Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 251415
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1014 AM EDT FRI JUL 25 2014

.SYNOPSIS...
A STALLED FRONT WILL BECOME INTERTWINED WITH THE SEABREEZE TODAY.
THE FRONT WILL LIFT NORTH AND DISSIPATE TONIGHT. HIGH PRESSURE WILL
FOLLOW AND BRING HOT...HUMID AND SULTRY CONDITIONS THIS WEEKEND AND
ON MONDAY. THE NEXT COLD FRONT WILL DROP ACROSS THE AREA TUESDAY. IN
ITS WAKE...COOLER AND DRIER CONDITIONS WILL OVERSPREAD THE AREA FOR
THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM FRIDAY...THE COLD FRONT HAS PUSHED SURPRISINGLY FAR TO
THE SOUTH AND IS EASILY VISIBLE ON SATELLITE IMAGERY AS A WALL OF
LOW STRATUS AND EVEN SOME PATCHY FOG. THIS BOUNDARY HAS PUSHED INTO
MYRTLE BEACH...CONWAY...AND KINGSTREE SC IN THE PAST HOUR AND SHOULD
STALL SHORTLY IN THE VICINITY OF PAWLEYS ISLAND...ANDREWS AND
GREELEYVILLE SC. MODELS SHOW THIS FRONT RETURNING NORTHWARD THIS
AFTERNOON AS HIGH PRESSURE MOVES OFF THE MID-ATLANTIC COAST...ALSO
HELPED BY A WEAK SEABREEZE CIRCULATION THAT SHOULD ADD SOME
NORTHBOUND MOMENTUM TO OUR LOW-LEVEL WINDS.

DIFFERENTIAL HEATING ALONG THE FRONT SHOULD HELP INTENSIFY LOW-LEVEL
CONVERGENCE BY EARLY AFTERNOON...AND THE LATEST FEW HRRR MODEL RUNS
PLUS LAST NIGHT`S NSSL WRF SHOW THUNDERSTORMS INITIATING ACROSS
GEORGETOWN AND HORRY COUNTIES EARLY THIS AFTERNOON. ALTHOUGH CELL
MOTION SHOULD BE EASTWARD AT 10-15 MPH...STORMS WILL INGEST THE
DRIER AIR ALOFT IN DOWNDRAFTS CREATING A COMPLEX NETWORK OF
BOUNDARIES THAT WILL ULTIMATELY DETERMINE STORM MOTION AND FUTURE
DEVELOPMENT. MY HIGHEST POPS (60-70 PERCENT) ARE CENTERED ACROSS
SOUTHERN HORRY COUNTY...WITH LOWER POPS (30-50 PERCENT) EXTENDING
INTO THE NORTHERN PEE DEE REGION AND SE NORTH CAROLINA.

WATER VAPOR IMAGERY SHOWS THE MID LEVELS HAVE DRIED SINCE YESTERDAY
EVENING. THE 12Z MHX SOUNDING WAS DOWN TO 1.75 INCHES PRECIPITABLE
WATER WITH AROUND 1.9 INCHES ON THE CHS SOUNDING. THE BULK OF THIS
DRYING IS ABOVE THE 700 MB LAYER. 0-6 KM BULK SHEAR HAS DECREASED
FROM YESTERDAY AS HAS OVERALL INSTABILITY VALUES WHICH ARE
ANTICIPATED TO AVERAGE 1500-2500 J/KG TODAY VERSUS 3000-4000 J/KG
YESTERDAY.

I HAVE BUMPED DOWN TEMPERATURES BY A COUPLE DEGREES WHERE CLOUDS
THIS MORNING PLUS ONSHORE WINDS THIS AFTERNOON WILL HELP HOLD DOWN
HEATING. OTHERWISE NO SIGNIFICANT CHANGES ARE PLANNED.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 330 AM FRIDAY...MODELS CONTINUE WITH THE ONGOING LONGWAVE
UPPER PATTERN THIS PERIOD...WITH TROFFING ALOFT ACROSS THE
EASTERN 1/3RD OF THE U.S. AND RIDGING ALOFT FOR THE WESTERN 2/3RDS
OF THE U.S. THE UPPER TROF AXIS...NOT AS AMPLIFIED AS WAS EARLIER
IN THE WEEK...IS PROGGED TO A POSITION JUST OFF THE CAROLINA
COASTS...BASICALLY ALONG THE EASTERN SEABOARD. AT THE SFC...MODELS
INDICATE THE SFC FRONT WILL DECAY ACROSS THE AREA ON SATURDAY.
THIS WILL LEAVE THE FA UNDER WEAK RIDGING FROM THE ATL
WATERS...AND THE FORMATION OF THE PIEDMONT TROF ACROSS THE CENTRAL
CAROLINAS DURING SATURDAY.

FOR SUNDAY THRU SUNDAY NIGHT...THE MODELS REMAIN IN GOOD
AGREEMENT WITH THE AMPLIFICATION OF BOTH THE UPPER TROF
OVERHEAD...AND THE UPPER RIDGING THAT IS CURRENTLY AFFECTING THE
WESTERN 2/3RDS OF THE U.S. A S/W TROF IS PROGGED TO DIVE OUT OF
CENTRAL CANADA EARLY SUNDAY...AND BASICALLY AID IN THE
AMPLIFICATION PROCESS OF THE FLOW ALOFT ACROSS THE CONTERMINOUS
U.S. AT THE SFC...THE WEAK RIDGING FROM OFF THE COAST WILL GET
SHUNTED SOUTH OF THE AREA. THE PIEDMONT SFC TROF WILL GAIN SOME
STRENGTH AS MODELS CONTINUE WITH THE TIGHTENING OF THE GRADIENT
ASSOCIATED WITH THE PIEDMONT TROF.

THIS PERIOD WILL BE HIGHLIGHTED BY THE 3HS...HAZY HOT AND HUMID.
VERY LITTLE IN THE WAY OF CONVECTION IS EXPECTED EXCEPT FOR ISOLATED
CHANCES ALONG THE SEA BREEZE BOUNDARY...AND ANY CONVECTION THAT
DRIFTS TO THE FA AFTER FIRING UP ALONG THE PIEDMONT TROF. THUS
20-30 POPS ARE THE HIGHEST WILL GO THIS PERIOD. OVERALL...WARMER
TEMPS ALOFT AS WELL AS SUBSIDENCE ALOFT...WILL BOTH AID IN KEEPING
A LID ON CONVECTION THIS WEEKEND. VARIOUS MODEL MOS GUIDANCE DOES
PAINT WIDESPREAD 90+ DEGREE TEMPS FOR SATURDAY...AND EVEN HOTTER
ON SUNDAY. HAVE GONE ALONG WITH THESE NUMBERS ESPECIALLY WITH THE
DECENT W-NW DOWNSLOPE FLOW ALOFT. IN FACT...HEAT ADVISORY CRITERIA
WILL LIKELY BE MET ON SUNDAY WITH HIGHS WELL INTO THE 90S ALONG
WITH HUMIDITY LEVELS HAVING INCHED BACK UPWARDS. THUS THE 2
COMBINED PROVIDE FORECAST HEAT INDICES REACHING A WIDESPREAD
104-106 DEGREES ACROSS THE FA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...MID LEVEL TROUGH WILL DOMINATE MUCH OF THE
PERIOD KEEPING TEMPERATURES ACROSS THE REGION BELOW CLIMO. THE
EXCEPTION WILL BE ON SUN WITH MID LEVEL RIDGE TO THE WEST
EXTENDING EAST. 850 TEMPS WILL FLIRT WITH 20-22C WHICH SHOULD
PRODUCE HIGHS IN THE MID TO UPPER 90S. DESPITE THE HOT TEMPS DO NOT
THINK THERE WILL BE MUCH CONVECTION AROUND. WESTERLY MID LEVEL FLOW
AND SUBSIDENCE ON THE RIDGES PERIPHERY WILL KEEP MID LEVELS DRY.
CANNOT RULE OUT ISOLATED CONVECTION...ESPECIALLY LATER IN THE DAY
ASSOCIATED WITH THE PIEDMONT TROUGH BUT SEE NO REASON TO GO ABOVE
INHERITED SILENT POP.

COLD FRONT MOVES INTO THE AREA LATE MON...PUSHED BY IMPRESSIVE MID
LEVEL TROUGH. DOES NOT LOOK LIKE MON WILL BE AS HOT AS SUN GIVEN
INCREASED MID LEVEL MOISTURE AND MORE WIDESPREAD CONVECTION LATER IN
THE DAY...JUST AHEAD OF THE FRONT. SHOULD THE FRONT BE DELAYED A BIT
MON COULD END UP AS HOT AS SUN GIVEN 850 TEMPS HANGING IN THE LOW
20C RANGE FOR MUCH OF THE DAY. LATER MON INTO TUE WILL BE THE MOST
ACTIVE PART OF THE PERIOD CONVECTIVELY SPEAKING AND WILL MAINTAIN
INHERITED HIGH CHC POP.

MID LEVEL TROUGH AXIS WILL REMAIN WEST OF THE AREA THROUGH THE
PERIOD WITH THE FRONT STALLING NOT TOO FAR OFF THE COAST. INITIALLY
MID LEVELS ARE DRY BUT INCREASING MOISTURE ALOFT WILL RESULT IN A
SLOW INCREASE IN POP THROUGH THE MIDDLE OF NEXT WEEK. TEMPS WILL RUN
A LITTLE BELOW CLIMO LATE IN THE PERIOD.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...AREAS OF MVFR/IFR FOR THE NEXT HOUR OR TWO DUE TO
ADVECTION FOG AND LOW CIGS ASSOCIATED WITH A FRONTAL BOUNDARY.
CONDITIONS IMPROVE TO VFR BY LATE MORNING. SHRA/TSRA POSSIBLE THIS
AFTERNOON...ESPECIALLY ALONG THE COAST.

IFR DUE TO LOW CIGS AND FOG IS CURRENTLY BEING OBSERVED AT
KILM/KFLO/KLBT. EXPECT THIS TO IMPROVE TO MVFR AND THEN VFR
WITHIN THE NEXT COUPLE OF HOURS AND FOR NORTHERLY WINDS TO
INCREASE TO AOB 5 KTS. INTO THIS AFTERNOON...WINDS WILL BECOME
SOUTHEAST AOB 10 KTS ALONG THE COAST WHILE LIGHT WINDS REMAIN
INLAND. CHANCES WILL INCREASE FOR ISOLATED TO SCATTERED
TSRA/SHRA...ESPECIALLY ALONG THE COAST...AS THE SEA BREEZE AND
FRONTAL BOUNDARY INTERACT. ANY CONVECTION WILL TAPER OFF LATER
TONIGHT...AND OVERNIGHT INTO THE EARLY MORNING HOURS WINDS WILL
BECOME LIGHT AND VARIABLE WITH MVFR/IFR IS POSSIBLE DUE TO FOG AT
ALL SITES.

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

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM FRIDAY...THE COLD FRONT HAS PUSHED ALL THE WAY DOWN TO
MYRTLE BEACH THIS MORNING WITH NORTH WINDS GUSTING AS HIGH AS 15
KNOTS ACROSS THE WATERS OF SOUTHEASTERN NORTH CAROLINA. THE FRONT
SHOULD STALL SOON NEAR MURRELLS INLET OR PAWLEYS ISLAND...THEN WILL
RETURN NORTHWARD THIS AFTERNOON. THE BIGGEST CHANGE TO THE FORECAST
REGARDS WIND DIRECTION THIS MORNING WHICH ARE MAINLY NORTH TO
NORTHEAST BEHIND THE FRONT...BUT REMAIN SOUTHWESTERLY ACROSS THE
GEORGETOWN COUNTY WATERS. LATEST MODELS SHOW A SLOWER VEERING OF THE
SURFACE WINDS NORTH OF THE FRONT THIS AFTERNOON...WITH DIRECTIONS
REMAINING EAST FOR A LONGER PERIOD OF TIME THAN EARLIER THOUGH.
FORTUNATELY WIND SPEEDS SHOULD REMAIN FAIRLY LIGHT.

SEAS ARE RUNNING 2-3 FT CURRENTLY...AND WITH NO SIGNIFICANT INCREASE
EXPECTED IN WIND SPEEDS THROUGH THE DAY I HAVE TRIMMED ABOUT A FOOT
OFF THE PREVIOUS FORECAST. A 9-SECOND SOUTHEAST SWELL CONTINUES.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 330 AM FRIDAY...FOR SATURDAY...THE AREA WATERS WILL BE
UNDER THE INFLUENCE OF A DECAYING FRONTAL BOUNDARY...RESULTING IN
MAINLY A VARIABLE WIND DIRECTION FOR MUCH OF THE DAY...AND WITH
THE LACK OF ANY GRADIENT...SPEEDS WILL GENERALLY BE 10 KT OR LESS.

FOR SUNDAY...THE AMPLIFYING FLOW ALOFT WILL RESULT IN A
STRENGTHENING SFC PIEDMONT TROF ACROSS THE CENTRAL CAROLINAS AND
THE RIDGING FROM THE BERMUDA HIGH BEING SHUNTED WELL SOUTH OF THE
AREA WATERS. THIS WILL PRODUCE A TIGHTENING SFC PG ACROSS THE
CAROLINAS INCLUDING THE COASTAL WATERS. THE SFC PRESSURE PATTERN
WILL YIELD A SFC SW-WSW WIND DIRECTION...WITH INCREASING SPEEDS
SUNDAY INTO SUNDAY NIGHT. SCEC AND/OR SCA CONDITIONS WILL LIKELY
BE MET SUNDAY AFTERNOON AND/OR NIGHT.

SIGNIFICANT SEAS WILL BE AT THEIR EBB DURING SATURDAY WITH AN ESE-
SE 1-3 FOOT GROUND SWELL DOMINATING THE WATERS. THE AFTN/EVENING SEA
BREEZE CIRCULATION WILL ADD SOME WIND CHOP NEAR SHORE. FOR
SUNDAY...LOOK FOR WIND DRIVEN WAVES TO STEADILY INCREASE IN BOTH
HEIGHT AND PERIODS...AND WILL LIKELY BE THE DOMINANT PLAYER IN THE
SIGNIFICANT SEAS FORMULA. WILL ADVERTISE 6 FOOTERS ACROSS THE
LOCAL WATERS LATE SUNDAY AFTERNOON BUT MORE LIKE SUNDAY NIGHT.

.LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 PM THURSDAY...MODEST SW FLOW ON SUN WILL INCREASE INTO MON
AS GRADIENT TIGHTENS AHEAD OF ADVANCING COLD FRONT. SPEEDS LATER SUN
MAY APPROACH SCEC THRESHOLDS AS PIEDMONT TROUGH STRENGTHENS. SCA
HEADLINES SEEM CERTAIN FOR AT LEAST MON AND POSSIBLY SUN NIGHT AS
PROLONGED STRONG SOUTHWEST FLOW BUILDS SEAS TO 4 TO 6 FT. FRONT
MOVES ACROSS THE WATERS MON NIGHT WITH NORTHERLY FLOW DEVELOPING.
GRADIENT RELAXES BEHIND THE FRONT AND SPEEDS WILL DROP UNDER 10 KT
BY MIDDAY TUE. FRONT ENDS UP STALLED JUST EAST OF THE WATERS WITH
THE PROXIMITY TO THE FRONTAL ZONE KEEPING GRADIENT WEAK AND WINDS
LIGHT AND VARIABLE. SEAS WILL DROP TO 3 TO 4 FT BEHIND THE FRONT AND
BELOW 3 FT BY THE END OF THE PERIOD.

&&

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

&&

$$

NEAR TERM...TRA
SHORT TERM...DCH
LONG TERM...III
AVIATION...SGL




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