINUE THROUGH THE AFTERNOON AND EVENING HOURS AS EASTERLY WINDS ALOFT PREVAIL AND A DRIER AIRMASS CONTINUES TO SUPPRESS ANY SIGNIFICANT CONVECTION. HOWEVER...GIVEN PEAK DAYTIME HEATING AND INSTABILITY...A FEW ISOLATED SHOWERS AND TSTMS CERTAINLY CANNOT BE RULED OUT OF THE FORECAST. IN THE DAYS AHEAD...THE SOUTHERN EXTENT OF A WEAK TROPICAL WAVE CURRENTLY ALONG 58W IS FORECAST TO CLIP ACROSS THE ISLAND SATURDAY PROVIDING A POSSIBLE SLIGHT INCREASE IN CONVECTION DURING THE AFTERNOON AND EVENING HOURS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH EXTENDS FROM OVER THE OHIO RIVER VALLEY SOUTHWESTWARD TO OVER THE NORTH CENTRAL GULF OF MEXICO THAT CONTINUES TO GENERATE AN OVERALL DIFFLUENT ENVIRONMENT ALOFT FOR MUCH OF THE SW NORTH ATLC N OF 24N W OF 70W. A STATIONARY FRONT EXTENDS FROM 29N70W INTO A 1008 MB LOW CENTERED NEAR 30N78W THEN WESTWARD TO THE FLORIDA PENINSULA NEAR JACKSONVILLE. WARM...MOIST...AND UNSTABLE CONDITIONS ARE NOTED SOUTH OF THIS BOUNDARY PROVIDING FOR WIDELY SCATTERED SHOWERS AND TSTMS OCCURRING N OF 25N W OF 70W WITH THE MOST INTENSE CONVECTION LOCATED EAST OF THE NW BAHAMAS NEAR 27N75W. THE AREA BETWEEN 28N AND 32N W OF 60W IS FORECAST TO BE CONDUCIVE FOR CYCLOGENESIS OVER THE NEXT FEW DAYS AS THE UPPER LEVEL TROUGH SWEEPS EAST AND THE FRONTAL BOUNDARY REMAINS A FOCUS CONVECTION. FARTHER EAST... ANOTHER UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY ALONG 58W DIPPING SOUTHWARD TO A BASE NEAR 30N. THIS TROUGH SUPPORTS A COLD FRONT ANALYZED FROM 32N60W SW TO 28N70W WITH A PRE-FRONTAL SURFACE TROUGH FROM THE COLD FRONT NEAR 29N63W TO 25N69W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE COLD FRONT...WITH SCATTERED SHOWERS AND TSTMS OCCURRING WITHIN 240 NM SE OF THE SURFACE TROUGH. WELL EAST OF THE COLD FRONT... AND MORE IN ASSOCIATION WITH MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL TROUGHING...AN AREA OF SCATTERED SHOWERS AND TSTMS IS NOTED FROM 28N-33N BETWEEN 45W-55W. OTHERWISE THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED NEAR 25N36W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN