Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 080833
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
333 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. A SECOND COLD FRONT
WILL CROSS THE AREA ON WEDNESDAY DROPPING TEMPERATURES EVEN
FURTHER BELOW NORMAL LATE IN THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 3 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 OR THE 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 DURING THIS
AFTN AND TONIGHT 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 SOUTH INTO
THE EASTERN UNITED STATES...INCLUDING THE SOUTH.

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 AIRFOR 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 /09Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...POWERFUL OFFSHORE LOW WILL MOVE NE FURTHER AWAY FROM
THE AREA OVERNIGHT. THE BACK EDGE OF THE MID AND UPPER LEVEL
CLOUDS WILL PULL TO THE NE DURING THE PRE-DAWN HRS...LEAVING CLEAR
SKIES IN ITS WAKE. THE GUSTY NW WINDS UNDER THE CLOUD DECKS WILL
TRANSITION TO WNW TO NW AT 4 TO 8 KT WITH NO GUSTS ONCE SKIES
CLEAR. A VIGOROUS MID-LEVEL VORT MAX WILL SWING AROUND THE BASE OF
THE UPPER TROF MIDDAY TODAY...AND LIFT NE ACROSS THE REGION
LATE MONDAY AFTERNOON AND EARLY EVENING. GUSTY SW WINDS WILL
INCREASE AHEAD OF THIS VORT AND AN APPROACHING COLD FRONT. THE
VORT WILL INTERACT WITH A COLD FRONT MOVING ACROSS THE REGION AND
RESULT IN A QUICK SHOT OF SHOWERS POSSIBLY MIXED WITH SNOW PRIOR
TO THE CFP MONDAY EVENING. THE AIRMASS WILL BE COLD ENOUGH ALOFT
TO SUPPORT A RAIN/SNOW MIXTURE BUT LOW LEVEL TEMPS ARE IN
QUESTION...MEANING WILL IT BE ABLE TO SUPPORT SNOW AT THE SFC OR
JUST PLAIN RAIN. FOR THE MID TO LATE EVENING...STRONG CAA WILL
ENSUE UNDER GUSTY WESTERLY WINDS.

EXTENDED OUTLOOK...PREDOMINATELY VFR. LOW CONFIDENCE FOR MVFR/IFR
RAIN/SNOW SHOWERS FRIDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM MONDAY...LOWERED GALES TO SMALL CRAFT ADVISORY FOR ALL
WATERS...AND CONTINUED IT INTO THE MID-WEEK PERIOD DUE TO A
TIGHTENED SFC PG COMBINING WITH COLD/ARCTIC SURGES NEARLY EACH DAY
OR ONGOING.

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...DCH


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