Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 181351
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
951 AM EDT Thu May 18 2017

.SYNOPSIS...
Bermuda high pressure will remain anchored off the Carolina
Coasts through the weekend, helping to maintain fair and very
warm conditions. Showers and thunderstorms will begin to
increase early next week ahead of a cold front from the west.
Next week will become a bit more unsettled as a series of
low pressure systems cross the Eastern Seaboard.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 952 AM Thursday...Adjustments were needed to increase sky
cover which may impact temperatures a degree or two today, but
otherwise the forecast remains precipitation free and warmer
than climatology today as advertised, with no significant
changes.

As of 330 AM Thursday...Southerly return flow around Bermuda
High will produce some gusty winds especially along the coast as
the afternoon sea breeze develops. High clouds continue to
stream in up an over the top of the ridge through the Carolinas.
The moisture profiles show a decent layer of RH close to 100
percent from H40 up to H20 through today into tonight. Therefore
expect cirrus to filter out some sunshine through much of the
day. The mid layers continue to remain very dry with increased
subsidence under weakening and flattening ridge aloft as it gets
suppressed farther south and east through the period. This
should also maintain another rain free and very warm day across
the eastern Carolinas. Pcp water values show less than three
quarters of an inch over the area but just west into central NC
the values jump up to 1.5 inches and there is also a slight
increase up to one inch along seabreeze front in the afternoon
indicative of a some cu development. Temps will soar well into
the 80s just inland of the coast but will be tempered by cooler
ocean air being brought inland by aftn sea breeze. Southerly
flow should help push sea breeze quite far inland.

Another nocturnal jet develops overnight Thurs with limited very
shallow moisture present. This should eliminate fog in most
places but may produce some very patchy fog or stratus just
around daybreak when winds become lightest. Temps overnight will
drop into the mid 60s inland to near 70 at the coast.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 330 AM Thursday...The longwave upper ridge will hold it`s
ground across the SE States this period. S/w trofs moving
within the westerlies aloft will ride up over the ridge and
across the Mid- atlantic and Northeast States. The upper ridge
axis will have been shunted to the northeast coming into this
period, but models do spring it back to the north and across the
FA during Fri and the upcoming weekend. At the sfc, look for
Bermuda high pressure ridging westward and inland in the
vicinity of Cape Romain. This axis will delineate wind
directions, with SSW to SW north of the ridge axis and SSE to
SSW south of the ridge axis. The sfc pg remains loosened thru
the period with the aftn and early evening inland progressing
sea breeze to temporarily boost winds to 10-15 kt with gusts up
to 20-25 kt mainly along the immediate coast. As for clouds,
mainly high level thin occasional opaque cirrus thru the period
with few/sct diurnally driven cu on Fri with additional cu
during Sat. The additional clouds during Sat are the result of a
sfc cold front having aligned from w to e across the Mid-
atlantic states, slowly sinks southward and likely temporarily
stalling across the FA. POPs for Sat and Sat night will be in
the 15 to 30 percent range, with the hier POPs across the
northern portions of the FA. Max temps 85 to 90 both days,
except upper 70s to the lower 80s at the coast due to an active
sea breeze both days. Min temps will run slightly above normal.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...Backdoor cold front near or over our
local area will quickly retreat back to the north Sunday as the
aforementioned high slides off the New England coast and ridging
persists aloft in response to a trough digging into the MS VLY.
Soundings indicated some mid- level drying on Sunday so while a
few showers are possible, Sunday looks also to be mostly dry
with temps again slightly above climo. More cloud cover is
forecast for Sunday though. A much more unsettled period begins
Sunday night and especially Mon-Tue as a Cold front trails
across the Carolinas with good shower and tstm chances. Much of
Monday appears wet before drying occurs by Tuesday aftn thanks
to the cold front pushing SE of the area. Broad trough remains
across the east behind this feature, so while the middle of the
week may again be dry, temps will be much cooler Mon-Wed than
Sat/Sun.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
As of 12Z...VFR conditions expected thruout this fcst period
with the exception of an hour or 2 this morning due to MVFR
conditions from whats left of the shallow ground fog burning
off. Only ceilings to contend with will be high level cirrus
with a few diurnal cu possible. Bermuda high pressure will ridge
westward and onshore in the vicinity of Cape Romain thru this
period. Wind will generally be SSW-SW at 5 kt initially and
increase to around 10 kt by noon and continuing into the
evening. The exception will be the coastal terminal where
the sea breeze will result in SSE-SSW winds to increase to
10 to 15 kt with occasional gusts 20+ kt during the afternoon
and early evening. Winds will back down to 5 kt or less by
late evening and overnight period.

Extended Outlook...Flight categories may lower to IFR or lower
during the pre-dawn hours of Sat. Reduced flight categories
will be possible in any showers and thunderstorms that develop
on Monday.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 952 AM Thursday...Southerly wave energy every 5-6 seconds
will propagate ashore. Chop will increase this afternoon near
shore as the sea breeze peaks.

As of 330 AM Thursday...Benign seas will continue across the
waters with a slight chop in afternoon sea breeze. A return flow
will continue around Bermuda High with southerly winds in the 10
to 15 kt range picking up in the afternoon near shore in decent
sea breeze with gusts up to 20 kts. Seas remain below 3 ft but
increase ever so slightly through tonight in continued fairly
weak southerly push.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 330 AM Thursday...Sfc ridge axis from the parent Bermuda
high will extend inland in the general vicinity of Cape Romain
during this period. This will delineate sfc synoptic wind
directions from SSW-SW north of the axis and SSE-SSW south of
the axis. The sfc pg will remain relatively loose thruout the
period. With wind speeds 5 to 10 kt or around 10 kt. The
exception will be the near shore waters each aftn/evening with
speeds of 10 to 15 kt with g20 kt due to an active sea breeze
cycle. Significant seas will hover around 2 to occasionally 3
ft. A pseudo or fresh ESE-SE swell at 6 to 8 second periods will
develop and affect the area this period. This a result of the
continuous wind field across the Atl Waters south of the center
of the Bermuda high pressure.

LONG TERM /SUNDAY THROUGH MONDAY/...
As of 300 PM Wednesday...A backdoor cold front over or just
north of our local waters lifts back north Sunday and winds
will veer back to the SE but at continued light speeds. This
will change during Monday ahead of an approaching cold front.
This front causes the gradient to pinch, and wind speeds become
15-20 kts while veering further to the SW late in the period.
These stronger winds will drive wave heights up to 3-4 ft Monday
as a Southerly wind wave amplifies, after persisting at 2-3 ft
on Sunday.

&&

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

&&

$$

NEAR TERM...RGZ/8
SHORT TERM...DCH
LONG TERM...JDW
AVIATION...DCH/43



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