Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 200249
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
949 PM EST FRI DEC 19 2014

.SYNOPSIS...
CLOUDS WILL INCREASE TONIGHT AHEAD OF WEAK LOW PRESSURE THAT WILL
MOVE ACROSS THE NORTHERN GULF OF MEXICO. THIS LOW WILL PASS OFF
THE COAST SATURDAY BRINGING RAIN AND COOL TEMPERATURES. ANOTHER
AREA OF LOW PRESSURE MOVING UP THE COAST WILL BRING MORE CLOUDS AND
RAIN MONDAY AND TUESDAY. A LARGE LOW PRESSURE SYSTEM WILL PASS TO
THE NORTHWEST WEDNESDAY AND DRIVE A STRONG COLD FRONT THROUGH THE
CAROLINAS. COLD AND DRY WEATHER IS EXPECTED FOR THE END OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 930 PM FRIDAY...HIGH CLOUDS ARE THICKENING ACROSS THE EASTERN
CAROLINAS. THE LEADING EDGE OF THE MID-LEVEL DENSE OVERCAST SHOULD
ARRIVE ALONG THE I-95 CORRIDOR SHORTLY AFTER MIDNIGHT. LATEST
HIGH-RES MODELS LOOK VERY SIMILAR TO OUR PREVIOUS THOUGHTS WITH RAIN
CHANCES INCREASING FROM THE SW LATE TONIGHT, BUT WITH THE BULK OF
THE PRECIPITATION HOLDING OFF UNTIL AFTER DAYBREAK. POPS LATE
TONIGHT HAVE BEEN TWEAKED DOWNWARD AGAIN ACROSS SE NORTH CAROLINA
WITH LITTLE CHANGE ELSEWHERE. HOURLY TEMPERATURES ARE RUNNING A FEW
DEGREES HIGHER THAN EARLIER PROJECTIONS, ESPECIALLY INLAND WHERE
CLOUDS HAVE INTERFERED MOST WITH RADIATIONAL COOLING. FORECAST LOWS
HAVE BEEN BUMPED UP IN RESPONSE WITH UPPER 30S ACROSS SE NORTH
CAROLINA TO LOWER 40S ACROSS THE PEE DEE. PREVIOUS DISCUSSION FROM
630 PM FOLLOWS...

RADAR COMPOSITES SHOW RAIN HAS ADVANCED AS FAR EAST AS EAST-CENTRAL
ALABAMA. THIS MATCHES UP WELL WITH ANALYZED & FORECAST LIFT ON THE
300K-305K ISENTROPIC SURFACES. WHILE VIRTUALLY ALL MODEL GUIDANCE
SHOWS MOIST LIFT DEVELOPING IN THE EASTERN CAROLINAS WITHIN THIS
LAYER (10000-15000 FT) SHORTLY AFTER 06Z/1 AM EST...THERE WILL BE
SIGNIFICANT DRY AIR BELOW THE CLOUD BASE TO OVERCOME. COMPARING
VARIOUS MODELS MEAN RH IN THE 1000-700 MB LAYER AT 06, 09, AND 12Z
THE GFS IS THE MOST MOIST WITH THE NAM THE DRIEST. 18Z GFS MOS POPS
APPEAR TO BE TAKING THE DRY AIR QUITE SERIOUSLY...AND EYEBALLING
FORECAST SOUNDINGS IT SHOULD TAKE A FAIRLY SIGNIFICANT AMOUNT OF
RAIN TO MOISTEN THE LOW LEVELS.

WITH THIS IN MIND I HAVE TRIMMED BACK POPS LATE TONIGHT ACROSS
COASTAL SE NORTH CAROLINA WHERE MEASURABLE RAIN PROBABLY WON`T OCCUR
UNTIL AFTER DAYBREAK. POPS HAVE ACTUALLY BEEN INCREASED FOR THE
FLORENCE-DARLINGTON-KINGSTREE AREA LATE. NO SIGNIFICANT CHANGES TO
TEMPERATURES HAVE BEEN MADE AS INCREASING CLOUD COVER WILL ALLOW
MOST OF OUR TEMPERATURE DROP TO OCCUR THIS EVENING, WITH FAIRLY
STEADY TEMPERATURES EXPECTED LATE TONIGHT.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...COOL AND CLOUDY WEEKEND ON TAP WITH A SERIES OF
WEAK SURFACE WAVES PASSING OFF THE SOUTHEAST COAST. THE FIRST
ARRIVES EARLY SATURDAY MORNING...ASSOCIATED WITH WEAKENING 5H
SHORTWAVE. THE SURFACE WAVE/LOW IS RATHER UNINSPIRING BUT DOES
PROVIDE A DECENT AMOUNT OF LOW LEVEL MOISTURE. SURFACE HIGH RIDGING
DOWN THE COAST ENHANCES ISENTROPIC LIFT...WHICH SHOULD BE ABLE TO
TAP INTO THE AVAILABLE MOISTURE. THERE IS A PERIOD SAT INTO SAT
EVENING WHERE DEEP MOISTURE...ASSOCIATED WITH THE SHORTWAVE...IS
PRESENT. ALTHOUGH POP REMAINS IN THE LIKELY TO CATEGORICAL RANGE
TOTAL QPF WILL BE LOW. RAIN WILL BE LIGHT WITH THE BULK OF THE
PRECIP CONFINED TO THE COAST. SURFACE AND MID LEVEL FEATURES MOVE
EAST SAT NIGHT FOLLOWED BY WEAK MID LEVEL SUBSIDENCE. ALTHOUGH
DRYING OCCURS ALOFT THE LOW LEVELS REMAIN QUIET MOIST WITH THE WEDGE
HOLDING STRONG. SKIES WILL REMAIN CLOUDY SAT NIGHT AND SUN WITH
HIGHS RUNNING BELOW CLIMO AND LOWS NEAR CLIMO. ALTHOUGH NO
MEASURABLE PRECIP IS EXPECTED SUN FORECAST SOUNDINGS DO SUGGEST THE
POSSIBILITY OF PATCHY DRIZZLE...SOMETHING TO KEEP AN EYE ON.

THE NEXT AND CURRENTLY BEST CHANCE AT SIGNIFICANT RAIN IN THE PERIOD
WILL BE SUN NIGHT INTO MON. ANOTHER MORE SIGNIFICANT SURFACE WAVE
MOVES UP THE BOUNDARY THAT WILL BE STALLED OFF THE COAST FOR MUCH OF
THE PERIOD. SURFACE HIGH CONTINUES PUSHING DOWN THE COAST AS THE LOW
AND ITS ASSOCIATED MOISTURE MOVES NORTHEAST. INCREASING ISENTROPIC
LIFT IN AN AREA OF INCREASE DEEP MOISTURE...PRECIPITABLE WATER
VALUES EXCEED 1.25 INCH BY THE END OF THE PERIOD...SHOULD LEAD TO
RAIN DEVELOPING ACROSS MUCH OF THE AREA BY MON MORNING. CLOUD COVER
AND NORTHERLY FLOW WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...LOOKS LIKE RAIN WILL BE ONGOING AT THE START
OF THE LONG TERM PERIOD. SHALLOW COOL AIR WILL BE IN PLACE THROUGH
THE MORNING WITH A NORTHEAST FLOW AT THE SFC AS HIGH PRESSURE
REMAINS WEDGED IN THROUGH INLAND CAROLINAS. AN AREA OF LOW
PRESSURE WILL MOVE UP THE SOUTHEAST COAST THROUGH THE DAY WITH A
TROUGH EXTENDING NE FROM THE LOW JUST OFF SHORE IN A MORE TYPICAL
WEDGE LIKE SCENARIO. AS THE LOW MOVES FARTHER NORTH BY MON
AFTERNOON THE COASTAL TROUGH WILL GET PUSHED INLAND SLIGHTLY
DRIVING WARMER TEMPS AND MORE SHOWERY WEATHER INTO COASTAL AREAS.
ITS ALWAYS TOUGH TO TIME WHEN THIS WILL OCCUR BUT FOR NOW WILL
SHOW A TREND OF WARMING ALONG THE COAST. PCP MAY BE MORE
INTERMITTENT AS THE LOW TRACKS NORTH AND COASTAL CAROLINAS END UP
IN A NW FLOW ON THE BACK END INITIALLY FOLLOWED BY A DEEPER WARMER
AND MOISTER SOUTHERLY FLOW ON TUES AHEAD OF NEXT SYSTEM. THEREFORE
SHALLOW COOL AIR IN PLACE MON MORNING WILL BE REPLACED BY DEEPER
WARMER AIR BRIEFLY ALONG THE COAST AND THEN COOLER AIR THROUGH MON
NIGHT.

DEEPER SOUTHERLY FLOW WILL SET UP ON TUES AHEAD OF NEXT STORM SYSTEM
SHIFTING EAST FROM THE MISSISSIPPI VALLEY. UNSETTLED WEATHER
WILL REMAIN AHEAD OF THIS SYSTEM THROUGH TUES INTO WED BEFORE COLD
FRONT MOVES THROUGH LATE WED. THE DIGGING MID TO UPPER TROUGH WILL
FINALLY MOVE OFF SHORE BY THURS MORNING LEAVING DRIER AND COOLER
WEATHER FOR CHRISTMAS DAY. OVERALL EXPECT CLOUDY AND DAMP TO WET
WEATHER THROUGH THE FIRST HALF OF THE PERIOD WITH COOLER MORE
SEASONABLE WEATHER THURS INTO FRI AS HIGH PRESSURE BUILDS ACROSS THE
SOUTH.

TEMPS WILL START OUT COOL BUT WILL WARM AS COASTAL TROUGH/WARM FRONT
PUSHES INLAND LATE MONDAY INTO TUES. TIGHT GRADIENT WILL EXIST ON
MON BETWEEN COOLER TEMPS INLAND...IN THE 40S MOST PLACES...TO
POSSIBLE 60S ALONG THE COAST. BY TUES THE WARMER AIR SHOULD MAKE IT
INTO THE WESTERN REACHES OF LOCAL FORECAST AREA LEAVING TEMPS CLOSER
TO 60 MOST PLACES FOR TUES AND WED UNTIL COLD FRONT MOVES THROUGH BY
THURS.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...VFR CONDITIONS TONIGHT WILL DETERIORATE INTO SAT MORNING
AS RAIN OVERSPREADS THE EASTERN CAROLINAS. CURRENT SATELLITE IMAGERY
INDICATES MID/HIGH CLOUDS WILL CONTINUE INCREASING IN COVERAGE
OVERNIGHT AHEAD OF AN UPPER DISTURBANCE. MOIST ISENTROPIC LIFT WILL
BRING -RA AND LOWERING CIGS FROM SOUTH TO NORTH BEGINNING AROUND
DAYBREAK. DRY AIR IN THE LOWER LEVELS WILL INITIALLY KEEP CIGS
VFR...BUT AS RAIN CONTINUES TO FALL...CIGS WILL LIKELY DROP TO MVFR
LEVELS BY AROUND MIDDAY. GFS SOUNDINGS HINT AT THE POSSIBILITY OF
IFR CIGS ESPECIALLY ALONG THE COAST...BUT FOR NOW WILL KEEP ALL
TERMINALS ABOVE 1KFT. WINDS ON SAT WILL BE NORTHEAST AOB 10 KT. RAIN
SHOULD TAPER OFF AT THE INLAND SITES BY 21Z...ALTHOUGH LOW CLOUDS
WILL HANG AROUND AREA WIDE THROUGH THE END OF THE PERIOD.

EXTENDED OUTLOOK...MVFR CIGS POSSIBLE ON SUN. RAIN LIKELY MON WITH
MVFR/IFR CONDITIONS AS A COASTAL TROUGH DEVELOPS OFFSHORE. MORE
SHOWERS EXPECTED TUE/WED AHEAD OF A STRONG COLD FRONT. GUSTY WINDS
WILL DEVELOP DURING THE DAY WED.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 930 PM FRIDAY...NO CHANGES ARE NECESSARY TO THE FORECAST.
PREVIOUS DISCUSSION FROM 630 PM FOLLOWS...

ADJUSTED INITIAL SEA HEIGHTS DOWN SLIGHTLY IN THE GRIDDED FORECAST
DATABASE GIVEN CURRENT OBSERVATIONS OF NOTHING HIGHER THAN 1 FOOT
WITHIN 20 MILES OF SHORE. NE WINDS SHOULD GRADUALLY BUILD SEAS TO 2
FEET OVERNIGHT WITH 3 FOOTERS STARTING TO SHOW UP BY DAYBREAK.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...HIGH PRESSURE CONTINUES TO BUILD DOWN THE COAST
THROUGH THE PERIOD WHILE A SERIES OF WEAK SURFACE WAVES/LOWS PASS
EAST OF THE WATERS. THE RESULT WILL BE A SLIGHTLY PINCHED GRADIENT
AND NORTHEAST FLOW OF 10 TO 15 KTS...WITH POTENTIAL FOR BRIEF
PERIODS OF 15 TO 20 KT. EXTENDED PERIOD OF NORTHEAST FLOW WILL BUILD
SEAS TO 2 TO 4 FT FOR MUCH OF THE WATERS. EXCEPTION WILL BE
LOCATIONS SHELTERED TO NORTHEAST FLOW OR WITH AN OFFSHORE COMPONENT.
HERE SEAS WOULD BE 1 TO 2 FT.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 330 PM FRIDAY...LOW PRESSURE WILL MOVE UP THE SOUTHEAST COAST
ON MONDAY. AN ELONGATED TROUGH WILL EXTEND UP THROUGH THE WATERS
WITH NORTHEAST FLOW ON THE WEST SIDE AND SOUTHERLY FLOW ON THE EAST
SIDE. AS THE LOW MOVES NORTH THERE MAY BE A PERIOD OF SOUTHERLY
WINDS ACROSS ALL OF THE WATERS BUT OVERALL EXPECT MORE VARIABLE
WINDS AT 10 TO 15 KTS. MAY SEE WINDS COME BACK AROUND TO OFF SHORE
AS THE LOW MOVES UP THE COAST BUT A DEEPER SOUTHERLY FLOW WILL SET
UP AHEAD OF NEXT SYSTEM BY TUES.

AS THIS LARGE AND POTENT STORM SYSTEM PUSHES A COLD FRONT EAST THE
GRADIENT WILL TIGHTEN TUES INTO WED WITH WINDS UP TO 15 TO 20 KTS.
THIS WILL PUSH SEAS UP FROM 2 TO 4 FT TO 3 TO 5 FT BY LATE TUES. WNA
SHOWS SEAS RAMPING UP ABOVE 6 FT BY WED MORNING AND POSSIBLE UP TO 7
TO 8 FT IN OUTER WATERS IN STRONGER SW TO W FLOW AS FRONT MOVES
THROUGH THE WATERS ON WED. EXPECT SMALL CRAFT CONDITIONS MAINLY ON
WED AND LASTING INTO THURS.

&&

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

&&

$$

NEAR TERM...TRA
SHORT TERM...III
LONG TERM...RGZ
AVIATION...BJR





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