-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 212348
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
748 PM EDT MON APR 21 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA TUESDAY NIGHT WITH SHOWERS
AND THUNDERSTORMS EXPECTED WITH ITS PASSAGE. HIGH PRESSURE WILL
BUILD OVER THE REGION WEDNESDAY THEN MOVE OFFSHORE THURSDAY AND
FRIDAY. HIGH PRESSURE WILL REMAIN IN PLACE THROUGH THE WEEKEND.
TEMPERATURES WILL GENERALLY BE ABOVE NORMAL.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM MONDAY...FAIR WEATHER IS EXPECTED TONIGHT AS HIGH
PRESSURE BUILDS INTO THE CAROLINAS. OTHER THAN A BIT OF CIRRUS
OVERNIGHT...CLEAR SKIES WILL PREVAIL AS A SURFACE RIDGE DOMINATES
OUR WEATHER. WINDS WILL SUBSIDE SOON AFTER SUNSET...BECOMING LIGHT
AND VARIABLE OVERNIGHT. GOOD RADIATIONAL COOLING SHOULD ALLOW
TEMPERATURES TO FALL INTO THE UPPER 40S INLAND AND AROUND 50 ALONG
THE COAST.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...SHORTWAVE TROUGH WILL DRIVE A COLD FRONT
ASSOCIATED WITH A NORTHERN STREAM SFC LOW/5H TROUGH ACROSS THE
CAROLINAS TOMORROW EVENING. AHEAD OF THE FRONT BRIEF PERIOD OF
SOUTHERLY RETURN FLOW AND DEEPER SOUTHWEST FLOW ALOFT WILL ADVECT
SOME MOISTURE INTO THE REGION. ALONG WITH INCREASING MOISTURE TEMPS
WILL CLIMB INTO THE LOWER 80S AWAY FROM THE COAST...LEADING TO A
FAIR AMOUNT OF INSTABILITY. HOWEVER THINK THE LIMITED STRENGTH AND
DURATION OF THE MOISTURE ADVECTION WILL KEEP COVERAGE OF CONVECTION
AHEAD OF/ALONG THE FRONT SCATTERED. THUS WILL MAINTAIN INHERITED CHC
POP. ANY CONVECTION THAT DOES DEVELOP SHOULD BE USHERED OFF THE
COAST BY MIDNIGHT. AT THIS POINT SEVERE WEATHER DOES NOT APPEAR TO
BE A CONCERN WITH WEAK TO NON-EXISTENT JETTING AND MARGINAL LAPSE
RATES.

COLD ADVECTION DEVELOPS LATE TUESDAY NIGHT AND CONTINUES INTO WED.
HOWEVER THE COMBINATION OF LATE APRIL SUN AND DOWNSLOPE COMPONENT TO
FLOW WILL WORK TO OFFSET THE ADVECTION. DEEP NORTHWEST FLOW WED AND
WED NIGHT DRIES THE MID LEVELS OUT...DROPPING PRECIPITABLE WATER
VALUES TO AROUND 0.30 INCH THROUGH THE END OF THE PERIOD. EXPECT
VERY LITTLE IN THE WAY OF CLOUDS AND NO PRECIP CHANCES. ELONGATED
SURFACE RIDGE AXIS EXTENDS SOUTH LATE WED AS WEAK MID LEVEL RIDGE
BUILDS NORTH. COMBINATION OF THESE 2 FEATURES SHOULD PRODUCE A NIGHT
WITH GOOD RADIATIONAL COOLING CONDITIONS. LOWS END UP IN THE LOW TO
MID 40S WITH A FEW AREAS ALONG THE COAST HANGING IN THE UPPER 40S.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 330 PM MONDAY...HIGH PRESSURE SETTLES OVER THE CAROLINAS THURS
WITH VERY LIGHT AND MORE VARIABLE WINDS. SHOULD SEE SEA/LAND BREEZE
DOMINATE UNDER LATE APRIL SUN. THIS WILL KEEP TEMPS COOLER IN THE
AFTERNOON CLOSER TO THE COAST REACHING AROUND 70 BUT INLAND SHOULD
MAKE IT INTO THE MID 70S. OVERNIGHT LOWS THURS NIGHT WILL BE IN THE
50S WITH DEWPOINTS STARTING TO CREEP UP BUT DECENT RADIATIONAL
COOLING IN PLACE.

BY LATE THURS INTO FRI A RETURN FLOW WILL SET UP AS HIGH PRESSURE
SHIFTS OFF THE SOUTHEAST COAST. THIS SOUTHERLY RETURN FLOW WILL
INCREASE HEADING INTO FRI AND SATURDAY AS A LOW PRESSURE SYSTEM
MOVING ACROSS THE GREAT LAKES DRAGS A COLD FRONT SOUTHEAST TOWARD
THE CAROLINAS. THE INCREASINGLY WARMER AND MORE HUMID RETURN FLOW
SHOULD HELP TO PUSH TEMPS UP AND PRODUCE CU AND POSSIBLY SOME
LOCALIZED SHWR ACTIVITY BY FRI AFTN AS GFS SHOWS PIEDMONT TROUGH
DEVELOPING. ANY SHOWERS THAT DO DEVELOP WILL HEAD TOWARD THE COAST
IN WESTERLY STEERING FLOW AS THE LOW LEVEL WIND FLOW ABOVE THE
SURFACE WILL BACK AND INCREASE OUT OF THE WEST. THIS WESTERLY
DOWNSLOPE FLOW WILL HELP TO HEAT THINGS UP HEADING INTO THE
WEEKEND...WITH TEMPS BACK UP AROUND 80. IT MAY ALSO HELP TO KEEP SEA
BREEZE PINNED CLOSER TO THE COAST AND LIMIT AMOUNT OF PCP. OVERALL
LOOKS LIKE BEST CHC OF CLOUDS AND SHWRS WILL COME FRI AFTN THROUGH
THE EVENING. WILL ALSO INCLUDE LOW END CHC ASSOCIATED WITH FRONT SAT
NIGHT...BUT LOOKS LIKE ANY UPPER LEVEL SUPPORT WILL BE BENIGN AND
FRONT SHOULD MOVE THROUGH AFTER HEATING OF THE DAY CUTS OFF. NEED TO
WAIT UNTIL WE MOVE CLOSER TO SEE HOW TIMING WORKS OUT. WARMEST DAYS
SHOULD BE FRI AND SAT. WITH DEWPOINT TEMPS UP AROUND 60 FRI
NIGHT...EXPECT WARMER OVERNIGHT TEMPS STAYING INT THE 60S MOST
PLACES. CLOUDS AND WARM AIR AHEAD OF COLD FRONT SHOULD KEEP TEMPS
WARMER MOST OF SAT NIGHT ALSO.

HIGH PRESSURE WILL BUILD IN ON SUNDAY BUT MODELS ARE IN DISAGREEMENT
AS TO HOW FAR SOUTH THIS COLD FRONT WILL GET BEFORE MOVING NORTH AS
A WARM FRONT. FOR NOW WILL KEEP WITH PREVIOUS FORECAST FOR SLIGHTLY
COOLER AND DRIER AIR BEHIND COLD FRONT FOR SUN INTO MONDAY.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 00Z...POTENTIAL FOR MVFR LATE OVERNIGHT INTO THE EARLY MORNING
HOURS DUE TO AREAS OF FOG. OTHERWISE EXPECT VFR AHEAD OF AN
APPROACHING COLD FRONT.

LATEST SATELLITE IMAGERY DEPICTS SOME LOW CLOUDS ALONG THE COAST
ALONG WITH FEW/SCT HIGH CLOUDS MOVING IN ACROSS THE AREA FROM THE
WEST. EXPECT LIGHT AND VARIABLE WINDS THROUGH THE OVERNIGHT HOURS
WITH LINGERING FEW HIGH CLOUDS. LATEST TIME-HEIGHT ANALYSIS AND FCST
SOUNDINGS SEEM TO BE IN A BIT OF A DISAGREEMENT REGARDING FOG
DEVELOPMENT OVERNIGHT. BUT GIVEN SOMEWHAT FAVORABLE
ENVIRONMENT...HAVE KEPT TEMPO GROUPS IN AT ALL SITES FOR POSSIBLE
MVFR FOG. AFTER DAYBREAK...ANY FOG WILL QUICKLY DISSIPATE GIVING WAY
TO HIGH CONFIDENCE FOR VFR TO PREVAIL ACROSS THE AREA. SOUTHWEST
WINDS WILL INCREASE INTO THE AFTERNOON HOURS AHEAD OF AN APPROACHING
COLD FRONT...WITH VCSH POSSIBLE FOR THE INLAND SITES TOWARDS THE END
OF THE VALID TAF PERIOD.

EXTENDED OUTLOOK...CHANCE OF SHOWERS/TEMPO MVFR TUESDAY NIGHT
WITH A COLD FRONT. VFR WEDNESDAY AND THURSDAY. LOW CONFIDENCE FOR
SCATTERED SHOWERS WITH TEMPO MVFR ON FRIDAY AND SATURDAY.
-- End Changed Discussion --

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM MONDAY...SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
AMZ250/252 THROUGH 01Z TUESDAY. WINDS AND SEAS WILL DIMINISH
TONIGHT AS LOW PRESSURE PULLS AWAY FROM THE CAROLINAS AND THE
GRADIENT WEAKENS. OVERNIGHT...SEAS WILL FALL TO AROUND 3-4 FT
NORTHERN WATERS AND 2-3 FT SOUTHERN WATERS WITH NORTH WINDS AROUND
10 KTS.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...SOUTHWEST FLOW AHEAD OF AN ADVANCING COLD FRONT
WILL APPROACH 20 KT LATE TUE JUST BEFORE THE FRONT PASSES. BRIEF
PERIOD OF INCREASED SOUTHWEST FLOW WILL NOT BE ABLE TO BUILD SEAS TO
HEADLINE CRITERIA BUT 3 TO 5 FT IS POSSIBLE. COMBINATION OF TIGHT
GRADIENT AND COLD ADVECTION BEHIND THE FRONT WILL KEEP WEST TO
NORTHWEST FLOW IN THE 15 TO 20 KT RANGE TUE NIGHT. OFFSHORE WIND
COMPONENT WILL QUICKLY DROP SEAS TO 2 TO 4 FT TUE NIGHT. GRADIENT
WEAKENS DURING THE DAY WITH SPEEDS DROPPING FROM 15 TO 20 KT IN THE
MORNING TO 10 TO 15 KT BY AFTERNOON. WINDS BECOME LIGHT AND VARIABLE
WEDNESDAY NIGHT AS ELONGATED SURFACE RIDGE AXIS MOVES OVER THE AREA.
SEAS 2 TO 3 FT WED MORNING DROP TO 2 FT OR LESS LATER WED AND WED
NIGHT.

LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 330 PM MONDAY...HIGH PRESSURE WILL SHIFT OVERHEAD ON THURS
WITH LIGHT AND VARIABLE WINDS OVER THE WATERS. AS THE HIGH SHIFTS
FURTHER OFF SHORE THURS NIGHT INTO FRI A LIGHT RETURN FLOW WILL SET
UP BUT IT WILL START INCREASING OUT OF THE S TO SW FRI AFTN AS
PIEDMONT TROUGH SETS UP. THE WINDS WILL VEER A LITTLE MORE THROUGH
SATURDAY AS A COLD FRONT APPROACHES THE WATERS BECOMING SW-W UP TO
15 KTS. A COLD FRONT SHOULD MOVE THROUGH THE WATERS SAT NIGHT
PRODUCING AN ABRUPT SHIFT TO THE NORTH BY SUNDAY MORNING.

SEAS AROUND 2 FT TO START WILL INCREASE TO 2 TO 4 FT IN INCREASING
RETURNING FLOW UP TO 15 KTS OUT OF THE SW. BY SATURDAY THE SEAS WILL
INCREASE FURTHER MAINLY IN THE OFF SHORE WATER WITH A MORE WESTERLY
FLOW UP TO 15 KTS KEEPING GREATER SEAS IN THE OUTER WATERS UP TO 4
TO 5 FT AS FRONT APPROACHES AND MOVES THROUGH SAT NIGHT.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 PM EDT THIS EVENING FOR AMZ250-
     252.

&&

$$

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