000 AXNT20 KNHC 261147 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 19N42W TO 10N40W MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 200 NM E OF THE WAVE S OF 15N. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 300 NM W OF THE WAVE. TROPICAL WAVE EXTENDS FROM 17N53W TO 9N50W MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF MODERATE TO DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. THIS IS WAVE IS BENEATH AN UPPER LOW ENHANCING CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 300 NM E OF THE WAVE. TROPICAL WAVE APPROACHING THE LEEWARD ISLANDS EXTENDS FROM 22N60W TO NEAR MARTINIQUE MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN DRY AIR AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED SHOWERS ARE POSSIBLE WITHIN 45 NM W OF THE WAVE INCLUDING THE LEEWARD ISLANDS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 14N17W AND CONTINUES ALONG 8N22W TO 6N28W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 6N32W 9N39W TO 8N43W. ANY CONVECTION IS ASSOCIATED WITH THE TWO TROPICAL WAVES. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH EXTENDS FROM AN UPPER LOW OVER VIRGINIA ACROSS NORTH CAROLINA THROUGH THE W ATLC THEN ACROSS FLORIDA NEAR CEDAR KEY THEN ALONG 26N90W TO 25N96W. A COMPLEX SYSTEM IS ACROSS THE N GULF WITH A LOW LEVEL SURFACE TROUGH EXTENDING FROM CEDAR KEY FLORIDA ALONG 28N86W TO A WEAK 1009 MB NEAR 27N90W TO 26N94W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE POSSIBLE WITHIN 45 NM OF THE SURFACE TROUGH E OF THE LOW. AN UPPER TROUGH IN THE CENTRAL ATLC IS SUPPORTING A STATIONARY FRONT THAT CROSSES N FLORIDA THROUGH JACKSONVILLE AND THE 1007 MB LOW NEAR 30N83W TO A 1009 MB LOW NEAR 30N87W WHERE THE FRONT BECOMES COLD AND CONTINUES ALONG 29N90W TO 27N93W. THIS FRONTAL BOUNDARY IS WELL DEFINED IN DEW POINTS ONLY. AN UPPER RIDGE EXTENDS OVER S MEXICO TO THE YUCATAN PENINSULA PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 22N INTO THE BAY OF CAMPECHE W OF 90W. CARIBBEAN SEA... AN UPPER RIDGE ANCHORED IN THE W ATLC COVERS THE FAR NW CARIBBEAN N OF LINE FROM CENTRAL CUBA TO BELIZE. AN INVERTED UPPER TROUGH AXIS EXTENDS FROM ACROSS COSTA RICA NEAR THE NICARAGUA BORDER TO THE WINDWARD PASSAGE ENHANCING THE ACTIVITY ASSOCIATED WITH THE MONSOON TROUGH AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE GULF OF GONAVE AND SW HAITI FROM 17N-20N BETWEEN 73W-76W. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N74W ALONG 11N78W TO ACROSS COSTA RICA NEAR 10N83W GENERATING SCATTERED TO NUMEROUS SHOWERS WITH SCATTERED THUNDERSTORMS S OF 12N BETWEEN 73W-80W TO INLAND OVER COLOMBIA AND PANAMA. EASTERLY TRADE WINDS WILL PREVAIL THROUGH MON. TROPICAL WAVE APPROACHING THE LEEWARD ISLANDS WILL ENTER THE E CARIBBEAN TODAY AND MOVE W ACROSS CARIBBEAN WITH LITTLE INCREASE IN WIND OR SEAS. 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 THIS MORNING. 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 A WEAK TROPICAL WAVE WILL MOVE ACROSS THE ISLAND LATE TODAY THROUGH SAT. THIS WILL POSSIBLY INCREASE OR INTENSIFY AFTERNOON SHOWERS/THUNDERSTORMS. ATLANTIC OCEAN... THE UPPER RIDGE IS ANCHORED OVER THE W ATLC NEAR 25N71W EXTENDING A RIDGE AXIS SW TO OVER W CUBA AND NE TO BEYOND 32N57W. THIS UPPER RIDGE IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 26N BETWEEN 68W-78W. AN UPPER TROUGH N OF 30N OVER THE CENTRAL ATLC IS SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N56W ALONG 28N64W TO 29N68W WHERE IT BECOMES A WARM FRONT TO A 1006 MB LOW NEAR 31N71W THEN CONTINUES AS STATIONARY TO A 1007 MB LOW NEAR 30N77W THEN ACROSS FLORIDA NEAR JACKSONVILLE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE COLD FRONT E OF 61W. THE REMAINDER OF THE ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1019 MB HIGH NEAR 25N39W. THE 1006 MB SURFACE LOW WILL MOVE E-NE S OF BERMUDA TODAY DRAGGING FRONTAL BOUNDARY SE ACROSS W ATLC N OF 27N. THE 1007 MB SURFACE LOW IS EXPECTED TO INTENSIFY THU AND MOVE SE TO 29N74W LATE FRI NIGHT THEN LIFT NE WITH COLD FRONT RACING SE ACROSS BAHAMAS AND FLORIDA LATE THU NIGHT REACHING CENTRAL BAHAMAS AND SE FLORIDA LATE FRI NIGHT OR SAT BEFORE STALLING AND BECOMING DIFFUSE SAT AND SUN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW