000 AXNT20 KNHC 181804 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN AUG 18 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 1722 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION ERIN IS CENTERED NEAR 20.5N 39.3W AT 18/1500 UTC OR ABOUT 912 NM W-NW OF THE CAPE VERDE ISLANDS MOVING WEST AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SAHARAN DRY AIR ENTRAINMENT TO THE SYSTEM ENVIRONMENT CONTINUES TO HINDER DEEP CONVECTION AND ERIN COULD BECOME A REMNANT LOW SOON. PLEASE SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE CAME OFF THE WEST AFRICAN COASTLINE AND EXTENDS AN AXIS FROM 15N16W TO A 1009 MB LOW CENTER EMBEDDED WITHIN THE MONSOON TROUGH NEAR 12N17W TO 04N18W. THE WAVE IS POSITIONED WITHIN THE HIGH MOIST ENVIRONMENT OF THE MONSOON TROUGH WHICH IS ENHANCING SCATTERED MODERATE CONVECTION WITHIN AN AREA BOUNDED BY 07N12W TO 01S26W TO 08N30W TO 15N17W. A TROPICAL WAVE IS MOVING ACROSS THE LESSER ANTILLES WITH AN AXIS EXTENDING FROM 20N60W TO 10N61W AND MOVING WEST NEAR 5 KT. THE WAVE REMAINS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT N OF 12N WHILE SOUTH OF THAT LATITUDE IT IS WITHIN A MOISTER ENVIRONMENT. MOST OF THE LESSER ANTILLES HAS REPORTED RAINSHOWERS WITHIN THE LAST COUPLE OF HOURS. A TROPICAL WAVE IS MOVING ACROSS THE WESTERN CARIBBEAN SEA WITH AXIS EXTENDING FROM 22N78W TO 10N79W AND MOVING W NEAR 10 KT. EXCEPT FOR THE NORTHERN AND SOUTHERN ENDS OF THE ITS AXIS...THE REMAINDER WAVE IS EMBEDDED IN A LOW TO MODERATE MOIST ENVIRONMENT. A CLUSTER OF MODERATE CONVECTION AND TSTMS IS S OF 13N BETWEEN 77W-81W ASSOCIATED WITH THE MONSOON TROUGH AXIS. SIMILAR CONVECTION IS FROM 21N-24N BETWEEN 75W-83W BEING ENHANCED BY UPPER LEVEL DIFFLUENCE FROM A CYCLONIC CIRCULATION IN THE WESTERN CARIBBEAN AND AN ANTICYCLONIC CIRCULATION OVER THE W ATLC EXTENDING A RIDGE ACROSS FLORIDA AND THE EASTERN GULF. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E ATLC OVER THE 1009 MB LOW/TROPICAL WAVE NEAR 12N17W CONTINUING ALONG 06N25W TO 07N34W. THE ITCZ BEGINS NEAR 07N35W AND CONTINUES TO 10N47W...THEN RESUMES WEST OF A 1012 MB LOW NEAR 12N53W AND CONTINUES TO 11N60W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALREADY DISCUSSED...ISOLATED MODERATE CONVECTION AND TSTMS ARE FROM 08N-14N BETWEEN 45W-61W. ...DISCUSSION... GULF OF MEXICO... A DEEP UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE GREAT LAKES SW TO THE WESTERN GULF CONTINUE TO SUPPORT A FRONTAL SYSTEM ACROSS THE GULF. AS OF 1500 UTC...A WARM FROM EXTENDS FROM A 1014 MB LOW OVER SE LOUISIANA NEAR 29N89W TO 30N85W TO SE GEORGIA. A DISSIPATING STATIONARY FRONT EXTENDS SW FROM THE LOW ALONG 27N91W 24N95W 21N97W. A SURFACE PRE-FRONTAL TROUGH ALSO EXTENDS SW FROM THE LOW ALONG 27N89W 24N92W 21N94W 18N95W. A CONTINUOUS LINE OF RAINSHOWERS AND TSTMS IS WITHIN 100 NM EITHER SIDE OF THE TROUGH AXIS. FAIR WEATHER IS ACROSS THE REMAINDER BASIN SUPPORTED BY DRY AIR SUBSIDENCE. THE FRONTAL BOUNDARY AND ASSOCIATED LOW ARE EXPECTED TO BE INLAND BY VERY LATE MONDAY WHILE THE PRE-FRONTAL TROUGH WILL BE OVER THE WESTERN BASIN ENHANCING MORE RAINSHOWERS. CARIBBEAN SEA... A TROPICAL WAVE IS MOVING ACROSS THE WESTERN CARIBBEAN SEA WITH AXIS EXTENDING FROM 22N78W TO 10N79W. EXCEPT FOR THE NORTHERN AND SOUTHERN ENDS OF THE ITS AXIS...THE REMAINDER WAVE IS EMBEDDED IN A LOW TO MODERATE MOIST ENVIRONMENT. A CLUSTER OF MODERATE CONVECTION AND TSTMS IS S OF 13N BETWEEN 77W-81W ASSOCIATED WITH THE MONSOON TROUGH AXIS. SIMILAR CONVECTION IS FROM 21N-24N BETWEEN 75W-83W BEING ENHANCED BY UPPER LEVEL DIFFLUENCE FROM A CYCLONIC CIRCULATION IN THE WESTERN CARIBBEAN AND AN ANTICYCLONIC CIRCULATION OVER THE W ATLC EXTENDING A RIDGE ACROSS FLORIDA AND THE EASTERN GULF. AN UPPER LEVEL HIGH IS CENTERED S OF THE MONA PASSAGE BETWEEN 65W-76W WHICH IS PROVIDING UPPER LEVEL DIFFLUENCE ACROSS THE HISPANIOLA AND THE WINDWARD PASSAGE. THIS DIFFLUENCE IS ENHANCING SCATTERED SHOWERS AND TSTMS ACROSS HISPANIOLA AND ADJACENT WATERS. FURTHER EAST...A TROPICAL WAVE MOVES ACROSS THE LESSER ANTILLES WITH AN AXIS EXTENDING FROM 20N60W TO 10N61W. THE WAVE REMAINS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT N OF 12N WHILE SOUTH OF THAT LATITUDE IT IS WITHIN A MOISTER ENVIRONMENT. MOST OF THE LESSER ANTILLES HAS REPORTED RAINSHOWERS WITHIN THE LAST COUPLE OF HOURS. THE WAVE OVER THE WESTERN BASIN IS EXPECTED TO MOVE ACROSS THE YUCATAN PENINSULA MONDAY AFTERNOON WHILE THE SECOND WAVE WILL START MOVING ACROSS HISPANIOLA. HISPANIOLA... AN UPPER LEVEL HIGH CENTERED S OF THE MONA PASSAGE BETWEEN 65W- 76W ALONG WITH AN UPPER LOW IN THE NW CARIBBEAN SEA PROVIDES UPPER LEVEL DIFFLUENCE ACROSS THE HISPANIOLA AND THE WINDWARD PASSAGE. THIS DIFFLUENCE IS ENHANCING SCATTERED SHOWERS AND TSTMS ACROSS THE ISLAND AND ADJACENT WATERS. IF THE UPPER LEVEL PATTERN PERSISTS RAINSHOWERS MAY CONTINUE THROUGHOUT THE DAY. HOWEVER IF THERE IS A BREAK IN RAINSHOWER ACTIVITY DUE TO A WESTWARD SHIFT OF THE UPPER LEVEL PATTERN...THIS ACTIVITY IS EXPECTED TO RESUME AGAIN MONDAY AFTERNOON AS A TROPICAL WAVE WILL START MOVING ACROSS THE ISLAND. ATLANTIC OCEAN... THERE ARE SCATTERED SHOWERS AND TSTMS S OF THE BAHAMAS BETWEEN 73W-81W ASSOCIATED WITH THE TROPICAL WAVE MOVING ACROSS THE WESTERN CARIBBEAN AND AN UPPER LEVEL DIFFLUENCE PATTERN FROM A CYLONIC CIRCULATION IN THE NW CARIBBEAN AND AN ANTICYCLONIC CIRCULATION OVER THE W ATLC EXTENDING A RIDGE ACROSS FLORIDA AND THE EASTERN GULF. FURTHER EAST...THE CONVECTION OVER HISPANIOLA EXTENDS AS ISOLATED SHOWERS S OF 23N BETWEEN 65W-70W. MIDDLE LEVEL DIFFLUENCE SUPPORTS ISOLATED SHOWERS AND TSTMS N OF 27N BETWEEN 54W-63W. OTHERWISE...BESIDES THE SPECIAL FEATURE/ERIN AND THE TROPICAL WAVES ALREADY DISCUSSED...FAIR WEATHER AND SURFACE RIDGING ANCHORED BY A SET OF HIGH PRESSURE CENTERS NORTH OF THE AREA DOMINATES THE REMAINDER BASIN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS