000 AXNT20 KNHC 171039 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT MON AUG 17 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURES... A TROPICAL WAVE SEVERAL HUNDRED MILES SW OF THE CAPE VERDE ISLANDS IS ASSOCIATED WITH A 1011 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR 09N30W. THE SYSTEM IS MOVING W AT 15 KT OVER A PERIOD OF 24 HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS ASSOCIATED WITH A BROAD AREA OF MODERATE MOISTURE THAT ALONG WITH A DIVERGENT WIND ENVIRONMENT ALOFT SUPPORT SCATTERED MODERATE CONVECTION FROM 06N TO 11N BETWEEN 27W AND 33W. SAHARAN DRY AIR AND DUST ENGULF THE SYSTEM...THUS HINDERING CONVECTION ELSEWHERE. THERE IS A MEDIUM CHANCE THIS SYSTEM WILL DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... A TROPICAL WAVE IS IN THE CENTRAL ATLC WITH AXIS NEAR 48W ...MOVING W AT 10 KT OVER THE PAST 24 HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS WITHIN A MODERATE MOIST ENVIRONMENT. UPPER-LEVEL DIVERGENCE SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS FROM 08N TO 11N BETWEEN 45W AND 51W. SAHARAN DRY AIR AND DUST IN THE WAVE ENVIRONMENT HINDER CONVECTION ELSEWHERE. A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN WITH AXIS NEAR 77W ...MOVING W AT 15-20 KT OVER THE PAST 24 HOURS. THE WAVE IS ASSOCIATED WITH A MODERATE MOIST ENVIRONMENT FROM THE SURFACE TO 850 MB ACCORDING TO CIRA LAYER PRECIPITABLE WATER IMAGERY. EXCEPT N OF 17N AND S OF 11N...THE WAVE IS DEVOID OF CONVECTION DUE TO DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER WIND SHEAR ACROSS THE CENTRAL AND EASTERN CARIBBEAN. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST NEAR 13N17W AND CONTINUES W-SW TO THE SPECIAL FEATURES 1011 MB LOW NEAR 09N30W THEN TO 08N38W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N38W TO 06N47W TO 06N56W. ASIDE FROM CONVECTION ASSOCIATED WITH THE SPECIAL FEATURES LOW AND TROPICAL WAVE ALONG 48W...SCATTERED MODERATE CONVECTION IS FROM 10N TO 15N E OF 18W. A CLUSTER OF MODERATE CONVECTION IS FROM 09N TO 12N BETWEEN 20W AND 23W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LOW OVER SOUTHERN ILLINOIS EXTENDS A TROUGH SW TO SOUTHERN TEXAS TO A BASE OVER CENTRAL MEXICO SUPPORTING A SURFACE TROUGH ALONG SOUTHERN MISSISSIPPI...ACROSS SOUTHERN LOUISIANA TO 29N94W...WHICH IS ENHANCING SCATTERED TO ISOLATED SHOWERS AND TSTMS N OF 28N BETWEEN 87W AND 94W. SIMILAR CONVECTION IS IN THE WESTERN BASIN FROM 22N TO 27N W OF 94W. AN ELONGATED UPPER RIDGE EXTENDS FROM THE SE CONUS...ACROSS THE FLORIDA PENINSULA AND THE NE GULF TO A HIGH CENTER OVER BELIZE AND GUATEMALA. DIFFLUENCE ALOFT BETWEEN THE UPPER TROUGH AND RIDGE ALONG WITH MOISTURE INFLOW ACROSS THE BASIN FROM THE CARIBBEAN SEA SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS S OF 22N BETWEEN 93W AND 97W AND ISOLATED SHOWERS S OF 24N BETWEEN 87W AND 92W...INCLUDING THE YUCATAN PENINSULA AND EASTERN GULF OF CAMPECHE. OTHERWISE...BROAD SURFACE HIGH PRESSURE OVER THE ATLC CONTINUES TO EXTEND A RIDGE AXIS SW ACROSS FLORIDA AND THE EASTERN BASIN...THUS PROVIDING MAINLY SE WIND FLOW OF LESS THAN 15 KT ACROSS THE GULF. SURFACE RIDGING WILL BE THE DOMINANT FEATURE ACROSS THE BASIN THE NEXT TWO DAYS. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE CENTERED OVER BELIZE AND GUATEMALA EXTENDS A RIDGE AXIS E-SE ACROSS THE CARIBBEAN...EXCEPT THE N-NE BASIN WHERE A DIFFLUENT ENVIRONMENT PREVAILS BEING GENERATED BY A SMALL UPPER LOW BETWEEN HISPANIOLA AND SOUTHERN BAHAMAS. DIFFLUENCE ALOFT ALONG WITH SHALLOW MOISTURE SUPPORT SCATTERED TO ISOLATED SHOWERS OVER WESTERN PUERTO RICO...THE MONA PASSAGE...DOMINICAN REPUBLIC AND ADJACENT WATERS. SHOWERS AND TSTMS ARE BETWEEN JAMAICA AND EASTERN CUBA. A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL BASIN...HOWEVER DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER WIND SHEAR ACROSS THE CENTRAL AND EASTERN CARIBBEAN HINDER CONVECTION. SEE TROPICAL WAVES SECTION FOR MORE DETAILS. EAST WINDS OF 20 TO 25 KT ARE FROM 11N TO 15N BETWEEN 70W AND 77W WITH SEAS TO 9 FT. THESE CONDITIONS ARE EXPECTED TO PREVAIL IN THIS REGION FOR THE NEXT TWO DAYS. THE WAVE WILL MOVE ACROSS THE WESTERN BASIN LATER TODAY AND OVER THE EPAC WATERS TUESDAY EVENING. ...HISPANIOLA... A DIFFLUENT ENVIRONMENT ALOFT PREVAILS OVER THE N-NE CARIBBEAN BEING GENERATED BY AN UPPER LEVEL ANTICYCLONE CENTERED OVER BELIZE AND GUATEMALA EXTENDING A RIDGE AXIS E-SE TO THE WINDWARD ISLANDS AND A SMALL UPPER LOW BETWEEN HISPANIOLA AND SOUTHERN BAHAMAS. DIFFLUENCE ALOFT ALONG WITH SHALLOW MOISTURE SUPPORT SCATTERED TO ISOLATED SHOWERS OVER THE MONA PASSAGE...DOMINICAN REPUBLIC AND ADJACENT N AND S WATERS. SHOWERS ARE EXPECTED TO CONTINUE THROUGH TONIGHT. ATLANTIC OCEAN... LINGERING SCATTERED TO ISOLATED SHOWERS ARE S OF 23N BETWEEN 61W AND 70W ASSOCIATED WITH A FORMER SURFACE TROUGH. FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW SUPPORTS A SURFACE TROUGH FROM 28N53W TO 23N57W WITH NO CONVECTION ASSOCIATED WITH IT. OTHERWISE...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1027 MB HIGH CENTERED NW OF THE AZORES NEAR 39N29W. FOR TROPICAL WAVES SEE SECTION ABOVE. THERE IS A MEDIUM CHANCE OF TROPICAL CYCLONE DEVELOPMENT ASSOCIATED WITH THE EASTERNMOST TROPICAL WAVE. SEE SPECIAL FEATURES FOR DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR