-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 140557
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
157 AM EDT TUE MAY 14 2013

.SYNOPSIS...
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COOL CANADIAN HIGH PRESSURE WILL KEEP TEMPERATURES WELL BELOW
NORMAL FOR THE NEXT COUPLE OF DAYS. THE HIGH WILL MOVE OVERHEAD
TODAY AND OFFSHORE ON WEDNESDAY...ALLOWING FOR A MARKED WARMING
TREND FOR THE SECOND HALF OF THE WEEK. ISOLATED SHOWERS OR STORMS
MAY ACCOMPANY A COLD FRONT AS IT TRIES TO MAKE ITS WAY SOUTH INTO
THE CAROLINAS THURSDAY NIGHT INTO FRIDAY.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
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AS OF 2:00 AM TUESDAY...CLEAR SKIES AND CALM TO LIGHT WINDS FOR
THE OVERNIGHT PERIOD. NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. TEMPERATURES NOW DOWN IN THE 40S MOST LOCATIONS...EVEN
ALONG THE COAST. PREVIOUS DISCUSSION FROM 7:30 PM STILL APPLIES
AND FOLLOWS BELOW:

1023 MB HIGH PRESSURE HAS A BROAD CENTER EXTENDING FROM OHIO THROUGH
TENNESSEE INTO SOUTHERN MS/AL. AN UNSEASONABLY COLD AIRMASS FOR THE
MIDDLE OF MAY HAS OVERSPREAD THE EASTERN THIRD OF THE NATION AND
WILL PRODUCE TEMPERATURES APPROACHING RECORD LOWS TONIGHT FROM THE
CAROLINAS NORTH INTO THE MID-ATLANTIC STATES.

THE STATISTICS ON THIS AIRMASS ARE IMPRESSIVE. THE 850 MB ZERO LINE
WILL DIVE AS FAR SOUTH AS THE ALBEMARLE SOUND IN NORTHEASTERN NORTH
CAROLINA LATE TONIGHT. AT 700 MB TEMPERATURES CURRENTLY RANGE FROM
-5C ACROSS EASTERN SC TO -12C ACROSS EASTERN NORTH CAROLINA...UP TO
4 SIGMA BELOW NORMAL AND INDICATIVE OF A STATISTICALLY QUITE RARE
EVENT. THIS AFTERNOON OUR MIXING HEIGHTS WERE AROUND 9000 FT DEEP
AND YET WE STILL ONLY BARELY REACHED THE LOWER 70S FOR HIGHS.

AS THE SURFACE HIGH DRIFTS INTO THE SOUTHERN APPALACHIANS OUR WINDS
WILL BECOME LIGHT AS THE SUN SETS THIS EVENING. RADIATIONAL COOLING
WILL BE VERY GOOD WITH CLEAR SKIES AND UNSEASONABLY DRY AIR...AND A
STRONG RADIATIONAL INVERSION SHOULD QUICKLY DEVELOP. AFTER MIDNIGHT
A MODEST SURGE OF NORTH WINDS WILL DEVELOP JUST ABOVE THE SURFACE
WITH WINDS AT 1000 FT AGL INCREASING TO 15-20 KNOTS. IT APPEARS THE
RADIATIONAL INVERSION WILL BE WELL-ENOUGH ESTABLISHED BY THIS POINT
THAT THE BOUNDARY LAYER SHOULD REMAIN DECOUPLED FROM THE FLOW
ALOFT...ENSURING VERY COOL NIGHTTIME SURFACE TEMPERATURES BY THE
TIME DAYBREAK ROLLS AROUND. IN FACT MY FORECAST IS VERY CLOSE TO
RECORD VALUES AT MANY STATIONS. RECORD LOWS FOR THE MORNING OF
TUESDAY MAY 14TH ARE...

ILM (WILMINGTON INTERNATIONAL AIRPORT) 44 IN 1917.
FLO (FLORENCE REGIONAL AIRPORT) 43 IN 1997.
CRE (NORTH MYRTLE BEACH) 45 IN 1952.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...EXPECT QUIET CONDITIONS THROUGH THE PERIOD AS
THE TWO MAIN SYNOPTIC FEATURES...A SFC HIGH ACROSS THE SOUTHEAST
US AND AN UPPER LEVEL RIDGE ASSOCIATED WITH A SFC LOW ACROSS NORTH
OF THE NEW ENGLAND STATES...TRANSITION ACROSS THE AREA.

ON TUESDAY...NORTHWEST FLOW...WHICH ALLOWED FOR AN UNSEASONABLY COLD
AIRMASS TO AFFECT THE AREA...WILL BECOME MORE NORTHERLY AT THE
BEGINNING OF THE PERIOD THANKS TO THE EASTWARD PROPAGATION OF AN
UPPER LEVEL RIDGE AND THE EXPANDING OF A SFC HIGH ACROSS THE
SOUTHEAST. RETURN FLOW WRAPPING AROUND THE SFC HIGH INTO THE
OVERNIGHT HOURS ON TUESDAY WILL ALLOW FOR TEMPS TO BE ON THE UPGLIDE
THROUGH THE REMAINDER OF THE PERIOD...WITH HIGHS IN THE LOW TO MID
70S ON TUESDAY AND LOWS IN THE LOW 50S. TEMPS WILL CLIMB EVEN MORE
ON WEDNESDAY AS UPPER LEVEL RIDGE SITUATES ITSELF OVERHEAD SPREADING
WARM AND DRY CONDITIONS ACROSS THE AREA. WITH SOUTH-SOUTHWEST
WINDS...ANTICIPATE HIGH TEMPS IN THE UPPER 70S ALONG THE COAST AND
UP INTO THE MID 80S INLAND. COULD POTENTIALLY SEE COASTAL AREAS
REACHING WELL INTO THE LOW 80S GIVEN THE DECENT WESTERLY FLOW
ALOFT...WILL BE A MATTER OF HOW QUICKLY THINGS WARM UP BEFORE THE
ONSET OF THE SEA BREEZE. WINDS WILL BECOME LIGHT OVERNIGHT AND INTO
THE MORNING HOURS ON THURSDAY...WITH LOWS IN THE LOW TO MID 60S.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...MEDIUM RANGE GUIDANCE CONTINUES TO ADVERTISE A
MID LEVEL PATTERN THAT IS BASICALLY ZONAL THROUGH THE PERIOD.
HOWEVER THERE WILL BE WEAK INCREASES IN AMPLITUDE FROM TIME TO TIME
AS WEAK SOUTHERN STREAM FEATURES CROSS THE SOUTHEAST. AT THE SURFACE
PIEDMONT TROUGH AND BERMUDA HIGH WILL BE IN PLACE THROUGH THE END OF
THE PERIOD AND...ALONG WITH THE SEABREEZE...WILL BE THE MAIN SOURCE
OF WEATHER. WEAK MID LEVEL TROUGHING THU NIGHT AND FRI MAY ENHANCE
DIURNAL CONVECTION WHILE WEAK RIDGING LATE IN THE PERIOD MAY
SUPPRESS CONVECTION. KEEPING THU DRY WITH SOME SUBSIDENCE EXPECTED
FROM EXITING MID LEVEL RIDGE. FRI WEAK MID LEVEL TROUGHING AND
INCREASED MOISTURE PROVIDE THE BEST CHANCE OF DIURNAL CONVECTION FOR
THE PERIOD. HAVE BUMPED FRI POP TO LOW CHC. PLAN TO CONTINUE WITH
DIURNAL SLIGHT CHC POP SAT THROUGH MON. TEMPERATURES WILL REMAIN
ABOVE CLIMO THROUGH THE PERIOD.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 06Z...CLEAR SKIES AND CALM WINDS ACROSS THE CWA TONIGHT WITH A
BROAD AREA OF HIGH PRESSURE SETTLED OVER THE EASTERN U.S. VFR WILL
PREVAIL DURING THIS TAF PERIOD. CALM TO LIGHT WINDS WILL PERSIST
THROUGH 12Z BEFORE BECOMING N-NE THIS MORNING. THE WINDS WILL SHIFT
TO THE S-SW...REMAINING AOB 10 KTS...THIS AFTN AS HIGH PRESSURE
SLIDES OFF THE ATLANTIC COAST. DO NOT EXPECT MUCH IN THE WAY OF
CLOUDS WITH SUBSIDENCE OVER THE CAROLINAS AND DRY NORTHWEST FLOW
ALOFT.

EXTENDED OUTLOOK...VFR LIKELY THROUGH THURSDAY. SLIGHT CHANCE OF
SHOWERS FRIDAY AND SATURDAY.
-- End Changed Discussion --

&&

.MARINE...
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.NEAR TERM /THROUGH TONIGHT/...
AS OF 2:00 AM TUESDAY...LIGHT WINDS CONTINUE OVER THE WATERS. OBS
TO OUR NORTH SHOW THAT A COLD SURGE MAY KICK UP WINDS EARLY THIS
MORNING...BUT NOT CLOSE ENOUGH FOR ANY SORT OF ADVISORY. PREVIOUS
DISCUSSION FROM 7:30 PM FOLLOWS:

CANADIAN HIGH PRESSURE WEST OF THE APPALACHIANS WILL CROSS THE
MOUNTAINS LATE TONIGHT...WITH NORTHWEST WINDS THIS EVENING VEERING
MORE NORTHERLY WITH TIME. A MODEST SURGE OF NORTH WINDS IS EXPECTED
AFTER MIDNIGHT BUT THE MAIN INCREASE IN WIND SPEEDS APPEARS TO
REMAIN OFFSHORE AND AWAY FROM THE COASTAL WATERS. SEAS CURRENTLY
RANGE FROM 4 FT OUT AT THE FRYING PAN SHOALS BUOY TO 3 FT AT THE
NEARSHORE WRIGHTSVILLE BEACH BUOY AND THE  WILMINGTON HARBOR BUOY
SOUTH OF THE MOUTH OF THE CAPE FEAR RIVER. NO SIGNIFICANT CHANGES
HAVE BEEN MADE TO THE FORECAST.

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...THOUGH THE MORNING HOURS WILL BEGIN WITH
NORTHERLY FLOW...A SFC HIGH ACROSS THE SOUTHEAST US AND AN UPPER
LEVEL RIDGE ASSOCIATED WITH A SFC LOW ACROSS NORTH OF THE NEW
ENGLAND STATES WILL BEGIN TO TRANSITION ACROSS THE AREA...ALLOWING
FOR FLOW TO BECOME SOUTHERLY BY TUESDAY EVENING...WITH WIND SPEEDS
AROUND 10 KTS. INTO WEDNESDAY...WINDS WILL TRANSITION FROM SOUTH TO
SOUTHWEST...WITH INCREASING WIND SPEEDS TO 15 TO 20 KTS...CONTINUING
INTO THURSDAY MORNING. SEAS WILL BEGIN AS 2-3 FEET EARLY IN THE
PERIOD...INCREASING TO 3-5 FEET BY WEDNESDAY MIDDAY...AND CONTINUING
INTO THURSDAY.

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 3 PM MONDAY...BERMUDA HIGH WILL DOMINATE THE WATERS THROUGH
THE PERIOD WITH SOUTH TO SOUTHWEST FLOW IN PLACE. PIEDMONT TROUGH
AND SEABREEZE WILL RESULT IN DIURNAL ENHANCEMENT OF WINDS BUT
GENERALLY SPEEDS WILL BE 10 TO 15 KT...HIGHEST IN AFTERNOON. SEAS
RUN 2 TO 4 FT WITH SOUTHERLY SWELL STARTING TO TAKE HOLD.
-- End Changed Discussion --

&&

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

&&

$$

NEAR TERM...REK/RGZ
SHORT TERM...MBB/SGL
LONG TERM...III
AVIATION...BJR
MARINE...REK/III/MBB/RGZ