Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 231420
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1019 AM EDT SAT AUG 23 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTH ACROSS THE AREA TODAY. THIS FRONT
WILL BRING A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS
TODAY...BEFORE COOLER AND DRIER AIR FILTERS INTO THE REGION FOR
SUNDAY. HIGH PRESSURE EXPANDING SOUTH FROM NEW ENGLAND WILL
MAINTAIN COOLER AND DRIER WEATHER FOR THE FIRST HALF OF NEXT WEEK
WITH A RETURN TO MORE SEASONABLE WEATHER LATER IN THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM SATURDAY...AMPLIFIED MID-LEVEL PATTERN SHAPING UP
TODAY AS A LARGE RIDGE OF HIGH PRESSURE STRENGTHENS ACROSS THE MS
VLY...WHILE A DEEPENING TROUGH DIVES ACROSS THE EAST COAST. THIS
LEAVES A REGION OF NW FLOW ENTRENCHED BETWEEN THESE TWO
FEATURES...FLOWING DIRECTLY ACROSS THE LOCAL AREA. TWO SEPARATE
MID-LEVEL IMPULSES EVIDENT ON WV IMAGERY...ONE OVER TN...AND THE
OTHER ACROSS IA...ARE CRESTING THE RIDGE AND WILL DROP SE TODAY IN A
"RING OF FIRE" TYPE EVENT...LIKELY SPAWNING CONVECTION LOCALLY THIS
EVENING. AT THE SURFACE...BACK DOOR COLD FRONT...WHILE WEAK...IS
CURRENTLY LOCATED BASICALLY ALONG THE NC/SC BORDER...AND WILL WAVER
IN THE VICINITY INTO TONIGHT BEFORE A STRONG PUSH OF NE WINDS DRIVES
IT SOUTH OF THE AREA.

MOST CHALLENGING ASPECT OF THE FORECAST TODAY IS HOW CONVECTION WILL
EVOLVE LOCALLY. ALTHOUGH INSTABILITY IS MUCH LESS THAN THE PAST FEW
DAYS THANKS TO CLOUD COVER AND COOLER TEMPERATURES...ENOUGH WILL BE
PRESENT THAT BOUNDARIES WILL DRIVE UPDRAFTS INTO SHOWERS AND STORMS
TODAY. CONVECTION WILL INITIALLY BE FAVORED IN THE NE ZONES WHERE
PWATS ARE HIGHER...AND SOME MID-LEVEL DRY AIR WILL HELP STEEPEN
LAPSE RATES...BUT EVENTUALLY ALL OF THE AREA WILL SEE DEVELOPMENT.
STILL HARD TO TIME EXACTLY WHEN AND WHERE THE MOST WIDESPREAD
CONVECTION WILL OCCUR...BUT THE HIGH RES GUIDANCE ARW/HRRR/WRF ALL
HAVE SIMILAR EVOLUTION WITH MOST WIDESPREAD/STRONGEST CONVECTION
DROPPING SE THROUGH THE CWA THIS EVENING. HAVE HIGHEST POP DURING
THIS TIMEFRAME. DO NOT EXPECT SEVERE STORMS TODAY...BUT SPC DOES
HIGHLIGHT THE AREA EVEN IN THE GENERAL RISK FOR ISOLATED STRONGER
STORMS TYPICAL IN NW FLOW REGIMES. THUNDERSTORMS WILL BEGIN TO WANE
NOCTURNALLY...BUT HIGH PWAT AND CONTINUED MID-LEVEL FORCING BENEATH
SHORTWAVES WILL LIKELY KEEP SHOWERS GOING MUCH OF THE NIGHT BEFORE
DRYING BEGINS FROM NE TO SW LATE.

TEMPS TODAY WILL RANGE CONSIDERABLY FROM NE TO SW ACROSS THE CWA.
HIGHS IN THE FAR S/SW ZONES WILL CLIMB WELL INTO THE 90S...COMBINING
WITH HIGH DEWPOINTS TO PRODUCE HEAT INDICES OF 100-104 DEGREES.
HIGHS ACROSS THE NC COUNTIES WILL RISE ONLY INTO THE UPPER 80S IN
THE FAR NE ZONES...TO THE LOW 90S NEAR THE SC BORDER. ALTHOUGH
COOL/DRY ADVECTION WILL BEGIN LATE TONIGHT...IT WILL NOT OCCUR FAST
ENOUGH TO INFLUENCE MINS MUCH...SO LOWS WILL REMAIN ABOVE
NORMAL...AROUND 70 IN THE FAR NORTH TO THE MID 70S NEAR THE SOUTH
SANTEE RIVER.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SATURDAY...RIDGE BECOMES HIGHLY AMPLIFIED UP THE
MISSISSIPPI VALLEY INTO THE NORTHEAST EARLY NEXT WEEK AND BUILDS
EASTWARD WITH TIME. AT THE SAME TIME SURFACE HIGH PRESSURE BUILDS
DOWN FROM THE NORTH. INCREASING SUBSIDENCE AND DRY AIR WILL ACT TO
INHIBIT CONVECTION. OVERALL MOISTURE THROUGH THE COLUMN WILL BE
DIMINISHING WITH PCP WATER VALUES DROPPING FROM CLOSE TO 2 INCHES
EARLY SUNDAY DOWN TO 1.25 BY SUN NIGHT AND LESS THAN AN INCH BY
MONDAY MORNING. MAY FEEL MORE LIKE EARLY FALL-LIKE WEATHER FOR THE
START OF THE WEEK WITH COOLER AND DRIER NORTHERLY FLOW OFFSET
SLIGHTLY BY LATE SUMMER SUNSHINE...WITH TEMPS REACHING BELOW
NORMAL INTO THE LOW TO MID 80S. ANY CLOUDS EARLY SUNDAY WILL
DISSIPATE AS DEWPOINT TEMPS DROP FROM NEAR 70 DOWN TO NEAR 60 BY
MONDAY MORNING. THESE LOWER DEWPOINT TEMPS WILL ALLOW TEMPS TO
DROP INTO THE MID 60S MOST PLACES OVERNIGHT.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 300 AM SATURDAY...CONTINUED COOL AND DRY WEATHER THROUGH
MID WEEK AS HIGH PRESSURE RIDGES DOWN FROM THE NORTHEAST INTO THE
CAROLINAS AND UPPER RIDGE CONTINUES TO BUILD EASTWARD. THE COOLER
NORTHEAST FLOW WILL BE OFFSET BY PLENTY OF SUNSHINE TO PRODUCE
TEMPS NEAR NORMAL...IN THE MID 80S. 850 TEMPS AND LOW LEVEL
THICKNESSES WILL BE ON THE RISE AS RIDGE BUILDS OVER THE SOUTHEAST
AND H5 HEIGHTS INCREASE WED. MOISTURE MAY BE ON THE RISE BY LATE
WED INTO THURS DEPENDING ON THE EXACT TRACK OF TROPICAL SYSTEM
FORECAST TO MOVE UP THROUGH THE OFF SHORE ATLANTIC WATERS TO OUR
EAST LATE WED/THURS TIME FRAME. THE ECMWF CONTINUES TO THE BE THE
FASTEST AND FURTHEST EAST WITH THE SYSTEM WHILE THE GFS REMAINS
THE SLOWEST AND FARTHEST WEST. AT THIS POINT LOOKS LIKE MAIN
EFFECTS OF THIS TROPICAL SYSTEM WILL BE ALONG THE COAST WITH
INCREASED ON SHORE WINDS AND SWELLS THROUGH MID WEEK. HIGH
PRESSURE SHOULD HOLD OVER LAND WITH RIDGE HOLDING STRONG ALOFT.
FOR NOW IT LOOKS LIKE THIS SHOULD HELP TO SUPPRESS SHWR ACTIVITY
THROUGH MUCH OF THE WEEK BUT MAY SEE SOME CLOUDS AND SHOWERS MOVE
ON SHORE...MAINLY OVER COASTAL AREAS AS TROPICAL SYSTEM PASSES TO
OUR EAST THROUGH MID WEEK. GFS ALSO SHOWS COLD FRONT MOVING INTO
THE CAROLINAS FROM THE NW BY THE WEEKEND. TEMPS NEAR OR BELOW
NORMAL TO START WILL BEGIN TO MODERATE AS MOISTURE INCREASES
THROUGH THE COLUMN THURS INTO FRI WITH DEEPER ON SHORE FLOW.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...A COLD FRONT WAS LOCATED IN THE VICINITY OF THE
TERMINALS THIS MORNING. MVFR CIGS WERE OCCURRING AT KILM AND WILL
MOVE INTO KLBT OVER THE NEXT HOUR OR TWO. MVFR VSBYS IN BR WERE
OCCURRING AT KCRE/KMYR. MOST SHRA/TSRA HAS BEEN OCCURRING WELL
BEHIND THE FRONT NE OF KILM.

THE BOUNDARY WILL SHIFT SOUTH OF ALL TERMINALS THIS EVENING.
WIDESPREAD LIGHT SHOWERS WITH ISOLATED TO WIDELY SCT HEAVIER
SHRA/TSRA EXPECTED ALONG AND BEHIND THE FRONT MAINLY DURING THE
AFTERNOON. HEAVIER SHRA/TSRA POTENTIAL SHOULD SHIFT SWRD AS THE
EVENING APPROACHES. THERE IS LOW CONFIDENCE ON TIMING OF THE HEAVIER
SHRA/TSRA IN THE TAFS. LIGHT WINDS EARLY THIS MORNING WILL EAST
BEHIND THE FRONT LESS THAN 10 KT. KCRE/KMYR WILL LIKELY SEE E-SE
WINDS IN THE AFTN BEHIND A SEA BREEZE BEFORE THE FRONT PASSES
THROUGH IN THE EVENING.

ISOLATED SHOWERS WILL LINGER INTO THE OVERNIGHT HOURS NEAR
KCRE/KMYR. POST FRONTAL MVFR CIGS ARE EXPECTED WITH REASONABLE
CONFIDENCE OF POST-FRONTAL IFR CIGS AT KFLO/KLBT OVERNIGHT.

EXTENDED OUTLOOK...MVFR/IFR CIGS/VSBYS POSSIBLE SUN MORNING.
OTHERWISE EXPECT VFR TO PREVAIL SUN THROUGH WED AS HIGH PRESSURE
RIDGES OVER THE EAST COAST IN THE WAKE OF THE COLD FRONT.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM SATURDAY...WEAK COLD FRONT IS BISECTING THE WATERS
THIS MORNING...LEAVING E/NE WINDS ACROSS THE NC WATERS...WITH A MORE
EASTERLY DIRECTION OFF THE SC COAST. THIS FRONT WILL WAVER IN THE
AREA BEFORE FINALLY PUSHING SOUTH OF THE WATERS LATE TONIGHT. AS
THIS FRONT PUSHES SOUTH...WINDS WILL BECOME FROM THE NE ALL
WATERS...AND BEGIN TO INCREASE AS A SURGE DEVELOPS LOCALLY. WINDS
THROUGH MOST OF THE DAY WILL BE LIGHT...BUT WILL INCREASE TO 10-15
KTS BY THE END OF THE PERIOD. WAVE HEIGHTS WILL BE JUST 1-2 FT
DURING THE DAYLIGHT HOURS AND THE BEGINNING OF THE TONIGHT
PERIOD...BEFORE THE RISING WINDS PUSH SEAS TO 2-4 FT...HIGHEST
ACROSS AMZ250.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SATURDAY...NORTHERLY SURGE AS COOL AND DRY HIGH
PRESSURE BUILDS DOWN FROM THE NORTHEAST. WINDS WILL RISE SHARPLY
THROUGH SUNDAY UP TO 15 TO 20 KTS ACROSS THE WATERS. THE INCREASE
IN WINDS WILL IN TURN PRODUCE AN INCREASE IN SEAS UP CLOSE TO SCA
THRESHOLDS BY SUN EVENING. SEAS WILL REMAIN UP CLOSE TO 4 TO 6 FT
OVER A GOOD PORTION OF OUR LOCAL COASTAL WATERS THROUGH MONDAY
NIGHT AND BEYOND IN PERSISTENT STRONG NORTHEASTERLY WINDS.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 300 AM SATURDAY...HIGH PRESSURE BUILDING DOWN FROM THE
NORTHEAST THROUGH THE CAROLINAS WILL PROVIDE A CONTINUOUS
NORTHEAST FLOW UP TO 15 TO 20 KTS THROUGH MID WEEK. THIS WILL KEEP
SEAS UP TO 4 TO 6 FT POSSIBLY INCREASING FURTHER WED INTO THURS
DUE TO INCREASING SWELLS FROM A TROPICAL SYSTEM MOST PROBABLY
MOVING NORTH THROUGH THE OFF SHORE WATERS. AT THIS TIME MUCH
UNCERTAINTY STILL EXISTS CONCERNING THE DEVELOPMENT AND FATE OF
THIS POTENTIAL TROPICAL SYSTEM.

&&

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

&&

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









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