000 AXNT20 KNHC 301737 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... GALE-FORCE WINDS THAT WERE OCCURRING OVER THE SW CARIBBEAN THIS MORNING ARE FORECAST TO WEAKEN BELOW GALE-FORCE THIS AFTERNOON. HOWEVER...WINDS TO 25 KT AND SEAS OF 8 TO 11 FEET WILL REMAIN ACROSS THE AREA THROUGH THIS EVENING. GALE-FORCE WINDS BETWEEN A 1012 MB LOW NEAR 31N77W AND A HIGH PRESSURE AXIS OVER THE W ATLC ARE FORECAST TO WEAKEN BELOW GALE- FORCE THIS AFTERNOON AS THE LOW MOVES NORTHWESTWARD. HOWEVER...WINDS UP TO 30 KT AND SEAS TO 11 FT ARE EXPECTED TO CONTINUE THROUGH TONIGHT WITHIN A COUPLE HUNDRED NM SE OF THE LOW. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 9N37W TO 20N40W MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. THE WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 36W AND 44W. A MODERATE INCREASE IN MOISTURE N OF 12N IS INDICATED IN SSMI TPW IMAGERY. SAHARAN DUST IN THE WAVE ENVIRONMENT IS INHIBITING CONVECTION WITH THIS WAVE. TROPICAL WAVE EXTENDS FROM 10N70W TO 21N69W MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. THIS WAVE IS AT THE LEADING EDGE OF AN INCREASE IN MID LEVEL MOISTURE. A 700 MB TROUGH IS NOTED BETWEEN 66W AND 73W. NO DEEP CONVECTION IS OCCURRING WITH THIS WAVE. TROPICAL WAVE IS OVER CENTRAL AMERICA AND THE E PAC. PLEASE REFER TO THE EASTERN PACIFIC TROPICAL WEATHER DISCUSSION FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO A 1012 MB LOW NEAR 11N27W TO 9N37W TO 09N47W...WHERE THE ITCZ BEGINS AND CONTINUES TO 10N60W. CLUSTERS OF MODERATE AND ISOLATED STRONG CONVECTION ARE FROM 11N TO 16N BETWEEN 16W AND 22W. WIDELY SCATTERED MODERATE CONVECTION ARE FROM 05N TO 14N BETWEEN 25W AND 41W. ...DISCUSSION... GULF OF MEXICO... A MOIST AIRMASS IN NOTED IN SSMI TPW IMAGERY N OF 24N AND E OF 95W OVER THE GULF BASIN TODAY. THIS DEEP MOISTURE SUPPORTS A BROAD AREA OF CLOUD COVER WITH EMBEDDED WIDELY SCATTERED MODERATE CONVECTION OVER THIS PORTION OF THE GULF BASIN. STEERING FLOW IS GENERALLY WEAK ACROSS THE GULF WITH A 1017 MB HIGH CENTERED NEAR 24N92W SUPPORTING 10 KT E WINDS OVER THE SW GULF...NW WINDS OF 5 TO 10 KT OVER THE NW GULF...AND NW TO W WINDS OF 5 TO 10 KT OVER THE EASTERN GULF. THIS MOISTURE AND ASSOCIATED CONVECTION ARE FORECAST TO PERSIST OVER THE NW GULF THROUGH SATURDAY. CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. DEEP MOISTURE OVER THE CARIBBEAN IS CONFINED TO THE WESTERN SHORES OF CENTRAL AMERICA...AND EAST OF THE TROPICAL WAVE. UPPER LEVEL DIFFLUENCE SUPPORTS CLUSTERS OF MODERATE TO STRONG CONVECTION OVER THE SW CARIBBEAN FROM 08N TO 13N BETWEEN 80W AND 85W. ADDITIONAL UPPER LEVEL DIFFLUENCE OVER THE EASTERN CARIBBEAN SUPPORTS ISOLATED MODERATE CONVECTION FROM SAINT VINCENT TO DOMINICA OVER THE LESSER ANTILLES. GALE FORCE WINDS OVER THE SW CARIBBEAN WILL WEAKEN SLIGHTLY THIS AFTERNOON TO UNDER GALE-FORCE. SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. MODERATE TO FRESH TRADE WINDS ARE MAINLY ELSEWHERE OVER THE CARIBBEAN. OVER THE NEXT 24 HOURS CONVECTION IS FORECAST TO PERSIST OVER THE SW CARIBBEAN. ...HISPANIOLA... A TROPICAL WAVE IS MOVING ACROSS THE ISLAND THIS AFTERNOON. ISOLATED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS WAVE PASSAGE THROUGH TONIGHT. REMNANT MOISTURE BEHIND THIS WAVE WILL BE SUFFICIENT TO SUPPORT ISOLATED TO SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE ISLAND ON FRIDAY. ATLANTIC OCEAN... A 1012 MB LOW CENTERED NEAR 31N77W SUPPORTS A SURFACE TROUGH TO 29N81W. SCATTERED MODERATE CONVECTION ARE WITHIN 250 NM SE OF THE TROUGH AXIS. A STRONG PRESSURE GRADIENT BETWEEN THE LOWER PRESSURES ASSOCIATED WITH THESE SURFACE FEATURES AND HIGH PRESSURE TO THE EAST WAS SUPPORTING GALE FORCE WINDS EARLIER TODAY. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A 1026 MB HIGH CENTERED NEAR 33N32W SUPPORTS GENERALLY FAIR WEATHER ACROSS THE CENTRAL AND EASTERN SUBTROPICAL ATLC E OF 67W. A TROPICAL WAVE IS OVER THE TROPICAL ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO