Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 270815 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 415 AM EDT THU AUG 27 2015 .SYNOPSIS... A FRONT WILL OSCILLATE ALONG THE COAST INTO THURSDAY WHILE GRADUALLY LOSING IDENTITY BEFORE IT SHIFTS FURTHER OFF THE COAST BY THE WEEKEND. HIGH PRESSURE WILL SLOWLY BUILD INTO THE CAROLINAS THIS WEEKEND. ERIKA IS EXPECTED TO APPROACH THE BAHAMAS AND SOUTH FLORIDA LATE IN THE WEEKEND INTO EARLY NEXT WEEK AND POSSIBLY AFFECT THE CAROLINAS BY NEXT WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 125 AM THURSDAY...HAVE LOWERED POPS WELL INLAND...AND INCREASED THEM SLIGHTLY ALONG THE IMMEDIATE COAST. BOTH CHANGES BASED ON LATEST KLTX AND SURROUNDING 88D TRENDS. PREVIOUS...................................................... AS OF 1030 PM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: ISOLATED SLOW MOVING CONVECTION CONTINUES NEAR THE COAST ALONG THE STALLED FRONTAL BOUNDARY. AT PRESENT ACTIVITY IS CONCENTRATED OVER PENDER AND GEORGETOWN COUNTIES. MINOR LOCALIZED FLOODING SEEMS TO BE THE PRIMARY THREAT FOR THE NEXT FEW HOURS. HAVE LOWERED POPS BASED ON PRESENT TRENDS...ALTHOUGH KEEPING LOW CHANCE POPS IN FOR THE COASTAL COUNTIES OVERNIGHT BASED ON LATEST GUIDANCE...THE PROXIMITY OF THE FRONT...AND A JUICY...UNSTABLE ATMOSPHERE WITH THE OCCASIONAL UPPER DISTURBANCE MOVING THROUGH OVERHEAD. PREVIOUS DISCUSSION FOLLOWS: STATIONARY FRONT ALIGNED VERY NEAR THE COAST IS SLOWLY BEING ABSORBED/COMBINED WITH THE SEA BREEZE WHICH IS JUST NOW BEGINNING TO DEVELOP. THIS LATE START TO HEATING IS DUE TO THE PRONOUNCED CLOUD COVER FROM THIS MORNING (POST FRONTAL STRATUS AND ANVIL DEBRIS) THAT ONLY RECENTLY ERODED. WHILE HEATING HAS BEEN SLOW...IT IS STILL VERY UNSTABLE OUTSIDE WITH SPC MESOANALYSIS SHOWING 2000-3000 J/KG OF SBCAPE ALONG THE EASTERN COUNTIES. THIS IS HIGHLY UNSTABLE...SO ANY UPDRAFTS FORCED BY SURFACE BASED CONVERGENCE ALONG THE SEA BREEZE...FRONT...OR DIFFERENTIAL HEATING BOUNDARIES...ARE STILL EXPECTED TO RISE QUICKLY INTO TSTMS. ADDITIONALLY...A SHORTWAVE EVIDENT ON WV IMAGERY LIFTING NE FROM THE GULF COAST WILL COMBINE WITH ENHANCING DIFFLUENCE AT 300 MB TO PROVIDE UPPER SUPPORT. IN OTHER WORDS...ALL SIGNS STILL POINT TO CONVECTION BLOSSOMING THIS EVENING...AND HIGH RES GUIDANCE...WHILE NOT AS AGGRESSIVE AS EARLIER STILL SHOWS SCATTERED TO WIDESPREAD CONVECTION DEVELOPING THROUGH THIS EVENING. HAVE TRIMMED POP BACK TO HIGH CHC FROM THE EARLIER LIKELY...BUT MANY PLACES STILL FACE THE RISK OF TORRENTIAL RAINFALL WITH ISOLATED FLOODING...SIGNIFICANT LIGHTNING...AND MAYBE AN ISOLATED DAMAGING WIND GUST. POP WILL WANE SLOWLY AFTER DARK WITH LOSS OF HEATING...BUT THE PRESENCE OF THE UPPER FEATURES WILL HAVE THE POTENTIAL TO MAINTAIN CONVECTION THROUGH THE OVERNIGHT HOURS...ALTHOUGH IN A WEAKER AND LESS WIDESPREAD FASHION. TEMPS TONIGHT WILL FALL SLOWLY AS CLOUDS AND SOUTHERLY WINDS EAST OF THE FRONT MAINTAIN A VERY WARM AND HUMID AIRMASS. A SIGNIFICANT TEMP GRADIENT IS FORECAST ACROSS THE CWA FOR MINS...DROPPING TO AROUND 69 WELL INLAND...BUT STAYING AS WARM AS 75 ALONG THE IMMEDIATE COAST. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM THURSDAY...LINGERING FRONT/TROUGH MAY BE A FEW HUNDRED MILES OFF THE CAPE FEAR COAST ON FRI LEAVING A WEAK NORTHEAST FLOW...BUT LOOKS LIKE BROADER HIGH PRESSURE WILL BEGIN TO PRODUCE A MORE EASTERLY FLOW INTO THE SOUTHEAST STATES BY SATURDAY. THE DRIER NORTHEAST FLOW ON FRI SHOULD KEEP PCP WATER VALUES DOWN NEAR 1.5 INCHES CLOSER TO THE COAST AND DIMINISHING INLAND. THE GREATEST MOISTURE WILL BE ALONG THE COAST AND AS SEA BREEZE DEVELOPS...SHOULD SEE ENOUGH LIFT AND MOISTURE TO PRODUCE SOME CONVECTION...BUT NOT EXPECTING IT TO BE TOO WIDESPREAD. BY SATURDAY...THE GREATER ON SHORE PUSH WILL INCREASE MOISTURE THROUGH THE COLUMN. WINDS MAY STILL REMAIN OUT OF THE NE MAINTAINING A DRIER FLOW OVER NC INITIALLY IN THE MORNING...BUT BY THE END OF SATURDAY...PCP WATER VALUES SHOULD BE UP NEAR 1.9 INCHES ACROSS THE AREA. THEREFORE EXPECT GREATER POTENTIAL FOR MORE WIDESPREAD CONVECTION ON SATURDAY. TEMPERATURES WILL RUN NEAR NORMAL. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 330 AM THURSDAY...LONG TERM FORECAST TOTALLY DEPENDS ON EVOLUTION OF ERIKA...WHICH...AT THIS POINT IS VERY UNCERTAIN. NHC FORECAST KEEPS ERIKA ON A ROUTE UP THROUGH THE BAHAMAS AND REACHING OFF THE FLORIDA COAST BY MON EVE. THE TROPICAL MODEL GUIDANCE WAS TAKING THIS TRACK AS WELL...BUT THE LATEST ECMWF AND GFS TRACK ERIKA FARTHER WEST AND KEEP IT WEAKER...WHILE THE PREVIOUS RUNS PRODUCED A HURRICANE OVER CAPE FEAR BY NEXT WEDNESDAY. WITH SUCH INCONSISTENCIES AT THIS TIME...WILL REMAIN MORE CONSERVATIVE AND WILL KEEP WITH MORE OF AN ON SHORE AND THAN NORTHERLY FLOW AS IF ERIKA WAS TRACKING OFF THE COAST TO OUR EAST. WE WILL HAVE TO MONITOR ERIKA QUITE CLOSELY. LOOKS LIKE GREATEST EFFECTS FROM ERIKA MAY BE EXTREME RUSH OF MOISTURE INTO THE CAROLINAS WITH GUSTY WINDS AND SWELLS AND STRONG ON SHORE PUSH AFFECTING THE COASTAL WATERS. ALSO EXPECT AN ELEVATED RIP CURRENT THREAT AS EARLY AS THE LATTER HALF OF THE WEEKEND. FOR NOW WILL GO WITH PLENTY OF CLOUDS THROUGH MOST OF THE PERIOD WITH DIURNAL CONVECTION AND GREATEST POPS FOR TUES INTO WED. TEMPS WILL REMAIN AROUND CLIMO WITH MAX TEMPS IN THE UPPER 80S TO AROUND 90 AND MINS IN THE 70S. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 06Z...DEBRIS CLOUDS WILL KEEP FOG ALONG THE COAST AT A MINIMUM...HOWEVER WITH ALL THAT WATER ON THE GROUND ESPECIALLY ACROSS COASTAL HORRY...SOME IFR CONDITIONS COULD OCCUR WITH ANY GRADUAL CLEARING OR THE COOL FRONT MOVES FURTHER OFF THE SC COAST. SOME LIGHT TO MODERATE FOG INLAND TERMINALS ALONG WITH MVFR TO POSSIBLY IFR STRATUS EXPECTED INTO DAYTIME THU MORNING. SHOULD BECOME PREDOMINATELY VFR BY MID TO LATE MORNING ACROSS ALL TERMINALS WITH NORTHEAST FLOW DOMINATING. COULD SEE ESE-SSE FLOW ALONG THE IMMEDIATE COAST DUE TO THE SFC FRONTS PARTIAL OSCILLATION ACROSS THE REGION. WITH THE FRONT OSCILLATING NEAR THE COAST...INSTEAD OF FURTHER INLAND...WILL LEAN TOWARD VCNTY CONVECTION INLAND FOR THE AFTN AND EARLY EVENING...AND TRY TO IDENTIFY A PREDOMINATE TIME FOR CONVECTION AT THE COAST. BEST COVERAGE SHOULD REMAIN ALONG THE IMMEDIATE COAST WITH THE COASTAL TERMINALS UNDER THE GONE FOR THURSDAYS THREAT FOR CONVECTION. EXTENDED OUTLOOK...PREDOMINATELY VFR WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE EXTENDED. BRIEF MORNING FOG/STRATUS IS ALSO EXPECTED EACH DAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 06Z...DEBRIS CLOUDS WILL KEEP FOG ALONG THE COAST AT A MINIMUM...HOWEVER WITH ALL THAT WATER ON THE GROUND ESPECIALLY ACROSS COASTAL HORRY...SOME IFR CONDITIONS COULD OCCUR WITH ANY GRADUAL CLEARING OR THE COOL FRONT MOVES FURTHER OFF THE SC COAST. SOME LIGHT TO MODERATE FOG INLAND TERMINALS ALONG WITH MVFR TO POSSIBLY IFR STRATUS EXPECTED INTO DAYTIME THU MORNING. SHOULD BECOME PREDOMINATELY VFR BY MID TO LATE MORNING ACROSS ALL TERMINALS WITH NORTHEAST FLOW DOMINATING. COULD SEE ESE-SSE FLOW ALONG THE IMMEDIATE COAST DUE TO THE SFC FRONTS PARTIAL OSCILLATION ACROSS THE REGION. WITH THE FRONT OSCILLATING NEAR THE COAST...INSTEAD OF FURTHER INLAND...WILL LEAN TOWARD VCNTY CONVECTION INLAND FOR THE AFTN AND EARLY EVENING...AND TRY TO IDENTIFY A PREDOMINATE TIME FOR CONVECTION AT THE COAST. BEST COVERAGE SHOULD REMAIN ALONG THE IMMEDIATE COAST WITH THE COASTAL TERMINALS UNDER THE GONE FOR THURSDAYS THREAT FOR CONVECTION. EXTENDED OUTLOOK...PREDOMINATELY VFR WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE EXTENDED. BRIEF MORNING FOG/STRATUS IS ALSO EXPECTED EACH DAY. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM THURSDAY...LINGERING FRONT/TROUGH SHOULD BE JUST EAST OF WATERS ON FRI WITH MORE OF A NE WIND FLOW. HIGH PRESSURE OVER ATLANTIC WITH CENTER TO THE NORTH OF AREA WILL BECOME MORE DOMINANT BY LATE SAT INTO SUNDAY ALLOWING WINDS TO SHIFT TO THE E THROUGH SUNDAY AND E-SE BY SUN NIGHT. OVERALL EXPECT WINDS TO REMAIN 10 KTS OR LESS WITH A SPIKE EACH AFTN IN SEA BREEZE. KEEPING SEAS 2 TO 3 FT WITH A LONGER PERIOD SWELL MIXING IN WITH SHORTER PERIOD WIND WAVES. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 330 AM THURSDAY...LONG TERM FORECAST BECOMES MORE DEPENDENT ON TRACK OF ERIKA. OVERALL EXPECT ON SHORE PUSH WITH EASTERLY WINDS AROUND 10 KTS AND SEAS REMAINING LESS THAN 4 FT THROUGH MUCH OF THE PERIOD. BY TUES MORNING...SEAS MAY BEGIN TO RAMP UP AS WINDS AND SWELLS FROM ERIKA BEGIN TO AFFECT THE AREA. LOOKS LIKE GREATEST AFFECT FROM ERIKA ACROSS THE LOCAL AREAS WILL COME TUES INTO WED....BUT MODEL INCONSISTENCIES MAY MAKE IT A BIT MORE DIFFICULT TO FORECAST. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...DCH SHORT TERM...RGZ LONG TERM...RGZ AVIATION...DCH/DL

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