000 AXNT20 KNHC 091703 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 09 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 1545 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE E ATLC WITH AXIS NEAR 28W EXTENDING FROM 07N TO 16N...MOVING W AT 10 TO 15 KT. THIS WAVE WAS RE- POSITIONED BASED ON A 12Z SOUNDING AT SAL...INDICATING THAT THE WAVE PASSED THE CAPE VERDE ISLANDS ON JULY 8. BASED ON THE ABOVE...AND CLOUD TURNING IN SATELLITE IMAGERY...THE ABOVE POSITION HAS BEEN DETERMINED. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATES THIS WAVE IS AT THE LEADING EDGE OF A SURGE OF MODERATE MOISTURE N OF 11N WITH HIGH MOISTURE AT AND BEHIND THE WAVE ALONG THE MONSOON TROUGH. ENHANCED METEOSAT IMAGERY INDICATE SAHARAN DUST N OF 12N ALONG THE WAVE...INHIBITING CONVECTION IN THE NORTHERN PORTION OF THE WAVE ENVIRONMENT. CLUSTERS OF MODERATE CONVECTION ARE FROM 05N TO 09N BETWEEN 24W AND 31W. A NEWLY ANALYZED TROPICAL WAVE IS ALONG 54W FROM 08N TO 16N...MOVING W AT AN ESTIMATED 20 TO 25 KT BASED ON LONG TERM SATELLITE TRENDS. SSMI TPW IMAGERY INDICATES MODERATE TO HIGH MOISTURE S OF 10N WITH DRY AIR NORTH OF 10N. METEOSAT IMAGERY INDICATES SAHARAN DUST N OF 11N IN THE WAVE ENVIRONMENT. SCATTERED MODERATE CONVECTION IS FROM 08N TO 13N BETWEEN 53W AND 57W. A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN ALONG 80W/81W FROM 10N TO 18N...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. SSMI TPW INDICATE LOW TO MODERATE MOISTURE IN THE ENVIRONMENT OF THE WAVE N OF 14N WITH HIGH MOISTURE S OF 14N. THE COMBINATION OF THE WAVE...MOISTURE...AND A DIFFLUENT ENVIRONMENT ALOFT SUPPORTS SCATTERED MODERATE TO STRONG CONVECTION S OF 13 W OF 81W. A TROPICAL WAVE CROSSING OVER CENTRAL AMERICA OVERNIGHT HAS ENTERED PORTIONS OF THE E PACIFIC. PLEASE REFER TO THE PACIFIC TROPICAL WEATHER DISCUSSION UNDER HEADER MIATWDEP FOR FURTHER DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 08N30W TO 08N42W...WHERE THE ITCZ BEGINS AND CONTINUES TO THE S AMERICA COAST NEAR 07N58W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 150 NM OF THE MONSOON TROUGH E OF 24W. ISOLATED MODERATE CONVECTION IS WITHIN 50 NM OF THE ITCZ/MONSOON TROUGH BETWEEN 34W AND 50W. ...DISCUSSION... GULF OF MEXICO... CYCLONIC FLOW EXTENDS OVER THE WESTERN GULF FRO AN UPPER LOW CENTERED OVER SOUTHERN MEXICO. THE COMBINATION OF LIFT UNDER THIS TROUGH AND A SURFACE TROUGH EXTENDING FROM 24N94W TO 18N94W. SUPPORTS A CLUSTER OF MODERATE CONVECTION FROM 20N TO 23N BETWEEN 94W AND 98W. A 1021 MB HIGH ANCHORED NEAR 29N85W SUPPORTS HAS AN AXIS THAT EXTENDS FROM WESTERN ATLC HIGH PRESSURE TO N FL TO LOUISIANA. VARIABLE GENTLE SURFACE WINDS COVER THE NE GULF NEAR THE HIGH CENTER. GENTLE TO MODERATE E TO SE SURFACE WINDS COVER THE MAJORITY OF THE NW AND S GULF...WITH A SMALL AREA OF FRESH TO STRONG WINDS IN THE VICINITY OF THE SURFACE TROUGH OVER THE SW GULF. OTHER THAN THE CONVECTION MENTIONED ABOVE...SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE SE QUADRANT OF THE GULF UNDER A BROAD AREA OF UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LOW OVER MEXICO...AND ANOTHER UPPER LOW NEAR THE CENTRAL BAHAMAS. OVER THE NEXT 24 HOURS EXPECT PERIODIC CONVECTION OVER THE SW GULF AND SCATTERED SHOWERS AND THUNDERSTORMS TO CONTINUE OVER THE EASTERN GULF WITH ONGOING SUPPORT BY UPPER LEVEL DIFFLUENCE IN THE REGION. CARIBBEAN SEA... UPPER LEVEL DIFFLUENCE AND MODERATE MOISTURE SUPPORT ISOLATED MODERATE CONVECTION FROM HONDURAS N TO 20N W OF 82W. A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN S OF 19N. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. DRY AIR AND STRONG SHEAR ARE PREVENTING DEEP CONVECTION ACROSS THE CENTRAL AND EASTERN CARIBBEAN TODAY. SAHARAN DUST IS ALSO BEING REPORTED AT SEVERAL STATIONS ACROSS THE CENTRAL AND EASTERN CARIBBEAN WITH THIS DUST EXPECTED TO CONTINUE OVER THESE LOCATIONS THROUGH AT LEAST FRIDAY. A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE WESTERN ATLC AND LOWER PRESSURE OVER N COLOMBIA SUPPORTS FRESH TO STRONG TRADE WINDS FROM THE N COAST OF COLOMBIA TO 16N OVER THE CENTRAL CARIBBEAN. MODERATE TO FRESH TRADE WINDS COVER THE REMAINDER OF THE BASIN...WITH THE LIGHTEST WINDS OVER THE NW CARIBBEAN. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE OVER THE SW CARIBBEAN. A TROPICAL WAVE WILL CROSS THE LEEWARDS ISLANDS TONIGHT INTO FRIDAY WITH CONVECTION POSSIBLE OVER THE SOUTHERN LEEWARD ISLANDS. ...HISPANIOLA... SHALLOW MOISTURE ALONG WITH ASCENT WITH AN UPPER LOW TO THE NORTH OF THE ISLAND WILL SUPPORT ISOLATED THUNDERSTORMS ACROSS THE ISLAND THIS AFTERNOON AND EVENING. MODELS ARE FORECASTING AN INCREASE IN MOISTURE FROM THE NE ON FRIDAY WHICH WOULD INCREASE CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS. ATLANTIC OCEAN... AN UPPER LOW NEAR THE CENTRAL BAHAMAS AT 23N74W SUPPORTS SCATTERED THUNDERSTORMS FROM 22N TO 26N BETWEEN 70W AND 78W. A 1022 MB HIGH CENTERED NEAR 30N70W HAS AN AXIS THAT EXTENDS W TO N FL. A SURFACE TROUGH EXTENDS FROM 28N63W TO 31N56W. ISOLATED THUNDERSTORMS ARE FROM 26N TO 29N BETWEEN 56W TO 67W. A STATIONARY FRONT EXTENDS ACROSS OUR AREA OF DISCUSSION FROM 31N56W TO 28N50W TO 31N46W. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE STATIONARY FRONT E OF 51W. TWO TROPICAL WAVES ARE OVER THE CENTRAL ATLC. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. THE STATIONARY FRONT WILL GRADUALLY DISSIPATE OVER THE NEXT 24 HOURS. THE UPPER LOW AND SURFACE TROUGH OVER THE WESTERN ATLC WILL CONTINUE TO GENERATE SCATTERED SHOWERS AND THUNDERSTORMS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO