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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 101145
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
745 AM EDT THU JUL 10 2014

.SYNOPSIS...
A COLD FRONT WILL STALL ACROSS THE REGION TONIGHT...PERSISTING
INTO EARLY SATURDAY. THIS WILL BRING GOOD CHANCES FOR
THUNDERSTORMS THE NEXT FEW DAYS...WITH PERIODS OF HEAVY RAINFALL.
THIS FRONT WILL DISSIPATE LATE IN THE WEEKEND WITH A RETURN TO
TYPICAL SUMMERTIME CONDITIONS...WITH A WARMING TREND DEVELOPING
EARLY NEXT WEEK. ANOTHER COLD FRONT WILL APPROACH ON WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:

THE LIKELIHOOD OF SHOWERS AND THUNDERSTORMS INCREASES TODAY AS THE
ATMOSPHERIC COLUMN MOISTENS IN ADVANCE OF A SLOW MOVING COLD
FRONT. MODEL SOUNDINGS SHOW THE COLUMN BECOMING NEARLY SATURATED
WITH P/W VALUES IN THE 2 INCH RANGE BY THIS AFTERNOON. AT THE
UPPER LEVELS A SERIES OF WEAK DISTURBANCES MOVING ALONG THE
LEADING EDGE OF AN H/5 LONGWAVE TROUGH WILL ACT ON A MODERATELY
UNSTABLE AND MOIST ATMOSPHERE TO KEEP IN THE THREAT OF
CONVECTION...WITH THE POSSIBILITY OF HEAVY RAIN AND TRAINING
STORMS THROUGH THE AFTERNOON AND EVENING HOURS.

EXTENSIVE CLOUD COVER AND LOWERING THICKNESS VALUES WILL ALLOW FOR
SIGNIFICANTLY LOWER DAYTIME TEMPERATURES THAN EXPERIENCED OVER THE
PAST COUPLE OF DAYS...ESPECIALLY INLAND. EXPECT HIGHS OF AROUND 90
MOST PLACES...WITH UPPER 80S CLOSER TO THE COAST.

MODEL CONSENSUS HAS FRONT STALLING OVER THE NORTHWESTERN PORTION OF
OUR CWA OVERNIGHT. THE FRONT WILL SERVE AS A CONTINUED FOCUS FOR
CONVECTION...SO WILL BE MAINTAINING LIKELY POPS WITH THE POSSIBILITY
OF HEAVY RAIN FOR TONIGHT. CONSIDERING RECENT MODEL PERFORMANCE HAVE
STAYED ON THE HIGH SIDE OF GUIDANCE FOR OVERNIGHT MINIMUMS. THIS
WILL GIVE US LOWS IN THE LOWER TO MID 70S MOST PLACES.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 330 AM THURSDAY...FRIDAY CONTINUES TO LOOK VERY WET LOCALLY AS
ELEMENTS COMBINE TO PRODUCE WIDESPREAD CONVECTION WITH HEAVY RAIN.
AT THE SURFACE...A WEAKENING COLD FRONT WILL BE WAVERING ACROSS THE
CWA...AND THIS...ALONG WITH REMNANT OUTFLOW BOUNDARIES FROM
CONVECTION ON THURSDAY...WILL SERVE AS FOCI FOR UPDRAFTS ON FRIDAY.
ALOFT...SHEAR LINE DEMARCATING THE LONGWAVE TROUGH AXIS WILL SWING
OVERHEAD AND NORTHEAST DURING THE DAY...WHILE 300MB 100KT JET MOVES
OVER NEW ENGLAND...LEAVING THE CAROLINAS WITHIN THE FAVORABLE RFQ
DIFLUENT REGION...IN A SETUP THAT RESEMBLES QUITE WELL A
MADDOX-TYPE EVENT FROM LITERATURE FOR HEAVY RAIN.

ALL THIS OCCURS IN A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY
SBCAPE OF 800-1000 J/KG...PWATS OVER 2 INCHES...AND WARM CLOUD
DEPTH APPROACHING 11 KFT. THE "LONG SKINNY" CAPE PROFILE SUGGESTS
EFFICIENT PRECIPITATION PROCESSES (LONGER PARCEL RESIDENCE TIMES
WITHIN STRONG COLLISION-COALESCENCE ENVIRONMENT) IN UPDRAFTS
FRIDAY AS WELL...SO ALL SIGNS POINT TO A VERY ACTIVE DAY WITH
HEAVY RAINFALL THE PRIMARY THREAT WITHIN THUNDERSTORMS. ALTHOUGH
DRIER AIR WILL SLOWLY BEGIN TO FILTER INTO THE MID-LEVELS AS AN
EMBEDDED SHORTWAVE PUSHES OFFSHORE LATE FRIDAY...STILL ANTICIPATE
A SIGNIFICANT QPF DAY...HIGHEST EASTERN HALF OF THE CWA. TEMPS
WILL BE TEMPERED BY THE WIDESPREAD CLOUDS AND RAIN...RISING ONLY
INTO THE MID/UPR 80S. LOWS AT NIGHT WILL DROP INTO THE MID 70S AT
THE COAST...BUT AROUND 70 WELL INLAND WHERE DRIER AIR WILL BECOME
MORE PRONOUNCED LATE.

SATURDAY WILL BE A TRANSITIONAL DAY AS RIDGING FROM THE SOUTHWEST
TRIES TO BLOSSOM ACROSS THE AREA. IT WILL GET SHUNTED EAST BY THE
AFOREMENTIONED LONGWAVE TROUGH...BUT THE WESTERLY FLOW BETWEEN THESE
TWO FEATURES WILL HELP TO DRY THE COLUMN FROM FRIDAY. AT THE SAME
TIME...THE SUBTLE THICKNESS INCREASE WILL HELP TO FURTHER ERODE THE
FRONT WHICH SHOULD BECOME INDISTINGUISHABLE ON SATURDAY.
HOWEVER...IT WILL CONTINUE TO HELP DRIVE CONVECTION...ALBEIT IN A
LESS SIGNIFICANT MANNER THAN FRIDAY. STILL ANTICIPATE SCATTERED
TSTMS SATURDAY AREA-WIDE...WITH TEMPS AGAIN JUST BELOW NORMAL IN
THE UPR 80S TO AROUND 90...AND LOWS A FEW DEGREES ABOVE 70.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...SEASONABLE CONDITIONS TO BEGIN THE PERIOD AS
RIDGING DEVELOPS ALOFT AND HIGH PRESSURE OFFSHORE RIDGES BACK
TOWARDS THE COAST. MID-LEVEL WESTERLY FLOW WILL CAUSE A RELATIVELY
DRY COLUMN ON SUNDAY...SO ONLY ISOLATED CONVECTION IS
ANTICIPATED...LIKELY LESS THAN CLIMATOLOGICALLY NORMAL. WITH HEIGHTS
BUILDING ALOFT AND RETURN FLOW DEVELOPING...TEMPS SUNDAY WILL WARM
TO SEASONABLE VALUES. THEREAFTER...HEAT WILL SLOWLY BUILD AGAIN
THROUGH TUESDAY THANKS TO SUBTLE THICKNESS INCREASE DOWNSTREAM OF A
LARGE TROUGH ACROSS THE MIDWEST...AND CONTINUED RETURN FLOW AT THE
SURFACE. THIS DRIVES MORE TYPICAL CONVECTION CHANCES
MONDAY/TUESDAY...BEFORE A COLD FRONT APPROACHES AND STALLS ACROSS
THE AREA BY WEDNESDAY. THIS WILL BRING MUCH MORE WIDESPREAD PRECIP
CHANCES FOR THE MIDDLE OF NEXT WEEK...ALONG WITH TEMPERATURES
COOLING BACK TO SEASONABLE LEVELS.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING NEAR
THE COASTAL TERMINALS WITH GENERALLY MVFR CIGS AND S-SW WINDS
5-10KT. AT KFLO/KLBT CIGS ARE VFR WITH MVFR VSBYS IN BR AND LIGHT
SE-S WINDS.

EXPECT LITTLE CHANGE THROUGH MID MORNING EXCEPT VSBYS SHOULD
INCREASE AT KFLO/KLBT AS BR BURNS OFF. BY LATE MORNING WINDS WILL
INCREASE FROM THE S AT THE COASTAL TERMINALS. SHRA/TSRA SHOULD
BECOME MORE LIKELY AT KFLO/KLBT AND LESS LIKELY AT THE COASTAL
TERMINALS. DURING THE AFTERNOON THE BULK OF THE CONVECTION WILL
AFFECT KFLO/KLBT...MOVING TO THE COASTAL TERMINALS IN THE EVENING.
DUE TO UNCERTAINTIES IN TIMING AND COVERAGE WILL INDICATE MVFR
CONDITIONS WITH CONVECTION. SHORT TERM IFR IS ALMOST CERTAIN TO
OCCUR BUT SHOULD NOT LAST 15-30 MINUTES AT ANY ONE TERMINAL...
UNLESS A TERMINAL HAPPENS TO BE UNDER TRAINING CELLS. CONVECTION
BECOMES ISOLATED 06-12Z...MOST LIKELY AT KLBT AND NEAR THE COASTAL
TERMINALS. MVFR VSBYS IN BR ARE ALMOST CERTAIN TO OCCUR 06-12Z AT
KFLO/KLBT. CONFIDENCE OF IFR IS LOW DUE TO CLOUD COVER.

EXTENDED OUTLOOK...A FRONT STALLS OVER THE REGION WITH A DECENT
CHANCE FOR SHRA/TSRA THROUGH SATURDAY...MAINLY IN THE AFTERNOON.
SHRA/TSRA ARE AGAIN POSSIBLE MONDAY. BRIEF IFR CONDITIONS ARE
POSSIBLE IN THE HEAVIER SHOWERS AND STORMS. OTHERWISE VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:

SOUTHWESTERLY FLOW WILL CONTINUE OVER THE WATERS THROUGH THE NEAR
TERM AS HIGH PRESSURE OVER THE WESTERN ATLANTIC INTERACTS WITH AN
APPROACHING COLD FRONT WELL INLAND. WINDS WILL STAY IN THE 10 TO
15 KT RANGE FOR MUCH OF THE PERIOD...WITH SEAS AVERAGING 2 TO 4
FT.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 330 AM THURSDAY...A WEAKENING COLD FRONT WILL WAVER IN THE
VICINITY THROUGH SATURDAY...LIKELY REMAINING JUST WEST OF THE
COASTAL WATERS DURING THIS PERIOD. THAT LEAVES A WEAK
GRADIENT...AND S/SE WINDS FRIDAY AND SATURDAY AT 10 KTS OR LESS.
LATE SATURDAY THE COLD FRONT WILL WASH OUT...AND AS HIGH PRESSURE
BECOMES DOMINANT OFFSHORE...WINDS WILL VEER TO BECOME MORE
SWLY...REMAINING AROUND 10 KTS. WAVE HEIGHTS WILL BE HIGHEST ON
FRIDAY...THANKS TO WINDS EASING FROM THURSDAY...WITH 3-4 FT SEAS
LIKELY ON A SOUTHERLY WIND CHOP. THESE HEIGHTS WILL DROP TO 1-3 FT
ON SATURDAY ON THE LIGHTER WINDS.

LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 330 AM THURSDAY...MORE TYPICAL SUMMERTIME PATTERN WILL DEVELOP
LATE IN THE WKND AND EARLY NEXT WEEK AS HIGH PRESSURE OFFSHORE
EXERTS ITS INFLUENCE ACROSS THE COASTAL WATERS. SW WINDS WILL SLOWLY
INCREASE THROUGH THE PERIOD...BECOMING 15-20 KTS LATE MONDAY. THE
COMBINATION OF THESE RISING WINDS AND AN AMPLIFYING GROUND SWELL
WILL DRIVE SEAS UP FROM 2-3 FT SUNDAY...TO 3-5 FT MONDAY...AND
CAUTIONARY STATEMENTS MAY BE NEEDED EARLY NEXT WEEK.

&&

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

&&

$$
SYNOPSIS...JDW
NEAR TERM...REK
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...MRR
MARINE...REK/JDW