Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 270521 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 121 AM EDT THU AUG 27 2015 .SYNOPSIS... A FRONT WILL OSCILLATE ACROSS THE COAST INTO THURSDAY WHILE GRADUALLY LOSING IDENTITY. 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. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 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 /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... AS OF 312 PM WEDNESDAY...LOCAL ATMOSPHERIC CONDITIONS WILL REMAIN FAVORABLE FOR CONVECTION ALONG THE COAST AND COASTAL INTERIOR THURSDAY AND FRIDAY...AS A WAVERING BUT DECAYING FRONTAL BOUNDARY REMAINS QUASI-STATIONARY NEAR THE LAND-SEA INTERFACE. TROPICAL MOISTURE WILL REMAIN DEEPEST OFFSHORE BUT RICH ENOUGH TO SERVE AS FUEL IN LATE AUGUST HEATING ACROSS THE EASTERN ZONES. EXPECTATION OF SEA-BREEZE CONVERGENCE MAY VERY WELL CO-MINGLE WITH THE DETERIORATING FRONT TO ADD ADDITIONAL UPDRAFT FOCUS BY THE AFTERNOON BOTH DAYS. TIME HEIGHT DEPICTIONS OF RH IN THE COLUMN SUGGEST GRADUAL DRYING AND ANTICYCLONIC TURNING OF THE ATMOSPHERE AS AN UPPER RIDGE BUILDS FROM THE SE FRIDAY...AND COULD REDUCE POP POTENTIAL FRIDAY COMPARED TO THURSDAY. TEMPERATURES OF MAX/MIN WILL HOLD CLOSE TO NORMALS FOR LATE AUGUST BOTH DAYS...ALTHOUGH CLOUD COVER AND WEAK POST FRONTAL AIR MAY RESULT IN MIDDLE 80S MOST LOCATIONS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 312 PM WEDNESDAY...BY SATURDAY ERIKA...OR REMNANTS OF...MAY BE MOVING INTO THE FAR EASTERN BAHAMAS. CURRENT MODEL SPREADS BY DAY 5 MONDAY BECOME HIGHLY DIVERGENT...PLACING ERIKA ANYWHERE FROM THE EASTERN GULF OF MEXICO TO SEVERAL HUNDRED MILES EAST OF FLORIDA. IN LIGHT OF THE PRESENT UNCERTAINTY...COUPLED WITH A DECENT CONSENSUS THAT UPPER RIDGING WILL STRENGTHEN INTO THE CAROLINAS...THE EXTENDED FORECAST DOES NOT REFLECT ANY DIRECT IMPACTS FROM ERIKA. EXCEPTION POTENTIALLY COULD BE ARRIVAL OF SWELL WAVE ENERGY...PROVIDED ERIKA INTENSIFIES AS DEPICTED BY THE OFFICIAL NHC TRACKS...THOUGH EVEN THIS PARAMETER CARRIES LIMITED CONFIDENCE. AS A RESULT...FORECAST IN DAYS 4-7 REPRESENTS NEAR CLIMATOLOGICAL CONDITIONS FOR LATE AUGUST WITH MAXIMUMS IN THE UPPER 80S TO AROUND 90...MINIMUMS IN THE LOW 70S...DOTTED WITH ISOLATED TO SCATTERED SHOWERS AND TSTMS. A LOCAL ELEVATED RIP CURRENT THREAT COULD ARRIVE ON OUR BEACHES BY THIS WEEKEND. && .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 100 AM THURSDAY...UPDATED WITH HIER POPS ACROSS THE LOCAL WATERS DUE TO ONGOING CONVECTION VIA KLTX AND SURROUNDING 88DS AND WITH THE SFC COLD FRONT ACROSS THE AREA WATERS LEADING TO ADDITIONAL SFC CONVERGENCE FOR CONVECTION TO DEVELOP OFF OF. ALL OTHER PARAMETERS UNTOUCHED ACROSS THE LOCAL WATERS. PREVIOUS...................................................... AS OF 1030 PM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: LATEST OBS SHOW LIGHT S AND SE WINDS WITH 2 FT SEAS. HAVE OPENED UP THE FORECAST SEA HEIGHT RANGE TO 2 TO 3 FT FROM PRIOR 3 FT LEVEL GIVEN LATEST OBS AND FORECAST OF CONTINUED LIGHT WINDS. PREVIOUS DISCUSSION FOLLOWS: COLD FRONT/SEA BREEZE HYBRID IS SLOWLY LIFTING BACK TO THE NW...WITH A WEAK GRADIENT REMAINING IN PLACE ACROSS THE WATERS. WINDS HAVE BEEN VARIABLE ACROSS THE WATERS...BUT ARE TURNING TO A PREDOMINANT SOUTHERLY DIRECTION...STRONGEST WITHIN THE SEA BREEZE CIRCULATION WHERE SPEEDS MAY REACH UP TO 15 KTS...10 KTS ELSEWHERE. LATEST BUOY OBS CONTINUE TO SHOW AN 10-11 SEC PERIOD SE SWELL AS THE DOMINANT WAVE GROUP...AND THIS WILL PERSIST THROUGH TONIGHT WITH WAVE HEIGHTS REMAINING AROUND 2-3 FT. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 312 PM WEDNESDAY...MANAGEABLE MARINE CONDITIONS THURSDAY AND FRIDAY...WITH ONSHORE E-SE WINDS 10-15 KT BOTH DAYS OUTSIDE OF TSTMS. SEA SPECTRUM WILL CONSIST OF ESE WAVE 2-3 FEET EVERY 10 SECONDS ACCOMPANIED BY A LIGHT TO MODERATE ONSHORE DIRECTED CHOP. TSTMS WILL BE SCATTERED OVER THE 0-20 NM WATERS AND MARINERS SHOULD GET A RADAR UPDATE BEFORE HEADING OUT...AS SOME STORMS BECOME STRONG AND CAPABLE OF PRODUCING MORNING WATER SPOUTS. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 312 PM WEDNESDAY...SATURDAY THROUGH MONDAY THERE APPEARS AGREEMENT AMONG GFS/ECMWF PLOTS THAT DESPITE THE SPECIFIC ARRANGEMENT OR CONFIGURATION OF THE SYNOPTIC PATTERN...THE PRESSURE GRADIENT/PATTERN WILL BE A FLAT ONE. THIS SUGGEST LIGHT WINDS. SEAS HOWEVER DEPENDING ON HOW ERIKA INTENSITY TRENDS PAN-OUT...MAY BE LACED WITH AN UNDERLYING LONG PERIOD SWELL THAT COULD ACCOMPANY THE LIGHT WIND-WAVES. THIS MAY INDUCE ENHANCED SHOALING PROCESSES IN SHALLOW WATER AREAS. ISOLATED TO SCATTERED SHOWERS AND TSTMS WILL REMAIN IN THE EXTENDED MARINE FORECAST BASED ON EXPECTED ATMOSPHERIC MOISTURE AVAILABILITY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MJC NEAR TERM...DCH/REK/JDW SHORT TERM...MJC LONG TERM...SHK AVIATION...DCH/DL MARINE...

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