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824
FXUS62 KILM 301721
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
121 PM EDT SAT AUG 30 2014

.SYNOPSIS...
STRENGTHENING BERMUDA HIGH PRESSURE OFFSHORE WILL BRING WARM
WEATHER THROUGH THE LABOR DAY WEEKEND WITH A FEW AFTERNOON SHOWERS
AND THUNDERSTORMS POSSIBLE. A WEAK COLD FRONT WILL APPROACH FROM
THE NORTH LATE IN THE PERIOD BUT IS LIKELY TO STALL BEFORE
REACHING THE AREA. BERMUDA HIGH PRESSURE AND A PIEDMONT TROUGH
WILL REMAIN THE DOMINANT FEATURES INTO NEXT WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1:20 PM SATURDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSIONS FOLLOW:

ISOLATED SEA-BREEZE RELATED SHOWERS HAVE POPPED UP OVER THE CAPE
FEAR REGION AND ARE MOVING INLAND. PLACES TO THE LEE OF THE SEA
BREEZE FRONT WILL LIKELY STAY DRY FOR THE REMAINDER OF TODAY.
MORNING SOUNDINGS SHOW A MARGINALLY TO MODERATELY UNSTABLE AIRMASS
WITH A MOIST LOWER LAYER AND PLENTY OF DRY AIR ALOFT. AGREE WITH
PREVIOUS REASONING THAT BEST CHANCES FOR CONVECTION THIS MORNING
AND EARLY AFTERNOON AS DRY AIR WILL BE MIXED DOWN LATER THIS
AFTERNOON. PREVIOUS DISCUSSION FROM 3:00 AM FOLLOWS:

MID AND UPPER LEVEL HIGH PRESSURE WILL BE ALMOST DIRECTLY OVERHEAD
TODAY. THIS WILL KEEP THE FLOW OF TROPICAL MOISTURE ORIGINATING FROM
THE WESTERN GULF ROUTED UP THE MISSISSIPPI RIVER VALLEY INTO THE
GREAT LAKES WITH NO IMPACT THIS FAR EAST. AT THE SURFACE A PESKY
LITTLE BACKDOOR COLD FRONT APPEARS TO HAVE SUNK AS FAR SOUTH AS
NORTHERN PENDER AND BLADEN COUNTIES THIS MORNING. THIS BOUNDARY MAY
ACTUALLY LINGER ACROSS SOUTHEASTERN NORTH CAROLINA FOR MUCH OF THE
MORNING BEFORE RETURNING NORTH EARLY THIS AFTERNOON...PUSHED BY A
COMBINATION OF THE LOCAL SEABREEZE CIRCULATION PLUS A SLOW VEERING
OF THE SYNOPTIC WIND AS HIGH PRESSURE MOVES FARTHER EAST OFF THE NEW
ENGLAND COASTLINE.

ALTHOUGH THERE IS NO SYNOPTIC FORCING PRESENT TODAY...AN UNSTABLE
AIRMASS WILL DEVELOP WITH SURFACE-BASED CAPE RISING TO 1500 J/KG AT
THE COAST AND NEAR 1000 J/KG INLAND. ONLY ISOLATED SHOWERS ARE
EXPECTED...MAINLY EAST OF I-95. IN TERMS OF TIMING...THE BETTER
SHOWER CHANCES MAY ACTUALLY OCCUR DURING THE MORNING AND EARLY
AFTERNOON HOURS WITH DEEPER MIXING DURING THE AFTERNOON DRAGGING
DOWN DRY AIR FROM ALOFT AND DILUTING THE SURFACE-BASED INSTABILITY.
PLENTY OF DRY AIR ALOFT AND VERY WEAK WINDS THROUGHOUT THE
TROPOSPHERE FAVOR ONLY SMALL THUNDER CHANCES AND NO STORM-CELL
ORGANIZATION. HIGHS TODAY SHOULD RISE INTO THE LOWER 90S INLAND WITH
UPPER 80S NEAR THE COAST.

MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND LIGHT WINDS WILL AGAIN FAVOR
AREAS OF LOW CLOUDS AND/OR FOG LATE TONIGHT. LOWS SHOULD FALL TO
NEAR 70.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...WEAKENING MID LEVEL RIDGE ON SUN WILL STILL BE
WORKING TO LIMIT AFTERNOON CONVECTION. FORECAST SOUNDINGS SHOW AN
ABUNDANCE OF MID LEVEL DRY AIR AND A WEAK SUBSIDENCE INVERSION.
ELONGATED BERMUDA HIGH WILL ENSURE PLENTY OF LOW LEVEL MOISTURE AND
WARMTH WITH THE WEAK GRADIENT ALLOWING SEA BREEZE DEVELOPMENT.
HOWEVER THE SEA BREEZE IS LIKELY TO BE THE ONLY FORCING MECHANISM
AND IT MAY NOT BE ENOUGH TO OVERCOME THE SUBSIDENCE. A WEAK PIEDMONT
TROUGH MAY DEVELOP IN THE AFTERNOON BUT IT PROBABLY WILL NOT BE OF
ENOUGH SIGNIFICANCE TO GENERATE CONVECTION.

CONTINUED DEEP SOUTHWEST FLOW MON COMBINED WITH WEAKENING MID LEVEL
RIDGE WILL LEAD TO AN INCREASE IN PRECIP CHANCES. PRECIPITABLE WATER
VALUES CLIMB TO 2 INCHES MON AFTERNOON WITH FORECAST SOUNDINGS
SHOWING NO EVIDENCE OF THE PREVIOUS DAYS INVERSION. WEAK SURFACE
GRADIENT WILL AGAIN ALLOW FOR SEA BREEZE DEVELOPMENT...WHICH SHOULD
BE MORE ACTIVE THAN ON SUN. PIEDMONT TROUGH WILL BE MUCH MORE
DEFINED AND SHOULD ALSO ACT AS A FOCUS FOR CONVECTION. WILL CONTINUE
TO CARRY AFTERNOON LOW CHC POP. TEMPERATURES WILL RUN ABOVE CLIMO
THROUGH THE PERIOD.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 AM SATURDAY...BERMUDA HIGH AND PIEDMONT TROUGH WILL BE THE
DOMINANT SURFACE FEATURES WHILE ALOFT WEAK ELONGATED 5H RIDGE
EXTENDS ACROSS MUCH OF THE SOUTHERN CONUS. THIS PATTERN IS FAIRLY
TYPICAL OF SUMMER AND COMBINED WITH PRECIPITABLE WATER VALUES AROUND
2 INCHES...ALSO TYPICAL FOR THIS TIME OF YEAR...WILL KEEP PRECIP
CHANCES NEAR CLIMO THROUGH THE PERIOD...30 TO 40 PERCENT. LACK OF
ANY FORCING ALOFT WILL LEAVE THE SEA BREEZE AND PIEDMONT TROUGH AS
TRIGGERS FOR CONVECTION. OUTFLOW FROM STORMS AS WELL AS LINGERING
BOUNDARIES FROM PREVIOUS DAYS CONVECTION WILL ALSO PLAY POTENTIAL
ROLES IN CONVECTIVE INITIATION. LATE IN THE PERIOD A COLD FRONT MAY
DROP IN FROM THE NORTH BUT THE STRENGTH OF THIS FEATURE WHEN IT
ARRIVES...IF IT ARRIVES...IS QUESTIONABLE. TEMPERATURES WILL BE NEAR
TO ABOVE CLIMO THROUGH THE PERIOD.

&&

.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
AS OF 18Z...A SLIGHT CHANCE OF MVFR CIGS AT KILM/KLBT THROUGH 20Z
...OTHERWISE VFR AT ALL TERMINALS THIS AFTERNOON. VCSH POSSIBLE AT
KLBT/KCRE/KMYR THROUGH 21Z WITH SHOWER ACTIVITY DECREASING AFTERWARD.

VFR EXPECTED THIS EVENING. SCT MVFR LEVEL CLOUDS EXPECTED AT THE
COASTAL TERMINALS. FOG WILL DEVELOP OVERNIGHT INLAND TERMINALS WITH
IFR LIKELY. MVFR WILL DEVELOP AT THE COASTAL TERMINALS OVERNIGHT.
NOCTURNAL SHOWERS WILL AGAIN MOVE ONSHORE TOWARDS DAYBREAK. VFR
EXPECTED 14-15Z WITH A CHANCE OF SHOWERS COASTAL TERMINALS DURING
THE MORNING.

EXTENDED OUTLOOK...CHC IFR/MVFR SUNDAY MORNING. ISOLATED SHOWERS
SUNDAY. INCREASING CHANCES FOR AFTN SHOWERS/TSTMS MONDAY THROUGH
THURSDAY WITH BRIEF AND LOCALIZED PERIODS OF MVFR POSSIBLE.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1:20 PM SATURDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:

A PESKY LITTLE BACKDOOR FRONT LOCATED NEAR JACKSONVILLE NC MAY
ACTUALLY SNEAK DOWN AS FAR SOUTH AS CAROLINA BEACH BEFORE STALLING
LATER THIS MORNING AND RETURNING NORTH THIS AFTERNOON. IT`S A
PRETTY INSIGNIFICANT FEATURE IN THE WEATHER- WORLD BUT COULD TURN
WIND DIRECTIONS EAST TO NORTHEASTERLY FOR A FEW HOURS. OTHERWISE A
LIGHT SOUTHEASTERLY WIND SHOULD PREVAIL THROUGH THE DAY...ENHANCED
BY THE AFTERNOON SEABREEZE.

ISOLATED SHOWERS OUT ACROSS THE OFFSHORE WATERS WILL MOVE TOWARD THE
COAST SHORTLY AFTER SUNRISE. RAINFALL COVERAGE SHOULD AVERAGE ONLY
10-20 PERCENT OF THE AREA...ALTHOUGH UNIDIRECTIONAL WIND THROUGH THE
LOWEST 6000 FEET OF THE ATMOSPHERE RAISES THE POTENTIAL THAT
WATERSPOUTS COULD DEVELOP EVEN IN A WEAK SHOWER CELL. SHOWER CHANCES
SHOULD DIMINISH RAPIDLY THIS AFTERNOON BEHIND THE DEVELOPING
SEABREEZE FRONT. WINDS WILL TURN MORE SOUTHERLY WITH TIME TONIGHT
WITH NO INCREASE IN WIND SPEED EXPECTED.

SEAS CURRENTLY AROUND 2 FEET MAY BUILD TO 3 FEET AWAY FROM SHORE AS
A SWELL SET PRODUCED BY THE BERMUDA HIGH ARRIVES AT THE COAST. NOAA
BUOY 41002 LOCATED ABOUT 200 MILES OFFSHORE STARTED PICKING UP THIS
SWELL ABOUT 6 PM YESTERDAY. THIS SOUTHEASTERLY 7 TO 8 SECOND SWELL
SHOULD BE OUR DOMINANT WAVE THROUGH TONIGHT.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SURFACE GRADIENT WILL REMAIN WEAK THROUGH THE
PERIOD WITH ELONGATED BERMUDA HIGH OFF THE COAST. THIS WILL MAINTAIN
LIGHT SOUTH TO SOUTHWEST FLOW THROUGH MON NIGHT. SPEEDS WILL RUN
AROUND 10 KT OVERNIGHT WITH DIURNAL INCREASES TO A SOLID 15 KT EACH
DAY. SEAS WILL RUN 2 TO 3 FT THROUGH THE PERIOD.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...ELONGATED BERMUDA HIGH REMAINS IN PLACE TUE
AND WED WITH PIEDMONT TROUGH BECOMING A LITTLE MORE DEFINED. SLIGHT
INCREASE IN GRADIENT EACH AFTERNOON WILL INCREASE SOUTHWEST FLOW TO
A SOLID 15 KT INTO THE EARLY EVENING HOURS. OTHERWISE SOUTHWEST FLOW
WILL BE 10 KT OR LESS. SEAS RUN 2 TO 3 FT.

&&

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

&&

$$

SYNOPSIS...III
NEAR TERM...REK/TRA
SHORT TERM...III
LONG TERM...III
AVIATION...MRR
MARINE...REK/TRA/III






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