Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 231404
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1004 AM EDT SAT JUL 23 2016

.SYNOPSIS...
A ridge of high pressure will expand across the Carolinas bringing
increasingly hot and humid conditions through the weekend and
much of next week. Isolated showers and thunderstorms are possible
each afternoon, and heat advisories will likely be needed each day
beginning Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Saturday...Admittedly surprised at the amount of
convection this morning along the immediate eastern coast of the ILM
CWA. Convection remains in a slowly weakening state, but several
SMW`s and even some FLS`s have been issued due to strong storms
drifting southward. WV imagery does not show any strong impulses,
but there is a 50-60 kt upper jet off the coast into which the RRQ
is above the local area. This increased diffluence is likely
creating enough lift on residual outflow boundaries from last night
to spawn and enhance the tstms across the coast and coastal waters.
Fortunately, this jet will push south late this morning and upper
diffluence will wane, bringing an end to this round of storms.

However, these storms and their associated clouds will create a
complex forecast this morning as they leave residual outflows and
differential heating boundaries - both of which will likely serve as
focus for tstms again this aftn during peak heating. However, clouds
may linger long enough along the coast to affect the temperatures,
and have dropped highs along the immediate coast back into the upper
80s, while maintaining low 90s inland. Humidity will be on the rise
today, but enough dry mixing aloft will allow dewpoints to fall into
the low 70s, which will keep heat indices just below the 105
threshold today, more in the 100-103 range. This will still serve as
fuel for scattered aftn convection, and with PWATS about 0.25 inches
higher on the morning soundings than yesterday, feel the HRRR/NSSL
WRF depiction of more widespread sea breeze and piedmont trough will
be correct and have schc/low chc pop this aftn/eve.

Convection is forecast to wane once again diurnally, and do not see
any forcing to drive tstms nocturnally, so have walked pop back to
silent by midnight. Another warm night is forecast as Bermuda
ridging and SW flow persists. Expect mins falling to a degree or two
either side of 75.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 400 AM SATURDAY...A HOT AND HUMID AIRMASS WILL CONTINUE TO
DOMINATE THE EASTERN CAROLINAS AS BROAD RIDGING PREVAILS ALOFT AND
THE BERMUDA HIGH PERSISTS AT THE SURFACE. BOTH DAYS WILL FEATURE
AFTERNOON HEAT INDEX VALUES EXCEEDING 100F, WITH A HEAT ADVISORY
QUITE POSSIBLE FOR SUNDAY. MUCH LIKE ON SATURDAY, VERY DRY AIR ALOFT
AND LACK OF STRONG FORCING WILL LIMIT CONVECTIVE COVERAGE TO
ISOLATED STORMS EACH DAY, PRIMARILY ALONG THE SEA BREEZE FRONT AND
ANY OTHER BOUNDRIES THAT HAPPEN BY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...OVERALL, BERMUDA HIGH AND PIEDMONT
TROUGH WILL BE THE MAIN PLAYERS IN FORECAST MUCH OF THE WEEK.
THEREFORE PERSISTENT S-SW WINDS WILL CONTINUE TO FEED WARM AND
MOIST AIR INTO THE AREA WITH POTENTIAL FOR LOCALIZED SHWRS/TSTMS
EACH DAY. THE UPPER RIDGE HELPING TO KEEP CONVECTION MORE LIMITED
WILL BREAK DOWN A BIT INTO MID WEEK AS A NORTHERN STREAM TROUGH
DIGS DOWN AS IT PUSHES A COLD FRONT SOUTH AND EAST. ALTHOUGH THE
FRONT DOES NOT LOOK LIKE IT WILL MAKE IT, IT WILL DROP SOUTH INTO
NORTH CAROLINA WHICH IN TURN MAY HELP TO INCREASE THE GRADIENT
FLOW AND LOCALIZED CONVERGENCE AROUND THE BERMUDA HIGH AND
PIEDMONT TROUGH INLAND. IT WILL ALSO TURN THE N-NE UPPER LEVEL
FLOW AROUND THE EAST SIDE OF RIDGE EXTENDING INTO THE CAROLINAS
FROM THE MIDWEST TO A MORE W-NW FLOW ALOFT, AROUND BASE OF
STRETCHED OUT UPPER TROUGH EXTENDING DOWN FROM THE NORTH. SHOULD
ALSO SEE A BIT MORE IN THE WAY OF CLOUDS AND CONVECTION REACHING
INTO AREA FROM UPSTREAM. DO NOT EXPECT MUCH IN THE WAY OF UPPER
LEVEL SUPPORT AS ATLANTIC RIDGE BUILDS QUICKLY BACK IN FROM THE
EAST BY THURS/FRI.

BY MID WEEK, THE INFLUENCE OF THE FRONT TO THE NORTH AND
RETREAT OF RIDGE EXTENDING IN FROM THE MIDWEST SHOULD INCREASE
CHC OF CONVECTION AND CLOUDS ACROSS THE AREA WHICH MAY SHAVE A FEW
DEGREES OFF THE MAX TEMPS. BUT RIDGE BUILDS BACK IN FROM ATLANTIC
AND OVERALL EXPECT VERY WARM TEMPS MOST OF THE WEEK. RIGHT NOW, IT
LOOKS LIKE HEAT ADVISORY CONDITIONS MAY EXIST OVER SEVERAL DAYS
NEXT WEEK.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
As of 12Z...Potential for MVFR due to fog late overnight into
early Sunday morning. Otherwise expect VFR through the valid TAF
period, with isolated SHRA/TSRA possible.

Latest radar imagery depicts an area of convection moving
southward off the coast. While this activity will continue to
affect the coastal sites over the next hour, do not anticipate
any restrictions. For the rest of today, VFR will prevail with
isolated showers and thunderstorms possible. Light winds this
morning will become south-southeasterly and increase to around 12
kts or less. Into tonight, any convection will taper off and
winds will become light. Latest guidance suggests the potential
for fog development towards the end of the forecast period. Given
lower confidence have not introduced attm.

EXTENDED OUTLOOK...Isolated afternoon convection through
into midweek may create periods of MVFR/IFR. Otherwise expect
VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Saturday...Bermuda high will remain the dominant
feature through tonight as it expands slowly from the Atlantic. The
gradient will remain rather light, so SW winds will be only around
10 kts, rising to 10-15 kts tonight. A SE 9 sec swell will remain in
the spectrum but in a slowly deamplifying manner, as a SW wind wave
develops. Wave heights will remain at 2-3 ft through the near term,
but develop a slightly lower average period tonight.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 400 AM SATURDAY...HIGH PRESSURE OVER THE WESTERN ATLANTIC
WILL CONTINUE TO KEEP WINDS FROM THE SW AT 10 TO 15 KTS THROUGH
MUCH OF THE THE PERIOD, WITH SEAS OF 2 OR 3 FT.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...SOUTH TO SOUTHWEST WINDS WILL CONTINUE
AROUND THE BERMUDA HIGH. WINDS WILL GENERALLY STAY IN THE 10 TO
15 KT RANGE WITH A SLIGHT SPIKE IN LATE AFTN INTO EARLY EVE,
ENHANCED BY THE SEA BREEZE AND PIEDMONT TROUGH. BY LATE WED
GRADIENT WILL TIGHTEN AS COLD FRONT DROPS INTO NORTH CAROLINA.
THIS SHOULD INCREASE WINDS AND SEAS WED NIGHT. OVERALL EXPECT SEAS
2 TO 3 FT BUT INCREASING SLIGHTLY THROUGH WED UP TO 3 TO 4 FT AND
MAY SEE A FEW 5 FTERS IN OUTER WATERS IN STIFFER 15 TO 20 KT SW
WINDS.

&&

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

&&

$$
SYNOPSIS...RGZ
NEAR TERM...JDW
SHORT TERM...REK
LONG TERM...RGZ
AVIATION...SGL
MARINE...


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