000 AXNT20 KNHC 070548 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU AUG 06 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... A CENTRAL ATLC TROPICAL WAVE EXTENDS FROM 16N43W TO 09N40W MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 36W AND 46W. DEEP MOISTURE IS CONFINED S OF 12N ALONG THE ENVIRONMENT OF THE WAVE. ISOLATED MODERATE CONVECTION IS FROM 07N TO 10N BETWEEN 36W AND 40W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 17N16W THROUGH A 1013 MB LOW NEAR 10N28W TO 09N40W TO 09N47W...WHERE THE ITCZ BEGINS AND CONTINUES TO 10N61W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM OF THE MONSOON TROUGH AND ITCZ W OF 15W. ...DISCUSSION... GULF OF MEXICO... GENERALLY FAIR WEATHER COVERS THE GULF BASIN EARLY THIS MORNING. A SURFACE RIDGE AXIS EXTENDS FROM THE W ATLC TO CENTRAL FL TO NEAR THE TX/MEXICO BORDER ALONG THE W GULF COAST. GENTLE TO MODERATE ANTICYCLONIC WINDS COVER THE BASIN. OVER THE NEXT 24 HOURS A TROUGH DIGGING SE ACROSS THE SE US WILL BRING INCREASING CHANCES FOR CONVECTION OVER THE NE GULF. A DIURNAL SURFACE TROUGH WILL MOVE ACROSS THE SW GULF WHICH COULD ENHANCE SHOWERS AND THUNDERSTORMS LATER THIS MORNING. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE SW CARIBBEAN DOMINATES MUCH OF THE CARIBBEAN. DRY AIR AND SUBSIDENCE COVERS THE BASIN E OF 80W S OF 16N AS NOTED IN LATEST WATER VAPOR IMAGERY. AN AREA OF DYNAMIC LIFT BETWEEN THE UPPER RIDGE AND UPPER LEVEL CYCLONIC FLOW OVER THE W ATLC IS INTERACTING WITH A MODERATELY MOIST AIRMASS TO SUPPORT WIDELY SCATTERED MODERATE CONVECTION FROM 17N TO 22N BETWEEN 70W AND 85W. THE REMAINDER OF THE CARIBBEAN IS FREE OF DEEP CONVECTION. THE PRESSURE GRADIENT BETWEEN W ATLC SURFACE RIDGING AND LOW PRESSURE OVER COLOMBIA SUPPORTS FRESH TO STRONG TRADE WINDS OVER THE S CENTRAL CARIBBEAN S OF 15N BETWEEN 68W AND 78W. GENTLE TO MODERATE TRADE WINDS COVER THE REMAINDER OF THE BASIN. OVER THE NEXT 24 HOURS CONVECTION WILL REMAIN POSSIBLE OVER THE NW CARIBBEAN...WHERE BETTER MOISTURE AND LIFT WILL REMAIN. SHOWERS AND CHANCES FOR CONVECTION WILL ALSO INCREASE TODAY OVER THE NORTHERN LESSER ANTILLES AND VIRGIN ISLANDS AS A WEAK LOW AND ACCOMPANYING SURFACE TROUGH MOVES NW FROM THE CENTRAL ATLC OVER THE ISLANDS. ...HISPANIOLA... MODERATE MOISTURE COMBINED WITH A BAND OF DYNAMIC LIFT BETWEEN AN UPPER LOW OVER THE W ATLC AND UPPER LEVEL RIDGING OVER THE SW CARIBBEAN SUPPORTS ISOLATED MODERATE CONVECTION OVER HAITI THIS MORNING. THIS CONVECTION IS CURRENTLY WEAKENING. ADDITIONAL THUNDERSTORMS ARE FORECAST TO REDEVELOP THIS AFTERNOON ACROSS THE ISLAND WITH SIMILAR ATMOSPHERIC CONDITIONS REMAINING IN PLACE. ATLANTIC OCEAN... A SHORTWAVE TROUGH ABOUT TO EMERGE OFF THE EASTERN US COAST IS SUPPORTING SCATTERED THUNDERSTORMS N OF 30N BETWEEN 74W AND 79W. A SURFACE RIDGE DOMINATES THE MAJORITY OF THE SUBTROPICAL N ATLC ANCHORED BY A 1026 MB HIGH CENTERED NEAR 36N42W. THE RIDGE AXIS EXTENDS W ACROSS THE W ATLC THROUGH A 1018 MB HIGH CENTERED NEAR 28N73W...AND CONTINUES W TO CENTRAL FL. AN UPPER LOW CENTERED NEAR 26N60W SUPPORTS A WEAKNESS IN THE SURFACE RIDGE WITH A 1016 MB LOW CENTERED NEAR 26N58W. A SURFACE TROUGH EXTENDS FROM 31N60W THROUGH THE LOW CENTER TO 21N61W. ISOLATED MODERATE CONVECTION AND SCATTERED THUNDERSTORMS ARE FROM 24N TO 31N BETWEEN 54W AND 58W. FARTHER S...A 1013 MB LOW IS CENTERED NEAR 14N56W WITH A SURFACE TROUGH EXTENDING FROM 16N56W THROUGH THE LOW CENTER TO 12N57W. ISOLATED MODERATE CONVECTION IS FROM 15N TO 18N BETWEEN 56W AND 60W. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE OVER THE W ATLC N OF 28 W OF 70W...AND NEAR THE UPPER LOW. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO