Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 262335

Area Forecast Discussion
National Weather Service Wilmington NC
735 PM EDT Wed Jul 26 2017

Isolated showers and storms will become more numerous Friday
into Saturday ahead of an unseasonably strong cold front, and a
few storms may be strong late Friday. Drier and slightly cooler
air is expected in wake of this system by early next week.


As of 730 PM Wednesday...One lonely shower is moving west across
Florence and Darlington Counties, otherwise all else is fading
with the sunset. Have lowered POPs to slight chance or less
throughout for the remainder of the overnight period. No other
changes to the forecast with the latest update. Relevant
portion of previous discussion follows:

As convection wanes this evening, most of the cloud cover will
erode as well thanks to the aforementioned dry air causing PWATS
to sink to around 1.3 inches. Low level winds become light and
veer to the E/SE, advecting at least near-surface moisture from
the ocean. Forecast profiles suggest this will be very shallow,
but there is at least a chance for some stratus/stratocu
tonight. Fog is possible as well, but should remain light and
patchy as hydrolapse rates weaken significantly above just 300
ft. Mins will drop to seasonable or slightly below in the clear
and calm airmass, with mins in the upper 60s to low 70s.

Thursday is shaping up to be a beautiful day locally as high
pressure builds down from New England before recentering
offshore,  and dry air persists in the column. Abundant
sunshine is forecast and while some diurnal CU is likely in the
aftn, no convection is expected. Late July sunshine will warm
temps to a degree or two either side of 90 and heat indices will
remain slightly below 100.


As of 3 PM Wednesday...The mid level pattern will once again be
undergoing change something that has seemingly been constant
this summer. Heights will be falling from what will turn out to
be a significant trough that develops over the Ohio Valley. The
attendant cold front will be well to the northwest to provide
any low level forcing but with the height falls, the Piedmont
Trough and seabreeze, expect good coverage of showers and
thunderstorms Friday and Friday night. There may be a few
coastal showers overnight Thursday but most inland areas should
be dry. Regarding temperatures, not much deviation from seasonal
values with overnight lows in the lower to mostly middle 70s and
highs mostly in the lower 90s.


As of 3 PM Wednesday...Primary weather features this period
include an unseasonably amplified upper trough, followed by
Canadian high pressure which may bring a brief feel of very
early Fall, as dewpoints dip below normal for the season. A
surface trough inland Saturday will move offshore Saturday
night, as relatively strong high pressure from Canada barges
in from the NW in earnest early Sunday. The high will drop
dewpoints deep into the 60s Sunday, removing the muggy edge
well into the next week, as the high remains anchored over the
mid- ATLC region. The best rain chances are Saturday, before
mid-level drying and lowering dewpoints inhibit convection. NE
flow in the low-levels may bring in bouts of oceanic cu and, in
conjunction with the Canadian high, will keep maximum
temperatures below normal from Sunday onward. This accompanied
by small rain chances, mainly by the coast. It`s possible a few
storms early Saturday could be capable of strong gusts.


As of 18Z...Good confidence VFR conditions will persist through
around midnight for all terminals. What happens thereafter is of
a bit lower confidence. Indications are that we will see MVFR to
IFR for vsbys in patchy fog and/or cig restrictions in stratus
in the early morning hours for LBT and FLO. The coastal
terminals may go down to around 5 nm in BR after midnight, but
confidence low regarding this.

Extended Outlook...MVFR or lower flight restrictions are likely
in association with numerous thunderstorms later Fri and Fri
night. Some of the thunderstorms may be strong to severe. Flight
restrictions may persist into portions of Sat as well. VFR
Sunday and Monday.


As of 730 PM Wednesday...Seas remain in the 2 to 3 ft range most
places as a light onshore flow continues. Latest update needed
no changes other than to decrease chances of precipitation
overnight. Previous discussion follows:

NE surge behind this mornings cold front will gradually weaken
tonight, so the current winds of 10-15 kts from the NE will ease
to around 10 kts by Thursday morning. Winds will ease further
Thursday while veering to the SE as high pressure offshore re-
asserts itself. This will keep speeds less than 10 kts Thursday,
although locally higher gusts are likely within the near shore
sea breeze during the aftn. Seas this aftn will feature a strong
NE wind wave component creating 2-3ft, with isolated 4ft seas,
highest off the Cape Fear Coast. As the winds ease and begin to
veer, wave heights will drop slowly overnight and on Thursday to
around 2 ft throughout.

As of 3 PM Wednesday...Expect the usual south to southwest flow
of ten knots or less into early Friday. As conditions become
more dynamic with a significant trough and cold front moving our
way expect winds to increase to 15-20 knots. This will increase
seas from the 1-3 foot range to 2-5 feet with a SCEC headline
possibly needed.

As of 3 PM Wednesday...A significant wind-shift will occur
Saturday from WSW to NNE, as a strong cold front for late July
crosses the coast Saturday afternoon or evening. It is possible
a Caution headline or even an Advisory may be needed for gusty
winds ahead of and just behind the front. In addition...TSTMS
and showers will be more numerous Saturday and a few storms may
be strong to severe. NE winds 15 KT Sunday will begin to veer
Monday to E-SE, with seas of 2-4 feet, highest offshore. Sunday
seas a bit messy, as residual SSW waves every 6 seconds mix with
a NE chop and weak SE swell waves. Isolated showers will dot
the waters Sunday and Monday but of light intensity.





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