Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 301915
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
315 PM EDT TUE JUN 30 2015

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL PERSIST THROUGH THE REMAINDER OF THE
WEEK AND INTO THE UPCOMING HOLIDAY WEEKEND. THIS WILL CREATE
SLIGHTLY ABOVE NORMAL TEMPERATURES...ALONG WITH TYPICAL SUMMERTIME
THUNDERSTORM CHANCES EACH AFTERNOON AND EVENING.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM TUESDAY...SHORTWAVE ROUNDING BASE OF 5H TROUGH OVER
NORTHERN AL/GA IS GENERATING SOME IMPRESSIVE CONVECTION TO THE
SOUTHWEST. THUS FAR LOCALLY VERY LITTLE IN THE WAY OF DEEP
CONVECTION HAS BEEN ABLE TO DEVELOP...LIKELY DUE TO AN ABUNDANCE
OF LOW AND MID LEVEL DRY AIR. A LOOK AT DEWPOINTS DOWN STREAM
SHOWS VALUES AS MUCH AS 10 DEGREES F HIGHER ACROSS INLAND GA/SC.
THIS LOW LEVEL MOISTURE WILL ADVECT INTO THE FORECAST AREA LATER
THIS AFTERNOON...JUST AS THE PVA AHEAD OF THE SHORTWAVE ARRIVES.
THE COMBINATION OF INCREASING LOW LEVEL MOISTURE AND UPWARD MOTION
ASSOCIATED WITH THE SHORTWAVE IN AN ALREADY UNSTABLE ENVIRONMENT
SHOULD LEAD TO DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. OVERALL
COVERAGE WILL BE LIMITED AS THERE WILL STILL BE SOME DRY AIR
PRESENT...ESPECIALLY ABOVE 600 MB. LOW LEVEL JETTING IS LIMITED
AND SHEAR IS MARGINAL...25 KT OR SO. HOWEVER MID LEVEL DRY AIR
DOES MAKE THE CASE FOR A FEW STRONG DOWNDRAFTS AND DAMAGING WIND
WILL BE THE MAIN THREAT. SPC HAS MAINTAINED THE SLIGHT RISK FOR
INLAND DARLINGTON/MARLBORO ALONG WITH A MARGINAL RISK FOR MUCH OF
THE REMAINDER OF THE FORECAST AREA.

ANY CONVECTION THAT DOES DEVELOP WOULD HAVE TROUBLE LINGERING PAST
LATE EVENING. POST SHORTWAVE SUBSIDENCE AND LOSS OF DIURNAL
HEATING WILL PLAY A LARGE PART IN ENDING STORMS. THERE WILL ALSO
BE AN INFLUX OF DRIER MID LEVEL AIR LATER IN THE PERIOD. IF
CONVECTION IS ABLE TO CONTINUE PAST MIDNIGHT IT WOULD BE ALONG THE
NC COASTAL PLAIN AND OVER THE NEARSHORE WATERS. CONFIDENCE IN THIS
IS LOW GIVEN A GENERALLY UNFAVORABLE ENVIRONMENT AND WILL ONLY
CARRY A SLIGHT CHC POP. DEBRIS CLOUD AND SOUTHWEST BOUNDARY LAYER
FLOW WILL KEEP LOWS ABOVE CLIMO OVERNIGHT.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...THE 500 MB TROUGH OVER THE EASTERN HALF OF
THE UNITED STATES WILL REMAIN WITH SEVERAL SHORTWAVE TROUGH MOVING
THROUGH THE LARGE TROUGH. AS THEY APPROACH THE REGION THEY WILL
WEAKEN. AT THE SURFACE...THE PIEDMONT TROUGH WILL REMAIN IN PLACE
WITH DIURNAL CONVECTION BOTH DAYS. THE FRONTAL BOUNDARY TO THE NORTH
LATE THURSDAY WILL BE INTO CENTRAL VIRGINIA SO THE FORECAST WILL
REMAIN WITH 20 TO 40 PERCENT POP EACH DAY. MAXIMUM TEMPERATURES
WILL RISE INTO THE LOWER 90S TO THE UPPER 80S AT THE BEACHES. LOWS
EACH NIGHT WILL BE IN THE LOWER 70S INLAND TO THE MIDDLE 70S AT
THE COAST. &&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...LONGER WAVE TROUGH IN THE MID TO UPPER LEVELS
REMAINS DOMINANT FEATURE OVER THE NORTHEASTERN CONUS WHILE A RIDGE
REMAINS OVER THE SOUTHEAST THROUGH THE WEEKEND. A SHORTWAVE RIDING
AROUND THE TROUGH WILL PUSH A BOUNDARY SOUTH ON FRI AND THIS SHOULD
REACH FAR ENOUGH INTO NC TO PRODUCE AN ENHANCED CHC OF SHWRS AND
THUNDERSTORMS. NOT CONFIDENT THAT THIS BOUNDARY WILL MAKE IT FAR
ENOUGH SOUTH BUT SHOULD SEE SOME DECENT CONVERGENCE TO OUR NORTH.
OVERALL IT LOOKS LIKE MOISTURE WILL POOL AHEAD OF THIS BOUNDARY IN
MOIST SOUTHWESTERLY FLOW AROUND BERMUDA RIDGE OVER LOCAL FORECAST
AREA AND LOCAL BOUNDARIES INCLUDING SEA BREEZE AND PIEDMONT TROUGH
WILL COME INTO PLAY AS INITIATING FACTORS FOR CONVECTION. PCP WATER
VALUES REACH UP TO 2 INCHES OVER THE AREA ENHANCED LLJ UP TO 40
KTS. A STRONGER WESTERLY STEERING FLOW WILL ACT TO DRIVE ANY STORMS
THAT DEVELOP EASTWARD TOWARD THE COAST. THE ECMWF SEEMS TO KEEP
BOUNDARY FARTHER NORTH WHILE THE GFS BRINGS IT DOWN A LITTLE CLOSER.
OVERALL WILL KEEP WITH MOISTURE RICH FLOW AROUND BERMUDA HIGH AND
SOME PERIODIC SHORTWAVE ENERGY RIDING THROUGH TO ENHANCE THE
CONVECTION OVER OUR AREA AND SOME PERIODS OF SUBSIDENCE TO LIMIT
CONVECTION BUT GENERALLY EXPECTING A MORE TYPICAL SUMMERTIME PATTERN
KEEPING SHWRS/TSTMS IN FORECAST EACH DAY. WE WILL HAVE TO KEEP AN
EYE ON FUTURE MODEL RUNS TO SEE JUST HOW FAR SOUTH THIS BOUNDARY
WILL MAKE IT.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...THIS AFTERNOON WINDS WILL BE SW AT 10-15 KTS EXCEPT
S- SSW AT 15-20 KTS AT THE COASTAL TERMINALS. VFR WILL CONTINUE
WITH SCT SKIES CONSISTING OF LOW LEVEL CUMULUS AND HIGH LEVEL
CIRRUS. THERE IS A CHANCE THAT VCSH COULD DEVELOP MAINLY SC
TERMINALS MID- LATE AFTERNOON BUT CONFIDENCE IS LOW. PROGS ARE IN
GENERAL AGREEMENT THAT SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS
THE TERMINALS THIS EVENING AS A SHORT WAVE MOVES THROUGH.
CONFIDENCE OF COVERAGE IS LOW HOWEVER DUE TO MOISTURE
AVAILABILITY. WILL INDICATE VCSH/VCTS IN TAFS BUT HIGHEST
CONFIDENCE OF VCTS WILL BE A KFLO/KLBT. WINDS SPEEDS WILL DECREASE
LATER IN THE EVENING AND EARLY MORNING HOURS TO SW 4-8 KT. VCSH
COULD A BIT LONGER AFTER MIDNIGHT AT THE COASTAL TERMINALS THAN IS
CURRENTLY INDICATED IN TAFS. AFTER SUNRISE VFR CONTINUES WITH WEST
WINDS.

EXTENDED OUTLOOK...PREDOMINATELY VFR WITH DECREASING CHANCES OF
SHOWERS AND THUNDERSTORMS EACH DAY THROUGH SUNDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM TUESDAY...SOUTHWEST FLOW WILL BECOME MORE SOUTHERLY
LATER THIS AFTERNOON AND EVENING WITH AN INCREASE IN SPEED AS
GRADIENT BECOMES MORE DEFINED. SPEEDS CURRENTLY 10 TO 15 KT WILL
PEAK ON THE HIGH END OF THE 15 TO 20 KT RANGE THIS EVENING THEN
WEAKEN AND BECOME MORE WESTERLY AS GRADIENT RELAXES AFTER MIDNIGHT
AND ANY LINGERING CONVECTION PUSHES OFF TO THE NORTHEAST. DO NOT
EXPECT A LOT OF STORMS OVER THE WATERS BUT THERE WILL BE SOME
POTENTIAL DURING THIS EVENING AND FIRST HALF OF THE OVERNIGHT.
SEAS 3 TO 4 FT WILL PEAK AROUND 4 FT LATE TODAY...WITH ISOLATED 5
FT POSSIBLE NEAR 20 NM. SEAS WILL DROP BACK TO 3 TO 4 FT OVERNIGHT
IN RESPONSE TO THE WIND SPEED REDUCTION.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...SOUTHWEST FLOW WILL CONTINUE WITH THROUGH
THE PERIOD WITH WINDS SPEEDS AROUND 15 KNOTS WITH AN INCREASE TO
15 TO 20 KNOTS AROUND 20 MILES OFF THE COAST LATE WEDENSDAY
THROUGH THURSDAY MORNING. THE LOCAL NEAR SHORE WAVE MODEL IS
SHOWING SEAS OF 3 TO 4 FEET WITH 2 TO 3 FEET NEAR SOUTH OF
MURRELLS INLET.

LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 PM TUESDAY...CONTINUED SOUTHWEST FLOW AROUND BERMUDA RIDGE
THROUGH THE PERIOD. SHOULD BE IN THE 15 TO 20 KT RANGE THROUGH MUCH
OF THE WEEKEND IN TIGHTENED GRADIENT FLOW DUE TO BOUNDARY PUSHING
DOWN FROM THE NORTH. NOT EXPECTING THIS BOUNDARY TO REACH INTO OUR
WATERS...BUT MAY VEER WINDS AROUND A BIT TO A MORE SW FLOW RATHER
THAN S-SW. THESE WINDS WILL COMBINE WITH A SE SWELL TO PUSH WAVE
HEIGHTS TO 3-5 FT...SLIGHTLY HIGHER AT TIMES IN THE EVENING AS THE
GRADIENT GETS PINCHED IN THE LEE OF THE SHARPENING PIEDMONT TROUGH
AND ENHANCED SEA BREEZE FLOW. MAY SEE PERIODS OF EXERCISE CAUTION
AND WNA SHOWS SEAS SURPASSING SCA THRESHOLDS LATE FRI INTO SAT.

&&

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

&&

$$

NEAR TERM...III
SHORT TERM...HAWKINS
LONG TERM...RGZ
AVIATION...MRR



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