Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 261906

Area Forecast Discussion
National Weather Service Wilmington NC
306 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 3 PM Wednesday...Cold front stalled south of the area is
still providing the impetus for showers and tstms, mostly across
the  coast and SC this aftn. These showers and tstms are
expected to slowly wane through the late aftn as dry air pushes
southward along and north of an axis of deformation dropping SE
across the Carolinas. While showers did become more widespread
than any high res guidance suggested, note a clear erosion in
the cumulus field across NW zones and this will continue to drop
south and squelch the convection over the next few hours. Temps
have warmed to 90 in the drier air inland, but have struggled
only to around 80 along the clouded/rainy areas in the coastal
plain of SC. Highs will only rise another degree or two from
current values.

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...Cold front has sunk south of the terminals this aftn
with dry air advecting in from the north. Before this dry air
can move into the terminals, scattered showers and tstms have
developed, mainly along the coast and into SC. However, latest
visible imagery shows clouds beginning to erode from the NW, and
have tempered tstm mention in TAFs. Still expect VCSH at all
terminals except LBT through this aftn, with tempo TS mentioned
at the Myrtles. Brief IFR is possible although MVFR is most
likely. Winds will be primarily E/NE through tonight at speeds
around 10 kts.

Any tstms will erode quickly this evening leaving a mostly clear
night with light NE winds. While moisture will be eroding in the
column, forecast profiles suggest enough low-level moisture on the
onshore winds to create some IFR stratus tonight. The hydrolapse
rates appear favorable only in the very lowest levels so confidence
is low, but have added few/sct at all terminals overnight before
returning to VFR again after sunrise on Thursday.

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 3 PM Wednesday...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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