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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 121523
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1023 AM EST THU DEC 12 2013

.SYNOPSIS...
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COOL AND DRY HIGH PRESSURE WILL OVERSPREAD THE AREA TODAY AND
FRIDAY. THE WEEKEND WILL TURN UNSETTLED AS A STORM SYSTEM TRACKS
ACROSS THE SOUTHEAST AND INTO THE CAROLINAS...BRINGING RAIN TO
THE REGION SATURDAY AFTERNOON AND OVERNIGHT INTO EARLY SUNDAY.
COOL AND DRY CONDITIONS ARE EXPECTED MUCH OF NEXT WEEK IN WAKE
OF THIS FEATURE.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
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AS OF 1020 AM THURSDAY...DRY COLD FRONT SWEEPING OFF THE COAST AT
DAYBREAK HIGHLIGHTED SUNRISE WITH CIRRO-CUMULUS CLOUDS PAINTED IN
VARYING TONES OF ORANGE EARLIER...A PICTURE OF THE HIGH CLOUDS
FROM THE NWS OFFICE WAS POSTED ON FACEBOOK PAGE FROM EARLIER.

REINFORCING WAVE OF COLD AIR WILL PROMPT BRIGHT AND COOL WEATHER
TODAY AND A DEEP-FREEZE AREA-WIDE OVERNIGHT. READINGS IN THE MID
20S AT DAYBREAK FRIDAY ANTICIPATED...AS COLD AS 20 DEGREES IN OUR
INTERIOR COLD POCKETS...AND NEAR FREEZING AT THE IMMEDIATE COAST.

MODERATE NORTH WINDS WILL AID IN MAINTAINING WIND CHILL VALUES IN
THE UPPER 30S TO LOWER 40S MUCH OF THE DAY...WITH MAXIMUM TEMPS
HOLDING BELOW 50S OVER MANY AREAS TODAY...OR ABOUT 10 DEGREES
BELOW NORMAL FOR MIDDLE DECEMBER...AND THEN EQUALLY AS COLD
RELATIVE TO CLIMATE STANDARDS TOMORROW MORNING.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...SURFACE RIDGE AXIS OVER THE AREA AT THE START
OF THE PERIOD WILL SHIFT OFFSHORE DURING FRI AS SOUTHERN STREAM
SHORT WAVE EMERGES FROM THE SOUTHWEST. INITIALLY SOUTHEAST FLOW
DEVELOPS AROUND THE BACKSIDE OF THE HIGH BUT THEN WEAK COASTAL
TROUGH TAKES SHAPE...BACKING WINDS TO EAST-NORTHEAST FRI NIGHT.
ALTHOUGH RETURN FLOW DOES BRIEFLY DEVELOP ON FRI COLD AIR MASS IN
PLACE WILL KEEP HIGHS BELOW CLIMO...MOSTLY LOWER 50S.

MOISTURE AHEAD OF THE PREVIOUSLY MENTIONED SOUTHERN STREAM SHORTWAVE
WILL INCREASE CLOUD COVER OVER THE AREA LATE FRI AND FRI NIGHT.
CLOUDS WILL INITIALLY BE CIRRUS BUT WILL LOWER AS DEEPER MOISTURE
ADVECTS INTO THE AREA. MEANWHILE INCREASING LOW LEVEL MOISTURE AND
ISENTROPIC LIFT ASSOCIATED WITH THE DEVELOPING COASTAL TROUGH WILL
RESULT IN AN INCREASE IN LOW CLOUD COVER EARLY SAT. AT THIS POINT
ISENTROPIC LIFT IS SUFFICIENTLY WEAK THAT IT DOES NOT APPEAR
MEASURABLE PRECIP WILL DEVELOP BEFORE 12Z. INCREASED CLOUD COVER AND
BOUNDARY LAYER FLOW FRI NIGHT WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE
CLIMO.

TRACK OF SOUTHERN STREAM WAVE AND SURFACE LOW SUGGEST THE COASTAL
TROUGH WILL MOVE ONSHORE DURING SAT MORNING BEFORE LIFTING NORTH AS
A WARM FRONT. DEEP MOISTURE FOLLOWS THE WARM FRONT WITH PRECIPITABLE
WATER VALUES EXCEEDING 1.5 INCHES LATE SAT. LOW LEVEL CONVERGENCE
AND INSTABILITY...MOST OF WHICH WILL NOT BE SURFACE BASED...COMBINED
WITH STRONG DIVERGENCE ALOFT SAT INTO SAT NIGHT LEADS TO A PERIOD OF
RAIN WHICH COULD BE QUITE HEAVY AT TIMES OVERNIGHT. CONFIDENCE IS
INCREASING BUT AT THIS POINT NOT CONFIDENT ENOUGH TO NAIL DOWN A
TIME FOR 100 POP...THOUGH THINK 100 WILL BE WARRANTED AT SOME POINT
LATE SAT OR SAT NIGHT. EXPECT A NARROW RANGE OF TEMPS SAT AND SAT
NIGHT...PROBABLY ON THE ORDER OF 10 DEGREES OR LESS GIVEN CLOUD
COVER AND SOUTHWEST FLOW THROUGH THE END OF THE PERIOD.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...RAIN WILL BE FALLING AT THE START OF THE
PERIOD AS COLD FRONT ENTERS THE FORECAST AREA FROM THE WEST. FRONT
TRAILS DEEPENING LOW OF THE MID ATLANTIC COAST WHICH WILL TRAVEL
NORTHEAST PASS OFF THE NEW ENGLAND COAST DURING SUN. WEAK SOUTHERN
STREAM SHORTWAVE TROUGH WILL BE SLOW TO MOVE EAST...SLOWING THE
FRONTS PROGRESSION. IT SEEMS LIKE PRECIP WILL LINGER INTO SUN
AFTERNOON...ESPECIALLY ALONG THE COAST. THERE WILL BE QUICK MID
LEVEL DRYING BEHIND THE FRONT BUT LOW LEVEL MOISTURE WILL LINGER
INTO MON MORNING SO SKIES ARE LIKELY TO REMAIN CLOUDY. DESPITE THE
CLOUD COVER LOWS WILL END UP NEAR TO SLIGHTLY BELOW CLIMO DUE TO
POST FRONT COLD ADVECTION.

SKIES SLOWLY CLEAR ON MON AS LOW LEVELS DRY OUT. NORTHERLY FLOW
WILL CONTINUE TO KEEP COLD AIR FILTERING INTO THE REGION...BUT THE
STRENGTH OF THE COLD ADVECTION IS RATHER WEAK. HIGHS WILL BE IN THE
LOW TO MID 50S DESPITE INCREASING SUNSHINE. WEAK SURFACE RIDGE AXIS
IN THE AREA MON NIGHT WILL ALLOW SOME RADIATIONAL COOLING MON NIGHT
AND LOWS WILL DROP BELOW CLIMO...LOW TO MID 30S.

MID LEVEL PATTERN FLATTENS OUT FOR TUE AND WED WITH MODIFYING HIGH
PRESSURE BUILDING IN FROM THE WEST. PRECIPITABLE WATERS WILL BE
AROUND 0.30 INCH TUE/WED WITH LIMITED CLOUD COVER AND ALMOST NO
CHANCE OF PRECIP. TEMPERATURES WILL BE NEAR CLIMO...UPPER 50S/LOWER
60S AND UPPER 30S/LOWER 40S.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
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AS OF 15Z...A DRY COLD FRONT IS PRESENTLY MAKING ITS WAY THROUGH
OUR CWA THIS MORNING...AS EVIDENCED BY THE MID/HIGH CLOUDS ON
SATELLITE IMAGERY AND THE SURGE OF N-NW WINDS. EXPECT GUSTY NORTH
WINDS 10-15 KTS TODAY AS REINFORCED DRY HIGH PRESSURE DOMINATES
OUR WEATHER. THE GUSTS WILL SUBSIDE THIS EVENING AS WINDS BECOME
LIGHT/CALM AFTER 00Z FRIDAY. DO NOT ANTICIPATE ANY FOG ISSUES
OVERNIGHT AS SFC DEWPOINTS DROP INTO THE LOW 20S.

EXTENDED OUTLOOK...VFR THROUGH FRIDAY NIGHT. SHOWERS LIKELY WITH
PERIODS OF MVFR/IFR CONDITIONS SATURDAY AND SUNDAY. VFR ON MONDAY.
-- End Changed Discussion --

&&

.MARINE...
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NEAR TERM /THROUGH TONIGHT/...
AS OF 1020 AM THURSDAY...CAUTIONARY CONDITIONS WILL PREVAIL THIS
MORNING DUE TO MODERATE N WIND GUSTS AND 5 FOOT SEAS OVER THE VERY
OUTER WATERS. WIND-SPEEDS WILL TAKE A SLOW ROAD TO DIMINISHING
TODAY BUT BY TONIGHT...EASING OF THE PRESSURE GRADIENT OCCURS.
THUS WE WILL MAINTAIN THE CAUTIONARY HEADLINE AT LEAST THROUGH A
PART OF THE AFTERNOON UNTIL OBSERVATIONS BEGIN TO SHOW THE ONSET
OF THE DOWNWARD WIND-SPEED TREND. THERE IS SOME DISAGREEMENT IN
MODELS ON WHEN THIS OCCURS...THIS AFTERNOON OR THIS EVENING. BY
DAYBREAK FRIDAY LIGHT WINDS CAN BE EXPECTED AS THE SURFACE HIGH
BECOMES POSITIONED NEARLY OVERHEAD OF THE AREA.

SHORT TERM /FRIDAY THROUGH SATURDAY
NIGHT/... AS OF 3 AM THURSDAY...LIGHT NORTHERLY FLOW FRI MORNING
WILL VEER TO NORTHEAST BY MIDDAY AS SURFACE HIGH MOVES OFF THE NC
COAST. WEAK GRADIENT WILL KEEP SPEEDS 10 KT OR LESS THROUGH FRI
NIGHT. DEVELOPMENT OF WEAK COASTAL TROUGH FRI NIGHT WILL HAVE
LIMITED IMPACT ON THE WIND FIELD UNTIL THE TROUGH MOVES
ONSHORE...SAT MORNING. ONCE THE TROUGH MOVES INLAND EAST TO
SOUTHEAST FLOW WILL DEVELOP WITH STEADY INCREASE IN SPEEDS.
SOUTHEAST FLOW WILL BE 15 TO 20 KT BY SAT AFTERNOON...INCREASING
TO 20 TO 25 KT SAT NIGHT AND BECOMING SOUTH-SOUTHWEST AS LOW
PRESSURE PASSES WEST OF THE AREA. INCREASING SOUTHERLY FLOW WILL
PUSH SEAS OVER 6 FT INTO THE NEAR SHORE WATERS AS EARLY AS SAT
AFTERNOON...REQUIRING HEADLINES FOR THE SECOND HALF OF THE PERIOD.
INCREASED SOUTHERLY FLOW SAT NIGHT COULD PUSH SEAS TO 8 FT IN
WATERS EXPOSED TO A SOUTHWEST WIND.

LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...LOW PRESSURE EXITING TO THE NORTHEAST SUN WILL
DRAG A COLD FRONT ACROSS THE WATERS DURING THE DAY. AHEAD OF THE
FRONT FLOW WILL BE FROM THE SOUTHWEST...AT 15 TO 20 KT. ONCE THE
FRONT PASSES WINDS WILL VEER TO NORTHWEST BUT GRADIENT REMAINS
SUPPORTIVE OF 15 TO 20 KT WINDS INTO SUN EVE. GRADIENT STARTS TO
WEAKEN OVERNIGHT WITH WINDS SLOWLY VEERING TO NORTHERLY AS SPEEDS
DROP TO 10 TO 15 KT. HIGH PRESSURE BUILDING IN FROM THE WEST WILL
VEER WINDS TO NORTHEAST FOR MON AND MON NIGHT WITH SPEEDS REMAINING
10 TO 15 KT...THOUGH PERIOD OF SOLID 15 KT CAN BE EXPECTED MON
AFTERNOON WITH WEAK COLD SURGE. DEVELOPMENT OF OFFSHORE FLOW LATER
SUN WILL DROP SEAS FROM 4 TO 7 FT TO 3 TO 5 FT BY SUN EVE. FURTHER
REDUCTION IN SEAS IS ANTICIPATED AS WINDS VEER TO NORTHEAST AND
SPEEDS DROP.
-- End Changed Discussion --

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...8
NEAR TERM...8
SHORT TERM...III
LONG TERM...III
AVIATION...BJR/8