Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 190541
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
141 AM EDT FRI SEP 19 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE CAROLINAS FROM THE NORTH AS LOW
PRESSURE DEVELOPS OFF THE SOUTHEAST COAST AND MOVES NORTHWARD INTO
THE WEEKEND. A COLD FRONT WILL MOVE ACROSS THE AREA MONDAY NIGHT
FOLLOWED BY COOL AND DRY HIGH PRESSURE DURING THE MIDDLE OF NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1:45 AM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:

LOWER DEWPOINTS ARE PRESSING SOUTHWARD INTO OUR NE ZONES THIS
EVENING AS SURFACE HIGH PRESSURE RIDGES SOUTHWARD. THIS FEATURE
WILL TIGHTEN THE LOCAL PRESSURE GRADIENT WHICH WILL INCREASE
ONSHORE WINDS OVERNIGHT...HIGHEST ALONG THE COAST WHERE MIXING
WILL BE MUCH MORE VIGOROUS. EVEN AT 2Z/10P ENE GUSTS TO 20 MPH
WERE COMMON ALONG BOTH THE SC AND NC COASTS. THE SLIGHT DRY AIR
INTRUSION WILL HINDER SHOWER DEVELOPMENT OVER MUCH OF NC BUT
FURTHER SOUTH OVERNIGHT MENTIONABLE POP VALUES WILL BE RETAINED
DUE TO STRONGER LOW-LEVEL CONVERGENCE...DEEPER MOISTURE AND MORE
PARCEL BUOYANCY IN THE LOWER TROPOSPHERE. MINIMUM TEMPS MAY
REQUIRE ADJUSTMENTS NEAR THE IMMEDIATE COAST WHERE MOUNTING WINDS
WILL LIKELY KEEP TEMPS LEVELED-OFF AND ELEVATED COMPARED TO
INTERIOR LOCATIONS MORE DECOUPLED FROM THE BOUNDARY LAYER FLOW.
1500 FOOT PATCHY STRATUS MAY FORM LATE BUT WINDS SHOULD KEEP FOG
AND MIST FROM GAINING A SUBSTANTIAL AND MENACING FOOTHOLD TONIGHT.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...HIGH PRESSURE WILL RIDGE DOWN THROUGH THE
INLAND CAROLINAS IN A TYPICAL WEDGE-LIKE FASHION WHILE LOW
PRESSURE OFF THE SOUTHEAST COAST STRENGTHENS AS IT TRACKS
NORTHWARD FRI THROUGH SATURDAY. THE MID TO UPPER TROUGH PULLS OFF
TO THE NORTHEAST LEAVING A WEAKNESS IN THE MID TO UPPER LEVELS
OVER GA/SC COAST. THE SFC LOW WILL TRACK NORTH REACHING EAST OF
THE CAPE FEAR COAST BY SAT NIGHT. THE INCREASING E-NE FETCH AHEAD
OF THE SYSTEM SHOULD AFFECT MAINLY COASTAL SECTIONS WITH CLOUDS
AND POSSIBLE SHOWERS. THE NAM CONTINUES TO BE MUCH SLOWER WITH THE
EVOLUTION OF THIS LOW...NOT REACHING THE CAPE FEAR COAST UNTIL
LATE SUNDAY. THEREFORE KEEPING A MORE EASTERLY FETCH...BEING MORE
AGGRESSIVE WITH ITS ONSHORE PUSH OF MOISTURE WITH PCP WATER VALUES
UP TO 1.8 INCHES OVER PORTIONS OF LOCAL FORECAST AREA FRI INTO
SAT. THE GFS HOLDS THE MOISTURE CLOSER TO THE COAST IN A TIGHTER
MORE NE FLOW AROUND THE LOW WITH MOIST AIR IN A TIGHTER GRADIENT
BETWEEN THE COAST AND INLAND. WILL NEED TO WATCH HOW THIS LOW
EVOLVES AS IT MAY EVEN TAKE ON SOME TROPICAL CHARACTERISTICS OVER
THE NEXT COUPLE OF DAYS. FOR NOW WILL MAINTAIN MAINLY SHALLOW
MOISTURE WITH CLOUDS AND PCP CONFINED CLOSER TO THE COAST AND
SPREADING NORTHWARD AS LOW APPROACHES. AS WINDS STRENGTHEN THERE
MAY BE INCREASED CONVERGENCE AND MORE WIDESPREAD SHWR CHANCES BUT
UNCERTAINTY EXISTS AS TO HOW FAST AND HOW CLOSE TO COAST THE LOW
WILL MOVE AND THEREFORE WILL KEEP BRUNT OF ACTIVITY ALONG AND OFF
SHORE.

CLOUD COVER MAINLY ALONG THE COAST AND EAST-NORTHEAST FLOW WILL
KEEP HIGH TEMPERATURES NEAR TO SLIGHTLY BELOW CLIMO THROUGH THE
PERIOD. LOWS WILL END UP NEAR TO SLIGHTLY ABOVE CLIMO...A
COMBINATION OF CLOUD COVER AND LINGERING LOW LEVEL MOISTURE.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...BIGGEST QUESTION MARK DURING THE EXTENDED
INVOLVES A LOW PRESSURE MOVING ALONG THE COAST SUNDAY. GFS/CMC/NAM
SUGGEST THAT A HYBRID/WARM-CORE LOW PRESSURE SYSTEM WILL BE JUST OFF
THE NC COAST SUNDAY MORNING...WHILE THE ECMWF SHOWS BARELY A TROUGH
MOVING TO THE NORTHEAST. TIMING DIFFERENCES EXIST...AS THE NAM IS
QUITE SLOW COMPARED TO THE OTHER GUIDANCE...AND IS LIKELY TOO SLOW
SINCE ANY LOW PRESSURE SHOULD BE PICKED UP AND SLUNG TO THE NE BY A
SECONDARY TROUGH DROPPING INTO THE GREAT LAKES. THE GFS SEEMS TO BE
A CONSISTENT COMPROMISE...AND IS FAVORED FOR THE EXTENDED. THIS
SUGGESTS THAT WHILE RAPID DRYING WILL OCCUR DURING SUNDAY...THE
FIRST PART OF THE DAY WILL BE CLOUDY AND POSSIBLY UNSETTLED WITH
SHOWERS...ESPECIALLY ALONG THE COAST. AS THIS SYSTEM PULLS
AWAY...RAPID DRYING WILL OCCUR AND THE SECOND HALF OF SUNDAY WILL BE
SUNNY WITH SEASONABLE TEMPERATURES.

A VERY BRIEF PERIOD OF WAA DEVELOPS LATE SUNDAY INTO MONDAY BEFORE A
STRONGER COLD FRONT CROSSES THE CAROLINAS LATE MONDAY. THIS FRONT
NOW LOOKS TO BE MOISTURE STARVED DUE TO SUCH A BRIEF PERIOD OF MOIST
ADVECTION AHEAD OF IT...AND THUS ONLY A SCHC OF SHOWERS IS EXPECTED
WITH SOME ENHANCED CLOUD COVER. THIS WILL RAPIDLY CLEAR AND DRY BY
TUESDAY...AND SOME BEAUTIFUL FALL WEATHER WILL OVERSPREAD THE REGION
WITHIN CANADIAN HIGH PRESSURE FROM LATE TUESDAY THROUGH THE REST OF
THE PERIOD. HIGHS AND LOWS ARE EXPECTED TO BE A FEW DEGREES BELOW
CLIMO...BUT LOW HUMIDITY AND LOTS OF SUNSHINE WILL PRODUCE GREAT
WEATHER AS THE CALENDAR TICKS OFFICIALLY INTO ASTRONOMICAL FALL.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...THE RADAR SHOWS SOME NOCTURNAL SHOWER ACTIVITY OVER
THE COASTAL WATERS...BUT RIGHT NOW NO THREAT TO ANY TAF SITES.
COULD SEE AREAS OF MVFR CIGS DEVELOP EARLY THIS
MORNING...PARTICULARLY ALONG THE COAST WHERE 2-3KFT MARINE
STRATOCU MAY CLIP KCRE/KMYR WITHIN THE LOW LEVEL E-NE FLOW. SOME
MVFR CIGS COULD ALSO DEVELOP INLAND AROUND AND JUST AFTER
DAYBREAK. WINDS ARE TOO STRONG FOR ANY FOG CONCERNS TONIGHT.
EASTERLY FLOW WILL STRENGTHEN ON FRI AS CANADIAN HIGH PRESSURE
CONTINUES BUILDING SOUTHWARD INTO THE CAROLINAS. EAST WINDS 10-15
KT WITH HIGHER GUSTS...ESPECIALLY AT THE COASTAL TERMS...WILL
PREVAIL DURING THE DAY. AN UPPER DISTURBANCE MAY HELP TO SPARK
SOME SHOWER ACTIVITY IN THE AFTN. FOR NOW...WILL MAINTAIN VCSH FOR
OUR SOUTHERN TERMINALS AS THIS IS WHERE THE BEST MOISTURE/LIFT IS
EXPECTED. WINDS WILL DIMINISH TO NORTHEAST AOB 10 KT DURING THE
EVENING HOURS.

EXTENDED OUTLOOK...CHANCE OF SHOWERS ALONG THE COAST SAT. GUSTY
NORTHEAST WINDS SAT WILL BECOME NORTHWEST ON SUN AS LOW PRESSURE
WELL OFFSHORE MOVES UP THE EAST COAST. VFR ON MON/TUE.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1:45 AM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:

WILL NEED TO TAKE A CLOSER LOOK AT POTENTIAL OF AN EXERCISE
CAUTION STATEMENT AS WINDS HOLD NEAR 20 KT INTO EARLY FRIDAY. SEAS
HOLDING AT 4 FEET BUT NOT GOING TO TAKE TOO MUCH MORE WIND TO
REACH 5 FT. STRONG HIGH PRESSURE WILL BUILD SOUTHWARD AND INCREASE
NE-ENE WINDS INTO EARLY FRIDAY. SEAS OF 3 TO 4 FT MAY SEE A 4-5 FT
RANGE EARLY FRIDAY...HIGHEST OFFSHORE AND NORTH OF CAPE FEAR. SEAS
SHOWING WANING SWELL FROM EDOUARD OF 1-2 FEET EVERY 10-11 SECONDS
BUT BUILDING E WAVES 3-4 FT EVERY 5-6 SECONDS. A FEW SHOWERS OR AN
ISOLATED TSTMS IS POSSIBLE ON THE 0-20 NM WATERS OVERNIGHT AS
NIGHT-TIME INSTABILITY RISES.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...WINDS WILL WILL INCREASE THROUGH FRI IN
PINCHED GRADIENT FLOW BETWEEN WEDGE OF HIGH PRESSURE INLAND AND
LOW PRESSURE DEVELOPING OFF THE SOUTHEAST COAST. NE WINDS WILL
INCREASE UP TO 20 KT WITH HIGHER GUSTS THROUGH FRI INTO FRI NIGHT.
AS NE WINDS INCREASE THROUGH FRI...SEAS WILL REACH SCA THRESHOLDS
INTO FRI EVE...ESPECIALLY NORTH OF CAPE FEAR...BUILDING TO 4 TO 6
FT. SEAS WILL REMAIN LOWER CLOSE TO THE COAST SOUTH OF CAPE FEAR
WHERE NE FLOW IS BLOCKED. HIGH PRESSURE WILL WEAKEN INLAND AS HIGH
SHIFTS FARTHER OFF THE NEW ENGLAND COAST LOSING ITS GRIP. THIS
SHOULD HELP GRADIENT WINDS TO DIMINISH AND SEAS TO LOWER THROUGH
SATURDAY...BUT AS LOW MOVES NORTHWARD CLOSER TO THE LOCAL
WATERS...NE WINDS SHOULD INCREASE ONCE AGAIN...POSSIBLY REACHING
SCA THRESHOLDS ONCE AGAIN.

LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 300 PM THURSDAY...LOW PRESSURE WILL BE MOVING UP THE COAST ON
SUNDAY...AND WILL BE JUST OFFSHORE...EAST OR NORTHEAST...OF THE
WATERS TO START THE PERIOD. THIS LOW WILL MOVE AWAY DURING
SUNDAY...WITH WINDS BACKING FROM NE TO NW...AND THEN WEST BY MONDAY
MORNING. STILL SOME UNCERTAINTY INTO THE STRENGTH AND TRACK OF THIS
LOW PRESSURE...BUT ATTM IT LOOKS LIKE IT WILL BE WEAK ENOUGH AND FAR
ENOUGH OFFSHORE TO KEEP WINDS TO 15 KTS OR LESS REGARDLESS OF
DIRECTION ON SUNDAY. SEAS WILL FEATURE HIGHLY VARIABLE DIRECTIONS ON
SUNDAY WHICH WILL MAKE A CONFUSED SPECTRUM...BUT WAVE HEIGHTS WILL
FALL FROM 3-5 FT EARLY TO 2-3 FT BY MONDAY MORNING. OF COURSE...IF
THIS LOW PRESSURE BECOMES STRONGER OR MOVES CLOSER...CONDITIONS
COULD END UP BEING WORSE THAN CURRENTLY FORECAST.

A BRIEF PERIOD OF W/SW WINDS MONDAY WILL QUICKLY BECOME NW BEHIND A
COLD FRONT WHICH WILL CROSS THE WATERS LATE IN THE DAY...FOLLOWED BY
A NE SURGE ON TUESDAY WITH WINDS AGAIN RISING TO 15 KTS.
LOW-AMPLITUDE SEAS OF 1-2 FT MONDAY WILL RISE SLOWLY DURING TUESDAY
AS THE NE WINDS INCREASE...BECOMING 3-5 FT LATE IN THE PERIOD.

&&

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

&&

$$

SYNOPSIS...RGZ
NEAR TERM...REK/RJD
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...BJR
MARINE...REK/RJD/JDW/RGZ




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