Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 191730 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 130 PM EDT SAT APR 19 2014 .SYNOPSIS... WET WEATHER ASSOCIATED WITH AN OFFSHORE STORM SYSTEM WILL LAST THROUGH TONIGHT AND EVEN THROUGH SUNDAY ALONG THE COAST. THE NEXT CHANCE FOR RAIN WILL COME TUESDAY WITH A WEAK COLD FRONT. WARMING TEMPERATURES ARE EXPECTED FOR THE LATTER PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM SATURDAY...IMPRESSIVE STACKED LOW PRESSURE CENTERED OVER NORTHERN FLORIDA WILL JUST DRIFT NORTHEAST TO OFF THE SC COAST BY TONIGHT. AN ELONGATED TROUGH/COASTAL FRONT IS EXTENDING NE FROM THIS LOW PRESSURE TO JUST OFF THE CAPE FEAR COAST...AND THIS BOUNDARY WILL WAVER JUST OFFSHORE THROUGH THE NEAR TERM. A RIDGE OF HIGH PRESSURE WILL PUSH DOWN TOWARDS THE AREA FROM THE MID-ATLANTIC TODAY AS WELL. ALL OF THESE FEATURES TOGETHER WILL CREATE A CONTINUED CLOUDY AND UNSETTLED DAY...WITH INCREASING NE WINDS. THE WIDESPREAD HEAVY RAINFALL WHICH FELL ACROSS THE REGION THIS MORNING HAS MOSTLY EXITED OFF TO THE NORTHEAST...WITH ONLY REMNANT SHOWERS REMAINING LOCALLY. ALL AVAILABLE HIGH-RES GUIDANCE MODELS THIS WELL...ALBEIT WITH A SLIGHTLY SLOWER PROGRESSION THAT WHAT IS ACTUALLY BEING OBSERVED. HOWEVER...THESE SAME MODELS SUGGEST THAT HEAVIER RAIN WILL ONCE AGAIN OVERSPREAD THE AREA THIS EVENING AND TONIGHT...AS MOISTURE CONTINUES TO WRAP ONTO THE COAST AHEAD OF THE LOW PRESSURE SYSTEM TO THE SOUTH. MODEL SOUNDINGS ARE QUITE SATURATED...MUCH MORESO THAN 12Z OBSERVED SOUNDINGS TO THE SOUTH...WHICH SHOW PRONOUNCED DRY AIR ABOVE 700MB. EXPECT THIS DRY AIR IS DUE TO THE RIDGE MOVING SOUTH AND SOME SUBSIDENCE BEHIND THE INITIAL WAVE OF PRECIP...BUT CONTINUED LOW-LEVEL SATURATION WILL DRIVE OVERCAST SKY COVER AND PERIODIC SHOWERS/DRIZZLE THROUGH THE AFTN. BY THIS EVENING...COLUMN WILL ONCE AGAIN SATURATE AND MORE WIDESPREAD SHOWERS WITH HEAVIER RAINFALL IS EXPECTED. AN ADDITIONAL ONE HALF TO ONE INCH OF QPF IS POSSIBLE AS SHOWN VIA THE 09Z SREF PLUMES...HIGHEST ALONG THE CAPE FEAR COAST...WHERE RAINFALL OF 2-4" HAS ALREADY FALLEN SINCE LAST NIGHT. IN ADDITION TO THE INCREASE IN RAINFALL THIS EVE...NE WINDS WILL GRADUALLY INCREASE AS WELL AS THE PRESSURE GRADIENT TIGHTENS. ALTHOUGH MIXING WILL REMAIN SHALLOW...NE WIND GUSTS OF 30 MPH ARE EXPECTED TO BECOME COMMON TONIGHT...WITH ISOLATED GUSTS TO 40 MPH POSSIBLE ALONG THE COAST. WHILE THIS WILL FALL BELOW WI.Y THRESHOLDS...MAY HAVE TO CONSIDER AN SPS FOR ISOLATED WIND IMPACTS...INCLUDING TREE DAMAGE ON THE SATURATED GROUND...WITH THE AFTN PACKAGE. TEMPS TODAY WILL BARELY MOVE THANKS TO THE COOL NE WINDS AND CLOUD COVER...AND EXPECT HIGHS ONLY IN THE MID 50S MOST PLACES...BUT SOME LOW 60S ARE LIKELY ALONG THE SOUTHERN GRAND STRAND NEAR THE SOUTH SANTEE RIVER. DIURNAL RANGES WILL ALSO BE LIMITED...AND THUS MINS TONIGHT WILL FALL ONLY INTO THE LOW 50S...WITH SOME UPPER 40S WELL INLAND. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...MOISTURE FROM THE NEAR TERM STORM SYSTEM TO LINGER INTO SUNDAY. THE MAIN FORECAST ISSUE THEN IS HOW FAR INLAND RAIN MANAGES TO SPREAD AND WHAT THE AMOUNTS END UP LOOKING LIKE. THIS SYSTEM WILL ALSO BRING VERY BREEZY CONDITIONS TO THE COAST THAT MAY APPROACH WIND ADVISORY LEVELS ESPECIALLY IF SSTS DO NOT INHIBIT VERTICAL MIXING IN THE STRONG ONSHORE JETTING. BL FLOW BACKS SUNDAY NIGHT ALLOWING FOR LESS OF AN INLAND PUSH OF MOISTURE. SOME LOW RAIN CHANCES MAY PERSIST ALONG THE IMMEDIATE COAST BUT THATS ABOUT IT. MONDAY BRINGS MID LEVEL RIDGING/DRYING. THE LOW LEVEL MOISTURE MAY BE SLOW TO ERODE FROM THE EASTERN ZONES HOWEVER ESPECIALLY IF THE INVERSION SHOWN IN GFS MODEL SOUNDINGS DEVELOPS TO HELP TRAP IT. THIS FEATURE DOES NOT APPEAR IN WRF MODEL SOUNDINGS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 AM SATURDAY...COLD FRONT APPROACHES ON TUESDAY BRINGING SOME LOW RAIN CHANCES ON ACCOUNT OF LIMITED PREFRONTAL MOISTURE FLUX. HEIGHT RISES ARE QUICK TO FOLLOW THE BOUNDARY OFFSETTING ANY LOW LEVEL COOL ADVECTION...WHICH THERE DOESNT SEEM TO BE MUCH OF ANYWAY. LATE WEEK TEMPS TO STAY ON THE WARM SIDE OF CLIMO AS MID LEVEL RIDGE BUILDS AND SURFACE HIGH ONLY VERY SLOWLY MIGRATES EASTWARD. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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AS OF 18Z...IFR CIGS ARE OCCURRING EARLY THIS AFTERNOON...BUT CIGS AT KFLO/KLBT HAVE BEEN FLIRTING WITH MVFR AT TIMES. VSBYS ARE VFR...BUT VSBYS AT KILM/KLBT HAVE BEEN MVFR/IFR IN -DZ -RA AND BR. ALTHOUGH PRECIPITATION IS CURRENTLY DECREASING FROM S-N...SHOWERS ARE REDEVELOPING TO THE SE OF KILM. THE LATEST HRRR SLINGS THIS NW INTO KILM THEN KLBT THIS AFTERNOON. EXPECT A DECENT CHANCE OF SHOWERS AT KILM/KLBT WITH VCSH ELSEWHERE THROUGH THE AFTERNOON. EXPECT IFR CIGS TO CONTINUE AT THE COASTAL TERMINALS...WITH MVFR VSBYS AT KILM DUE TO SHOWERS. EXPECT IFR CIGS INLAND AS WELL....WITH TEMPO MVFR/IFR VSBYS AT KLBT DUE TO SHOWERS. SHOWERS WILL INCREASE TONIGHT JUST OFFSHORE AS A SURFACE LOW MOVES ENE WELL SOUTHEAST OF THE COASTAL TERMINALS. KLBT/KFLO SHOULD HAVE THE LEAST POTENTIAL FOR RAIN WITH THE BEST POTENTIAL AT THE COASTAL TERMINALS. AS THE ATTENDANT UPPER LOW PASSES EAST THE BEST RAIN POTENTIAL SHOULD END AND CIGS IMPROVE TO MVFR 08-10Z. PERIODS OF VFR COULD OCCUR BY 12Z BUT KEPT CIGS MVFR ATTM. EXTENDED OUTLOOK...TEMPO MVFR CIGS SUNDAY...OTHERWISE VFR. VFR ON MONDAY. CHANCE OF SHOWERS/TEMPO MVFR ON TUESDAY WITH A COLD FRONT. VFR WEDNESDAY AND THURSDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM SATURDAY...GALE WARNING REMAINS IN EFFECT THROUGH THE PERIOD. SLOW MOVING LOW PRESSURE ACROSS NORTHERN FLORIDA IS DRAPING A COASTAL FRONT NE INTO THE LOCAL COASTAL WATERS. THIS LOW WILL DRIFT NORTHEAST TODAY...WHILE A RIDGE OF HIGH PRESSURE ATTEMPTS TO STRENGTHEN DOWN THE COAST. THESE TWO FEATURES IN TANDEM WILL DRIVE A TIGHTENING PRESSURE GRADIENT...AND WINDS WILL INCREASE THROUGH TODAY...AND ESPECIALLY TONIGHT. CURRENT OBS SHOW THAT THE WEAKEST WINDS ARE...SURPRISINGLY...AT FRYING PAN SHOALS WHICH IS SE OF THE COASTAL FRONT AND THUS EXPERIENCING THE WEAKEST GRADIENT. BUOYS 41036...41037...AND 41038 ARE ALL WEST OF THE FRONT...AND HAVE NE WINDS OF 20-30 KTS THIS MORNING. THESE NE WINDS WILL ONLY STRENGTHEN THROUGH TONIGHT...SO EVEN THOUGH GALE CONDITIONS ARE NOT BEING MET YET...THERE IS HIGH CONFIDENCE THAT THEY WILL BE LATER TODAY AND TONIGHT. SEAS WILL CONTINUE TO GROW ON THE HIGHER WINDS...RISING FROM THE CURRENT 4-7 FT...TO AS MUCH AS 7-10 FT TONIGHT...WITH 12+ FT EXPECTED AT FRYING PAN SHOALS. THE EXCEPTION TO THIS WILL BE IN THE TYPICAL WAVE SHADOW REGION ALONG THE BRUNSWICK COUNTY COAST...WHERE 2-4 FT SEAS WILL BE PREDOMINANT. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...VERY UNSETTLED WITH FLAGS IN PLACE FOR THE ENTIRE PERIOD. THOSE FLAGS LIKELY IN THE FORM OF GALE WARNING EARLY IN THE PERIOD AND THERE IS JUST ENOUGH MODEL DIFFERENCES TO ERODE CONFIDENCE AS TO WHEN THAT WILL LOWER TO SMALL CRAFT ADVISORY...COULD BE DURING THE DAY SUNDAY OR NOT UNTIL SUNDAY NIGHT. MEANWHILE WAVES REMAIN VERY STEEP AND LARGE. ABATING TREND ON MONDAY SHOULD DROP WINDS BELOW ADVISORY THRESHOLDS ALTHOUGH THE LAGGING SEAS COULD MAKE IT UNTIL LATE DAY WHEN FLAGS ARE LOWERED. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 300 AM SATURDAY...BACKING WIND ON TUESDAY ASSOC WITH THE APPROACH OF A COLD FRONT FROM THE NW. A SHARP VEER TO OFFSHORE ON TUESDAY NIGHT WITH FROPA MAY ALSO BE ACCOMPANIED BY A BRIEF SURGE THAT COULD NECESSITATE A BRIEF ADVISORY BUT THINGS LOOK TO SETTLE PRETTY QUICKLY HEADING INTO WEDNESDAY. THE COOL AIR HAS TROUBLE MAKING IT THIS FAR SOUTH AND THUS THERE IS NO BIG PUSH OF HIGH PRESSURE...THE CENTER OF WHICH REMAINS OVER THE GREAT LAKES. IT WILL HOWEVER DROP SOUTH AND EAST BY THURSDAY AND BE FOUND CENTERED UP AND DOWN MUCH OF THE EAST COAST. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...GALE WARNING UNTIL 6 PM EDT SUNDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...JDW SHORT TERM...MBB LONG TERM...MBB AVIATION...MRR/JDW

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