000 AXNT20 KNHC 072358 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI AUG 07 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N32W TO 20N31W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A RELATIVELY SHARP 700 MB TROUGH BETWEEN 28W-35W. THIS AREA OF TROUGHING WAS PREVIOUSLY THE LOW- LEVEL MONSOON GYRE THAT WAS LOCATED ALONG THE MONSOON TROUGH THE PAST FEW DAYS AND HAS NOW STARTED TO LIFT NORTHWARD DUE TO AN UPPER LEVEL LOW CENTERED TO THE W-NW NEAR 24N34W. NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. TROPICAL WAVE EXTENDS FROM 09N46W TO 16N48W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING OVER THE CENTRAL TROPICAL ATLC THAT CONTINUES WESTWARD AS LOW-AMPLITUDE ENERGY THAT LACKS ANY SIGNIFICANT CONVECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 19N67W TO 10N32W TO 10N43W TO 09N47W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N47W TO 10N60W. ISOLATED MODERATE CONVECTION IS FROM 08N-11N BETWEEN 54W-57W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS OVER THE OFFSHORE WATERS OF THE CAROLINAS THAT EXTENDS AN AXIS SW OVER NORTHERN FLORIDA AND THE NE GULF TO 26N87W. IN ADDITION...ANOTHER SHORTWAVE IS NOTED OVER ALABAMA SLIDING SOUTHEASTWARD THIS EVENING. WITH MIDDLE TO UPPER LEVEL TROUGHING IN PLACE ACROSS THE NE GULF AND PORTIONS OF FLORIDA...SCATTERED SHOWERS AND TSTMS ARE OCCURRING PRIMARILY ACROSS INLAND PORTIONS OF NORTHERN FLORIDA AND THE ADJACENT COASTAL WATERS OF THE FLORIDA BIG BEND REGION. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1018 MB HIGH CENTERED NEAR 25N87W. SKIES REMAIN MOSTLY CLEAR WITH FAIR CONDITIONS EXPECTED THROUGH THE EVENING AND OVERNIGHT HOURS. THE RIDGE SUPPORTS GENERALLY GENTLE TO MODERATE BREEZE CONDITIONS THAT ARE EXPECTED TO PERSIST THROUGH SUNDAY AS THE RIDGE REMAINS QUASI-STATIONARY. CARIBBEAN SEA... MUCH OF THE CARIBBEAN IS UNDER THE INFLUENCE OF WEST-NORTHWEST FLOW ALOFT AND RELATIVELY STRONG SUBSIDENCE ALOFT. WATER VAPOR IMAGERY INDICATES ONLY A VERY BROAD BASE TO A SW NORTH ATLC TROUGH LIES OVER THE GREATER ANTILLES THIS EVENING HELPING TO GENERATE ENOUGH LIFT FOR SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH PEAK DAYTIME HEATING AND INSTABILITY. THIS ACTIVITY WILL LIKELY DIMINISH THROUGH THE LATE EVENING INTO THE EARLY OVERNIGHT HOURS. OTHERWISE...THE PRIMARY MARINE IMPACT REMAINS FRESH TO STRONG TRADES GENERALLY ACROSS THE CENTRAL CARIBBEAN WITH GENTLE TO MODERATE TRADES ELSEWHERE. ...HISPANIOLA... A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE ISLAND THIS EVENING...BUT THIS ACTIVITY IS LIKELY TO DIMINISH THROUGH THE EVENING HOURS DUE TO A LACK OF DAYTIME HEATING AND OVERALL INSTABILITY. SKY CONDITIONS SHOULD CONTINUE TO IMPROVE DURING THE OVERNIGHT HOURS INTO SATURDAY AS UPPER LEVEL TROUGHING MOVES OVER THE ISLAND FROM THE NORTH THAT CONTAINS VERY DRY AIR. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE EASTERN SEABOARD WATERS WITH AXIS EXTENDING FROM 34N76W TO A BASE IN THE EASTERN GULF OF MEXICO NEAR 26N87W. THE TROUGHING SUPPORTS A RELATIVELY LARGE AND BROAD AREA OF LOW PRESSURE FOCUSED ON A 1008 MB LOW CENTERED NEAR 37N72W AND A 1007 MB LOW CENTERED ACROSS EASTERN NORTH CAROLINA NEAR 35N78W. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE CONTINUES TO GENERATE SCATTERED SHOWERS AND TSTMS ACROSS THE FAR WESTERN SW NORTH ATLC N OF 27N W OF 73W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE AXIS EXTENDING ALONG 26N BETWEEN 66W-82W PROVIDING MOSTLY CLEAR SKIES AND FAIR CONDITIONS THIS EVENING. FARTHER EAST...A CUT-OFF UPPER LEVEL LOW IS CENTERED NEAR 25N63W THAT SUPPORTS ISOLATED SHOWERS AND POSSIBLE ISOLATED TSTMS FROM 23N-29N BETWEEN 55W-64W. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH NORTH OF THE DISCUSSION AREA CENTERED NEAR 43N22W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN