-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 231029
AFDILM

AREA FORECAST DISCUSSION...COR
NATIONAL WEATHER SERVICE WILMINGTON NC
628 AM EDT THU MAY 23 2013

.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL PRECEDE A COLD FRONT TODAY. THE
FRONT WILL MOVE THROUGH EARLY FRIDAY AND USHER COOLER AIR INTO
THE CAROLINAS OVER THE WEEKEND. NEXT WEEK WILL BRING A GRADUAL
WARMUP.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 628 AM THURSDAY...MINOR POP ADJUSTMENTS WERE MADE TO
ACCOUNT FOR SHOWERS SCRAPING OUR FAR NW ZONES...WHILE TRIMMING
POP VALUES ALONG THE VERY NORTHERN SC COAST. ALL OTHER ELEMENTS
REMAIN REPRESENTATIVE. PREVIOUS MORNING DISCUSSION FOLLOWS.

VAPOR ANALYSIS SHOWS ONE SHORT-WAVE MOVING OFF THE GA/SC COAST
EARLY THIS MORNING...TRIPPING OFF NOCTURNAL OCEAN CONVECTION FROM
CAPE FEAR SOUTH THROUGH EAST. AREAS OF LOW-LEVEL MOISTURE
CONVERGENCE OFFSHORE WAS ADDITIONALLY HELPFUL IN BLOSSOMING SHOWERS
WITH EMBEDDED TSTMS OVER THE WATERS. THE BERMUDA HIGH CIRCULATION
OVER OUR LOCALITY IS MARKED BY DEEP SOUTHERLY FLOW THAT WILL GUIDE
THE OCEAN CONVECTION ONSHORE THIS MORNING...GENERALLY EAST OF A KMYR
TO KCPC TO KEYF LINE. THIS ACTIVITY WILL BEGIN TO WANE IN THE MID
MORNING AS BUOYANCY OVER THE WATER DECREASES WITH DIURNAL WARMING.

THE CONVECTIVE FOCUS WILL SHIFT FROM WATER TO LAND BY MIDDAY AND
LOW-LEVEL WIND CONVERGENCE WILL SPREAD INLAND ALONG A RESULTANT
SEA BREEZE BOUNDARY HELPING TO PRODUCE LIFT. SHORT-WAVE ENERGY
WILL APPROACH FROM THE WEST IN THE AFTERNOON TO PROVIDE UPPER
SUPPORT. THE INLAND ADVANCING MARINE LAYER WILL SHIFT THE HIGHEST
POP VALUES INLAND AWAY FROM THE COAST THROUGH THE AFTERNOON.
FORECAST SOUNDINGS INDICATE 1100-1700 J/KG OF CAPE AT 18Z INLAND
WITH PWAT VALUES AROUND 1.6 INCHES. PROJECTED STORM MOTION 210/10
KT. LIGHT ENVIRONMENTAL WINDS AND BULK SHEAR PARAMETERS WILL LIMIT
STRENGTH OF CONVECTION...BUT CERTAINLY SOME STRONG WET DOWNBUSRTS
CAN BE EXPECTED.

LOSS OF HEATING WILL TAKE A TOLL ON CONVECTION THIS EVENING AND
DRYING IN THE MID LEVELS OF THE ATMOSPHERE AFTER 6Z TONIGHT SHOULD
BEGIN TO CURTAIL SHOWER ACTIVITY. MID-LEVEL DRYING WILL OUT-PACE
THE SURFACE FRONT. THE FRONT WILL BRING A WIND-SHIFT TO THE COAST
AROUND 12Z FRIDAY.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...STRONG UPPER TROUGH ESPECIALLY FOR LATE MAY
SWINGS ACROSS ON FRIDAY. THE COLD FRONT AND DEEP MOISTURE WILL BE
OFFSHORE BEFORE THE START OF THE PERIOD BUT IF THE TROUGH AXIS LAGS
ENOUGH TO PREVENT DOWNSLOPING/DRYING THEN THERE COULD BE ENOUGH SW
FLOW AND PVA FOR SOME INSTABILITY SPRINKLES. FCST SOUNDINGS SHOW
ENOUGH MID LEVEL DRY AIR TO PRECLUDE MEASURABLE PRECIP AT THIS TIME
SO THE FORECAST WILL REMAIN DRY. OTHERWISE FRIDAY LOOKS INCREASINGLY
BREEZY WITH PLUMMETING DEWPOINTS AND PERHAPS EVEN STRONG ENOUGH LATE
DAY CAA TO MAKE FOR A RATHER FLAT DIURNAL TEMPERATURE CURVE. CAA
SUFFICIENT TO BRING A DOWNRIGHT COOL FRIDAY NIGHT. WIND STAYS UP TO
PRECLUDE RAD COOLING BUT LOWS COULD STILL DIP DOWN CLOSE TO RECORDS.
NORTHERLY FLOW AND COLD ADVECTION CONTINUES INTO SATURDAY KEEPING
TEMPERATURES A SOLID CATEGORY OR MORE BELOW CLIMO DESPITE FULL
SUNSHINE. AS THE TROUGH DEEPENS AND CUTS OFF OFF THE NEW ENGLAND
COAST BY SATURDAY NIGHT THE COLD ADVECTION WILL BE MAINTAINED INTO
THE PERIOD. WITH THE SOLAR MODIFICATION FIGHTING THE PROCESS THE
WHOLE TIME SAT NIGHT LOWS MAY END UP VERY NEAR THOSE OF FRIDAY
NIGHT.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 AM THURSDAY...LARGE VORTEX MORE TYPICAL OF COOLER SEASON
WEATHER TO ONLY VERY SLOWLY LIFT OUT OF NEW ENGLAND STATES MONDAY
THROUGH WEDNESDAY. LOCAL RESULT WILL BE AN ABATING OF THE SURFACE
HIGH PRESSURE THAT UNTIL THEN WILL HAVE BEEN PUSHING IN FROM
POINTS NORTH. THE SPEED AT WHICH THIS HAPPENS IS STILL UP FOR
DEBATE BUT THE TREND WILL BE ONE OF GRADUALLY INCREASING WARMTH
AND MOISTURE. AT SOME POINT MOISTURE MAY BE SUFFICIENT TO SUPPORT
ISO OR SCTD CONVECTION OR THERE COULD EVEN BE AN ACTUAL SURFACE
WARM FRONT THAT DEVELOPS IN THE RETURN FLOW...WHICH COULD ADD TO
COVERAGE A LITTLE BIT. EITHER WAY BOTH SCENARIOS SEEM TO OFFER
LITTLE IN THE WAY OF RAIN CHANCES AREA-WIDE. BY THE END OF THE
PERIOD THE SURFACE HIGH WILL BE OFF THE COAST AND AN UPPER LEVEL
RIDGE BUILDING SO TEMPS SHOULD END UP NEAR OR ABOVE CLIMO.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...PERIODS OF MVFR/POSSIBLE IFR OVERNIGHT AND INTO THE
MORNING HOURS DUE TO LOWERED CIGS/AREAS OF FOG/LOWERED VSBYS AS WELL
AS SCATTERED CONVECTION ALONG THE COAST. VFR WILL PREVAIL BY LATE
MORNING WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ON
THURSDAY...WITH REDUCED RESTRICTIONS POSSIBLE IN HEAVIER DOWNPOURS.

VFR WITH AREAS OF MVFR WITH VCSH ARE ON TAP TONIGHT WITH SOUTH WINDS
AOB 10 KTS. EXPECT MVFR/POSSIBLE IFR TO DEVELOP AS GUIDANCE IS IN
GOOD AGREEMENT WITH REDEVELOPMENT OF SHOWERS ALONG THE COAST GIVEN
AN EXTREMELY SATURATED ATMOSPHERIC PROFILE. CANNOT RULE OUT ISOLATED
THUNDERSTORMS THROUGH THE ENTIRE PERIOD BUT HAVE OPTED TO NOT
INCLUDE ATTM GIVEN LOWERED CONFIDENCE. AFTER DAYBREAK...CIGS WILL
GRADUALLY LIFT ALLOWING FOR RESTRICTIONS TO RETURN TO VFR STATUS.
EXPECT SCT/BKN CLOUDS WITH SHOWERS AND ISOLATED THUNDERSTORMS.
SOUTHERLY WINDS WILL CONTINUE WITH SUSTAINED SPEEDS AOB 12 KTS AND
GUSTS UP TO 20 KTS. INTO THE EVENING HOURS ON THURSDAY...ANY
LINGERING CONVECTION WILL TAPER OFF AND WINDS WILL BECOME LIGHT.

EXTENDED OUTLOOK...SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY
THROUGH EARLY FRIDAY. OTHERWISE VFR.

&&

.MARINE...
-- Changed Discussion --
NEAR TERM/THROUGH TONIGHT/...
AS OF 628 AM THURSDAY...SOUTH WINDS WILL INCREASE TODAY INTO
THIS EVENING AHEAD OF AN APPROACHING COLD FRONT. THE WINDS WILL
REMAIN BELOW ADVISORY LEVELS...BUT GUSTS TO 20 KT CAN BE EXPECTED
THIS AFTERNOON AND TONIGHT. SSW WINDS WILL SHIFT TO WNW AFTER
DAYBREAK ON FRIDAY. SEAS MAY REACH 5 FEET OUTER PORTION LATER
TODAY AND TONIGHT...AND 3-4 FEET MOST LOCATION. SHOWERS AND TSTMS
WILL IMPACT THE WATERS THIS MORNING AND MOVING FROM SOUTH TO NORTH
BUT DECREASING BY LATE MORNING. SEAS WILL BE COMPOSED OF A
MIX...SSE WAVES OF 3 FEET EVERY 7 SEC AND SSW WAVES OF 1-2 FEET
EVERY 4-5 SECONDS. WINDS AND SEAS WILL BE LOCALLY HIGH IN AND NEAR
TSTMS.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...THE PERIOD BEGINS WITH A COLD FRONT MOVING OFF
TO THE EAST OF THE WATERS. THE SHARP VEER ASSOCIATED WITH FROPA WILL
GIVE WAY TO A MORE GRADUAL VEERING OF WIND DIRECTION AS HIGH
PRESSURE/COOL AIR SPILLS SOUTHWARD ACROSS THE EASTERN U.S.  FRIDAY
NIGHT WILL ALSO BRING A CATEGORY OF SPEED INCREASE IN THE COOL
SURGE. TOO EARLY TO TELL WHETHER OR NOT ANY HEADLINES WILL BE NEEDED
AS MODEL GUIDANCE WIND SPEEDS SEEMS TO HAVE DECREASED SLIGHTLY
RESULTING IN SLIGHTLY LOWER SEAS IN SWAN OUTPUT. EVEN SO EXPECT
STEEP AND CHOPPY WAVES FROM ALL OF THE CHANGING WIND DIRECTION. HIGH
PRESSURE CONTINUES TO BUILD IN FROM THE N ON SATURDAY KEEPING THE
WINDS NORTHERLY BUT THERE SHOULD BE A RELAXATION BY SATURDAY NIGHT
AS RIDGE CENTER DRAWS CLOSER.


LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...HIGH THAT BUILDS IN BEHIND FRIDAY COLD
FRONT WEAKENS AS LOW PRESSURE DEEPENS AND OCCLUDES NEW ENGLAND
COAST. AS THE LOW BECOMES THE DOMINANT WIND MAKER LOCALLY A NW TO
W FLOW WILL BE ESTABLISHED BUT WIND SPEEDS MAY STAY CAPPED AT 10
FT. WIND WAVES FAIRLY DIMINUTIVE WITH A LITTLE BACKSWELL
DEVELOPING FROM THE STORM. AS THIS SYSTEM PULLS AWAY TO THE NE AND
FILLS THE GRADIENT LOCALLY WILL START TO BE MOST DEFINED BY WEAK
HIGH DEVELOPING OVER THE WEST ATLANTIC AND A LIGHT AND MORE
TYPICAL SOUTHERLY COMPONENT GETS RE-ESTABLISHED.
-- End Changed Discussion --

&&

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

&&

$$

NEAR TERM...MJC
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...DL/MJC