Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 211044 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 644 AM EDT SUN SEP 21 2014 .SYNOPSIS... DEEPENING LOW PRESSURE OFFSHORE WILL MOVE NORTHEAST AWAY FROM THE AREA THIS MORNING...LEAVING DRY AND WARM CONDITIONS BY THIS AFTERNOON. A COLD FRONT WILL CROSS THE AREA EARLY MONDAY WITH ISOLATED SHOWERS AND THUNDERSTORMS. MUCH COOLER AIR WILL FOLLOW FOR THE MIDDLE OF THE WEEK. A TROUGH WILL SHARPEN OFFSHORE AND MOVE TOWARDS THE COAST...BRINGING INCREASING RAIN CHANCES FOR THE LATTER PART OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM SUNDAY...DEEPENING LOW PRESSURE EAST OF CAPE LOOKOUT WILL ACCELERATE OUT TO THE NORTHEAST TODAY...TAKING CLOUDS AND RESIDUAL LIGHT RAIN ALONG WITH IT. MUCH DRIER AIR THROUGHOUT THE ATMOSPHERIC COLUMN WILL WORK INTO THE EASTERN CAROLINAS BY LATE MORNING WITH PRECIPITABLE WATER VALUES FALLING FROM 1.5 TO 2 INCHES DOWN TO NEAR 1 INCH BY NOON. THE BUBBLE OF COOL AIR ALONG THE BACK SIDE OF THE LOW WILL BE A FADING MEMORY BY THIS AFTERNOON AS WESTERLY DOWNSLOPING FLOW OFF THE SOUTHERN APPALACHIANS REBOUNDS 850 MB TEMPS TO +17C. WITH NEARLY FULL SUNSHINE EXPECTED BY NOON HIGHS SHOULD REACH THE UPPER 80S INLAND WITH MID 80S AT THE COAST...APPROXIMATELY 10 DEGREES WARMER THAN YESTERDAY. AS WE MOVE DEEPER INTO SEPTEMBER (AND METEOROLOGICAL AUTUMN) THE SYNOPTIC PATTERN DOES NOT RESEMBLE SUMMER ANYMORE. AN ACTIVE POLAR JET ACROSS THE GREAT LAKES AND NORTHEAST WILL WHIP ANOTHER UPPER DISTURBANCE EASTWARD INTO THE APPALACHIANS TONIGHT. THE SURFACE REFLECTION OF THIS WILL BE A COLD FRONT PUSHED SOUTHEASTWARD BY HIGH PRESSURE OVER THE CENTRAL PLAINS. THIS FRONT SHOULD ARRIVE IN THE EASTERN CAROLINAS BY DAYBREAK MONDAY...ACCOMPANIED ONLY BY A WIND SHIFT AT THE SURFACE SINCE THE LOW OR MID LEVEL WINDS SHOULD NOT BACK ENOUGH TO PROMOTE MOISTURE ADVECTION FROM THE ATLANTIC OR GULF. A MODEST LOW LEVEL JET SHOULD ADD ENOUGH WIND TO THE BOUNDARY LAYER TO KEEP LOW TEMPERATURES NEAR THE WARMER NAM MOS NUMBERS. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM SUNDAY...MONDAY BRINGS THE LAST DAY OF ASTRONOMICAL SUMMER...AS THE FALL EQUINOX OCCURS AROUND 1030 PM MONDAY NIGHT. RIGHT ON CUE...A FALL-LIKE COLD FRONT WILL CROSS THE AREA DURING MONDAY...USHERING IN TRUE FALL-LIKE AIR FOR TUESDAY. BEFORE THE COOL DRY AIR CAN OVERSPREAD THE CAROLINAS...SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG THE COLD FRONT MONDAY AFTN. ALTHOUGH MOIST ADVECTION AHEAD OF THIS FEATURE IS LIMITED...THE FROPA TEMPORALLY MATCHING PEAK HEATING SHOULD PROVIDE ENOUGH FORCING FOR SCT SHOWERS/TSTMS...WITH HIGHEST POP EXPECTED ALONG THE COAST WHERE THE DEEPER...YET STILL MODERATE...MOISTURE WILL RESIDE. INHERITED FORECAST HAS SCHC FOR MONDAY...AND WILL MAKE ONLY MINOR UPTICKS ALONG THE COAST. PRECIP WILL WANE QUICKLY AFTER DARK THANKS TO LOSS OF HEATING AND THE COLD FRONT MOVING FURTHER AWAY...ALLOWING FOR RAPID COOL/DRY ADVECTION TO ENGULF THE AREA. THIS WILL LEAVE A BEAUTIFUL...ALTHOUGH A BIT WINDY...FALL DAY ON TUESDAY AS EXPANSIVE CANADIAN HIGH PRESSURE RIDGES DOWN FROM THE GREAT LAKES. ALTHOUGH SUNSHINE WILL BE PLENTIFUL ON TUESDAY...HIGHS WILL STRUGGLE ON CONTINUED...BUT WEAKENING...CAA...LEAVING HIGHS IN THE UPPER 70S...A FEW DEGREES COOLER THAN THOSE EXPECTED MONDAY. MINS BOTH NIGHTS WILL DROP TO SOME OF THE COOLEST VALUES WE HAVE SEEN IN A WHILE...WITH MID/UPR 50S EXPECTED INLAND...AND RIGHT AROUND 60 AT THE COAST. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 AM SUNDAY...STALLED COLD FRONT OFFSHORE WILL TRANSITION INTO A COASTAL TROUGH...AIDED BY DEVELOPING SHORTWAVE ENERGY MID-TO-LATE WEEK. THIS WILL COMBINE WITH A STRENGTHENING HIGH PRESSURE WEDGE JUST INLAND OF THE COAST TO PRODUCE COOL AND INCREASINGLY UNSETTLED WEATHER DURING THE EXTENDED. ALTHOUGH THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS ABOUT THE AMOUNT OF CLOUDS/PRECIP EXPECTED...THEY ARE ALL MORE PESSIMISTIC IN THEIR SOLUTIONS FOR LATE WEEK. DEEP EASTERLY FLOW THROUGH AT LEAST HALF THE ATMOSPHERIC COLUMN WILL ADVECT AMPLE MOISTURE TOWARDS THE CAROLINAS...WHILE AT THE SAME TIME DRIVING THE COASTAL TROUGH TOWARDS SHORE. THIS COMBINING WITH THE AFOREMENTIONED VORT ENERGY ALOFT MAY EVEN SPAWN WEAK LOW PRESSURE...ALL OF WHICH POINT TO DETERIORATING WEATHER CONDITIONS LOCALLY. COOL E/NE WINDS AT THE SURFACE WITH EASTERLY FLOW TOPPING THAT WILL CREATE WIDESPREAD LOW-CLOUD COVER AND PERIODS OF SHOWERS...WITH THE BEST CHANCE ALONG THE COAST LATE IN THE WEEK AS ISENTROPIC LIFT AMPLIFIES. WITH A STRONG WEDGE IN PLACE AND A STRENGTHENING COASTAL TROUGH IN THE VICINITY...THE FIRST WEEK OF FALL LOOKS TO TAKE ON A DECIDEDLY WINTER-LIKE FEEL WITH CLOUDS...PERIODS OF RAIN...AND TEMPS BELOW CLIMO. DRYING SHOULD FINALLY BEGIN BY THE WEEKEND AS RIDGING DEVELOPS ALOFT...SQUELCHING THE COASTAL TROUGH AND ERODING MUCH OF THE MID AND UPPER LEVEL MOISTURE. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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AS OF 12Z...LOW PRESSURE OFFSHORE IS NOW TRACKING AWAY FROM THE REGION...TAKING THE DEEP MOISTURE ALONG WITH IT. SOME IFR CEILINGS REMAIN AT ILM...WITH SOME LINGERING SHOWERS AT THE MYRTLES. VFR CONDTIONS WILL PREVAIL AT ALL TERMINALS IN A COUPLE OF HOURS. WINDS ALREADY NORTHWEST AND THIS WILL CONTINUE WITH SOME GUSTINESS THROUGHOUT THE DAY. DIMINISHING WINDS THIS EVENING AS THEY BACK TO THE SOUTHWEST. EXTENDED OUTLOOK...VFR THROUGH WED WITH A CHANCE OF A SHOWER WITH A COLD FRONT ON MONDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM SUNDAY...DEEPENING LOW PRESSURE EAST OF CAPE LOOKOUT WILL ACCELERATE OUT TO THE NORTHEAST TODAY...TAKING THE ROUGH WEATHER OF THE PAST 24 HOURS WITH IT. LINGERING LIGHT RAIN NEAR AND NORTH OF CAPE FEAR SHOULD END NO LATER THAN 9 OR 10 AM WITH DRY WEATHER EXPECTED THROUGH TONIGHT. BEHIND THIS LOW THE STRONGEST OFFSHORE WINDS SHOULD OCCUR AROUND DAYBREAK THIS MORNING...EXPECTED TO REACH 25 KNOTS SUSTAINED AWAY FROM SHORE IN THE CAPE FEAR AREA. SEAS UP TO 7 FEET AWAY FROM SHORE MAY CONTINUE INTO LATE MORNING...AND THE SMALL CRAFT ADVISORY WILL REMAIN POSTED. WINDS WILL BACK MORE WESTERLY THIS AFTERNOON...THEN SOUTHWESTERLY TONIGHT WITH ANOTHER INCREASE IN SPEED EXPECTED AS A LOW LEVEL JET ORGANIZES OUT AHEAD OF A DRY COLD FRONT THAT WILL REACH THE WATER MONDAY. WHILE WINDS/SEAS SHOULD REMAIN BELOW ADVISORY LEVELS TONIGHT IT`S JUST ONE MORE SIGN THAT THE SEASONS ARE CHANGING. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM SUNDAY...WESTERLY WINDS AROUND 10 KTS WILL START THE PERIOD...BEFORE A COLD FRONT CROSSES THE WATERS DURING MONDAY AFTN. THIS WILL CAUSE A WIND SHIFT TO THE NORTH MONDAY EVENING...WITH FURTHER VEERING TO THE NORTHEAST OCCURRING MONDAY NIGHT. AS THESE WINDS BECOME FROM THE NE...THEY WILL BE ACCOMPANIED BY A STRENGTHENING SURGE WITH WIND SPEEDS RISING TO 15-20 KTS. HIGH PRESSURE RIDGING DOWN THE COAST ON TUESDAY...COMBINED WITH THIS COLD FRONT STALLING OFFSHORE...WILL KEEP A PINCHED GRADIENT...AND NE WINDS WILL STEADILY RISE TO 20-25 KTS THROUGHOUT TUESDAY. SEAS THROUGH THE DAYLIGHT HOURS OF MONDAY WILL BE 2-3 FT WITH A VARIABLE WIND DIRECTION CAUSING A CONFUSED SPECTRUM. BEGINNING MONDAY NIGHT HOWEVER...AS THE NE SURGE DEVELOPS AND PERSISTS...SEAS WILL BUILD FROM 2-3 FT TO 4-6 FT...AND A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED BEGINNING TUESDAY NIGHT. LONG TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 300 AM SUNDAY...HIGH PRESSURE WILL RIDGE DOWN THE COAST THROUGH THE PERIOD...WHILE A COASTAL TROUGH STRENGTHENS OFFSHORE. THIS CREATES A PINCHED GRADIENT BOTH WED AND THU...DRIVING PERSISTENT AND STRONG NE WINDS OF 20-25 KTS INTO LATE WEEK. THESE WINDS WILL DRIVE SEAS TO 4-7 FT THROUGH THE COASTAL WATERS...WITH THE EXCEPTION BEING ALONG THE NEAR-SHORE WATERS OF AMZ252 AND AMZ254 WHERE WAVE SHADOWING IS LIKELY AND AMPLITUDES WILL THUS BE LOWER. EVEN SO...AN EXTENDED SMALL CRAFT ADVISORY IS EXPECTED DURING THIS PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR AMZ250-252-254- 256. && $$ SYNOPSIS...JDW NEAR TERM...TRA SHORT TERM...JDW LONG TERM...JDW AVIATION...43 MARINE...TRA/JDW

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