Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 130738 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 338 AM EDT SAT SEP 13 2014 .SYNOPSIS... A FLOOD WATCH HAS BEEN ISSUED FOR SATURDAY AS A STALLED COLD FRONT CONTINUES UNSETTLED WEATHER ACROSS THE AREA. THIS FRONT WILL REMAIN IN THE VICINITY ON SUNDAY...BEFORE LIFTING BACK NORTH ON MONDAY...BUT UNSETTLED WEATHER WILL PERSIST. A STRONGER COLD FRONT WILL CROSS THE AREA ON TUESDAY...BRINGING COOLER AND DRIER WEATHER FOR THE LATTER HALF OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10:30 PM FRIDAY...ALTHOUGH MOST OF THE FORECAST AREA THIS EVENING SAW STRATIFORM RAIN OF GRADUALLY DIMINISHING EXTENT...THE CAPE FEAR REGION AND WILMINGTON IN PARTICULAR EXPERIENCED A HEAVY RAIN EVENT COMPLETE WITH LOCALIZED FLOODING. IT APPEARS THAT A SERIES OF UNFORTUNATELY PLACED BOUNDARY COLLISIONS AND A JUICY AIR-MASS WERE RESPONSIBLE. LIGHT TO MODERATE RAIN IS STILL BLANKETING NEW HANOVER COUNTY AND A FLOOD WARNING IS OUT FOR THAT AREA. GIVEN P/W VALUES IN EXCESS OF 2 INCHES SHOWER ACTIVITY AREA- WIDE CONTINUES TO BE A POSSIBILITY...ESPECIALLY GIVEN THE PROXIMITY OF THE COLD FRONT...WHICH SEEMS TO NOW EXTEND ACROSS THE NORTHERN HALF OF THE FORECAST AREA WITH A FRONTAL WAVE NOW PLACED OVER THE CAPE FEAR REGION. THIS ALSO NO DOUBT ENHANCED OUR RECENT BOUT OF HEAVY RAIN. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...AN EXPANDING TROUGH AND A PERSISTENT RIDGE WILL ENGAGE IN BATTLE OVERHEAD THROUGH EARLY NEXT WEEK FOR POSITION OVER THE CAROLINAS. ALMOST LIKE THE OLD CHILDHOOD GAME OF "RED ROVER"...EACH FEATURE WILL TRY TO BREAK THROUGH THE OTHER...BUT THE RIDGE WILL CALL THE TROUGH OVER ONE TOO MANY TIMES...EARNING THE TROUGH A VICTORY...DISPLACING THE RIDGE BY MONDAY NIGHT. THIS FORCES THE COLD FRONT BELOW TO BECOME NEARLY STATIONARY SUNDAY AND MONDAY...WAVERING BACK AND FORTH ACROSS THE AREA...CONTINUING THE UNSETTLED WEATHER PATTERN. SURFACE FRONT WILL BE ALONG THE SOUTHERN TIER...OR JUST SOUTH...OF THE CWA DURING SUNDAY BEFORE SLOWLY LIFTING NORTH AGAIN ON MONDAY. WHILE INSTABILITY WILL BE LIMITED DUE TO WIDESPREAD CLOUD COVER...AND UPPER SUPPORT WILL REMAIN MINIMAL...PERSISTENT MOIST FLOW ATOP THE FRONT COMBINED WITH SURFACE CONVERGENCE ALONG IT (AND RESIDUAL BOUNDARIES) IN A VERY MOIST COLUMN WILL PRODUCE PERIODS OF RAIN/TSTMS SUNDAY AND MONDAY. BEST PRECIP CHANCES MAY BE IN THE SOUTHERN AND WESTERN ZONES SUNDAY AND THIS IS WHERE THE HIGHEST QPF IS EXPECTED...BUT ALL AREAS WILL LIKELY SEE SHOWERS AND STORMS. A BRIEF RESPITE IN CONVECTIVE COVERAGE WILL OCCUR WITH LOSS OF HEATING SUNDAY NIGHT...BEFORE MORE SCATTERED CONVECTION DEVELOPS MONDAY AS THE FRONT LIFTS TO THE NORTH PRODUCING A BRIEF PERIOD OF WAA AND SUMMER-LIKE CONVECTION. THIS WILL BE SHORT LIVED HOWEVER...AS THIS FRONT WILL RETURN BACK TO THE SOUTHEAST AS A COLD FRONT BENEATH A STRONG VORTICITY IMPULSE MOVING TO THE NORTH EITHER VERY LATE MONDAY NIGHT...OR JUST BEYOND THIS PERIOD. ANOTHER ROUND OF HEAVIER PRECIP MAY ACCOMPANY THIS FRONT LATE MONDAY HOWEVER...AND CANNOT AT ANY TIME FORECAST POP BELOW CHC THROUGH THE PERIOD...WITH HIGHEST OCCURRING SUNDAY AND THEN AGAIN LATE MONDAY. HIGHS SUNDAY WILL BE SEVERAL DEGREES BELOW NORMAL THANKS TO CLOUDS...RAIN...AND COOL NORTHERLY SURFACE FLOW...WITH MAX TEMPS EXPECTED TO REACH ONLY THE MID 70S FAR NW...TO MID 80S NEAR THE SOUTH SANTEE RIVER. THE AFOREMENTIONED WAA WILL DRIVE HIGHS INTO THE LOW/MID 80S CWA-WIDE ON MONDAY. LOWS SUNDAY NIGHT WILL DROP TO NEAR-NORMAL LEVELS OF THE MID 60S...BUT WILL BE SEVERAL DEGREES WARMER MONDAY NIGHT AHEAD OF THE NEXT COLD FRONT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 SATURDAY...STRONG COLD FRONT WILL PUSH ACROSS THE AREA ON TUESDAY...USHERING IN COOL CANADIAN AIR FOR MOST OF THE UPCOMING WEEK. STRONG VORTICITY IMPULSE SPAWNING A SURFACE LOW PRESSURE WILL BE RACING EAST WELL NORTH OF THE AREA...BUT A STRONG COLD FRONT BEHIND THIS WILL DRAG ACROSS THE CWA DURING TUESDAY. A PERIOD OF UNSETTLED WEATHER IS EXPECTED TUESDAY WITH SHOWERS AND THUNDERSTORMS...BUT THIS FRONT SHOULD PUSH OFFSHORE BY WEDNESDAY AS A DEEP UPPER TROUGH DIVES INTO THE EAST. THEREAFTER...GUIDANCE CONTINUES TO DIFFER ON HOW FAR OFFSHORE THIS FRONT WILL STALL...WITH THE GFS CONTINUING TO INDICATE THAT IT WILL BE JUST OFFSHORE AND CONTINUE UNSETTLED CONDITIONS LOCALLY. THE ECMWF...WHICH IS PREFERRED...PUSHES THIS FRONT WELL OFF THE COAST...WHICH SEEMS ACCURATE BASED OFF THE STRENGTH OF THE UPPER TROUGH AND SINCE WE HAVE HAD SEVERAL FROPAS ALREADY THIS YEAR. USING THE ECMWF AS A GUIDE...WED-FRI WILL FEATURE DRYING CONDITIONS AND TEMPS AROUND 5 DEGREES BELOW CLIMO THANKS TO THE CANADIAN ORIGIN OF THE SURFACE HIGH RIDGING DOWN THE COAST. IN ADDITION...IT APPEARS THE AREA WILL SEE SUNSHINE FOR THE FIRST TIME IN SEVERAL DAYS BY WEDNESDAY. HOWEVER...MUST NOTE THE PERSISTENCE OF THE GFS WHICH KEEPS THE FRONT JUST OFF THE COAST AND DEVELOPS A LOW PRESSURE SYSTEM ALONG THE TAIL END OF THE BOUNDARY. THIS WOULD KEEP UNSETTLED CONDITIONS ACROSS THE AREA...ESPECIALLY NEAR THE COAST...WITH MORE WET WEATHER POSSIBLE LATE IN THE WEEK. WILL KEEP INHERITED LOW-CHC/SCHC POP FOR POTENTIAL...BUT WITH A SLIGHT DECREASE IN SPECIFIC VALUES TO ACCOUNT FOR THE MUCH DRIER ECMWF. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...STRATIFORM LIGHT RAIN NEAR KILM SHOULD DISSIPATE OVER THE NEXT SEVERAL HOURS...ALTHOUGH THE HRRR MODEL SUGGESTS ISOLATED CONVECTIVE SHOWERS WILL RE-DEVELOP EARLY THIS MORNING ACROSS THE AREA. EXPECT THICK MID/UPPER CLOUD COVER THROUGH THE TAF VALID PERIOD WITH COPIOUS AMOUNTS OF LOW LEVEL MOISTURE. IFR/LIFR CONDITIONS WILL DEVELOP THIS MORNING KLBT/KILM/FLO WITH HIGHEST CONFIDENCE AT KLBT/KILM WHICH IS NEAREST A STATIONARY FRONT. KCRE/KMYR ARE MORE LIKELY TO EXPERIENCE MVFR CONDITIONS THIS MORNING. ANY IFR IMPROVES TO MVFR FAIRLY QUICKLY AFTER SUNRISE WITH VFR DEVELOPING MID-LATE MORNING. CLOUD COVER SHOULD INITIALLY INHIBIT HEATING AND LIFT SO THINK WORSE CASE VCSH COASTAL TERMINALS IN THE MORNING HOURS. BY AFTERNOON THUNDERSTORM POTENTIAL SHOULD BE GREATEST AT KLBT. THIS POTENTIAL SHOULD SHIFT SE-E TO KFLO AND THE THE COASTAL TERMINALS IN THE LATE AFTERNOON/EARLY EVENING. EXTENDED OUTLOOK...A CHANCE OF SHOWERS WITH MAINLY AFTERNOON THUNDERSTORMS/TEMPO MVFR THROUGH TUESDAY. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 10:30 PM FRIDAY...LIGHT AND VARIABLE WINDS WITH 2 FT SEAS CONTINUE ACROSS THE WATERS THIS EVENING. FORECAST REMAINS UNCHANGED. PREVIOUS DISCUSSION FOLLOWS: OUTSIDE OF TSTMS NO REAL PROBLEMS EXPECTED ON THE WATERS WITH LIGHT WINDS OVERALL AND SEAS 2 FEET OR LESS...AS A WEAK FRONTAL BOUNDARY REMAINS IN VICINITY OF THE AREA. MOST STORMS SHOULD STAY OVER LAND BUT TONIGHT CELLS MAY BEGIN TO FAVOR THE 0-20 NM WATERS. SEAS AROUND 2 FEET IN A MIX OF SE WAVES 1-1.5 FT EVERY 8-9 SECONDS AND S WAVES 0.5-1 FT EVERY 3-4 SECONDS. WITHIN TSTMS WINDS AND SEAS WILL BE LOCALLY AND SIGNIFICANTLY HIGHER. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...COLD FRONT SOUTH OF THE WATERS TO START THE PERIOD WILL REMAIN NEARLY STATIONARY SUNDAY...BEFORE LIFTING BACK TO THE NORTH AS A WARM FRONT MONDAY. THIS DRIVES NE WINDS ALL SUNDAY AND INTO MONDAY...BEFORE VEERING TO BECOME S/SE LATE ON MONDAY. SPEEDS WILL BE 5-10 KTS REGARDLESS OF DIRECTION. A COLD FRONT WILL APPROACH AT THE VERY END OF THE SHORT TERM WITH WINDS BEGINNING TO VEER TO THE WEST LATE MONDAY NIGHT. SEAS WILL BE 1-3 FT THROUGH THE PERIOD...WITH A NE WIND WAVE PREDOMINANT ON SUNDAY...BECOMING SOUTHERLY DURING MONDAY. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 300 AM SATURDAY...THE BEGINNING OF AN EXTENDED PERIOD OF POOR MARINE CONDITIONS EXPECTED TUESDAY AS A COLD FRONT CROSSES THE WATERS. ALTHOUGH WINDS TUESDAY WILL BE PRETTY LIGHT...5-10 KTS WITH SEVERAL VEERING WIND DIRECTIONS...THE CONFUSED SPECTRUM WILL COMBINE WITH THE SLOWLY AMPLIFYING LONG PERIOD 13-14 SEC SE SWELL ASSOCIATED WITH TROPICAL STORM EDOUARD MOVING THROUGH THE CENTRAL ATLANTIC...TO DRIVE INCREASING WAVE HEIGHTS. ADDITIONALLY...A NE SURGE WILL BEGIN TUESDAY NIGHT BEHIND THIS BOUNDARY...WITH NE WINDS RISING TO AROUND 15 KTS ON WEDNESDAY. THE COMBINATION OF THE LONG-PERIOD SWELL AND INCREASING WINDS WILL DRIVE WAVE HEIGHTS FROM 2-4 FT TUESDAY TO 4-6 FT WEDNESDAY...AND A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED BEGINNING WEDNESDAY. ALTHOUGH IT IS BEYOND THIS PERIOD...IT APPEARS WEDNESDAY COULD BE THE FIRST OF SEVERAL CONSECUTIVE DAYS WITH HEADLINES NEEDED ACROSS THE COASTAL WATERS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...FLOOD WATCH THROUGH LATE TONIGHT FOR SCZ017-023-024-032-033- 039-053>056. NC...FLOOD WATCH THROUGH LATE TONIGHT FOR NCZ087-096-099-105>110. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...DCH/REK SHORT TERM...JDW LONG TERM...JDW AVIATION...DCH/MRR MARINE...DCH/REK/JDW

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