000 AXNT20 KNHC 260533 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU SEP 26 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 19N41W TO 10N39W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. THE WAVE THE W IS BENEATH AN UPPER LOW ENHANCING THE ACTIVITY WHICH IS SPREADING E TO THIS WAVE. SCATTERED MODERATE/STRONG CONVECTION IS ASSOCIATED WITH THE ITCZ RATHER THAN THIS WAVE. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE FROM 12N-18N BETWEEN 36W-44W. TROPICAL WAVE EXTENDS FROM 18N52W TO 10N48W MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. THIS IS WAVE IS BENEATH AN UPPER LOW ENHANCING SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF ISOLATED STRONG CONVECTION FROM 9N-17N BETWEEN 44W-52W. TROPICAL WAVE JUST E OF THE LEEWARD ISLANDS EXTENDS FROM 22N59W TO 14N60W MOVING W-NW 10-15 KT. WAVE IS EMBEDDED WITHIN DRY AIR AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED SHOWERS ARE POSSIBLE WITHIN 45 NM OF THE WAVE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 14N17W AND CONTINUES ALONG 11N17W 7N19W TO 7N27W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 7N31W 10N40W TO 9N45W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120/150 NM N OF THE ITCZ BETWEEN 36W-42W. CLUSTERS OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION ARE FROM 4N-8N BETWEEN 21W-23W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH EXTENDS FROM AN UPPER LOW OVER WEST VIRGINIA ACROSS THE CAROLINAS TO NE FLORIDA INTO THE GULF TO 26N90W. A LOW LEVEL SURFACE TROUGH IS BENEATH THIS UPPER TROUGH EXTENDING FROM A 1007 MB LOW OVER TALLAHASSEE FLORIDA ALONG 28N87W THROUGH A 1008 MB LOW NEAR 28N89W TO 25N93W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 60 NM OF THE 1008 MB LOW. AN UPPER TROUGH IN THE W ATLC IS SUPPORTING A STATIONARY FRONT THAT CROSSES N FLORIDA THROUGH JACKSONVILLE AND THE 1007 MB LOW OVER TALLAHASSEE TO THE FLORIDA/ALABAMA BORDER WHERE IT BECOMES A COLD FRONT ALONG 29N90W TO 27N93W. AN UPPER RIDGE EXTENDS OVER S MEXICO TO THE YUCATAN PENINSULA PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND OVER S MEXICO AND WITHIN 60 NM ALONG THE COAST IN THE BAY OF CAMPECHE BETWEEN MERIDA AND TAMPICO. THE 1008 MB SURFACE LOW WILL MOVE NE AND DISSIPATE LATER TONIGHT. THE WEAK COLD FRONT WILL MOVE SE ACROSS THE E GULF THU AND FRI. A SURFACE RIDGE WILL BUILD ACROSS THE GULF THU THROUGH MON. CARIBBEAN SEA... AN UPPER RIDGE ANCHORED IN THE W ATLC COVERS THE FAR NW CARIBBEAN N OF LINE FROM CENTRAL CUBA TO THE NE TIP OF THE YUCATAN CHANNEL. AN INVERTED UPPER TROUGH AXIS EXTENDS FROM ACROSS COSTA RICA TO OVER HISPANIOLA ENHANCING THE ACTIVITY ASSOCIATED WITH THE MONSOON TROUGH AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 45 NM RADIUS OF THE E TIP OF THE DOMINICAN REPUBLIC INCLUDING PORTIONS OF THE MONA PASSAGE...OVER THE GULF OF GONAVE AND PORTIONS OF HAITI FROM 17N- 20N BETWEEN 71W-74W...OVER SE CUBA FROM 20N-21N BETWEEN 76W- 78W...AND W OF JAMAICA FROM 17N-19N BETWEEN 78W-81W. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N74W ALONG 10N80W TO ACROSS COSTA RICA NEAR 9N84W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 14N W OF 75W TO INLAND OVER PANAMA TO NICARAGUA. ISOLATED SHOWERS ARE POSSIBLE OVER THE E CARIBBEAN FROM 13N-7N E OF 67W USHERED IN ON THE EASTERLY TRADE WINDS. EASTERLY TRADE WINDS WILL PREVAIL THROUGH MON. A BROAD LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE SW CARIBBEAN SAT AND CONTINUING THROUGH MON. HISPANIOLA... SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER SW HAITI AND THE GULF OF GONAVE WHILE THE SKIES REMAIN MOSTLY CLEAR ACROSS THE REMAINDER OF THE ISLAND TONIGHT. EASTERLY FLOW ALOFT AND AT THE SURFACE WILL CONTINUE THROUGH FRI. THE UPPER RIDGE RESPONSIBLE FOR THE E FLOW ALOFT WILL THEN RETREAT E AS AN UPPER RIDGE ANCHORED TO THE S CHANGES THE UPPER FLOW TO WESTERLY. THE REMNANTS OF A WEAK TROPICAL WAVE WILL MOVE ACROSS THE ISLAND LATE FRI BEFORE COMPLETELY DISSIPATING SAT. THIS WILL POSSIBLY INCREASE OR INTENSIFY AFTERNOON SHOWERS/THUNDERSTORMS. ATLANTIC OCEAN... THE UPPER RIDGE IS ANCHORED OVER THE W ATLC NEAR 25N75W EXTENDING A RIDGE AXIS SW TO OVER W CUBA AND NE TO BEYOND 32N62W. THIS UPPER RIDGE IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 28N BETWEEN 66W-78W. AN UPPER TROUGH N OF 30N OVER THE CENTRAL ATLC IS SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N58W ALONG 29N63W TO 29N67W WHERE IT BECOMES WARM FRONT ALONG 31N71W TO A WEAKENING 1007 MB LOW NEAR 30N73W THEN CONTINUES AS STATIONARY TO A DEVELOPING 1007 MB LOW NEAR 30N79W THEN ACROSS FLORIDA NEAR JACKSONVILLE. SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS ARE WITHIN 120 NM OF LINE FROM 27N55W TO 33N49W. THE REMAINDER OF THE ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH NEAR 25N38W. THE EASTERN 1007 MB LOW WILL MOVE MAINLY EAST PASSING TO THE S OF BERMUDA ON THU WHILE DRAGGING A WEAK COLD FRONT ACROSS AREA N OF 27N. THE WESTERN DEVELOPING 1007 MB LOW WILL MOVE TO NEAR 28N75W BY FRI WITH THE ASSOCIATED COLD FRONT EXTENDING ACROSS THE NW BAHAMAS AND THE STRAITS OF FLORIDA. THIS SECOND FRONT WILL STALL ACROSS THE CENTRAL BAHAMAS ON FRI NIGHT. A REINFORCING NORTHERLY SURGE WILL MOVE INTO THE W ATLC LATE FRI MERGING WITH THE INITIAL FRONT ACROSS THE CENTRAL BAHAMAS ON SUN THEN DISSIPATING THROUGH MON NIGHT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW