Area Forecast Discussion
Issued by NWS Wilmington, NC

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443 FXUS62 KILM 081200 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 700 AM EST MON FEB 8 2016 .SYNOPSIS... A POWERFUL LOW PRESSURE SYSTEM WILL CONTINUE MOVING AWAY FROM THE REGION TODAY AS WEAK HIGH PRESSURE BRIEFLY BUILDS IN. THE FIRST OF TWO COLD FRONTS WILL CROSS THE AREA TONIGHT...FOLLOWED BY THE NEXT ONE...AN ARCTIC COLD FRONT...DURING WEDNESDAY. AFTER TODAY...LOOK FOR TEMPERATURES DURING THIS WORK WEEK TO TREND LOWER...ESPECIALLY DURING THE MID TO LATE WEEK PERIOD WHEN ARCTIC AIR WILL SPREAD INTO THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 600 AM MONDAY...PROGRESSIVE FLOW AT ALL LEVELS WILL DOMINATE THIS PERIOD. EXITING POWERFUL LOW TO THE NE WILL FIND THE ILM CWA WITHIN A TEMPORARY LOW AMPLITUDE RIDGE ALOFT AND AT THE SFC. THE CLEAR SKIES AND SUBSIDENCE ALOFT AND TRANQUIL WX WILL LAST THRU THE LATE MORNING AND MIDDAY HRS OF TODAY. MODELS ARE IN AGREEMENT THAT CHANGES IN THE LONGWAVE PATTERN ALOFT WILL OCCUR THAT WILL RESULT IN AN AMPLIFYING UPPER TROF THAT WILL TAKE CONTROL OF THE U.S. MAINLY EAST OF THE MISSISSIPPI RIVER...AND DOWN TO THE GULF COAST STATES AND FLORIDA. AT THE SAME TIME...A WELL AMPLIFIED UPPER RIDGE WILL CONTROL ROUGHLY THE WESTERN HALF OF THE UNITED STATES. THIS WILL ALLOW COLD CANADIAN AND ARCTIC AIR MASSES TO DROP DOWN TO THE SOUTHEAST U.S...INCLUDING THE ILM CWA. MODELS INDICATE THE 1ST COLD FRONTAL PASSAGE TO OCCUR DURING THIS EVENING. A RATHER POTENT MID-LEVEL VORT ROUNDS THE BASE OF THE UPPER TROF THIS AFTN...AND LIFTS ACROSS THE FA LATE THIS AFTN AND EVENING AND IN THE PROCESS AIDS IN THE DEVELOPMENT OF LOW PRESSURE ALONG THIS FRONT IN THE VICINITY OF THE NORTHERN OUTER BANKS. MODELS INDICATE MOISTURE ALONG AND AHEAD OF THE COLD FRONT WITH THE GFS MOST BENEFICIAL. HAVE GONE WITH THE NAM THAT IS SOMEWHAT DRIER BUT NEVERTHELESS ENOUGH FORCING AND DYNAMICS FROM THE UPPER VORT TO PRODUCE SHOWERS ALONG AND AHEAD OF THE COLD FRONT. THE FREEZING LEVEL IS PROGGED TO RUN 4K TO 5K FT AT THE TIME WHEN THE PCPN OCCURS. THE FREEZING LEVEL IS JUST TOO HIGH FOR ANY POSSIBLE FROZEN PCPN WITH THIS CFP. IN ADDITION...SFC TEMPS LATE THIS AFTN AND EARLY EVENING WILL DROP FROM THE DAYS HIGHS IN THE 50S TO THE LOW TO MID 40S BY THIS EVENING. CAA IN THE WAKE OF THE CFP WILL OVERSPREAD THE FA UNDER GUSTY WESTERLY WINDS DURING MON NIGHT WITH 1000-500MB THICKNESS DROPPING FROM THE 540S EARLY MON EVENING TO THE 520S BY DAYBREAK TUE. VARIOUS MODEL MOS GUIDANCE SEEMS TOO HIGH FOR TONIGHTS LOWS AND THUS HAVE SHAVED SEVERAL DEGREES OFF THEIR CONSENSUS TO AT OR JUST ABOVE THE FREEZING MARK. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...IMPRESSIVE CUTOFF LOW OVER THE OH VALLEY TO START THE PERIOD WILL HELP MAINTAIN CLOUD COVER OVER THE LOCAL AREA ON TUE. SHORTWAVE ROTATING AROUND THE LOW COMBINED WITH INCREASED MID LEVEL MOISTURE WILL SPREAD CLOUD COVER OVER THE AREA TUE AND MAY EVEN LEAD TO SOME VIRGA. HOWEVER MEASURABLE PRECIP SEEMS UNLIKELY GIVEN THE AMOUNT OF LOW LEVEL DRY AIR. THE SHORTWAVE ALSO HELPS DRIVE A SECONDARY COLD FRONT ACROSS THE AREA. THE ACCOMPANYING ARCTIC SURGE WILL DROP 850 TEMPS FROM AROUND -7C TUE TO NEAR -13C LATER WED. COMBINATION OF COLD ADVECTION AND CLOUD COVER ON TUE WILL KEEP HIGHS AROUND 10 DEGREES BELOW CLIMO. COLD ADVECTION TUE NIGHT WILL KEEP BOUNDARY LAYER WELL MIXED BUT THE AIR MASS IS RATHER COLD AND LOWS ARE LIKELY TO DIP INTO THE MID 20S. TEMPERATURES WILL DIP EVEN LOWER WED AND WED NIGHT DESPITE AN INCREASE IN SUNSHINE ON WED. COLD ADVECTION WILL KEEP HIGHS IN MOST AREAS IN THE LOW 40S WITH LOWS WED NIGHT IN THE LOWER 20S. WIND CHILL VALUES DURING THE PERIOD WILL BE QUITE COLD...WITH MOST AREAS IN THE 20S BY DAY AND MID TEENS TO SINGLE DIGITS AT NIGHT...ESPECIALLY WED NIGHT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 3 AM MONDAY...MID LEVEL TROUGHING WILL REMAIN A DOMINANT FEATURE THROUGH THE PERIOD...KEEPING TEMPERATURES BELOW CLIMO INTO NEXT WEEK. THE ONLY FEATURE OF NOTE DURING THE PERIOD WILL BE PASSAGE OF A SHORTWAVE ROUNDING THE BASE OF THE TROUGH ON FRI. THERE WILL BE A CHANCE OF PRECIP AS THIS FEATURE PASSES BUT THE LIMITED NATURE OF THE MOISTURE COMBINED WITH THE DEEP WEST TO NORTHWEST FLOW SUGGESTS QPF WILL BE VERY LOW. PLAN TO MAINTAIN INHERITED SLIGHT CHC POP FOR THE END OF THE WEEK. SHORTWAVE HELPS DRIVE A COLD FRONT ACROSS THE AREA FRI NIGHT...BRINGING A REINFORCING SHOT OF COLD AIR FOR THE WEEKEND. MEDIUM RANGE GUIDANCE IS SHOWING 850 TEMPS IN THE -15C TO -20C RANGE SAT NIGHT AND SUN. NOT READY TO BUY INTO TEMPERATURES THAT COLD...ESPECIALLY GIVEN IT IS 6 DAYS OUT...BUT IT IS SOMETHING TO KEEP AN EYE ON. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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AS OF 12Z...INCREASING CLOUDS EXPECTED THIS AFTERNOON WITH A PASSING COLD FRONT THIS EVENING. CHANCE FOR SHOWERS AND BRIEF MVFR. OTHERWISE EXPECT VFR. QUIET CONDITIONS PREVAIL THIS MORNING WITH VFR...LIGHT WINDS AND CLEAR SKIES. WILL SEE INCREASING CLOUDS THIS AFTERNOON ALONG WITH INCREASING SOUTHWEST WINDS...AROUND 10 KTS WITH GUSTS AROUND 20KTS...AHEAD OF AN APPROACHING COLD FRONT. POTENTIAL FOR ISOLATED TO SCATTERED SHOWERS FOR A FEW HOURS LATE THIS AFTERNOON/EARLY EVENING...WITH ANY HEAVY DOWNPOUR POTENTIALLY CREATING BRIEF MVFR. WITH A COLD AIRMASS IN PLACE...WILL NOT ENTIRELY RULE OUT A RAIN/SNOW MIX...BUT CONFIDENCE IS QUITE LOW GIVEN WARMER LOW LEVEL TEMPS. THUS HAVE NOT INTRODUCED INTO GOING FORECAST. CONDITIONS IMPROVE TONIGHT WITH GUSTY WESTERLY WINDS AND PREVAILING VFR. EXTENDED OUTLOOK...PREDOMINATELY VFR. LOW CONFIDENCE FOR MVFR/IFR RAIN/SNOW SHOWERS FRIDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 600 AM MONDAY...SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL WATERS...AND CONTINUES INTO THE MID-WEEK PERIOD DUE TO A CONTINUED TIGHTENED SFC PG COMBINING WITH COLD/ARCTIC SURGES. THERE WILL BE A BRIEF PERIOD THIS MORNING INTO EARLY THIS AFTN THAT CONDITIONS LIKELY TO FALL BELOW SCA THRESHOLDS. HOWEVER...SW WINDS AND WEAK WAA DO PICKUP AHEAD OF THE APPROACHING COLD FRONT THIS AFTN...AND WILL FLIRT WITH SCA CRITERIA. HOWEVER...ITS AFTER THE CFP WHEN WESTERLY WINDS AND CAA OVERSPREADS THE FA. THE COLD SURGE WILL COMBINE WITH A WELL TIGHTENED SFC PG TONIGHT...RESULTING WITH WESTERLY WINDS REACHING SCA VALUES. SIGNIFICANT SEAS WILL BE AT THEIR LOWEST LATER THIS MORNING INTO THE AFTN...THEN PICK BACK UP FOR THIS EVENING AND OVERNIGHT WITH SHORT PERIOD WIND DRIVEN WAVES AGAIN LEADING THE CHARGE. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...PERIOD WILL BE MARKED BY STRONG WEST TO NORTHWEST FLOW...A RESULT OF STRONG COLD ADVECTION AND PINCHED SURFACE GRADIENT. OTHER THAN A BRIEF DECREASE IN SPEEDS WED MORNING...A PAUSE BETWEEN ROUNDS OF COLD ADVECTION...WINDS WILL REMAIN ABOVE SCA HEADLINE CRITERIA THROUGH THE ENTIRE PERIOD. THE LOCATION OF THE MID LEVEL TROUGH AXIS AND SURFACE FEATURES WILL KEEP WINDS WESTERLY THROUGH THE PERIOD BUT THE COLD ADVECTION WILL STILL BE VERY STRONG. WIND GUSTS IN EXCESS OF OF GALE FORCE ARE EXPECTED WITH POTENTIAL FOR GUSTS APPROACHING 40 KT WED NIGHT DURING THE STRONGEST PERIOD OF COLD ADVECTION. DESPITE THE OFFSHORE COMPONENT TO THE WINDS SEAS WILL REMAIN ABOVE 6 FT NEAR THE 20 NM BORDER...AND ALONG MUCH OF THE SOUTHERN HALF OF AMZ252...THROUGHOUT THE PERIOD. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 AM MONDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST DURING THE PERIOD. CONDITIONS WILL GRADUALLY IMPROVE ON THU AS COLD ADVECTION COMES TO AN END AND SURFACE GRADIENT STARTS TO WEAKEN. FLOW WILL REMAIN OFFSHORE BUT SPEEDS WILL DROP FROM AROUND 20 KT THU MORNING TO UNDER 10 KT THU NIGHT. LIGHT NORTHWEST FLOW BECOMES SOUTHWEST FRI AS NEXT SHORTWAVE/COLD FRONT COMBO APPROACH THE AREA. FRONT PUSHES ACROSS THE WATER FRI NIGHT WITH COLD ADVECTION DEVELOPING AS THE PERIOD ENDS. SEAS WILL BE FALLING FOR MUCH OF THE PERIOD...DROPPING FROM 3 TO 5 FT THU MORNING TO 2 TO 3 FT BY FRI AND 2 FT OR LESS FRI NIGHT. LATE IN THE PERIOD THE COMBINATION OF SOUTHWEST FLOW AHEAD OF THE FRONT AND INCREASED OFFSHORE FLOW BEHIND THE FRONT WILL RESULT LEAD TO BUILDING SEAS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR AMZ250-252- 254-256. && $$ NEAR TERM...DCH SHORT TERM...III LONG TERM...III AVIATION...SGL

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