000 AXNT20 KNHC 201806 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED NOV 20 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. ...SPECIAL FEATURE... TROPICAL STORM MELISSA IS CENTERED NEAR 35.6N 47.7W AT 20/1500 UTC OR ABOUT 1004 NM W OF THE AZORES. MELISSA IS MOVING E-NE AT 25 KT AND HAS AN ESTIMATED MINIMUM CENTRAL PRESSURE OF 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. NUMEROUS MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 36N-39N BETWEEN 47W-50W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 34N-40N BETWEEN 46W-50W. PLEASE SEE LATEST PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/ WTNT34 KNHC AND THE FULL FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE EAST TROPICAL ATLC NEAR 07N13W AND CONTINUES TO 06N17W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 05N27W TO 04N40W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE FROM 04N-08N E OF 20W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 03N-11N E OF 20W...FROM 01N-09N BETWEEN 20W-30W AS WELL AS FROM 0N-09N BETWEEN 30W-43W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER-LEVEL TROUGH OVER THE NW ATLC N OF THE DISCUSSION AREA DRAPES A COLD FRONT FROM THE W ATLC SW TO THE EASTERN- CENTRAL COAST OF FLORIDA NEAR 27N79W. FROM THERE THE FRONT TRANSITIONS INTO A STATIONARY FRONT ALONG 26N82W TO THE CENTRAL GULF NEAR 25N90W TO THE EASTERN-CENTRAL COAST OF TEXAS NEAR 27N96W. RADAR IMAGERY SHOW SHOWERS AND TSTMS ON THE NW GULF WITHIN 100 NM N OF THE FRONTAL BOUNDARY BETWEEN 92W-97W. IN THE EASTERN GULF...SCATTERED SHOWERS AND ISOLATED TSTMS ARE N OF 25N E OF 86W. OVER THE SW GULF...A SURFACE TROUGH EXTENDS FROM 22N94W TO SOUTHERN MEXICO NEAR 15N92W ENHANCING ISOLATED SHOWERS S OF 20N E OF 95W. OTHERWISE...E-SE WIND FLOW IN THE RANGE OF 10- 15 KT DOMINATES ACROSS THE BASIN WHILE A BROAD UPPER RIDGE EXTENDING FROM OVER CENTRAL AMERICA INTO THE W ATLC PROVIDES WESTERLY FLOW ALOFT. THE STATIONARY FRONTAL BOUNDARY IS EXPECTED TO DISSIPATE WITHIN 24 HOURS WHILE A SURFACE RIDGE OVERTAKE THE GULF WATERS ANCHORED BY A HIGH PRESSURE CENTER N OF THE DISCUSSION AREA. CARIBBEAN SEA... A MIDDLE TO UPPER LEVEL RIDGE CENTERED NEAR JAMAICA COVERS THE WESTERN CARIBBEAN WITH DRY AIR SUBSIDENCE TO SUPPORT FAIR WEATHER. A WEAKNESS IN THE RIDGE NE PERIPHERY SUPPORTS A SURFACE TROUGH ACROSS THE EASTERN DOMINICAN REPUBLIC SW TO 13N75W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS. ANOTHER SURFACE TROUGH EXTENDS FROM EASTERN HONDURAS TO NORTHERN COSTA RICA GENERATING ISOLATED SHOWERS S OF 16N W OF 82W. A BROAD UPPER-LEVEL TROUGH EXTENDS OVER THE CENTRAL ATLC SW TO THE EASTERN CARIBBEAN...HOWEVER EXCEPT FOR THE WINDWARD ISLANDS...DRY AIR SUBSIDENCE IS INHIBITING CONVECTIVE ACTIVITY. GENTLE TO MODERATE TRADE WINDS WILL PREVAIL ACROSS MOST OF THE REGION THROUGH SAT. ...HISPANIOLA... A WEAKNESS IN THE NE PERIPHERY OF AN UPPER-LEVEL RIDGE CENTERED OVER THE WESTERN CARIBBEAN SUPPORTS A SURFACE TROUGH ACROSS THE EASTERN DOMINICAN REPUBLIC SW TO 13N75W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS. NE TO E SURFACE FLOW IS FORECAST TO BRING IN MILD TEMPERATURES AND LIGHT RAINS TO THE ISLAND FOR THE NEXT FEW DAYS. ATLANTIC OCEAN... A BROAD UPPER-LEVEL TROUGH OVER THE NW ATLC N OF THE DISCUSSION AREA DRAPES A COLD FRONT FROM THE W ATLC SW TO 30N61W TO THE EASTERN-CENTRAL COAST OF FLORIDA NEAR 27N79W. A PRE-FRONTAL TROUGH EXTENDS FROM THE NORTHERN BAHAMAS SW TO THE STRAITS OF FLORIDA SUPPORTING SHOWERS IN THOSE REGIONS. SCATTERED SHOWERS AND TSTMS ARE ALSO WITHIN 60 NM N OF THE COLD FRONT W OF 72W. A 1018 MB HIGH IS SE OF THE FRONT NEAR 26N63W...WHICH IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS. AN UPPER-LEVEL TROUGH COVERS THE CENTRAL ATLC INTO THE E CARIBBEAN. TROPICAL STORM MELISSA IS BENEATH THIS UPPER TROUGH. AN UPPER RIDGE TO THE E EXTENDS FROM THE TROPICS TO BEYOND 30N PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 15N BETWEEN 39W-45W. A SURFACE RIDGE DOMINATES THE E ATLC ANCHORED BY A 1025 MB HIGH JUST S OF THE AZORES. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR