Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 100901
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
401 AM EST WED FEB 10 2016

.SYNOPSIS...
A DRY ARCTIC FRONT WILL REINFORCED THE COLD AIR TODAY. BELOW
NORMAL TEMPERATURES ARE EXPECTED TODAY AND THROUGH THE REST OF THE
WEEK. ANOTHER ARCTIC FRONT WILL CROSS THE AREA FRIDAY WITH A SMALL
CHANCE FOR SOME SHOWERS. EVEN COLDER AIR WILL FOLLOW AND THE
COLDEST AIR OF THE SEASON IS FORECAST THIS WEEKEND. TEMPERATURES
WILL BEGIN TO MODERATE EARLY NEXT WEEK AS THE CENTER OF THE ARCTIC
HIGH MODIFIES AND MOVES AWAY FROM THE REGION. A LOW PRESSURE
SYSTEM MAY IMPACT THE AREA ON TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM WEDNESDAY...A LARGE AMPLITUDE UPPER TROF WILL BE THE
MAIN PLAYER ALOFT FOR THE ILM CWA AS WELL AS ROUGHLY THE EASTERN 1/2
OF THE UNITED STATES. THIS WILL RESULT IN A CONTINUED ROUGHLY 15
DEGREE BELOW NORMAL TEMPERATURE REGIME DURING THIS PERIOD. FOR
TODAYS HIGHS...WENT WITH A 40 TO 45 DEGREE RANGE AND THIS MAY BE
TOO MILD GIVEN TEMPERATURES AT 850MB ARE PROGGED TO DROP TO
-10 TO -13 DEGREES C BY THIS EVENING. ENOUGH MOISTURE IN THE LOWER
LEVELS AND THE DYNAMICS FROM THE SHEARED VORT OVERHEAD...MAY BE
ENOUGH TO PRODUCE SCATTERED...TO POSSIBLY A BROKEN DECK OF STRATOCU
CLOUDS OVER NORTHERN PORTIONS OF THE ILM CWA WHERE SKIES WILL
BE PARTLY CLOUDY.

FOR TONIGHT...850MB TEMPS ACTUALLY WARM TO -6 TO -9 DEGREES C BY
DAYBREAK THU. THIS IS IN RESPONSE TO A TRANSITION TO A SLIGHTLY
LOWER AMPLIFICATION TO THE LONGWAVE UPPER TROF ACROSS THE FA...AND A
NORTHWARD PLACEMENT/ADJUSTMENT OF THE LINE OF SHEARED VORTICITY IN
THE MID-LEVELS. AT THE SFC...THIS WILL RESULT IN A RELAXING SFC PG
DURING TONIGHT. AND WITH THE CAA BECOMING NEUTRAL AT THE SFC...NO
GUSTY WINDS ARE EXPECTED. THE WAA ALOFT WILL NOT BE REALIZED AT THE
SFC TONIGHT...AND AS A RESULT HAVE STAYED WITH THE COLDEST OF THE
AVBL MODEL MOS GUIDANCE...WHICH IS IN THE LOW 20S WITH POSSIBLE
OUTLIER UPPER TEENS WEST OF THE I-95 CORRIDOR.

SFC DEWPOINTS ARE PROGGED TO DROP INTO THE TEENS LATER TODAY AND
CONTINUE THRU TONIGHT. THIS IS TYPICAL OF A DRY ARCTIC AIRMASS. THE
INFLUX OR ADVECTION OF THIS COLD DRY AIR MASS WILL BE DELIVERED BY
WEST TO NW WINDS AT 10 TO 20 MPH...WITH OCCASIONAL GUSTS UP TO 25+
MPH DURING DAYLIGHT HOURS TODAY WHERE MIXING IN THE LOW LEVELS WILL
BE ABLE TO PULL DOWN THOSE HIER WINDS ALOFT. WIND CHILL READINGS
FORA COUPLE HOURS THIS MORNING WILL RANGE FROM THE UPPER TEENS
INLAND...IE. IN THE VICINITY OF THE I-95 CORRIDOR...TO THE LOW 20S
AT THE COAST.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...WELL BELOW NORMAL TEMPERATURES TO RULE THE
SHORT TERM AS A LARGE UPPER TROUGH DOMINATES THE EASTERN CONUS.
WITHIN THIS TROUGH...A PIECE OF VORT ENERGY WILL ROTATE THROUGH THE
CAROLINAS LATE FRIDAY...WITH SOME INCREASING CLOUDINESS AND MAYBE
SOME PRECIP BENEATH IT. THE ANTECEDENT COLUMN IS QUITE DRY...PWATS
AROUND 0.25 INCHES THURSDAY INTO FRIDAY...SO AS THE IMPULSE MOVES
OVERHEAD PRECIP WILL BE TOUGH TO DEVELOP. SOUNDINGS DO SUGGEST
SATURATION BOTH ABOVE 600MB AND BELOW 800MB...BUT THE DENDRITIC ZONE
REMAINS VERY DRY. THIS COULD BE A SITUATION WHERE SNOWFLAKES WILL
EVAPORATE INTO THE DENDRITIC ZONE ALOFT...LEAVING JUST A FEW COLD
SPRINKLES/SHOWERS LOCALLY. HOWEVER...CANNOT RULE OUT A FEW
SNOWFLAKES IF THE VORT BECOMES MORE POTENT AND CAN SATURATE THE
ENTIRE COLUMN BEFORE TEMPS WARM NEAR THE SURFACE...BUT ATTM LOCAL
TOPDOWN METHODOLOGY PRODUCES ALL LIQUID AND WILL CARRY JUST -RW
WITH VERY LIGHT QPF.

THE PRIMARY STORY THEN IS THE BELOW NORMAL TEMPS...FORECAST TO BE 10-
15 DEGREES BELOW CLIMO FOR EARLY FEBRUARY. HIGHS THURSDAY AND FRIDAY
WILL BOTH STRUGGLE INTO THE MID 40S...MAYBE APPROACHING 50 IN THE
FAR SOUTHERN ZONES ON FRIDAY. MINS THURSDAY NIGHT WILL DROP WELL
INTO THE 20S AWAY FROM THE COAST...BUT BE MUCH WARMER FRIDAY
NIGHT...30-35...DUE TO CLOUDS AND WIND BEFORE COLD ADVECTION
DEVELOPS LATE.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...EXTREMELY COLD TEMPERATURES FOR THE WEEKEND
WILL SLOWLY MODERATE NEXT WEEK BEFORE A LOW PRESSURE SYSTEM IMPACTS
THE REGION LATE IN THE EXTENDED.

ANOMALOUS TROUGH ACROSS THE EAST STRENGTHENS OVER THE WEEKEND AS A
PIECE OF VORT ENERGY DRIVES A COLD FRONT OFFSHORE ON SATURDAY. 850MB
TEMP PLUMMET TO NEAR -15C...WARMER THAN PREVIOUS GUIDANCE BUT STILL
VERY COLD...AND AS THE CORE OF THE COLDEST AIR MOVES OVERHEAD LATE
SATURDAY AND SUNDAY...HIGHS AND LOWS MAY BE CLOSE TO 30 DEGREES
BELOW CLIMO. SUNDAY MORNING LOWS ARE FORECAST TO BE IN THE MID TO
UPPER TEENS...WITH HIGHS ON SUNDAY LIKELY REMAINING RIGHT AROUND
FREEZING. AFTER ANOTHER COLD NIGHT SUNDAY NIGHT TEMPS BEGIN TO
MODERATE AS THE LONGWAVE TROUGH AXIS SHIFTS OFFSHORE ALLOWING FOR
SUBTLE SHORTWAVE RIDGING AND A PERIOD OF RETURN FLOW AT THE SURFACE
AHEAD OF THE NEXT SYSTEM. THIS WILL BRING TEMPS WARM ENOUGH FOR THE
TUESDAY LOW PRESSURE TO LIKELY BE AN ALL-RAIN EVENT...BUT IT WILL
NEED TO BE MONITORED CLOSELY FOR ANY PTYPE ISSUES.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
AS OF 06Z...LARGE AMPLITUDE LONGWAVE UPPER TROF WILL CONTINUE TO
INJECT COLD ARCTIC AIR INTO THE REGION THROUGH THE PASSAGES OF MID-
LEVEL S/W TROFS/VORTS ROTATING THRU. MUCH OF THIS IS SHEARED
VORTICITY BUT NEVERTHELESS ENOUGH TO WORK WITH THE AVBL MOISTURE
TO PRODUCE AN OCCASIONAL STRATOCU AND/OR ALTOCU CLOUD DECKS ALONG
WITH ISOLATED SNOW SHOWERS OR FLURRIES WITH LITTLE OR NO
ACCUMULATION. CONTINUED COLD/ARCTIC AIR ADVECTION ALONG WITH
LOWER DEWPOINTS WILL PUSH ACROSS THE AREA THIS PERIOD. LOOK FOR
260-280 WIND DIRECTIONS THRUOUT...WITH SPEEDS 10-15 KT EARLY
THIS MORNING AND THIS EVENING...10-20 KT WITH GUSTS 24 TO 28 KT
DURING THE LATE MORNING AND AFTERNOON DUE TO MIXING OF THE
STRONGER WINDS ALOFT TO THE SFC.

EXTENDED OUTLOOK...PREDOMINATELY VFR. EXPECT W TO NW WINDS GUSTING
UP TO 15 TO 25 KT THURSDAY...AND 20 TO 30+ KT DURING SATURDAY INTO
SUNDAY. CHANCE OF PRECIP ON FRIDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM WEDNESDAY...SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
ALL WATERS...THROUGH THURSDAY MORNING. THIS A RESULT OF A TIGHTENED
SFC PG COMBINED WITH CONTINUED COLD AIR ADVECTION OR ARCTIC AIR
ADVECTION SURGES RESPECTIVELY. THIS COLD/ARCTIC AIR WILL BE
ADVECTING ACROSS SSTS IN THE 40S AND 50S WHICH WILL ALLOW THE
STRONGER WINDS JUST OFF THE DECK TO MIX DOWN TO THE OCEAN SURFACE.
WINDS WILL BASICALLY RUN 260-280 DEGREES AT 20 TO 25 KT WITH GUSTS
UP TO 30 KT...AND VEER SLIGHTLY TO 280-300 DEGREES AT 15 TO 20 KT
TONIGHT. WILL SEE GUSTS UP TO 25 KT THIS EVENING. DUE TO THE
OFFSHORE NATURE OF THE WINDS...THE HIGHER WIND SPEEDS WILL PRIMARILY
OCCUR OVER THE OUTER WATERS WHERE THERE IS LESS FRICTIONAL EFFECTS
FROM LAND. THE EXCEPTION ARE THE WATERS SOUTH OF CAPE FEAR TO LITTLE
RIVER INLET...WHERE WESTERLY WIND DIRECTIONS ARE NEARLY PARALLEL TO
THE COAST. BUT THIS WILL CHANGE TONIGHT WHEN WIND DIRECTIONS VEER TO
THE NW...A TRUE OFFSHORE DIRECTION FOR ALL ILM WATERS.

SIGNIFICANT SEAS WILL RUN 3 TO 7 FT...WITH A FEW 8 FOOTERS POSSIBLE
ACROSS THE OUTER WATERS OFF CAPE FEAR. DUE TO A SLIGHTLY LONGER
FETCH FOR WHICH TO BUILD SEAS UPON...THE WATERS BETWEEN CAPE FEAR
SOUTH TO LITTLE RIVER WILL HAVE LESS OF A RANGE. AS WINDS VEER TO
THE NW...A TRUE OFFSHORE COMPONENT FOR ALL WATERS...SEAS WILL
HAVE A RANGE FROM 2 TO 3 FT NEAR SHORE TO 4 TO 5 FT OUTER
WATERS...EXCEPT UP TO 6 FT POSSIBLE OFF CAPE FEAR. SHORT PERIOD...4
TO 6 SECONDS...WIND DRIVEN WAVES WILL DOMINATE THE SIGNIFICANT SEAS
SPECTRUM.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...GUSTY NW WINDS WILL PLAGUE THE WATERS
MOST OF THE SHORT TERM BEHIND A COLD FRONT JUST BEFORE THIS
PERIOD...AND AGAIN LATE FRIDAY BEHIND A WEAK WAVE OF LOW PRESSURE.
MOST OF THURSDAY...AND THEN AGAIN LATE FRIDAY...WINDS ACROSS THE
WATERS WILL BE FROM THE NW AT 10-20 KTS. IN BETWEEN...THE
AFOREMENTIONED LOW PRESSURE WILL CAUSE A FLUCTUATION IN THE
GRADIENT AND WINDS TO VEER TO THE NE AROUND 10 KTS...DEPENDING ON
THE EXACT TRACK OF THIS LOW PRESSURE...BEFORE RETURNING TO THE NW
QUICKLY AS MENTIONED ABOVE. SEAS WILL BE PRIMARILY WIND-WAVE
DRIVEN...WITH SOME RESIDUAL 6 FT SEAS NECESSITATING THE SCA TO
CONTINUE INTO THURSDAY BEFORE FALLING TO JUST 1-2 FT BY FRIDAY AS
THE OFFSHORE WINDS AND DECREASING SPEEDS DRIVE LOWER AMPLITUDES.
RENEWED 2-4 FT SEAS WILL DEVELOP LATE AS THE WINDS INCREASE ONCE
AGAIN.

LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 300 AM WEDNESDAY...GUSTY WINDS FOR THE WKND WILL INITIALLY BE
NW AT 15-25 KTS...BEFORE SLOWLY VEERING TO THE NE ON SUNDAY WHILE
REMAINING AT ELEVATED SPEEDS. ALTHOUGH THIS WIND DIRECTION FEATURE A
SIGNIFICANT OFFSHORE COMPONENT...THE STRONG VELOCITIES WILL PUSH
SEAS UP TO 4-6 FT LATE SATURDAY AND INTO SUNDAY BEFORE WAVE HEIGHTS
DROP BACK TO 2-3 FT LATE IN THE WKND. A SMALL CRAFT ADVISORY WILL
LIKELY BE REQUIRED FOR ALL THE WATERS FOR PORTIONS OF SATURDAY AND
SUNDAY.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THURSDAY FOR AMZ250-252-
     254-256.

&&

$$
SYNOPSIS...JDW
NEAR TERM...DCH
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...DCH
MARINE...DCH/JDW


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