Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 300723
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
323 AM EDT SUN AUG 30 2015

.SYNOPSIS...
MOISTURE FROM THE GULF OF MEXICO WILL BRING INCREASING
COVERAGE OF SHOWERS AND ISOLATED THUNDERSTORMS FOR THE UPCOMING
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM SATURDAY...INFRARED SATELLITE IMAGERY SHOWS THE HIGH
LEVEL STREAM OF MOISTURE CONTINUES FROM THE SOUTH...WHILE AIRPORT
ASOS/AWOS OBS SHOW THE 3000-FOOT CLOUD DECK CONTINUES ALONG THE
GRAND STRAND AND AS FAR NORTH AS SOUTHPORT. TEMPERATURES ARE FALLING
INLINE WITH THE UPDATE EARLIER THIS EVENING AND ONLY A FEW TWEAKS
ARE NEEDED TO THE FORECAST. DISCUSSION FROM 730 PM FOLLOWS...

MULTILAYERED CLOUDS ACROSS THE AREA ARE IN AT LEAST THREE DISTINCT
GROUPS: SCATTERED 3000 FOOT CLOUDS WHERE MARINE MOISTURE
EXISTS...SCATTERED 6000 FOOT CLOUDS AT THE TOP OF THE DEEPER MIXED
LAYER...AND BROKEN 18000-30000 FOOT CLOUDS IN A VERY MOIST SOUTH-
SOUTHWEST FLOW ALOFT. THIS MOIST FLOW ALOFT IS KEY TO OUR FORECAST
OVER THE NEXT 12 HOURS AS IT WILL DEEPEN AND EVENTUALLY LEAD TO
SHOWERS CROSSING THE SANTEE RIVER INTO NORTHEASTERN SOUTH CAROLINA.
UNTIL THEN...PARTLY CLOUDY SKIES SHOULD TURN MOSTLY CLOUDY LATE.
VERY FEW CHANGES WERE NEEDED TO THE FORECAST WITH THIS EARLY-EVENING
UPDATE. DISCUSSION FROM 330 PM FOLLOWS...

UNUSUALLY STRONG UPPER LOW OVER THE NE/NORTH-CENTRAL GOMEX TO WEAKEN
AND START MOVING ASHORE IN FL PANHANDLE THROUGH THE PERIOD. MOISTURE
WILL THUS OVERSPREAD THE AREA FROM SW TO NE AND BE MOST PRONOUNCED
AT THE MID LEVELS. LOW LEVEL WILL LAG BEHIND BUT SHOULD STILL KICK
IN OVER SOUTHERN ZONES. SOME RAIN CHANCES WILL THUS RAMP UP LATE
TONIGHT OVER FAR SOUTHERN COUNTIES. IN THE VERY NEAR TERM SOME
MOISTURE MOVING OUT OF CHS CWA APPEARS TO BE DISSIPATING BEFORE
REACHING THE GROUND DUE TO LIGHT FORCING AND LARGE DEWPOINT
DEPRESSIONS. AS THE NIGHT WEARS ON A STRENGTHENING OF THE LIFT AND
LESSENING OF THE DEWPOINT WILL FAVOR SOME LIGHT RAIN BY THE END OF
THE PERIOD OVER ROUGHLY THE SOUTHERN HALF OF THE CWA.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...SHAPING UP TO BE A RATHER UNSETTLED COUPLE OF
DAYS AS THE STREAM OF MOISTURE AS SEEN ON INFRARED IMAGERY
EXTENDING DEEP INTO THE TROPICS CONTINUES TO MOVE ACROSS. I HAVE
ELEVATED POPS MAINLY FOR MONDAY TO LIKELY ALONG THE COAST WHERE
THE DEEPEST MOISTURE WILL RESIDE. SOME DRYING IS NOTED IN THE
PROFILES FOR TUESDAY MAINLY IN THE GFS BUT THE NAM REMAINS BULLISH
ON POPS. TO COMPROMISE I DID DECREASE THE POPS SOMEWHAT TUESDAY
BUT STILL ADVERTISING CHANCE VALUES AREA WIDE. I TRIMMED BACK
EXPECTED HIGHS A DEGREE OR TWO MONDAY AND INCREASED THE MORNING
LOWS THE SAME DUE TO THE EXPECTED MOISTURE.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...MEDIUM RANGE GUIDANCE CONTINUES TO DEPICT A WEAK
PATTERN BOTH AT THE SURFACE AND ALOFT. THERE REMAINS AMPLE MOISTURE
TO GENERATE CONVECTION AND WITH A SUBTLE PIEDMONT TROUGH AND COASTAL
TROUGH FROM TIME TO TIME...PRUDENT TO KEEP GOOD CHANCE POPS IN THE
FORECAST THROUGH FRIDAY. MODELS DO HINT AT A BACKDOOR FRONT SLIDING
THROUGH SATURDAY WHICH WOULD DRY THINGS OUT. THIS TREND IS REFLECTED
IN THE FORECAST WITH LOWER POPS AND SLIGHTLY LOWER TEMPERATURES.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
AS OF 05Z...EXPECT VFR THROUGH THE VALID 06Z ISSUANCE
PERIOD...WITH INCREASING CLOUD COVER AT ALL LEVELS EARLY THIS AM
THROUGH MIDNIGHT MONDAY. PATCHY MVFR DURING THE PRE-DAWN SUN HRS
FROM GROUND FOG REMAINS POSSIBLE. ISOLATED/SCATTERED -SHRA
POSSIBLE THIS SUN AFTN AND EVENING.

VFR WILL PREVAIL THROUGH OVERNIGHT WITH LIGHT WINDS AND SOME
LINGERING LOW CLOUDS 2-3K FT ACROSS THE NE SOUTH CAROLINA AREA
EARLY ON. SATELLITE IMAGERY VIA WATER VAPOR AND IR CHANNELS...
CONTINUE TO DEPICT A GRADUAL INCREASING TREND OF MAINLY MID TO
HIGH LEVEL CLOUDS ACROSS THE AREA. EXPECT THIS TREND TO CONTINUE
THRUOUT THE VALID FORECAST ISSUANCE PERIOD AS VARIOUS MODEL FCST
SOUNDINGS SUPPORT INCREASING MOISTURE INTO THE AREA. BKN/OVC
MID-HIGH LEVEL CLOUDS BECOMING COMMON THRUOUT THE FCST PERIOD.
SOME GUIDANCE DOES SUGGEST POSSIBLE BKN LOW CIGS WHICH COULD
CREATE MVFR TOWARDS DAYBREAK SUN MORNING...BUT CONFIDENCE IS
LOW...THUS HAVE NOT INTRODUCED IN GOING FCST. AFTER
DAYBREAK...ANTICIPATE LOWERING CLOUD HEIGHTS THRUOUT THE DAY WITH
DIURNALLY INDUCED CU/SC ADDING TO THE CLOUD SPECTRUM.

HAVE STAYED CLOSER TO THE DRIER GFS BIAS FOR LOWER PCPN CHANCES
AND COVERAGE...AND ALSO A SLOWER LOWERING OF CEILINGS DURING
THE DAYTIME AND EVENING SUN HOURS. THUS...WILL INDICATE VCNTY
SHRA AND HOLD OFF WITH THUNDER FOR THIS 06Z PACKAGE AT ALL SITES.
WINDS AT THE 06Z INITIAL TIME WILL EITHER START OUT WITH CALM
INLAND...TO NE 2 TO 4 KT AT THE COAST...BECOMING NE 4 TO 8 KT
DURING DAYTIME SUN MORNING AT ALL SITES. LOOK FOR FURTHER
VEERING TO E-SE AT 5 TO 10 KT DURING SUN AFTN AND EARLY
EVENING...DROPPING TO LESS THAN 5 KT BY MID TO LATE SUN EVENING.

EXTENDED OUTLOOK...PREDOMINATELY VFR WITH MVFR/IFR CONDITIONS
FROM ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE
EXTENDED. BRIEF MVFR/IFR MORNING FOG/STRATUS IS ALSO EXPECTED EACH
DAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...AS OF 1030 PM SATURDAY...WIND
DIRECTIONS ARE FROM THE NE OFFSHORE BUT VEER MORE EASTERLY AT THE
BEACHES. WITH THE EXCEPTION OF THE 18Z NAM ALL MODELS SHOW WINDS
BACKING TO THE NE EVEN ALONG THE COAST OVERNIGHT. VERY FEW CHANGES
WERE NEEDED TO THE FORECAST WITH THIS EARLY-EVENING UPDATE.
DISCUSSION FROM 330 PM FOLLOWS...

DROPPED THE SCEC A BIT EARLY AS SEAS HAVE DECREASED TO 3 FT AT NEAR
SHORE BUOY 41110 AND 4.5 FT ALL THE WAY OUT AT FRYING PAN SHOALS
BUOY 41035. CONDITIONS ARE STILL QUITE CHOPPY WITH EVEN THE LATTER
BUOY SHOWING A WAVE POWER PEAK AT JUST 5 SECONDS. THE HIGH TO OUR
NORTH IS FORECAST TO WEAKEN THIS EVENING AND THE LOCAL GRADIENT AND
RESULTING WINDS WILL DO THE SAME.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 325 AM SUNDAY...IT APPEARS THE STRONGEST WINDS WILL OCCUR EARLY
MONDAY AS GOOD MID LEVEL FORCING LEADS TO THE DEVELOPMENT OF A
COASTAL TROUGH. SHOULD SEE SOUTHEAST WINDS OF 10-15 KNOTS FOR A FEW
HOURS. THIS TROUGH MOVES INLAND WITH THE SEA BREEZE AND BASICALLY
DISSIPATES EARLY TUESDAY. IN ITS WAKE WEAK WINDS OF TEN KNOTS OR
LESS DEVELOP WITH THE DIRECTIONS MAINLY DICTATED BY THE LAND AND SEA
BREEZES. SEAS WILL SEE A BRIEF PERIOD OF 2-4 FEET MONDAY MORNING
AND TREND DOWNWARD SLIGHTLY THEREAFTER.

LONG TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 325 AM SUNDAY...VERY LITTLE IN THE WAY SYNOPTICALLY TO SHOW ANY
DEVIATION FROM THE STANDARD SUMMERTIME PATTERN OF WEAK SOUTHEAST
WINDS AND SEAS OF 2-4 FEET. SOME CONVECTION COULD BRIEFLY DISTORT
THESE FIELDS OCCASIONALLY BUT THESE SHOULD HOLD FOR THE MOST PART.

&&

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

&&

$$
SYNOPSIS...SHK
NEAR TERM...DCH/TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DCH/SGL



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