Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 210243 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 943 PM EST SAT DEC 20 2014 .SYNOPSIS... WEAK HIGH PRESSURE ALONG WITH A FRONT JUST OFFSHORE WILL KEEP CLOUDY AND COOL CONDITIONS IN PLACE THROUGH SUNDAY. ANOTHER ROUND OF RAIN IS EXPECTED...ESPECIALLY LATE SUNDAY INTO MONDAY WHEN A STORM MOVES UP THE COAST. SHOWERS AND THUNDERSTORMS RETURN TUESDAY NIGHT INTO WEDNESDAY WITH A COLD FRONT. BREEZY BUT CLEAR WEATHER IS EXPECTED FOR CHRISTMAS DAY. DRY CONDITIONS WILL PERSIST INTO NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 940 PM SATURDAY...SHORTWAVE ACROSS WEST TEXAS IS ENABLING THE SOUTHERN STREAM TO BUCKLE INTO THE SOUTHERN STATES THIS EVENING. THUS THE SWATH OF MID LEVEL DRY AIR CURRENTLY ACROSS THE CAROLINAS WILL BE SHORT-LIVED. REGIONAL RADAR SHOWS LIGHT RAIN ACROSS PORTIONS OF SOUTHERN SC AND SOUTHEASTERN GA...MOVING E-NE. THINK MOST OF THIS VERY LOW QPF RAINFALL WILL REMAIN TO OUR SOUTH TONIGHT. ISENTROPIC LIFT DOESN`T RETURN IN EARNEST ACROSS OUR AREA UNTIL SUNDAY. HAVE HEDGE POPS UPWARD ACROSS THE SOUTHERN ZONES BY 1200 UTC SUN. OTHERWISE WITH WEAK COLD AIR ADVECTION AT THE SURFACE AND AMPLE CLOUD COVER TEMPS WILL ONLY SLOWLY DROP THROUGH THE EARLY MORNING HOURS. BUMPED UP MINS A FEW DEGREES GIVEN THIS TREND... ESPECIALLY ACROSS THE PEE DEE AND LBT AREA WHERE TEMPS ARE STILL HANGING ON IN THE LOWER 40S. PATCHY FOG IS ALSO A GOOD BET THROUGH THE OVERNIGHT. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... AS OF 330 PM SATURDAY...DREARY CONDITIONS WILL CONTINUE FOR THE SHORT TERM PERIOD. A BROAD SOUTHWEST FLOW ALOFT WILL INTERACT WITH A PERSISTENT BAROCLINIC ZONE JUST OFFSHORE AND A WEDGE OF HIGH PRESSURE INLAND. THE MODELS ARE IN GENERAL AGREEMENT ON SUNDAY REMAINING DRY FOR THE MOST PART. THERE COULD BE THE ISOLATED SPRINKLE OR MORE LIKELY PATCH OF DRIZZLE BUT OVERCAST SKIES AND COOL CONDITIONS SHOULD DO IT. A 300MB JET STREAK BRINGS ANOTHER ROUND OF RAIN FOR LATE SUNDAY INTO MONDAY MORNING. THE NAM AND GFS PAINT MOST OF THE HEAVIER QPF OFFSHORE WHERE THE BEST DIVERGENCE ALOFT RESIDES. THE BEST ISENTROPIC LIFT ON THE 300K SURFACE RESIDES WEST OF I-95 AND THE COAST IS LEFT IN BETWEEN WITH WEAK FORCING. HOWEVER THE QPF AMOUNTS WEST OF THE INTERSTATE ARE CERTAINLY NOT IMPRESSIVE MAKING THE OVERALL QPF AMOUNTS FAIRLY PALTRY. BEYOND MONDAY MORNING THE BEST FORCING MOVES OFF QUICKLY LEAVING OVERCAST/DRIZZLY SKIES. TEMPERATURE GUIDANCE IS IN GENERAL AGREEMENT OTHER THAN MONDAYS HIGHS WHEN THE GFS/MAV NUMBERS ARE MUCH WARMER. HARD TO TRUST THESE HOWEVER AS SURFACE PRESSURE PLOTS SHOW THE WEDGE...ALTHOUGH WEAKENING REMAINING IN PLACE. I DID USE A BLEND BUT WOULD NOT BE SURPRISED TO SEE SUBSEQUENT BULLETINS FROM THE GFS COOL. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 330 PM SATURDAY...WEDGE WILL BE ERODED ON TUES AS A WAVE OF LOW PRESSURE MOVES NORTH ALONG THE CAROLINA COAST. AT THE SAME TIME A HIGH AMPLITUDE MID TO UPPER TROUGH WILL DIG DOWN FROM THE UPPER GREAT LAKES INTO TEXAS PUSHING A COLD FRONT EAST. A DEEP S-SW FLOW WILL BRING PLENTY OF WARM AIR AND MOISTURE INTO THE SOUTHEAST AHEAD OF THE FRONT. INITIALLY ON TUES SHALLOW COOLER AIR WILL BE IN PLACE AS THE WARMER AIR OVERRIDES IT PRODUCING INCREASED ISENTROPIC LIFT AND INCREASED RAIN CHANCES. AS THE DAY WEARS ON...THE WINDS WILL COME AROUND WITH WARMER AND MOISTER AIR FLOWING IN. ALWAYS TOUGH TO TIME THIS AS COLD DENSE AIR HOLDS ON LONGER THAN MODELS USUALLY PREDICT. FOR NOW WILL KEEP WITH TEMPS WARMING THROUGH LATE DAY WITH WARMER AND MORE HUMID AIR MASS IN PLACE TUES NIGHT INTO WED. UNSETTLED WEATHER WILL REMAIN AHEAD THE COLD FRONT THROUGH TUES NIGHT INTO WED BEFORE COLD FRONT MOVES THROUGH LATE WED. INCREASING LOW LEVEL JET UP TO 40 KTS WILL COMBINE WITH BETTER UPPER LEVEL FORCING TO PRODUCE MORE WIDESPREAD SHOWERS THROUGH TUES NIGHT INTO WED. KEPT ISOLATED THUNDERSTORMS IN FORECAST TUES NIGHT INTO WED AS WARM FRONT LIFTS NORTH AND LOCAL AREA GETS INTO BEST MOISTURE AND LIFT. PCP WATER VALUES REACH UP TO 2 INCHES ALONG THE COAST WED AFTN THE DIGGING MID TO UPPER TROUGH WILL PUSH THE COLD FRONT THROUGH WED NIGHT BEFORE FINALLY MOVE OFF SHORE BY THURS MORNING LEAVING DRIER AND COOLER WEATHER FOR CHRISTMAS DAY. OVERALL EXPECT CLOUDY AND DAMP TO WET WEATHER THROUGH THE FIRST HALF OF THE PERIOD WITH COOLER MORE SEASONABLE WEATHER THURS INTO FRI AS HIGH PRESSURE BUILDS ACROSS THE SOUTH. THE HIGH WILL SHIFT OFF SHORE THROUGH FRI LEAVING A LIGHT RETURN FLOW AND WARMER TEMPS FRI INTO SATURDAY WITH A GOOD DEAL OF SUNSHINE. NEXT COLD FRONT SHOULD MOVE THROUGH SAT NIGHT BUT LOOKS LIKE IT MAY BE LACKING ANY DEEP MOISTURE. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... AS OF 00Z...CIGS WILL LIKELY BOUNCE AROUND BETWEEN MVFR/VFR LEVELS OVERNIGHT AND INTO SUNDAY AS WE ENTER A PERIOD OF UNSETTLED WEATHER. FCST SOUNDINGS REMAIN SATURATED IN THE 3-10KFT LAYER THROUGH MUCH OF THE PERIOD. WILL MAINTAIN MVFR CIGS THROUGH TONIGHT...LOWEST AT THE COASTAL TERMINALS. THERE HAVE BEEN PATCHES OF STRATUS AROUND 1KFT REPORTED ALONG THE COAST THIS EVENING...BUT DO NOT ANTICIPATE ANY PERSISTENT IFR CIGS TONIGHT AS FCST SOUNDINGS NEVER COMPLETELY LOCK IN THIS LOW LEVEL MOISTURE. THE LATEST HRRR AND SREF CIG PROBS ALSO SUPPORT KEEPING IFR OUT OF THE TAFS ATTM. IN FACT...CIGS SHOULD GRADUALLY LIFT TOWARD DAYBREAK IF THE CURRENT GUIDANCE TRENDS ARE CORRECT. NORTHEAST WINDS AOB 10 KT WILL PERSIST THROUGH THE DAY SUNDAY. ANOTHER ROUND OF MOIST ISENTROPIC LIFT WILL BRING MORE -RA/DZ TO THE AREA DURING THE DAY...SPREADING FROM SOUTH TO NORTH BEGINNING AROUND 15Z AT THE SOUTHERN TERMINALS AND AFTER 18Z AT KILM/KLBT. THIS SHOULD AGAIN HELP LOWER CIGS TO MVFR LEVELS THROUGH THE AFTERNOON. EXTENDED OUTLOOK...RAIN LIKELY MON WITH MVFR/IFR CIGS AS A COASTAL TROUGH DEVELOPS OFFSHORE. SHOWERS/TEMPO MVFR EXPECTED TUE/WED AHEAD OF A STRONG COLD FRONT. GUSTY WINDS WED/THU BEFORE AND AFTER FROPA. THU WILL BE VFR AT ALL TERMINALS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 940 PM SATURDAY...NORTH TO NORTHEAST FETCH WITH LOW PRESSURE TO THE SOUTH AND RIDGING FROM THE NORTH HAS RESULTED IN STEEP 3 TO 5 FT. THE DOMINANT PERIOD IS AROUND 5 SECONDS THIS EVENING...AND A SIMILAR SEA STATE IS EXPECTED OVERNIGHT. FIRST BATCH OF LIGHT RAIN IS EXITING THE CAPE FEAR COASTAL WATERS. TRENDS FOR INCREASING LIGHT RAIN...ESPECIALLY SOUTHERN WATERS...DURING THE EARLY MORNING HOURS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 PM SATURDAY...A FAIRLY BRISK NORTHEAST FLOW WILL PERSIST ACROSS THE COASTAL WATERS SUNDAY IN BETWEEN A BAROCLINIC ZONE TO THE EAST AND HIGH PRESSURE INLAND. AS LOW PRESSURE DEVELOPS AND MOVES UP ALONG THIS FRONT SUNDAY NIGHT...THE FLOW WILL TURN MORE EASTERLY. SPEEDS THROUGHOUT WILL BE 15-20 KNOTS. SOME HIGHER SEAS CAN BE EXPECTED WITH THE SOMEWHAT PROLONGED NATURE OF THE WINDS...3-5 FEET. CANT RULE OUT A FEW SIX FOOTERS BUT THINK A SMALL CRAFT HEADLINE CAN BE AVOIDED. LIGHTER WINDS AND SEAS CAN BE EXPECTED MONDAY ALTHOUGH THE FLOW WILL GENERALLY BE THE SAME. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 330 PM SATURDAY...WAVE OF LOW PRESSURE WILL MOVE UP THE CAROLINA COAST ON TUES WITH WINDS COMING AROUND THROUGH THE DAY. LIGHT NORTHERLY WINDS WILL SHIFT AROUND BECOMING MORE ON SHORE THROUGH THE DAY AND EVENTUALLY SOUTHERLY BY TUES EVENING. A LARGE AND POTENT STORM SYSTEM WILL PUSH A COLD FRONT EAST WITH INCREASING SOUTHERLY WINDS IN A TIGHTENING GRADIENT FLOW TUES NIGHT INTO WED. WINDS WILL INCREASE UP TO 15 TO 25 KTS TUES NIGHT INTO WED AHEAD OF THE COLD FRONT. THIS WILL PUSH SEAS UP FROM 2 TO 4 FT EARLY TUES TO 3 TO 5 FT BY LATE TUES. WNA SHOWS SEAS RAMPING UP ABOVE 6 FT BY WED MORNING AND POSSIBLE UP TO 7 TO 9 FT IN OUTER WATERS IN STRONGER SW TO W FLOW AS FRONT MOVES THROUGH THE WATERS LATE WED INTO WED NIGHT. EXPECT SMALL CRAFT CONDITIONS WED AND LASTING INTO THURS WITH HIGHEST SEAS GETTING PUSHED FARTHER OFF SHORE IN STRONGER W-NW FLOW BEHIND FRONT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...SRP SHORT TERM...SHK LONG TERM...RGZ AVIATION...BJR

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