000 AXNT20 KNHC 261805 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN JUL 26 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 1645 UTC. ...SPECIAL FEATURES... A TIGHT PRESSURE GRADIENT OVER THE S CENTRAL CARIBBEAN THAT WAS SUPPORTING GALE-FORCE WINDS THIS MORNING WILL RELAX SLIGHTLY THIS AFTERNOON THROUGH MONDAY...RESULTING IN WINDS JUST BELOW GALE-FORCE. HOWEVER...THE GRADIENT WILL TIGHTEN AGAIN MONDAY NIGHT WITH A RETURN OF GALE-FORCE WINDS FORECAST BY 0600Z TUESDAY MORNING FROM 11N TO 14N BETWEEN 73W AND 77W. SEA HEIGHTS WILL RANGE FROM 11 FEET TO 16 FEET. FOR MORE DETAILS PLEASE READ THE HIGH SEAS FORECAST... MIAHSFAT2/FZNT02 KNHC...AND THE OFFSHORE FORECAST...MIAOFFNT3/ FZNT23 KNHC. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AXIS EXTENDING FROM 16N31W TO 08N31W...MOVING W AT AROUND 15 TO 20 KT OVER THE PAST 24 HOURS. THE LOW THAT WAS ACCOMPANYING THIS WAVE HAS BEEN LEFT BEHIND AND HAS WEAKENED ALONG THE MONSOON TROUGH. MODERATE MOISTURE IS N OF 11N ALONG THE WAVE AXIS WITH SAHARAN DUST EVIDENT N OF 14N...WHICH IS INHIBITING CONVECTION OVER THE NORTHERN PORTION OF THE WAVE. ISOLATED MODERATE CONVECTION IS 06N TO 09N BETWEEN 29W AND 33W...WHICH MAY ALSO BE ASSOCIATED WITH THE MONSOON TROUGH. A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM 16N50W TO 06N51W...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. THIS WAVE APPEARS IN 700 MB MODEL ANALYSIS WITH AN INVERTED TROUGH BETWEEN 49W AND 53W. THIS WAVE CONTINUES TO BE EMBEDDED IN SAHARAN DUST N OF 9N...WHICH IS INHIBITING CONVECTION ALONG THE WAVE. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AN AXIS EXTENDING FROM 18N69W TO 11N70W...MOVING W TO WNW AT 20 TO 25 KT OVER THE PAST 24 HOURS. THIS WAVE IS WELL DEFINED IN THE SSMI TPW IMAGERY...ACCOMPANYING AN AREA OF HIGH MOISTURE CONTENT. VISIBLE AND IR SATELLITE IMAGERY CONFIRM A WELL DEFINED INVERTED TROUGH ASSOCIATED WITH THE WAVE. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM 14N TO 19N BETWEEN 67W AND 73W...INCLUDING THE SOUTHERN DOMINICAN REPUBLIC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 13N16W TO 09N27W TO 08N39W...WHERE THE ITCZ BEGINS AND EXTENDS TO 06N49W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 100NM N AND 200 NM S OF THE MONSOON TROUGH AXIS. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH OVER THE NW ATLC SUPPORTED A STATIONARY FRONT ACROSS CENTRAL FL AND INTO THE NE GULF THIS MORNING. SINCE THAT TIME...IT WAS NOTED THAT THE STATIONARY FRONT TRANSITIONED INTO A SURFACE TROUGH THAT AS OF 1500 UTC EXTENDED FROM NEAR THE MOUTH OF THE MISSISSIPPI AT 29N89W TO A POORLY DEFINED SURFACE LOW CENTER OF 1011 MB ABOUT 30 NM W OF SARASOTA...FL NEAR 27N83W...AND EAST ACROSS CENTRAL FL TO THE W ATLC. DEEP MOISTURE COMBINED WITH LOW LEVEL CONVERGENCE ASSOCIATED WITH THE BROAD TROUGH AND LOW CENTER SUPPORTS SCATTERED MODERATE CONVECTION WITHIN 250 NM S AND W OF THE SURFACE TROUGH. MAINLY E WINDS OF 10 TO 15 KT ARE N OF THE TROUGH AXIS. SW TO W WINDS ARE WITHIN 100 NM S AND W OF THE TROUGH AXIS. A SURFACE RIDGE AXIS FROM W CUBA TO THE TX COAST IS PRODUCING LIGHT TO MODERATE ANTICYCLONIC WINDS OVER THE REMAINDER OF THE GULF. LASTLY...A CONVECTION FREE DIURNAL SURFACE TROUGH IS OVER THE SW GULF FROM 22N94W TO 18N95W. THE LOW AND TROUGH OVER THE NE GULF IS EXPECTED TO MOVE VERY LITTLE OVER THE NEXT 48 HOURS. MEANWHILE...MODELS ARE FORECASTING AN INCREASE IN UPPER LEVEL DIFFLUENCE OVER THE SFC TROUGH WHICH WILL ENHANCE CONVECTION OVER THE EASTERN GULF TONIGHT THROUGH MONDAY. OVERALL...UNSETTLED WEATHER IS EXPECTED OVER PORTIONS OF THE EASTERN GULF THROUGH MID WEEK. CARIBBEAN SEA... OTHER THAN THE TROPICAL WAVE DISCUSSED IN THE TROPICAL WAVES SECTION...DRY AIR IS INHIBITING CONVECTION OVER MUCH OF THE CARIBBEAN TODAY. THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE ATLC AND LOWER PRESSURES OVER S AMERICA SUPPORTING GALE FORCE WINDS THIS MORNING OVER A PORTION OF THE S CENTRAL CARIBBEAN HAS WEAKENED SLIGHTLY THIS AFTERNOON. THIS WILL RESULT IN WINDS DROPPING BELOW GALE FORCE THIS AFTERNOON THROUGH MONDAY. FRESH TO STRONG TRADE WINDS ARE EXPECTED FOR THE NEXT 24 HOURS S OF 17N BETWEEN 71W AND 79W. LIGHT TO MODERATE TRADE WINDS ARE ELSEWHERE OVER THE CARIBBEAN...EXCEPT WINDS TO 25 KT NEAR THE TROPICAL WAVE AXIS. THE TROPICAL WAVE WILL BRING AN INCREASE IN CONVECTION OVER JAMAICA BY MONDAY...AND THE CAYMAN ISLANDS MONDAY NIGHT. ...HISPANIOLA... THE NORTHERN PORTION OF A TROPICAL WAVE IS CROSSING S HISPANIOLA THIS AFTERNOON WITH SHOWERS AND ISOLATED THUNDERSTORMS ALONG WITH AN INCREASE IN WINDS TO NEAR 20 KT. THE WAVE WILL GENERATE SHOWERS AND THUNDERSTORMS OVER S HAITI LATER THIS AFTERNOON AND EVENING. THE WAVE WILL BE WEST OF THE ISLAND BY MONDAY WITH A RETURN OF DRY AIR. THIS SHOULD INHIBIT SHOWER AND THUNDERSTORM ACTIVITY FOR MONDAY AND MONDAY NIGHT. ATLANTIC OCEAN... AN UPPER TROUGH OVER THE NW ATLC WAS SUPPORTING A STATIONARY FRONT OVER THE SW N ATLC THAT AS OF 1500 UTC HAS TRANSITIONED INTO A SURFACE TROUGH THAT EXTENDS FROM 31N78W TO CENTRAL FL NEAR 29N81W. SCATTERED SHOWERS AND THUNDERSTORMS ARE WITHIN 275 NW SE OF THE SURFACE TROUGH. JUST NORTH OF OUR AREA OF DISCUSSION IS A STATIONARY FRONT THAT SUPPORTS ISOLATED MODERATE CONVECTION OVER OUR AREA FROM 28N TO 31N BETWEEN 57W AND 75W. A 1028 MB HIGH CENTERED NEAR 35N34W SUPPORTS GENERALLY FAIR WEATHER OVER THE SUBTROPICAL N ATLC E OF 50W. TWO TROPICAL WAVES ARE OVER THE TROPICAL N ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE ALONG AND WITHIN A FEW HUNDRED NM S OF THE NEARLY STATIONARY SURFACE TROUGH FROM CENTRAL FL AND OFFSHORE ATLC WATERS INCLUDING THE CENTRAL AND NORTHERN BAHAMAS. CONVECTION WILL ALSO CONTINUE N OF 30N BETWEEN 60W AND 75W NEAR A STATIONARY FRONT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO