Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 190717 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 317 AM EDT SAT APR 19 2014 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 300 AM SATURDAY...PRECIPITABLE WATER VALUES WILL BE NEAR 1.5 INCHES FOR MOST OF THE PERIOD...DROPPING SLIGHTLY FROM W TO E LATE TONIGHT AND SUN MORNING. INTO THIS AFTERNOON...A SHALLOW E AND SE FLOW WILL BE TOPPED BY A MOIST AND DEEP S TO SW FLOW WITH SPEEDS INCREASING WITH HEIGHT AND THIS WILL ALLOW STRONG ISENTROPIC LIFT TO PERSIST. LATER IN THE DAY AND TONIGHT...THE DEPTH OF EASTERLY WINDS INCREASES SUBSTANTIALLY. LOW PRESSURE AT THE SURFACE IS TRAPPED BY AN UPPER LEVEL LOW. AS IS TYPICAL IN THESE SITUATIONS...ANY MOVEMENT OF THE SYSTEM WILL BE SLOW. LOW PRESSURE ACROSS N FLORIDA TODAY WILL MOVE ENE AND OFF THE EAST COAST OF FLORIDA AND GEORGIA TONIGHT. A VERY PRONOUNCED COASTAL TROUGH WILL EXTEND FROM THE LOW CENTER AND ACROSS THE OFFSHORE WATERS OF THE CAROLINAS. SATELLITE AND RADAR TRENDS SHOW THE MOIST CONVEYOR BELT TRENDING UP THE SOUTHEAST COAST AT THIS TIME. ALTHOUGH THE RAIN MAY FALL HEAVILY AT TIMES...IT WILL BE THE PERSISTENT NATURE OF THE PRECIPITATION THAT WILL RESULT IN TOTAL RAINFALL AMOUNTS NEAR 2 INCHES WITH SOME LOCATIONS RECEIVING MORE THAN 3 INCHES. THIS MAY BE ENOUGH RAINFALL TO CAUSE SOME LOCALIZED PONDING OF WATER IN LOW-LYING AND POOR DRAINAGE AREAS. WE WILL ALSO HAVE TO WATCH FOR THE DRY SLOT WHICH WILL ROTATE INTO THE FORECAST AREA BEFORE STALLING AND REORIENTING. THUS...IT WILL LIKELY NOT RAIN ALL DAY IN MOST AREAS. WHERE RAIN DOES END FOR A TIME...IT WILL LIKELY RETURN. WILL FORECAST 100 POPS THIS MORNING WITH POPS TRENDING LOWER LATER THIS MORNING AND THIS AFTERNOON...BUT STILL A LIKELIHOOD OF RAINFALL. WILL CONTINUE THE DOWNWARD TREND TONIGHT...DROPPING TO CHANCE...ESPECIALLY LATE AND DURING SUN MORNING. WILL KEEP THUNDERSTORMS OFF THE COAST...ON THE S AND E SIDE OF THE COASTAL TROUGH. IN ADDITION TO THE RAINFALL...WE WILL HAVE TO CONTEND WITH STIFF AND PERSISTENT NE WINDS. THESE WINDS SHOULD ONLY INCREASE TONIGHT AND SUN AS THE PRESSURE GRADIENT REALLY TIGHTENS UP BETWEEN OFFSHORE LOW PRESSURE AND STRONG HIGH PRESSURE TO THE N. EXPECT WIND GUSTS AS HIGH AS 35 TO 40 MPH AT THE COAST AND 30 TO 35 MPH FOR INLAND LOCATIONS. THE STRONGEST WINDS WILL OCCUR AT THE BEACHES. THE STRONG AND PERSISTENT WINDS MAY RESULT IN SOME BEACH EROSION...MAINLY IN AREAS EXPOSED TO NE WINDS. THE RISK WILL BE HIGHEST DURING EACH HIGH TIDE CYCLE. HIGH TIDE IS AT 11 AM AND NEAR MIDNIGHT. MOISTURE PROFILES AND MODEL SOUNDINGS INDICATE WE WILL NOT BE ABLE TO SHRUG OFF THE THICK CLOUDS...EVEN IF THE RAIN SHOULD CUT-OFF IN ANY GIVEN LOCATION FOR A PERIOD OF TIME. THE COOL NE WINDS AND CLOUDS SHOULD ONLY ALLOW TEMPS TO RISE TO THE UPPER 50S AND LOWER 60S FOR MOST OF US. TEMPS MAY NOT RISE ABOVE THE MID 50S WEST OF INTERSTATE 95. PORTIONS OF THE THE SOUTHERN GRAND STRAND AND SOUTH SANTEE RIVER AREA MAY EEK OUT MID 60S. NOT A SIGNIFICANT TEMP CHANGE TONIGHT. TEMPS WILL BE COOLEST WELL INLAND...UPPER 40S. NEARER TO THE COAST...LOWER TO MID 50S WILL BE MORE COMMON.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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AS OF 3 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 IMMED 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.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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AS OF 3 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.
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&& .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...EXPECT IFR CONDITIONS TO PREVAIL OVERNIGHT AS -RA/RA CONTINUES TO SPREAD ACROSS THE EASTERN CAROLINAS. THE CONSTANT RAINFALL SHOULD HELP TO LOWER CIGS BELOW 1KFT AT MOST TERMS. NORTHEAST WINDS 15 KT WITH GUSTS OVER 20 KT WILL CONTINUE INTO THIS MORNING. SLOW-MOVING LOW PRESSURE OVER NORTH FLORIDA WILL BRING RAIN THROUGH MUCH OF THE DAY. FCST SOUNDINGS AND GUIDANCE ARE IN GOOD AGREEMENT ABOUT IFR STRATUS PERSISTING THROUGH THE MORNING HOURS. CIGS MAY LIFT TO MVFR IN THE AFTERNOON...BUT THIS LOOKS LIKE THE BEST CASE SCENARIO. LOOK FOR GUSTY NORTHEAST WINDS 15-25 KT DURING THE DAY AS A WARM FRONT REMAINS POSITIONED OFFSHORE. MVFR/IFR CIGS ARE EXPECTED TO REMAIN IN PLACE THROUGH THE END OF THE TAF PERIOD...EVEN AS THE RAIN TAPERS OFF BY EVENING. EXTENDED OUTLOOK...MVFR/IFR CIGS WILL LINGER OVERNIGHT SATURDAY INTO SUNDAY...LOWEST ALONG THE COAST. BECOMING VFR ON MONDAY. CHANCE OF SHOWERS ON TUESDAY WITH A COLD FRONT. VFR ON WEDNESDAY. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM SATURDAY...A GALE WARNING IS IN EFFECT INTO SUN. LOW PRESSURE ACROSS NORTH FLORIDA...SURFACE AND ALOFT...WILL EVER SO SLOWLY MOVE UP THE SOUTHEAST COAST...WITH A TRACK MORE EAST THAN NORTH...ESPECIALLY AS IT GAINS LATITUDE THROUGH THE WEEKEND. A VERY PRONOUNCED COASTAL TROUGH EXTENDS FROM THE AREA OF LOW PRESSURE UP THROUGH THE OFFSHORE WATERS OF THE CAROLINAS. THE PATTERN WILL EVOLVE VERY SLOWLY WITH THE CENTER OF LOW PRESSURE STILL SOUTH OF THE WATERS SUN MORNING. THIS WILL KEEP STRONG NE WINDS IN PLACE. IN FACT...A VERY TIGHT PRESSURE GRADIENT IS EXPECTED TO DEVELOP BETWEEN OFFSHORE LOW PRESSURE AND STRONG HIGH PRESSURE ACROSS THE CAROLINAS. THE TIGHTEST OF THE GRADIENT SHOULD BE REALIZED LATE TONIGHT AND ON SUN. FREQUENT GUSTS TO GALE FORCE ARE EXPECTED AND A PERIOD OF SUSTAINED GALES IS POSSIBLE. THESE STRONG AND PERSISTENT NE WINDS WILL DRIVE SEAS UP TO 8 TO 12 FT WITH 14 FT POSSIBLE AROUND FRYING PAN SHOALS. LOCATIONS BLOCKED BY NE FLOW...SUCH AS LONG BAY WILL HAVE SIGNIFICANTLY LOWER WAVE HEIGHTS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 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 THURSDAY/... AS OF 3 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.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...NONE. NC...NONE. MARINE...GALE WARNING UNTIL 6 PM EDT SUNDAY FOR AMZ250-252-254-256.
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&& $$ NEAR TERM...RJD SHORT TERM...MBB LONG TERM...MBB AVIATION...BJR/RJD

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