-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 271207
AFDILM

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE WILMINGTON NC
804 AM EDT SUN JUL 27 2014

.SYNOPSIS...
SWELTERING HEAT AND HUMIDITY WILL PREVAIL THE NEXT FEW DAYS AHEAD
OF AN APPROACHING AND UNUSUALLY STRONG LATE JULY COLD FRONT. THE
FRONT MAY FORCE SEVERAL SEVERE STORMS INTO THE AREA LATE MONDAY.
DRY AND UNSEASONABLY COOL AIR WILL OVERSPREAD THE CAROLINAS FROM
TUESDAY THROUGH MUCH OF THE UPCOMING WEEK...AS HIGH PRESSURE FROM
CENTRAL CANADA DROPS SOUTHEAST AND SETTLES INTO THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 8 AM SUNDAY...UPDATES MADE TO THE EARLY MORNING FORECAST TO
ACCOUNT FOR THE MESO-SCALE VORTICY POISED TO SPIN AND GRAZE OUR NW
ZONES FROM A BENNETTSVILLE TO LUMBERTON CORRIDOR. ADJUSTMENTS
INCLUDE SKY COVER INCREASES AND A SWATH OF ISOLATED SHOWERS ACROSS
AND NORTH OF THIS AREA. NO OTHER CHANGES TO THE ONGOING FORECAST AND
A HEAT ADVISORY IS EFFECTIVE FOR MUCH OF THE AREA AWAY FROM THE
IMMEDIATE COAST...AND EXCLUDING PENDER AND NEW HANOVER COUNTIES
THIS AFTERNOON. THE PREVIOUS EARLY MORNING DISCUSSION FOLLOWS.

AMPLIFYING LONGWAVE UPPER TROF ACROSS THE EASTERN 1/3RD TO HALF OF
THE U.S. WILL BECOME THE STORY TONIGHT THRU SUBSEQUENT PERIODS. A
TIGHTENING SFC PG WILL OCCUR WITH THE PIEDMONT TROF REMAINING ACROSS
THE CENTRAL CAROLINAS. LOOK FOR AN ACTIVE SW WIND ACROSS THE
FORECAST AREA TONIGHT. THIS WILL KEEP MIN TEMPS UP ACROSS THE
REGION WITH A RANGE OF 75-80 DEGREES COMMON. LACK OF DYNAMICS IE.
FORCING...TO SUPPORT LET ALONE INITIATE CONVECTION REMAIN THE
STORY FROM THIS AFTERNOON THROUGH TONIGHT...AND THUS WILL CONTINUE
WITH NO POPS THRU DAYBREAK MON.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM SUNDAY...STRONG COLD FRONT SLATED TO CROSS THE REGION
LATE MON WILL BRING ABOUT A SIGNIFICANT AIR MASS CHANGE FOR TUE.
AHEAD OF THE FRONT INCREASING SOUTHWEST FLOW WILL CONTINUE TO PUMP
MOISTURE INTO THE SOUTHEAST WHILE 850 TEMPS IN THE LOW 20C RANGE
KEEP THE HEAT ON. HIGHS WILL CLIMB INTO THE MID TO UPPER 90S ACROSS
MUCH OF THE AREA WHILE STRONG SOUTHWEST FLOW KEEPS THE SEA BREEZE
CONFINED TO SMALL CORNERS OF THE FORECAST AREA...MAINLY SE
BRUNSWICK. A HEAT ADVISORY MAY BE NEEDED FOR MUCH IF NOT ALL OF THE
AREA.

STILL APPEARS TO BE POTENTIAL FOR SEVERE WEATHER MON BUT COVERAGE IS
LOOKING LESS CERTAIN. A NARROW RIBBON OF DEEPER MOISTURE MAY PUSH
OFF THE COAST BEFORE INSTABILITY IS ABLE TO OVERCOME THE WEAKENING
MID LEVEL CAP. DESPITE THE QUESTIONABLE MOISTURE THERE WILL STILL BE
PLENTY OF INSTABILITY. MLCAPE MON AFTERNOON SHOULD EASILY EXCEED
2500 J/KG...JUST AS 500MB HEIGHTS ARE STARTING TO FALL. FORECAST
AREA IS IN A SOMEWHAT FAVORABLE LOCATION WITH RESPECT TO THE
POSITION OF JETTING ALOFT...THOUGH BOTH GFS/NAM PORTRAY A WEAKER JET
WHEN COMPARED TO LAST NIGHT. THERE WILL ALSO BE A 25 KT LOW LEVEL
JET TAKING SHAPE IN THE AFTERNOON. ALL OF THIS SUGGESTS STORMS THAT
DO DEVELOP WILL HAVE POTENTIAL FOR STRONG UPDRAFTS AND DAMAGING WIND
ALONG WITH LARGE HAIL. JUST NOT SURE WHAT COVERAGE IS GOING TO BE
LIKE GIVEN THE INCREASING DRY AIR ALOFT. SPC SLIGHT RISK CONTINUES
FOR MUCH OF THE FORECAST AREA ON MON.

SIGNIFICANT AIR MASS CHANGE ON TAP FOR TUE...SO MUCH THAT IT WILL
FEEL LIKE FALL HAS ARRIVED EARLY. NORTHERLY FLOW BEHIND THE FRONT
WILL KEEP HIGHS IN THE MID 80S IN MOST AREAS BUT MORE SIGNIFICANTLY
HUMIDITY VALUES WILL FALL. DEWPOINTS WILL DROP WELL INTO THE 60S
WITH PRECIPITABLE WATER VALUES DOWN AROUND 1 INCH...MORE THAN -2 SD
FROM WHAT IS TYPICAL FOR THE END OF JULY. GIVEN THE AMOUNT OF DRY
AIR AND SOME WEAK SUBSIDENCE FROM CONVERGENCE ALOFT DO NOT SEE MUCH
CHANCE FOR PRECIP TUE. WILL CONTINUE TO CARRY THE INHERITED DRY BUT
NOT ZERO POP FORECAST.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 3 AM SUNDAY...UNUSUALLY STRONG MID LEVEL TROUGH WILL REMAIN IN
PLACE OVER THE EASTERN CONUS THROUGH THE PERIOD. 5H TROUGH AXIS JUST
WEST OF THE AREA WILL MAINTAIN DEEP WESTERLY FLOW...PREVENTING ANY
APPRECIABLE MOISTURE RETURN. INSTEAD DEEP DRY AIR HOLDS ON FOR MUCH
OF THE PERIOD WITH PRECIPITABLE WATER VALUES RUNNING BETWEEN 1 AND
1.25 INCHES INTO FRI. TROUGH DIGS A LITTLE LATE IN THE PERIOD AS 5H
RIDGE OVER THE ATLANTIC TRIES TO EXPAND WEST. FLOW ALOFT BACKS FROM
WEST TO SOUTHWEST RESULTING IN A SLOW BUT STEADY INCREASE IN
MOISTURE NEXT WEEKEND. PRECIP CHANCES WILL BE INCREASING LATE IN THE
PERIOD BUT THE EXTENT OF THE INCREASE REMAINS UNCERTAINTY. WHILE
THERE IS CERTAINLY POTENTIAL FOR SHORTWAVES ROUNDING THE BASE OF THE
MID LEVEL TROUGH CANNOT SAY IF ANY WILL ACTUALLY EXIST GIVEN THE
TIME FRAME. WILL MAINTAIN DRY FORECAST WED WITH SILENT POP THU/FRI
AND LOW CHC FOR SAT. TEMPERATURES WILL RUN BELOW CLIMO THROUGH THE
PERIOD WITH HIGHS EXPECTED TO REMAIN BELOW 90 WHILE LOWS DROP INTO
THE MID 60S.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 12Z...AREAS OF MVFR DUE TO FOG THIS MORNING ACROSS THE
AREA...WITH CONDITIONS IMPROVING TO VFR IN THE NEXT FEW HOURS AND
CONTINUING THROUGH THE OVERNIGHT HOURS. MVFR POSSIBLE BEFORE THE END
OF THE VALID TAF PERIOD DUE TO AREAS OF FOG.

MOSTLY MVFR PREVAILS ACROSS THE AREA THIS MORNING DUE TO FOG. EXPECT
THIS TO MIX OUT WITHIN THE NEXT HOUR...GIVING WAY TO VFR FOR THE REST
OF TODAY. EXPECT INCREASING SOUTHWEST WINDS TODAY AS A PRESSURE
GRADIENT TIGHTENS...WITH GUSTS UP TO 20 KT POSSIBLE ALONG THE
COAST. COULD NOT ENTIRELY RULE OUT AN ISOLATED THUNDERSTORM OR TWO
THIS AFTERNOON...THOUGH ANTICIPATE MAIN CONVECTION TODAY TO REMAIN
NORTH OF THE AREA. INTO THE OVERNIGHT HOURS GUSTS WILL
SUBSIDE...BUT SUSTAINED WINDS WILL REMAIN AROUND 10 TO 12 KTS.
CONDITIONS WILL REMAIN VFR...POSSIBLY DETERIORATING TO MVFR
TOWARDS THE END OF THE PERIOD DUE TO FOG.

EXTENDED OUTLOOK...SHOWERS/TSTMS/TEMPO MVFR POSSIBLE MONDAY.
OTHERWISE EXPECT VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SUNDAY...PROGRESSIVELY INCREASING SW WINDS AND SLOWLY
BUILDING SIGNIFICANT SEAS WILL RULE THE NEAR TERM PERIOD. MAY NEED
TO ISSUE A SCEC FOR TONIGHT AND LATER PERIODS...OR POSSIBLY GO
STRAIGHT WITH A SCA WITH WINDS/SEAS ON THE CUSP OF PRODUCING SCA
CONDITIONS TONIGHT AND LIKELY DURING MONDAY.

MODELS AGREE THAT THE SFC PRESSURE PATTERN AND TIGHTENING GRADIENT
WILL YIELD SW WINDS THAT INCREASE TO 15 TO 20 KT DURING
TODAY...AND 15 TO 20 KT...POSSIBLY AS HIGH AS SUSTAINED 25 KT
LATER TONIGHT. WILL ATLEAST HAVE FEW/OCCASIONAL GUSTS UP TO 25 KT
TONIGHT. SIGNIFICANT SEAS WILL BUILD UP TO 4 FT TODAY...3 TO 5 FT
TONIGHT...AND POSSIBLY UP TO 6 FT OFF CAPE FEAR ACROSS FRYING PAN
SHOALS LATE TONIGHT. WIND DRIVEN WAVES EXHIBITING 3 TO 6 SECOND
PERIODS WILL BECOME THE DOMINATE PLAYER FOR SIGNIFICANT SEAS. THE
ESE-SE DOMINATE GROUND SWELL OF THE PAST WEEK WILL REMAIN EVIDENT
ACROSS THE AREA WATERS JUST SMALLER IN HEIGHT...VIA CURRENT BUOY
DATA AND LATEST WAVEWATCH3 MODEL DATA.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SUNDAY...STRONG SOUTHWEST FLOW AHEAD OF ADVANCING COLD
FRONT WILL PROBABLY REQUIRE HEADLINES FOR THE WATERS AT SOME POINT
MON. EVENT MAY END UP AS A MARGINAL SCA...BUT CONFIDENCE IS NOT
HIGH ENOUGH TO GO WITH A HEADLINE AT THIS POINT IN TIME. WINDS
WILL LIKELY FALL SHORT OF 25 KT BUT EXTENDED PERIOD OF SOUTHWEST
FLOW COMBINED WITH INCREASING SPEEDS MON COULD PUSH SEAS OVER 6 FT
BY MID AFTERNOON. FRONT MOVES ACROSS THE WATERS MON NIGHT WITH
OFFSHORE FLOW IN ITS WAKE. BRIEF PERIOD WITH PINCHED GRADIENT
BEHIND THE FRONT WILL SEE NORTHWEST FLOW INCREASE TO 10 TO 15 KT
BUT BY MID MORNING TUE SPEEDS WILL BE UNDER 10 KT WITH VARIABLE
DIRECTION. DEVELOPMENT OF OFFSHORE FLOW BEHIND THE FRONT WILL DROP
SEAS FROM 4 TO 6 FT PRE FRONT TO 2 TO 3 FT BY TUE MORNING. SEAS
WILL REMAIN 2 TO 3 FT THROUGH THE END OF THE PERIOD.

LONG TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 3 AM SUNDAY...NORTHEAST FLOW AROUND 10 KT WED WILL INCREASE TO
10 TO 15 KTS THU AS HIGH PRESSURE TO THE WEST EXPANDS EAST AND
GRADIENT BECOMES MORE DEFINED. SEAS 2 TO 3 FT ON WED BUILD TO 3 TO 4
FT BY THU AFTERNOON.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...HEAT ADVISORY FROM NOON TODAY TO 7 PM EDT THIS EVENING FOR
     SCZ017-023-024-032-033-039-053-055.

NC...HEAT ADVISORY FROM NOON TODAY TO 7 PM EDT THIS EVENING FOR
     NCZ087-096-099-109.

MARINE...NONE.

&&

$$

SYNOPSIS...MJC
NEAR TERM...DCH/MJC
SHORT TERM...III
LONG TERM...III
AVIATION...SGL