000 AXNT20 KNHC 130553 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN SEP 13 2015 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. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 09N29W TO 16N26W MOVING W AT 10 KT. THE WAVE COINCIDES WITH LOW AMPLITUDE 700 MB TROUGHING S OF 15N BETWEEN 25W-32W. SCATTERED MODERATE CONVECTION REMAINS CONFINED TO THE MONSOON TROUGH REGION DUE TO SAHARAN DUE ON THE NORTHERN PERIPHERY OF THE WAVE AXIS FROM 07N-14N BETWEEN 24W-32W. TROPICAL WAVE EXTENDS FROM 09N52W TO 16N51W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGHING BETWEEN 45W- 55W. ISOLATED MODERATE CONVECTION IS FROM 14N-16N BETWEEN 46W- 51W. TROPICAL WAVE EXTENDS FROM 12N71W TO 19N71W MOVING W AT 15 KT. THE WAVE COINCIDES WITH A 700 MB TROUGHING BETWEEN 68W-74W AND A 850 MB RELATIVE VORTICITY MAXIMUM OVER HISPANIOLA NEAR 19N72W. ISOLATED MODERATE CONVECTION IS FROM 16N-20N BETWEEN 66W-74W. TROPICAL WAVE EXTENDS FROM 08N85W TO 15N85W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH SUBTLE 700 MB TROUGHING OVER CENTRAL AMERICA BETWEEN 83W-87W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 08N-16N BETWEEN 80W-89W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO 09N29W TO 10N49W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 09N-15N BETWEEN 12W-17W AND FROM 06N-12N BETWEEN 38W-45W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 06N-13N BETWEEN 31W-47W. ...DISCUSSION... GULF OF MEXICO... AS OF 13/0300 UTC...LONGWAVE TROUGHING IS NOTED ON WATER VAPOR IMAGERY OVER MUCH OF THE EASTERN CONUS SUPPORTING A COLD FRONT EXTENDING FROM THE FLORIDA PANHANDLE SW TO THE TEXAS COAST NEAR CORPUS CHRISTI. WHILE THIS REMAINS THE PRIMARY BOUNDARY...A PRE- FRONTAL TROUGH EXTENDS FROM THE FLORIDA BIG BEND REGION SW TO 27N86W WHERE THE LOW PRESSURE VALUES ARE CURRENTLY ANALYZED. AS SURFACE RIDGING HAS BUILT IN ACROSS SOUTHERN TEXAS AND EASTERN MEXICO...ANOTHER SURFACE TROUGH IS ANALYZED OFFSHORE OF THE MEXICO COAST FROM 26N97W TO 21N96W. MOST OF THE LOW-LEVEL MOISTURE CONVERGENCE...CLOUDINESS...AND ONGOING SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 300 NM SOUTHEAST OF THE COLD FRONT. OTHERWISE...GENERALLY GENTLE TO MODERATE NE FLOW PREVAILS NORTH OF THE COLD FRONT AND RELATIVELY VARIABLE GENTLE TO MODERATE BREEZE CONDITIONS IN THE FRONTAL TROUGH ZONE AND ACROSS THE SE GULF. THE MAJORITY OF THE FRONT WILL SLIDE INTO THE SW NORTH ATLC REGION BY MONDAY WITH A DIFFUSE BOUNDARY EXTENDING ALONG 25N/26N THAT WILL GRADUALLY LIFT NORTH THROUGH TUESDAY. CARIBBEAN SEA... GENERALLY NORTHERLY FLOW ALOFT PREVAILS OVER MUCH OF THE WESTERN CARIBBEAN THIS EVENING BETWEEN AN UPPER LEVEL RIDGE ANCHORED OVER CENTRAL MEXICO AND AN UPPER LEVEL LOW CENTERED NEAR 17N69W. MOSTLY CLEAR SKIES AND FAIR CONDITIONS ARE NOTED ACROSS THE NW CARIBBEAN...HOWEVER THE PRESENCE OF A TROPICAL WAVE ALONG 85W IMPACTING CENTRAL AMERICA IS GENERATING SCATTERED SHOWERS AND TSTMS S OF 17N BETWEEN 80W-89W. THE WAVE IS EXPECTED TO CONTINUE WESTWARD ON SUNDAY WITH PRECIPITATION AND CONVECTION PERSISTING ACROSS COSTA RICA...NICARAGUA...HONDURAS...EL SALVADOR...AND GUATEMALA UNTIL THE WAVE FULLY ENTERS THE EAST PACIFIC REGION. FARTHER EAST...A TROPICAL WAVE ALONG 72W IS INTERACTING WITH THE UPPER LEVEL LOW PREVIOUSLY MENTIONED AND CONTINUES TO GENERATE ISOLATED SHOWERS AND TSTMS FROM 15N-21N BETWEEN 64W-70W...AND ACROSS WESTERN HISPANIOLA INCLUDING THE ADJACENT COASTAL WATERS. LOW-LEVEL MOISTURE AND POSSIBLE ISOLATED SHOWERS STRETCH SE ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL CENTRAL ATLC. OTHERWISE...MODERATE TO FRESH TRADES PREVAIL AND ARE EXPECTED TO INCREASE SLIGHTLY ACROSS THE CENTRAL CARIBBEAN WITH THE APPROACHING TROPICAL WAVE ON SUNDAY INTO MONDAY. ...HISPANIOLA... CURRENTLY ISOLATED SHOWERS AND TSTMS ARE APPROACHING THE ISLAND FROM THE EAST IN ASSOCIATION WITH A TROPICAL WAVE ALONG 72W. THE OVERALL INCREASE IN MOISTURE AND CLOUDINESS WILL CONTINUE TO PROVIDE A HIGHER PROBABILITY OF PRECIPITATION ON SUNDAY AS THE WAVE CONTINUES TO MOVE WEST OF THE ISLAND BY LATE SUNDAY. ATLANTIC OCEAN... MIDDLE TO UPPER LEVEL ENERGY ASSOCIATED WITH LONGWAVE TROUGHING OVER THE EASTERN CONUS IS SUPPORTING A FRONTAL BOUNDARY ANALYZED ALONG THE EASTERN COAST AND FLORIDA PANHANDLE. PRE-FRONTAL SURFACE TROUGHING ALSO EXTENDS FROM 32N78W SW TO THE CENTRAL AND SOUTHERN FLORIDA PENINSULA PROVIDING FOCUS FOR SCATTERED SHOWERS AND TSTMS GENERALLY N OF 26N W OF 72W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING WITH AXIS EXTENDING FROM 28N59W SW TO THE CENTRAL CUBA COAST NEAR 23N79W. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS DOMINATED BY BROAD SURFACE RIDGING ANCHORED BY A 1027 MB HIGH CENTERED EAST OF THE AZORES NEAR 39N38W. A WEAK 1016 MB LOW IS EMBEDDED WITHIN THE SOUTHERN PERIPHERY OF THE RIDGE CENTERED NEAR 29N43W THAT CONTINUES TO GENERATE AN AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS FROM 29N-32N BETWEEN 41W- 44W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN