Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 221948
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
348 PM EDT FRI AUG 22 2014

.SYNOPSIS...
LARGE UPPER RIDGING WILL MAINTAIN HEAT AND HUMIDITY ACROSS THE
AREA ONE MORE DAY...AHEAD OF A BACK DOOR COLD FRONT WHICH WILL
SLIP SOUTH ON SATURDAY. THIS FRONT WILL BRING A GOOD CHANCE FOR
SHOWERS AND THUNDERSTORMS SATURDAY...BEFORE MUCH COOLER AND DRIER
AIR FILTERS INTO THE REGION FOR SUNDAY. HIGH PRESSURE EXPANDING
SOUTH FROM NEW ENGLAND WILL BRING COOL AND DRY WEATHER FOR THE
FIRST HALF OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 300 PM FRIDAY...MAMMOTH UPPER RIDGE MAINTAINING A STRONG-
ARM GRIP OVER THE AREA WITH MILD TEMPERATURES ALOFT AND CONVECTIVE
INHIBITION WINNING OUT SO FAR. A DIFFUSE FRONTAL BOUNDARY IS
POSITIONED INLAND ACROSS THE SE NC INTERIOR PRESENTLY. LITTLE TO
NO TSTMS THROUGH MIDDLE-AFTERNOON BUT SEVERAL IMPULSES WILL DIVE
SE OVER THE RIDGE THIS EVENING AND TONIGHT. SPC HAS REMOVED THE
SLIGHT RISK FOR OUR AREA BUT ISOLATED SEVERE TSTMS CANNOT BE RULED
OUT NORTH OF CAPE FEAR...MAINLY THIS EVENING AND OVERNIGHT. HEAT
ADVISORIES REMAIN POSTED FOR PORTIONS OF SC THIS AFTN.

DISCREET POP-UP CELLS CERTAINLY POSSIBLE OUT AHEAD OF THE MAIN
UPPER IMPULSE FEATURES...AND CONVERGENCE WILL INCREASE THROUGH
LATE AFTERNOON INTO EARLY EVENING NEAR THE COAST WHERE A SEA BREEZE
BOUNDARY REMAINS NEARLY HELD IN CHECK JUST INLAND FROM THE COAST.
ANY STORMS THAT FIRE WILL DRIFT TO THE SE-S AT 10 KT. OVERNIGHT OUR
NE ZONES REMAIN THE FAVORED AREA FOR STORMS. EVEN THROUGH DIURNAL
LATE NIGHT COOLING WE WILL MAINTAIN ISOLATED POP VALUES MAINLY NORTH
OF A LINE FROM CAPE FEAR TO LUMBERTON. ELSEWHERE THE REMNANT UPPER
RIDGE SHOULD OFFER MORE SHIELDING FROM STORMS THROUGH DAYBREAK
SATURDAY. MINS OVERNIGHT UNDER PARTIAL CLEARING...LOW/MID 70S INLAND
AND MID/UPPER 70S CLOSER TO THE COAST. THE IMPULSE LATE TONIGHT WILL
HELP DRIVE A COLD FRONT SOUTH TO OUR NORTH ZONES EARLY SATURDAY BUT
NO COLD AIR ADVECTION EXPECTED IN THE NEAR TERM PERIOD.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 300 PM FRIDAY...FEATURE OF INTEREST THIS WEEKEND IS A BACK
DOOR COLD FRONT WHICH WILL DROP ACROSS THE AREA FROM NE TO SW ON
SATURDAY. THIS FRONT WILL BE DRIVEN BY AN AMPLIFYING 5H
PATTERN...WITH A STRONG RIDGE GETTING SQUEEZED NORTH ACROSS THE
MIDDLE OF THE COUNTRY BETWEEN TROUGHS ON BOTH COASTS. IT IS THIS
EASTERN TROUGH DIVING SW THROUGH THE WKND THAT PUSHES THE BACK DOOR
FRONT INTO...AND THROUGH...THE CWA SATURDAY. ALTHOUGH THE SURFACE
FRONT CROSSES SATURDAY...STRONG CAA LAGS ABOUT 18 HRS BEHIND...AND
THUS SATURDAY WILL AGAIN BE A WARM DAY LOCALLY. HOWEVER...INCREASED
CLOUDINESS...LOWERED THICKNESSES...AND SHOWERS/STORMS WILL KEEP
TEMPS MUCH COOLER THAN THE PAST FEW DAYS...WITH HIGHS RISING TO
AROUND 90 IN THE FAR NORTH...MID 90S IN THE SOUTHERN PEE DEE. WHILE
FORCING IS NOT STRONG WITH THE FRONT...AND A DIVING UPPER JET WILL
ACTUALLY PUT THE REGION BENEATH THE RFQ...AN UNFAVORABLE POSITION
FOR UPPER SUPPORT...STILL EXPECT CLIMO POP FOR SCT SHOWERS AND TSTMS
THANKS TO PWATS NEAR 2 INCHES AND STRONG SURFACE CONVERGENCE INTO AN
UNSTABLE ENVIRONMENT. ALTHOUGH COOL ADVECTION WILL BEGIN
OVERNIGHT...LOWS WILL REMAIN ABOVE NORMAL...LOW 70S AREA-WIDE.

COOL AND DRY ADVECTION BEGINS IN EARNEST SUNDAY MORNING...AND PWATS
DROP TO LESS THAN 1 INCH...LOWEST NORTH...WITH 850MB TEMPS DROPPING
5C THROUGH THE DAY. LOTS OF LATE-AUGUST SUNSHINE WILL SOMEWHAT
COUNTERACT STRONG CAA...BUT HIGHS SUNDAY WILL LIKELY BE 5-10 DEGREES
COOLER THAN SATURDAY...AND IN FACT ARE EXPECTED TO BE BELOW
NORMAL...LOW 80S FAR NORTH TO UPR 80S IN THE SOUTH. A FEW SHOWERS
ARE POSSIBLE...ESPECIALLY EARLY IN THE DAY ACROSS THE SC ZONES
CLOSER TO THE FRONT...BUT ACTIVITY WILL NOT BE WIDESPREAD OR STRONG.
MUCH COOLER MINS SUNDAY NIGHT WITH MID 60S EXPECTED FAR NORTH IN THE
DRY COLUMN...UPPER 60S NEAR THE SOUTH SANTEE RIVER AND ON THE
BEACHES.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 300 PM FRIDAY...THE EXTENDED FORECAST WILL GENERALLY BE DRY
AND SEASONABLE AS A MID LEVEL RIDGE INITIALLY OVER THE MISSISSIPPI
VALLEY SHIFTS TO MORE OF A SOUTHERN POSITION BY THE END OF THE
PERIOD. AT THE SURFACE...HIGH PRESSURE WILL WEDGE DOWN THE EAST
COAST AND EXTEND DOWN INTO GEORGIA FOR MONDAY THROUGH WEDNESDAY.
BEYOND THIS...THE FEATURE BREAKS DOWN LEAVING A WEAK PATTERN AT
THE SURFACE AND ISOLATED SHOWERS AND THUNDERSTORMS MAKE AN
APPEARANCE IN THE FORECAST. THE CHANCES WILL NOT BE GOOD UNTIL
FRIDAY WHEN ANOTHER FRONT DROPS INTO THE REGION PROVIDING A BETTER
FOCUS. TEMPERATURES WILL BE SLIGHTLY BELOW CLIMATOLOGY MONDAY
THROUGH WEDNESDAY WITH THE AXIS OF SURFACE HIGH PRESSURE PROVIDING
A COOL NORTHEAST FLOW. THURSDAY AND FRIDAY SEE MODERATING VALUES
CLOSER TO OR EVEN A BIT ABOVE NORMAL.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...ANOTHER WARM DAY WITH WESTERLY FLOW. DEWPOINTS WILL NOT
BE QUITE AS HIGH TODAY...WITH HEAT INDICES PROBABLY STAYING BELOW
100. THINGS GET INTERESTING TOWARD EVENING AS FRONT DROPS SOUTHWARD
INTO THE REGION WITH A POSSIBLE PRE-FRONTAL SQUALL LINE DEVELOPING
BY EARLY EVENING. THINK ALL TERMINALS WILL SEE SOME SORT OF
CONVECTION THIS EVENING. MODELS ARE NOT TOO KEEN FOR WIDESPREAD
COVERAGE HOWEVER. WINDS WILL SHIFT TO THE NORTHWEST/NORTH TOWARD
MORNING WITH FRONTAL PASSAGE. LOOK FOR CEILINGS TO LOWER TO MVFR
POST FRONT...CONTINUING FOR A GOOD PORTION OF THE DAY SATURDAY.

EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH SUNDAY.
EXPECT VFR MON THRU WED WITH HIGH PRESSURE OVER THE EAST COAST.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM FRIDAY...A SFC TROF WILL EXTEND N-S ACROSS THE
EASTERN CAROLINAS INTO TONIGHT. RIDGING FROM HIGH PRESSURE
CENTERED WELL OFFSHORE WILL EXTEND TO THE SE STATES...SOUTH OF THE
AREA WATERS. THE 2 COMBINED WILL PRODUCE SW WINDS ACROSS THE LOCAL
WATERS TODAY. FOR TONIGHT...A BACKDOOR COLD FRONT WILL DROP SOUTH
REACHING THE DOORSTEPS AT SURF CITY TOWARD DAYBREAK SAT. THIS WILL
RESULT IN WINDS VEERING TO THE WEST ACROSS THE ILM NC WATERS LATE
TONIGHT. THE SFC PG WILL YIELD A 10 TO OCCASIONALLY 15 KT WIND
SPEED. SIGNIFICANT SEAS WILL RANGE BETWEEN 2 AND 3 FT. SHORT
PERIOD WIND DRIVEN WAVES WILL DRIVE THE SIGNIFICANT SEAS FOR THE
MOST PART. IE. WINDS FROM THE SEA BREEZE CIRCULATION. AN
UNDERLYING 1 FOOT ESE GROUND SWELL AT 9 SECOND PERIODS WILL REMAIN
IDENTIFIABLE.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 PM FRIDAY...BACK DOOR COLD FRONT WILL DROP ACROSS THE
WATERS FROM NE TO SW DURING SATURDAY...CAUSING A WIND SHIFT TO THE
N/NE BEHIND THIS BOUNDARY. WIND SHIFT WILL OCCUR FIRST ACROSS THE
FAR NORTHERN LEGS OFF THE CAPE FEAR COAST...WITH WINDS BECOMING N
THEN NE SATURDAY MORNING...WITH THE WATERS OFF GEORGETOWN COUNTY NOT
EXPERIENCING THE WIND SHIFT UNTIL SATURDAY NIGHT. THE GRADIENT
REMAINS RELAXED SATURDAY...SO WIND SPEEDS THROUGH THIS FRONTAL
PASSAGE WILL BE 5-10 KTS REGARDLESS OF DIRECTION. VERY LATE SATURDAY
NIGHT AND ESPECIALLY ON SUNDAY...A NE SURGE OCCURS AND WINDS QUICKLY
RISE TO 15-25 KTS ACROSS THE WATERS. SEAS THROUGH THE WKND WILL BE
PRIMARILY WIND DRIVEN...RISING FROM 2-3 FT SATURDAY...TO 4-6 FT ON
SUNDAY...AND A SMALL CRAFT ADVISORY MAY BE NEEDED.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 300 PM FRIDAY...EXPECT NORTHEAST WINDS THROUGH THE PERIOD
COURTESY OF HIGH PRESSURE ALIGNED ALONG THE EASTERN SEABOARD. WIND
SPEEDS WILL BE 15-20 KNOTS MONDAY INTO MIDDAY TUESDAY RETREATING
FROM THAT POINT ON TO SINGLE DIGITS BY LATER WEDNESDAY. LOWER
CONFIDENCE IN SEAS AS THE SPECTRUM IS HIGHLY DEPENDENT ON HOW
INVEST AL96 DOES. CURRENTLY THERE IS A FEW SIX FOOTERS ACROSS THE
OUTER WATERS OF AMZ252 BUT OTHERWISE THE SEAS ARE 3-5 FEET. IF THE
SYSTEM DEVELOPS MORE THAN ANTICIPATED THE SWELL ADDED TO THE
SPECTRUM COULD INCREASE THE SIGNIFICANT SEAS.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...HEAT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR SCZ032-033-039-
     053>056.

NC...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...JDW
NEAR TERM...MJC
SHORT TERM...JDW
LONG TERM...SHK
AVIATION...MJC
MARINE...MJC/JDW/SHK








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