-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 240744
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
344 AM EDT THU JUL 24 2014

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTHWEST TODAY...BRINGING
INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON
AND TONIGHT. THIS FRONT WILL STALL ACROSS THE AREA FRIDAY BEFORE
DISSIPATING ON SATURDAY. HIGH PRESSURE WILL BRING VERY HOT AND
HUMID CONDITIONS SUNDAY AND MONDAY. A STRONG COLD FRONT WILL
CROSS THE AREA EARLY TUESDAY...BRINGING COOLER AND DRIER
CONDITIONS FOR THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM THURSDAY...A COLD FRONT WILL DROP INTO THE LEE SIDE
TROUGH POSITION TODAY AND THE FRONT WILL THEN SLIDE ACROSS THE
FORECAST AREA TONIGHT...LIKELY LYING ACROSS SOUTHERN AND EASTERN
PORTIONS OF THE FORECAST AREA AT DAYBREAK FRI. THE UPPER TROUGH WILL
STILL BE UPSTREAM FRI MORNING.

THE ATMOSPHERE WILL BE WARM AND MOIST THROUGH A DEEP LAYER WITH
PRECIPITABLE WATER VALUES IN EXCESS OF 2 INCHES AND ALONG THE
COAST...ABOVE 2.25 INCHES. TEMPERATURES ARE EXPECTED TO REACH THE
LOWER TO MID 90S TODAY. THIS WILL BRING MIXED LAYER CAPE VALUES IN
THE NEIGHBORHOOD OF 2000-2500 J/KG. MID LEVEL LAPSE RATES AND SHEAR
VALUES ARE UNIMPRESSIVE...BUT MID-LEVEL WINDS WILL BE ON THE ORDER
OF 40 KT. THE BIGGEST RISK WITH THUNDERSTORMS TODAY AND TONIGHT WILL
BE FREQUENT LIGHTNING AND HEAVY RAIN...ALTHOUGH STORM MOTIONS ARE
MUCH HIGHER THAN EARLIER IN THE WEEK WHICH SHOULD LIMIT THE
EXCESSIVE RAINFALL THREAT. HOWEVER...THE DEEPEST CONVECTION WILL BE
CAPABLE OF STRONG WIND GUSTS AND AN ISOLATED WET MICROBURST WITH
DAMAGING WINDS CAN NOT BE RULED OUT.

THUNDERSTORMS SHOULD DEVELOP ALONG A RATHER SHARP SEABREEZE BOUNDARY
LATER THIS MORNING/MIDDAY. ELSEWHERE...AFTERNOON THUNDERSTORMS WILL
POP AS THE CONVECTIVE TEMPS ARE EXCEEDED. THE CONVECTION SHOULD TEND
TO BECOME MORE ORGANIZED MID AND LATE AFTERNOON AS IT MOVES TOWARD
THE COAST. WE EXPECT CONVECTION TO LAST WELL INTO THE NIGHT IF NOT
THROUGH THE NIGHT AS A MODEST SHORTWAVE ALOFT INTERACTS WITH THE
SURFACE FRONT.

HEAT INDEX VALUES LATE MORNING AND THIS AFTERNOON WILL REACH 100
DEGREES IN MOST AREAS AND AS HIGH AS 104 DEGREES. OF COURSE...ONCE A
STRONG THUNDERSTORM MOVES OVERHEAD...THE HEAT WILL GET KNOCKED
DOWN...BUT NOT THE HUMIDITY.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...COLD FRONT STALLED ACROSS THE AREA WILL
CONTINUE SHOWER AND THUNDERSTORM CHANCES ON FRIDAY...BUT AT THE SAME
TIME DRIER AIR WILL BEGIN TO ADVECT IN FROM THE WEST...DRYING OUT
THE MID AND UPR PORTIONS OF THE COLUMN. STILL...WITH THE FRONT IN
PLACE...TEMPS RISING TO AROUND 90...AND DEWPOINTS IN THE LOW
70S...THERE WILL BE PLENTY OF FUEL AROUND FOR CONVECTION BEFORE THE
DRIER AIR WORKS INTO THE CWA. THUS WILL CARRY CHC POP
FRIDAY...HIGHEST ACROSS THE EASTERN PORTIONS OF THE CWA. THE DIURNAL
TREND FOR CONVECTION MAY BE A BIT ATYPICAL AS THE DRY AIR INTRUDES
OVERHEAD...AND THE HIGHEST COVERAGE OF CONVECTION MAY BE LATE
MORNING/EARLY AFTN BEFORE TAPERING OFF INTO THE EVE. THIS FRONT WILL
WASH OUT FRIDAY NIGHT LEAVING MOSTLY CLEAR SKY CONDITIONS...BUT AS
LIGHT SW FLOW RE-DEVELOPS...MINS WILL FALL ONLY INTO THE MID 70S AT
THE COAST...AND TO AROUND 70 INLAND.

ANY AIRMASS CHANGE ASSOCIATED WITH THE PRIOR FRONT QUICKLY ERODES
SATURDAY...LEAVING A HOT DAY ACROSS THE CWA. FORTUNATELY...THE
COLUMN WILL BE DRIER...AND THUS HUMIDITY VALUES WILL BE MUCH
LOWER...KEEPING APPARENT TEMPS TO BELOW 100 EVEN AS HIGHS CLIMB TO
AROUND 90 AT THE COAST...MID 90S WELL INLAND. WILL CONTINUE WITH THE
INHERITED SCHC POP ON SATURDAY SIMPLY DUE TO THE HEAT...BUT ONLY
ISOLATED STORMS ARE POSSIBLE AS PWATS DROP TO LESS THAN 1.5 INCHES.
INCREASING SW RETURN FLOW SATURDAY NIGHT WILL PREVENT SIGNIFICANT
COOLING...AND THUS LOWS SAT NIGHT WILL BE WELL ABOVE NORMAL...UPR
70S AT THE BEACHES TO LOW 70S ONLY WELL INLAND.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...A HOT START TO THE PERIOD...BUT IT WILL BE
SHORT LIVED AS...ONCE AGAIN...AN ANOMALOUSLY STRONG UPPER TROUGH
DIVES ACROSS THE EASTERN CONUS.

SUNDAY LOOKS TO BE THE HOTTEST DAY OF THE PERIOD AS SUBTLE MID-LEVEL
RIDGING AND STRONG SW RETURN FLOW AROUND A RIDGE OF HIGH PRESSURE
PUSH TEMPS INTO THE MID AND MAYBE UPR 90S...AND WE MAY EXPERIENCE
OUR FIRST HEAT ADVISORY OF 2014 (HEAT INDEX OF 105 OR GREATER). ALTHOUGH
HUMIDITY WILL INCREASE ON SUNDAY AS WELL...CONVECTIVE COVERAGE MAY
BE QUITE LIMITED DUE TO SOME MID-LEVEL DRY AIR PERSISTING...AND A
LID WITHIN A LOW-LEVEL THERMAL RIDGE. MONDAY WILL BE
SIMILAR...ALTHOUGH A DEGREE OR 2 COOLER AS CLOUD COVER INCREASES
AND MID-LEVEL HEIGHTS DECREASE AHEAD OF AN ADVANCING COLD FRONT.
INCREASING POP IS WARRANTED MONDAY AS WELL...WITH THE BEST CHANCE
OCCURRING MONDAY NIGHT AS THE COLD FRONT MOVES INTO THE AREA. LOWS
BOTH NIGHTS WILL BE ABOVE NORMAL IN MID AND UPR 70S.

BIG AIR MASS CHANGE OCCURS THEREAFTER AS -3 SD TROUGH DROPS INTO
THE MIDWEST...DRIVING A STRONG COLD FRONT INTO THE CWA AND OFFSHORE
DURING TUESDAY. THIS TROUGH WILL PRODUCE LOWERED HEIGHTS ALL THE WAY
INTO THE GULF OF MEXICO THROUGH THE MIDDLE OF NEXT WEEK...BUT
FORTUNATELY FOR THE AREA THE TROUGH AXIS REMAINS DISPLACED WEST OF
THE COASTAL CAROLINAS. WHILE DRIER AND COOLER AIR IS ANTICIPATED
TUE/WED...WITH TEMPS RUNNING SEVERAL DEGREES BELOW NORMAL...LOCALLY
WE WILL NOT BE AS COOL AS OUR NEIGHBORS WELL WEST. LOWER POP IS
EXPECTED THROUGH MID-WEEK...BUT INCREASING E/NE FLOW MAY ALLOW FOR
RESIDUAL RAIN CHANCES TO PERSIST ALONG THE COAST THROUGH THE END OF
THE PERIOD.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...CURRENTLY VFR AT THE TERMINALS. WINDS WILL STAY ELEVATED
EARLY THIS MORNING FROM THE SW. THIS SHOULD WORK AGAINST ANY
SIGNIFICANT FOG FORMATION...BUT COULD STILL SEE TEMPO MVFR VSBYS/SCT
STRATUS AT KFLO/KLBT IN THE PRE-DAWN HOURS. COASTAL TERMINALS SHOULD
REMAIN VFR.

SW WINDS INCREASE BY MID MORNING TO 10-20KT AT THE COASTAL TERMINALS
AND TO AROUND 10KT AT KFLO/KLBT. EXPECT A DECENT CHANCE OF TEMPO
TSRA/MVFR BY 18Z. BEST LIFT PLAYS OUT AFTER 21-22Z AS THE AIRMASS
STABILIZES...BUT SHOWERS COULD PERSIST INTO THE EVENING HOURS.

EXTENDED OUTLOOK...SHOWERS/TSTMS/TEMPO MVFR POSSIBLE THROUGH
FRIDAY...AS WELL AS SUNDAY AND MONDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM THURSDAY...A TIGHTER PRESSURE GRADIENT WILL BE REALIZED
TODAY INTO THIS EVENING AS A RATHER IMPRESSIVE TROUGH FOR THIS TIME
OF YEAR APPROACHES. SOUTHWEST SUSTAINED WIND SPEEDS ARE EXPECTED TO
REACH 20 KT WITH GUSTS TO 25 KT. SEAS TODAY ARE EXPECTED TO REACH UP
TO 4 TO 5 FT...WITH SOME 6 FT SEAS POSSIBLE ACROSS THE OUTERMOST
WATERS LATE DAY AND THIS EVE. AT THIS TIME...WILL ISSUE A SMALL
CRAFT SHOULD EXERCISE CAUTION HEADLINE. THE FRONTAL ZONE SHOULD BE
NEARING THE WATERS LATE TONIGHT AND EXPECT THE WIND DIRECTION
OVERNIGHT WILL VEER TO A MORE WESTERLY DIRECTION WITH WIND SPEEDS
DECREASING TO 10 TO 15 KT.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...WESTERLY WINDS WILL BEGIN THE PERIOD AS A
COLD FRONT WAVERS JUST OFF THE COAST. THIS FRONT WILL LIFT SLOWLY
BACK TO THE NORTH DURING FRIDAY...WITH WINDS REMAINING
LIGHT...AROUND 10 KTS...BUT BACKING TO THE SW THROUGH SUNDAY
MORNING. THEREAFTER...WINDS WILL INCREASE THROUGH SATURDAY AS THE
PRESSURE GRADIENT TIGHTENS ABOUT AROUND HIGH PRESSURE RIDGING BACK
TOWARDS THE COAST...WITH SPEEDS RISING FROM THE SW TO AROUND 15 KTS.
SEAS WILL BE 3-4 FT EARLY FRIDAY...AND RISE AGAIN TO 3-4 FT LATE
SATURDAY. IN BETWEEN 1-3 FT SEAS WILL BE COMMON THANKS TO THE
EXTENDED PERIOD OF LIGHTER WINDS.

LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...HIGH PRESSURE OFFSHORE RIDGING TOWARDS THE
COAST...AND A STRONG COLD FRONT SLOWLY APPROACHING FROM THE
NW...WILL PINCH THE GRADIENT SUNDAY AND MONDAY. THIS DRIVES SW WINDS
UP TO 20 KTS OR MORE BOTH DAYS...AND PUSHES WIND-DRIVEN SEAS UP TO
4-6 FT. AN SCA MAY BE NEEDED FOR AN EXTENDED PORTION OF THIS PERIOD
AHEAD OF THE COLD FRONT WHICH IS PROGGED TO CROSS THE WATERS BY
TUESDAY MORNING.

&&

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

&&

$$
SYNOPSIS...JDW
NEAR TERM...RJD
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...RJD
MARINE...RJD/JDW