Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 190153

Area Forecast Discussion
National Weather Service Wilmington NC
953 PM EDT Wed Jul 18 2018

A weak cold front will continue to move southward along the
South Carolina coastline, and will stall south of Charleston on
Thursday. The front should return northward on Friday. Unsettled
weather is possible Saturday through Tuesday with a chance of
showers and thunderstorms each day.


As of 1000 PM Wednesday...With the exception of a shower near
Surf City, rainfall has ended across our forecast area. I`ve
adjusted PoPs downward or removed them entirely for the
overnight period in agreement with the latest HRRR and RAP
models, although I did hang on to isolated showers a bit longer
across Darlington and Florence counties where recent convective
development across the Camden and Columbia area could
conceivably drift eastward. Elevated instability will persist
overnight, particularly across South Carolina and offshore
closer in proximity to the surface front which continues to sink
southward. Discussion from 645 PM follows...

A cluster of storms near Southport and another near Georgetown
and the Santee River are all that`s left of today`s convection.
The front appears to have been bumped southward by the
convection, with either northeast or northwest winds now
observed in Georgetown and Kingstree, SC. Dewpoints have fallen
into the mid 60s from Kenansville to Fayetteville to Rockingham,
and some of this drier air should bleed into the area
overnight. Updates early this evening focused on reducing rain
chances this evening (particularly across SE North Carolina) and
showing a faster onset of northeasterly winds. The latest HRRR
appears very reasonable currently. Discussion from 300 PM

The cold front has shifted into the southern 1/3 of the
forecast area. Models continue to show it shifting southward to
a location south of our area on Thursday.

The convection has formed in two broken lines along boundaries and
is moving south-southeast. The convection is expected to continue
throughout the late evening hours. As dry air aloft moves into the
northern 2/3 of the area the convection for Thursday is expected to
be confined to a line mainly south of Myrtle Beach to just south of

Lows tonight are expected to fall into the lower 70s inland to the
middle 70s along the coast. Highs on Thursday will reach into the
upper 80s to near 90 inland to the middle 80s at the beaches.


As of 315 PM Wednesday...Latest guidance suggests the frontal
boundary will be quasi-stationary along the Carolina coast Thursday
night and Friday. A wave of low pressure is expected to develop
Thursday evening off the southern SC coast and lift north to the
Outer Banks of NC by Friday afternoon. This will keep the highest
PoPs through the period focused along the coast, trailing off to
slight chance west of the I-95 corridor. The front may move inland
across the forecast area Friday night, but the bulk of moisture will
be shunted offshore as a 500 mb closed low drops into the Ohio River
valley. Clouds and northeast surface flow will keep temperatures a
few degrees below climo through this period.


As of 315 PM Wednesday...GFS/ECMWF very similar with development of
mid/upper low pressure across the OH valley during Saturday. Both
drop this feature southward to near AL or GA Monday and the central
Gulf Coast during Tuesday. As a result, a higher precipitable water
environment will likely become focused across the Carolinas with an
increasing potential for showers and thunderstorms each day through
the early part of next week. The increased cloud cover and southerly
flow will support above normal low temperatures each night and
slightly cooler than normal highs each day.


As of 00Z...VFR through the period. Showers near KILM will decrease
by 01Z. Cloud cover will become scattered by midnight. Although
winds will be light and low levels are moist, expect wind speeds to
increase enough by midnight to inhibit fog formation. VFR
Thursday with ENE-E winds around 10 kt.

Extended Outlook...Occasional MVFR to IFR conditions due to
scattered to numerous showers and TSTMs Friday through Monday.


As of 945 PM Wednesday...Northeast winds have begun to increase
north of Cape Fear, and should spread beyond Cape Fear to the
Grand Strand and Georgetown vicinity overnight as the surface
cold front continues to sink southward. Only minor changes were
made to the forecast with this late evening update. Discussion
from 645 PM follows...

Thunderstorms this afternoon have thinned out in coverage, but
remain active near Southport, Bald Head Island, and also 20-40
miles east of Georgetown, SC. The trend overnight should be for
convective activity to largely end north of Cape Fear, with
scattered showers and perhaps a thunderstorm offshore of Myrtle
Beach or Georgetown. A cold front has been pushed southward by
thunderstorm activity from around the Santee River entrance to
near Frying Pan Shoals buoy. Models are unanimous that the front
will continue to shift farther south overnight, with east to
northeast winds increasing to 10-15 knots, strongest near Cape
Fear. Seas currently 2-4 feet will change little in height
overnight, but could begin to shift more toward the shorter end
of the wave period spectrum due to increasing wind speeds.
Discussion from 300 PM follows...

A cold front has shifted just south of Little River and will
continue sliding south of the coastal waters overnight. Winds
will become northeast at 10 to 15 knots behind this front and
will become easterly by the end of Thursday. Seas are running 2
to 4 feet this afternoon with a southwest to west fetch. Seas
are expected to fall to 2 to 3 feet before increasing to 3 to 4
feet by Thursday with the northeast flow.

As of 315 PM Wednesday...A frontal boundary will be located just
south of the waters Thursday evening, and lift slowly northward
through the period as a wave of low pressure develops off the SC
coast. The low will lift north to the Outer Banks by Friday
afternoon. Winds are expected to be directed onshore Thursday night,
then become variable Friday as the low moves south to north across
the waters. By Friday night, southwesterlies should develop in the
wake of the low as the frontal boundary shifts northward. With the
frontal boundary and low pressure impacting the waters through the
period, numerous showers and thunderstorms are expected.

As of 315 PM Wednesday...A southwesterly fetch is expected to
increase during Saturday with areas of low pressure found across
the eastern U.S. and high pressure far offshore. The fetch could
carry into the first part of next week resulting in a prolonged
period of Small Craft conditions. Seas will likely average 4-6 ft
which is not a typical mid-July sea state.





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