Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 060534
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1234 AM EST FRI MAR 6 2015

.SYNOPSIS...
ARCTIC HIGH PRESSURE WILL SETTLE ACROSS THE AREA IN THE WAKE OF A
STRONG COLD FRONT AND PERSIST THROUGH THE WEEKEND. THERE IS A SMALL
RISK FOR SOME VERY LIGHT WINTRY PRECIPITATION ACROSS PORTIONS OF
COASTAL NORTH CAROLINA BEFORE THE RAIN AND DRIZZLE COMPLETELY
SHUTOFF FRIDAY MORNING. WINTER-LIKE TEMPERATURES WILL BEGIN TO
MODERATE DURING THE WEEKEND. THE SLOW WARMUP WILL CONTINUE NEXT WEEK
WITH SHOWERS POSSIBLE.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 1230 AM FRIDAY...THE MAIN PRECIP SHIELD HAS CLEARED THE COAST WITH
ASOS/AWOS OBS INDICATING ONLY PATCHY DRIZZLE REMAINING. WHILE THIS
WOULD NORMALLY MEAN THE EVENT IS OVER...THE 00Z WAS MOST EMPHATIC
THAT A SECOND WAVE OF ISENTROPIC LIFT WILL DEVELOP ALONG THE 300K
SURFACE OVERHEAD JUST BEFORE DAYBREAK...ACCOMPANIED BY A SUBTLE
BACKING OF THE 700-800 MB FLOW. THE GFS IS FLATTER WITH THIS
DEVELOPING WAVE WITH LITTLE IF ANY IMPACT ON LAND. I HAVE MADE NO
CHANGES TO THE LATE-NIGHT/FRIDAY MORNING FORECAST...HOWEVER I
BELIEVE GIVEN THE PRESENCE OF AN INCREASINGLY DEEP COLD LAYER WITH
SUB-FREEZING TEMPERATURES THICKENING TO 3500-4000 FEET DEPTH BENEATH
THE WARM CLOUD ALOFT...SLEET WOULD BE THE PREFERRED PRECIP TYPE
RATHER THAN FREEZING RAIN. DISCUSSION FROM 900 PM FOLLOWS...

ISENTROPIC LIFT IS THE MAIN DRIVER IN ONGOING PRECIPITATION. THE
BACK EDGE OF THE ACCUMULATING RAIN WAS ALONG A CKI TO LBT LINE AND
THIS WAS IN LINE WITH THE HRRR. RADAR SHOWED THE BACK EDGE OF THE
RAIN SHIELD CREEPING SLOWLY EASTWARD. TEMPERATURES WERE IN THE LOWER
40S FOR THE MOST PART...BUT A FEW SPOTS HAVE DIPPED INTO THE UPPER
30S. FACTOR IN A N WIND OF 15 TO 20 MPH WITH HIGHER GUSTS...AND IT
FEELS AS IF IT WERE IN THE 20S LATE THIS EVE.

THE HIGH RESOLUTION HRRR MODEL IS SHOWING A SLOW...BUT STEADY
EASTWARD PROGRESSION OF THE PRECIPITATION SHIELD THROUGH MIDNIGHT
WITH THE RAIN MAINLY OFFSHORE BY AROUND MIDNIGHT...LASTLY ALONG THE
CAPE FEAR COAST. HOWEVER...THE COLD AIR IS SHALLOW WITH N TO NE
WINDS THROUGH 4 KFT BEING TOPPED BY A DEEP AND STILL STRONG SW TO
WSW FLOW. THIS DOES SUGGEST THE PRECIPITATION MAY LINGER LONGER INTO
THE NIGHT. WILL HANG ONTO THE PRECIPITATION IN THE FORM OF LIGHT
RAIN AND DRIZZLE FOR MOST INLAND LOCATIONS THROUGH ABOUT MIDNIGHT.
WILL THEN SHOW THE PRECIPITATION ENDING ACROSS THE REMAINDER OF THE
AREA OVERNIGHT AS THE COLUMN CONTINUES TO SLOWLY DRY FROM ALOFT TO
THE SURFACE. SINCE THE PRECIPITATION ENDS BEFORE AIR TEMPS DROP TO
32 DEGREES OR LOWER...WILL NOT INCLUDE MENTION OF WINTRY
PRECIPITATION.

THE EXCEPTION WILL BE ACROSS PORTIONS OF THE CAPE FEAR AREA WHERE
VERY LIGHT PRECIPITATION MAY LINGER INTO EARLY FRI MORNING AS THE
CONVEYOR BELT OF DEEPER MOISTURE WILL BE RELUCTANT TO PUSH WELL
OFFSHORE. AS COLDER AIR CONTINUES TO FILTER INTO THIS AREA IN THE
LOW LEVELS...TEMPERATURES WILL CREEP DOWN TO AROUND 30 DEGREES.
ACROSS THE CAPE FEAR AREA...THIS WILL COMPLICATE THINGS AS ANY LIGHT
PRECIPITATION WITH TEMPS BELOW FREEZING DOES HAVE THE POTENTIAL TO
FREEZE. HOWEVER...GIVEN THE VERY WARM TEMPS OF THE LAST TWO
DAYS...GROUND TEMPS TO INCLUDE ROADWAYS...AND EXPOSED SURFACES TO
INCLUDE BRIDGES...TREES...POWER LINES AND CARS ARE NOT EXPECTED TO
HAVE SUFFICIENT TIME TO REACH FREEZING BEFORE THE LIGHT
PRECIPITATION ENDS. THUS...ALTHOUGH INSTRUMENTS MAY REPORT SOME
LIGHT FREEZING RAIN OR FREEZING DRIZZLE...NO ICE ACCRUAL IS EXPECTED.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...WINTER WILL MAKE AN APPEARANCE THROUGH THE
SHORT TERM AS ARCTIC HIGH PRESSURE BUILDS INTO THE CAROLINAS. WHILE
WELL BELOW NORMAL TEMPERATURES ARE A CERTAINTY FOR FRIDAY AND
SATURDAY...WHAT IS UNCERTAIN IS WHETHER ANY PRECIP WILL LINGER
FRIDAY MORNING...POTENTIALLY AS A WINTRY TYPE.

COLD FRONT WILL BE WELL OFFSHORE FRIDAY MORNING...BUT SOME RESIDUAL
LOW-LEVEL MOISTURE WILL PERSIST IN THE COLUMN FOR THE FIRST FEW
HOURS OF FRIDAY. GUIDANCE HAS BACKED OFF CONSIDERABLY ON AMOUNT OF
MOISTURE LEFT IN THE COLUMN...AND SREF PROBABILITIES ARE LESS THAN
MENTIONABLE. FOR THIS REASON HAVE CUT BACK POP TO SILENT FOR ALL BUT
THE IMMEDIATE BEACHES...AND EVEN THERE ONLY A SCHC IS WARRANTED FOR
A COUPLE OF HOURS FRIDAY MORNING. THIS PRECIP MAY BE A BIT OF IP/ZR
BUT NO IMPACTS ARE ANTICIPATED FROM ANY WINTRY PRECIP.
THEREAFTER...RAPID DRYING OCCURS AND AMPLE SUNSHINE WILL ENVELOP THE
AREA FRIDAY AFTN. EVEN WITH FULL MARCH SUN...TEMPS ON FRIDAY WILL
RISE ONLY INTO THE MID/UPR 30S - A FULL 25-30 DEGREES BELOW NORMAL!
HIGH PRESSURE BUILDS TOWARDS THE AREA FRIDAY CAUSING CAA TO
WEAKEN...AND A VERY COLD NIGHT IS EXPECTED AS THE DRY COLUMN AND
WEEK WINDS SUPPORT STRONG LONGWAVE COOLING. GUIDANCE HAS COOLED A
BIT...AND WE MAY APPROACH RECORD LOWS FRIDAY NIGHT (20 AT WILMINGTON
AND 20 AT FLORENCE). CURRENT FORECASTS ARE JUST ABOVE THESE
NUMBERS...BUT AN EXCEEDINGLY COLD NIGHT IS EXPECTED.

A WARMER DAY EXPECTED SATURDAY AS THE AIRMASS BEGINS TO MODIFY...BUT
TEMPS WILL STAY ABOUT 10 DEGREES BELOW NORMAL EVEN BENEATH THE
INCREASING MARCH SUN ANGLE. HIGH PRESSURE SHIFTS OFFSHORE LATE
SATURDAY ALLOWING FOR WARM RETURN FLOW TO DEVELOP. THIS WILL KEEP
MINS MUCH WARMER SATURDAY NIGHT THAN FRIDAY NIGHT...SO WHILE STILL
EXPECTING BELOW NORMAL VALUES FOR LOWS...MOST OF THE AREA WILL
REMAIN JUST ABOVE FREEZING.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 330 PM THURSDAY...MEDIUM RANGE GUIDANCE IS SHOWING A SPLIT
FLOW DEVELOPING AS THE MAIN BELT OF WESTERLIES JOGS TO THE NORTH
WITH A WEAKER SOUTHWEST FLOW OVER THE SOUTHERN U.S. SURFACE
FEATURES INCLUDE A WEAK AND DRY BACKDOOR FRONT SUNDAY WITH A BROAD
BAROCLINIC ZONE ALIGNED OFFSHORE. THIS IS WHAT REMAINS OF OF THE
ARCTIC FRONT THAT MOVES ACROSS LATER TODAY. BEYOND THIS WEAK HIGH
PRESSURE WILL PREVAIL AT THE SURFACE BUT POPS WILL REMAIN IN THE
FORECAST DUE TO MID AND UPPER LEVEL INFLUENCES. WITH THE WEAK
FORCING...CONFIDENCE IS LOWER THAN USUAL BUT FOR NOW WE HAVE THE
HIGHEST POPS...CHANCE VALUES FOR TUESDAY AND THURSDAY WHEN THE
FORCING IS SLIGHTLY BETTER. TEMPERATURE TRENDS SHOW A LITTLE BELOW
NORMAL FOR DAYTIME HIGHS BUT OVERNIGHT LOWS...MODERATED QUITE A
BIT BY THE MOISTURE...WELL ABOVE NORMAL WITH 45-50 DEGREES.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...AT THE INLAND TERMINALS MVFR CIGS WILL IMPROVE TO VFR
AROUND 09Z...BUT THERE WILL STILL BE SOME POTENTIAL FOR A TEMPO MVFR
CIG UNTIL SHORTLY AFTER SUNRISE. WINDS WILL BE N GUSTING TO AROUND
25 KT DECREASING TO NE AROUND 12 KT BY LATE MORNING.

AT THE COASTAL TERMINALS THE SAME TREND IN CIGS IS EXPECTED EXCEPT
IMPROVEMENT WILL BE SEVERAL HOURS LATER. PRECIPITATION WILL MOVE
OFFSHORE EARLY THIS MORNING BUT LINGER JUST ALONG THE COAST THROUGH
POTENTIALLY 12-14Z. THERE COULD BE A FEW ICE PELLETS AT KILM
AROUND SUNRISE. WINDS WILL BE N GUSTING TO 25-30KT DECEASING TO NE
AROUND 12 KT BY EARLY AFTERNOON.

VFR EXPECTED BY LATE MORNING WITH CLOUDS BECOMING SCT BY AFTERNOON.
N WINDS WILL CONTINUE.

EXTENDED OUTLOOK...VFR.
EXTENDED OUTLOOK...VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM FRIDAY...NO SIGNIFICANT CHANGES NEEDED TO THE
FORECAST. DISCUSSION FROM 900 PM FOLLOWS...

A GALE WARNING REMAINS IN EFFECT. THE STRONGEST NORTHERLY SURGE AND
THE TIGHTEST PRESSURE GRADIENT WILL BE IN PLACE OVERNIGHT AND FRI
MORNING. WIND SPEEDS WILL BE UP TO 30 TO 35 KT. SEAS WILL PEAK IN
THE RANGE OF 5 TO 9 FT. SEAS WILL BE LOWER ACROSS THE VERY NEAR
SHORE WATERS TO INCLUDE LONG BAY.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...ARCTIC COLD FRONT WILL BE WELL OFFSHORE
FRIDAY MORNING...BUT A TIGHT GRADIENT WILL REMAIN OVER THE WATERS
AND THE GALE WARNING CURRENTLY IN PLACE WILL PERSIST THROUGH 10AM
FOR NORTH WINDS GUSTING ABOVE 34 KTS. WINDS BEGIN TO EASE
THEREAFTER...BUT WILL ONLY SLOWLY FALL THROUGH FRIDAY...REMAINING
15-20 KTS INTO SATURDAY MORNING. THESE CONTINUED STRONG NORTH WINDS
WILL KEEP WAVE HEIGHTS ABOVE 6 FT ALL OF FRIDAY...AND AN SCA WILL BE
NEEDED ONCE THE GALE WARNING DROPS. HIGH PRESSURE WILL MOVE
TOWARDS...AND THEN OVER...THE WATERS ON SATURDAY BEFORE DRIFTING
OFFSHORE SATURDAY NIGHT. THIS WILL DRIVE PRIMARILY LIGHT AND
VARIABLE WINDS SATURDAY AND SATURDAY NIGHT...EVENTUALLY TAKING ON A
PREDOMINANT SW DIRECTION LATE. WAVE HEIGHTS WILL FALL STEADILY ON
SATURDAY...LEVELING OFF AT 1-2 FT TOWARDS THE END OF THE PERIOD.

LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 330 PM THURSDAY...A RATHER WEAK PRESSURE PATTERN WILL
CONTINUE THROUGH THE PERIOD. THIS LEADS TO MODEST WIND FIELDS AND
SIGNIFICANT SEAS. WITH WEAK HIGH PRESSURE TO THE WEST...NORTHWEST
AND AN OLD BOUNDARY LINGERING OFFSHORE WIND DIRECTIONS WILL BE
MOSTLY NORTHEAST. SPEEDS WILL DISPLAY SOME VARIATION BUT OVERALL A
RANGE OF 10-15 KNOTS SHOULD BE GOOD. SIGNIFICANT SEAS WILL START
OFF VERY LOW...1-2 FEET SUNDAY AND INCREASE MONDAY AND TUESDAY AS
WINDS HOVER AROUND THE HIGHER END OF THE RANGE FOR SEVERAL
PERIODS. COULD EVEN SEE SMALL CRAFT CONDITIONS TUESDAY.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...GALE WARNING UNTIL 10 AM EST FRIDAY FOR AMZ250-252-254-256.

&&

$$

NEAR TERM...RJD/TRA
SHORT TERM...JDW
LONG TERM...SHK
AVIATION...MRR





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