Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 260829 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 329 AM EST MON JAN 26 2015 .SYNOPSIS...
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LOW PRESSURE AND A COLD FRONT WILL CROSS THE AREA TODAY AND CONGEAL INTO A POWERFUL NEW ENGLAND NOR`EASTER. HIGH PRESSURE WILL MOVE INTO THE CAROLINAS BY THURSDAY FOLLOWED BY ANOTHER COLD FRONT THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST OVER THE WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 300 AM MONDAY...A CLIPPER LOW WAS CENTERED ACROSS WESTERN VIRGINIA WITH ITS TRAILING COLD FRONT DRAPED ACROSS THE APPALACHIANS. THIS SYSTEM WILL RACE ACROSS THE CAROLINAS AND VIRGINIA THIS MORNING WITH THE CENTER REDEVELOPING OFF THE VIRGINIA CAPES THIS AFTERNOON. THE CENTER WILL THEN INTENSIFY RAPIDLY AS IT MOVES SLOWLY NNE. THE LONGWAVE UPPER TROUGH WILL REACH THE EASTERN CAROLINAS TODAY...BUT AS THE SYSTEM INTENSIFIES AND BECOMES NEGATIVELY TILTED...THIS TROUGH WILL LINGER ACROSS THE AREA THROUGH THE PERIOD. VIGOROUS MID-LEVEL SHORTWAVE TROUGHS WILL ROUND THE BASE OF THE MAIN TROUGH...PROVIDING ENERGY AND LIFT WHILE BRINGING PROGRESSIVELY CHILLIER AIR UPSTAIRS. TEMPS AT 500 MB WILL DROP TO AROUND MINUS 26 DEG C TODAY AND MINUS 28 DEG C TONIGHT. STEEP LAPSE RATES WILL DEVELOP AS TEMPS IN THE LOW LEVELS RISE WELL INTO THE 50S TODAY. THIS WILL CREATE AN UNSTABLE ENVIRONMENT AND HELP TO WRING OUT THE LIMITED MOISTURE THIS FAR SOUTH. MID LEVEL LAPSE RATES APPROACH 7 DEG C/KM AND MIXED LAYER CAPE VALUES DO SHOW THE INSTABILITY ALTHOUGH THEY ARE VERY MODEST...ON THE ORDER OF 100-200 J/KG... HIGHEST ACROSS NE PORTIONS OF THE FORECAST AREA. ALTHOUGH NO HEAVY RAIN IS EXPECTED...INSTABILITY SHOWERS SHOULD INCREASE IN NUMBER WITH PERHAPS THE BEST COVERAGE ACROSS OUR NORTHERN ZONES IN CLOSEST PROXIMITY TO THE SURFACE LOW. WILL SHOW POPS UP TO HIGH CHANCE LOW-END LIKELY ALONG AND N OF LBT AND EYF. POPS WILL TRAIL OFF AS YOU PROGRESS SOUTH WHERE COVERAGE SHOULD BE MORE SPOTTY. A RUMBLE OF THUNDER IS NOT IMPOSSIBLE...BUT REMOTE AND DID NOT INCLUDE MENTION AT THIS TIME. INVERTED-V SOUNDINGS INDICATE SOME GUSTY WINDS ARE LIKELY WITH ANY OF THE MORE PERSISTENT SHOWERS. AS LOW PRESSURE INTENSIFIES OFF THE MID-ATLANTIC COAST...ITS DEVELOPING PRECIPITATION SHIELD SHOULD EXPAND. WRAP AROUND PRECIPITATION COULD BACK BUILD/PERSIST INTO PORTIONS OF THE FORECAST AREA. THE HIGHEST RISK FOR SHOWERS AFTER DARK WILL BE ACROSS THE CAPE FEAR AREA AND BACK TOWARDS EYF. IN FACT...THERE IS A VERY SMALL CHANCE THAT SNOW WILL MIX IN WITH ANY RESIDUAL RAIN SHOWERS AS FAR SOUTH AS PENDER COUNTY TOWARD MORNING. NO ACCUMULATION OF SNOW IS EXPECTED GIVEN GROUND TEMPS WILL BE WELL ABOVE FREEZING AND EVEN AIR TEMPS WILL NOT BE ANY LOWER THAN THE MID 30S. TEMPS SHOULD DROP TO NEAR FREEZING FURTHER SW AND ESPECIALLY W OF THE AFOREMENTIONED AREA WHERE THICK CLOUDS SHOULD EXHIBIT A DECREASING TREND OVERNIGHT. A TIGHTENING PRESSURE GRADIENT WILL KEEP WINDS UP LATER THIS AFTERNOON AND FOR MUCH OF THE NIGHT...W TO NW AT 15 TO 20 MPH WITH GUSTS UP TO 25 TO 30 MPH.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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AS OF 3 AM MONDAY...BLOCKBUSTER STORM CLOBBERING NEW ENGLAND ON TUESDAY AND AS AS USUAL WHEN THIS IS THE CASE COLD AIR WILL READILY INVADE MOST AREAS EAST OF THE APPALACHIANS. A SMALL LAYER OF LOW LEVEL MOISTURE STARTS OUT THE DAY BUT WITH A GREAT DEPTH OF THE COLUMN A DRY NWRLY FLOW THIS SHOULD MIX OUT FOR NEARLY FULL SUNSHINE. EVEN SO, THE CAA WILL CAP HIGHS IN THE MID 40S, SOME 10 DEGREES BELOW CLIMO. OFT TIMES WITH SUCH A LARGE AND STRENGTHENING STORM OVER THE NORTHEASTERN U.S. IT IS OFTEN RATHER BLUSTERY LOCALLY BUT THIS DOES NOT APPEAR TO BE IN THE OFFERING THIS TIME AROUND. WE SEEM TO FIND OURSELVES IN A RELATIVE MINIMUM IN THE LOW LEVEL WIND FIELD BETWEEN THE JET ASSOC WITH THE ACTUAL STORM CENTER AND THE MAIN AXIS OF COLD AIR ADVECTION WEST OF THE LOW LVL THERMAL TROUGH OVER THE GULF STATES. THERE WILL BE JUST ENOUGH WINDS TUESDAY NIGHT TO PREVENT RADIATIONAL COOLING. SO IN AN AIRMASS COLD ENOUGH TO BRING LOWS CLOSE TO 20 WE SHOULD INSTEAD REMAIN IN THE UPPER 20S...PERHAPS LOW 30S FAR SRN ZONES. UPPER TROUGH AXIS WELL OFFSHORE BY WEDNESDAY WHILE THE AXIS OF HIGHEST SURFACE PRESSURES BUILDS RIGHT OVERHEAD. SO WHILE THERE MAY BE SOME MINOR RECOVERY IN THE BOUNDARY LAYER TEMPERATURES THE SHALLOW NATURE OF THE MIXING (2200FT?) WILL BRING CHILLY HIGHS NEARLY IDENTICAL TO THOSE OBSERVED TUESDAY. FORECAST SOUNDINGS WEDNESDAY NIGHT MUCH MORE TYPICAL OF RADIATIONAL COOLING WITH NEAR ISOTHERMAL LAYER POSSIBLY AS DEEP AS 9KFT. HOWEVER DUE TO THE AFOREMENTIONED RECOVERY IN TEMPERATURES WEDNESDAY NIGHT LOWS WILL BE SIMILAR TO THOSE OF THE NIGHT BEFORE.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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AS OF 3 AM MONDAY...SURFACE HIGH MOVES OVERHEAD EARLY THURSDAY AND JUST OFFSHORE IN A WEAKENING STATE LATER IN THE DAY. ZONAL MID LEVEL FLOW NORMAL QUITE DRY BUT SOME PVA INDUCED BY THE WESTERLIES REACTING WITH SOME LOW LEVEL MOISTURE FLOW IN THE SW WINDS TO BRING AN INCREASE IN CLOUDS. MEANWHILE AFTERNOON TEMPS REBOUND CLOSE TO CLIMO. WILL THIS MOISTURE BE ADEQUATE TO SUPPORT SOME PRECIPITATION AS THE NEXT UPPER WAVE AND COLD FRONT PASS THROUGH THURSDAY NIGHT INTO FRIDAY MORNING? HARD TO SAY THIS FAR OUT BUT GIVEN THE FAIRLY ROBUST STRENGTH OF THE TROUGH THE SLIGHT CHANCE INHERITED POPS LOOK FINE. EITHER WAY IT WILL STAY MILD ENOUGH TO PRECLUDE ANY PTYPE CONCERNS. THE WEEKEND WILL BASICALLY JUST FEATURE COLD AIR ADVECTION IN NORTHWESTERLY FLOW AROUND HUDSON BAY VORTEX. THERE MAY AT SOME TIME BE ENOUGH OF A SPOKE OF ENERGY WITHIN THIS FLOW TO YIELD ASCENT AND EVEN OFFSHORE PRESSURE FALLS. ANY SUCH DISTURBANCE IS FAR BEYOND BEING SAMPLED BY UPPER AIR NETWORK AND SO SOLUTIONS MAY SHOW HIGH VARIABILITY FROM RUN TO RUN. AT THIS TIME IT SEEMS MOST PRUDENT TO FOCUS ON THE CHILLY TEMPS AND ADDRESS ANY CLOUD COVER AND LOW RAIN CHANCES AT A FUTURE TIME.
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...EXPECT VFR TO PREVAIL THROUGH THE VALID PERIOD...WITH CLOUDS INCREASING OVERNIGHT AND SHOWERS POSSIBLE ON MONDAY AS A QUICKLY PROPAGATING SYSTEM MOVES THROUGH THE AREA. WHILE ONE MODEL SUGGESTS MARGINAL MVFR FOG DEVELOPMENT AT THE INLAND SITES...AM EXPECTING INCREASED BOUNDARY LAYER WINDS TO KEEP DEVELOPMENT CHANCES LOW. THROUGH THE OVERNIGHT HOURS WILL SEE A GRADUAL INCREASE OF MID TO HIGH LEVEL CLOUDS AHEAD OF THE NEXT SYSTEM...WITH VARIABLE WINDS AROUND 5 KT. AFTER DAYBREAK...WINDS THROUGHOUT THE DAY WILL VEER...BECOMING WESTERLY WITH SUSTAINED WINDS AOB 10 KT BY MORNING AND THEN INCREASING EVEN MORE TO AOB 12 KT WITH GUSTS AROUND 20 KT INTO THE EARLY AFTERNOON HOURS. ISOLATED TO SCATTERED SHOWERS ARE POSSIBLE...THUS HAVE INTRODUCED VCSH ATTM. LOW CLOUDS MOVE IN AS WELL...AND COULD NOT RULE OUT A BRIEF PERIOD OF MVFR DUE TO LOW CIGS IN THE AFTERNOON...BUT CONFIDENCE IS LOW ATTM. INTO THE LATE EVENING HOURS CHANCES OF PRECIPITATION WILL DIMINISH...AND WINDS WILL BECOME NORTHWEST... WITH GUSTS UP TO AROUND 20 KT CONTINUING. EXTENDED OUTLOOK...SLIGHT CHANCE OF -RA/MVFR CIGS MONDAY. VFR WEDNESDAY THROUGH FRIDAY. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM MONDAY...A SMALL CRAFT ADVISORY IS IN EFFECT BEGINNING LATE MORNING ACROSS THE SOUTHERN WATERS AND EARLY AFTERNOON NORTHERN WATERS. THE SMALL CRAFT ADVISORY WILL CONTINUE INTO TUE MORNING. A TIGHTENING PRESSURE GRADIENT WILL BRING SUSTAINED WINDS UP TO 20 TO 30 KT WITH GUSTS NEAR 35 KT FOR A TIME. WINDS WILL BE STRONGEST TONIGHT AS LOW PRESSURE RAPIDLY INTENSIFIES OFF THE MID-ATLANTIC COAST. THE DIRECTION WILL BE WSW THIS MORNING AND THEN W THIS AFTERNOON AND EVE...VEERING TO NW OVERNIGHT. ALTHOUGH THE WIND DIRECTION THIS PERIOD IS NOT ESPECIALLY CONDUCIVE FOR BUILDING SEAS...SEAS WILL STILL MANAGE TO REACH 6 FT OR HIGHER ACROSS PORTIONS OF THE OUTER WATERS AND UP TO 8 OR 9 FT AROUND FRYING PAN SHOALS. DEVELOPING BACKSWELL MAY ALLOW THESE HIGHER SEAS TO PERSIST ACROSS THE NORTHERN WATERS WELL INTO TUE. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...MODERATE OFFSHORE FLOW ON TUESDAY AS LOW PRESSURE BOMB OFF THE NEW ENGLAND COAST BRINGS CYCLONIC FLOW ACROSS THE ENTIRE EAST COAST. DUE TO THE DISTANCE OF THIS STORM AND THE FACT THAT ITS BACKSWELL DOES NOT SIGNIFICANTLY REFRACT AROUND CAPE HATTERAS TOWARDS OUR REGION IT SEEMS THAT WE MAY NOT SEE ANY ADVISORIES SAVE FOR PERHAPS THE FIRST FEW HOURS OF THE PERIOD. THEREAFTER DECREASING WINDS AND SEAS EXPECTED AS THE GRADIENT EASES. NOT TOO FAR OFFSHORE HOWEVER THERE WILL STILL BE A BROAD AGITATED WIND FIELD AND MARINERS VENTURING OUT PAST OUR 20NM ZONES ARE URGED TO CHECK WITH THE OFFSHORE WATERS FORECAST FROM OPC. A FURTHER ABATING OF THE WIND FIELD IS SLATED FOR WEDNESDAY AND THE WIND DIRECTION WILL ALSO BE VEERING AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...TAKING UP RESIDENCE ALONG THE COASTLINE BY AFTERNOON/EVENING. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 AM MONDAY...AN INITIALLY LIGHT SOUTH TO SOUTHWESTERLY RETURN FLOW WILL BECOME ESTABLISHED ACROSS THE SOUTHEAST AS A WEAKENING HIGH PRESSURE CELL MOVES OFF THE COAST. BY EVENING THIS WIND FIELD WILL INCREASE A BIT IN RESPONSE TO AN APPROACHING COLD FRONT FROM THE NORTHWEST. THE APPROACH AND PASSAGE OF THIS BOUNDARY WILL BRING AN EXTENDED PERIOD OF VEERING DIRECTION WHICH PAIRED WITH THE HIGHER WIND SPEEDS COULD LEAD TO SOME MARGINAL 6 FT SEAS OVER MAINLY NORTHERN ZONES. NW WINDS BEHIND THE FRONT ON FRIDAY WITH WIND AND SEAS BOTH SHOWING A DOWNWARD/IMPROVING TREND.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 7 AM EST TUESDAY FOR AMZ254-256. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 7 AM EST TUESDAY FOR AMZ250-252.
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&& $$ SYNOPSIS...MBB NEAR TERM...RJD SHORT TERM...MBB LONG TERM...MBB AVIATION...RJD/SGL MARINE...

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