Area Forecast Discussion
Issued by NWS Wilmington, NC

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935
FXUS62 KILM 230743
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
340 AM EDT Fri Jun 23 2017

.SYNOPSIS...
Bermuda High pressure will build westward over the Eastern Carolinas
through today. The remnants of Cindy moving up from the Gulf coast
will get absorbed into a cold front marching east reaching the
Carolinas Saturday with an increasing chance of showers and
thunderstorms heading through the weekend. This cold front will
reach the coast by Sunday but will not get pushed completely
out of the area until a second front sweeps through by Tuesday.
Dry High pressure will build in through the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Friday...An area of pcp will just miss our local
forecast area to the west early this morning but plenty of deep
layer moisture continues. A southwest flow around 5 mph or so
should keep fog out of the forecast but expect some low clouds
around especially inland through daybreak.

The Atlantic ridge extending back westward over the Southeast
coast will provide a drier upstream flow as compared to the
plentiful moisture we saw from Cindy the last several days.
Water Vapor imagery shows drier air in the mid to upper levels
working its way northward toward the Carolinas. Therefore expect
the overcast mid to high level deck of clouds to break up today
leaving increasing sunshine through this afternoon. The
gradient will tighten as the remnant low of Cindy moves up ahead
of a cold front which will be approaching the Carolinas from
the west tonight. This will produce gusty S-SW winds through
today, especially along the coast in the afternoon sea breeze.
Expect some cu development along the sea breeze front as it
pushes inland and have included mainly isolated shwrs along this
boundary this afternoon. HRRR once again shows best chc along or
just inland of SC coast this afternoon, but overall more
isolated in coverage. A warm start to the day, with temps in
the mid 70s, combined with sunshine will push temps up near 90 most
places in a continued moist tropical air mass. Heat index values
will reach over 100 degrees in many spots inland this afternoon.

This diurnal convection will come to an end this evening with
gusty winds continuing across the area. Temps will remain warm
once again with lows in the mid 70s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 am Friday...The upper pattern will support unsettled
weather across the Carolinas this weekend as a series of
shortwaves dig out a longwave trough from the Great Lakes down
through the Mississippi Valley. The 500 mb subtropical ridge
that has been centered off the Florida east coast for much of
the week will relocate out near Bermuda Sunday as upper level
heights steadily fall along the Southeast coast. Tropical Storm
Cindy`s remnants will not directly affect our area, however the
airmass advected in with Cindy and covering the Carolinas
Saturday into Sunday should be exceptionally humid with
precipitable water values expected to reach 2.1 to 2.6 inches.
That will potentially reach the top 5 June PW values recorded
since 1948 using the MHX/HAT data from the SPC sounding
climatology webpage.

At the surface, the remnant circulation of Cindy should race off the
Mid-Atlantic coast around daybreak Saturday. A cold front extending
from the Appalachians into central Texas will slowly move into the
eastern Carolinas late Saturday night, stalling Sunday before
reaching the beaches. Saturday should begin dry with some sunshine,
but deeper moisture arriving during the afternoon will intercept an
unstable atmosphere with CAPE 1500-2500 J/kg. Scattered showers and
storms should develop along and west of the seabreeze front. Along
with plenty of lightning due to large CAPE up in the -10C to -30C
region aloft, the strongest of these storms could also produce wet
microbursts. Storms should remain only loosely organized due to weak
environmental shear.

The most serious weather might occur Saturday night as what`s left
of Cindy`s gulf inflow jet moves across the eastern Carolinas. This
is when the GFS and NAM both show excessive precipitable water
values present, and indicate a larger proportion of environmental
CAPE moving down below the freezing level which favors efficient
coalescence raindrop growth processes that can produce excessive
rainfall rates. I`ve beefed up wording in the forecast to mention
"heavy rain" possible Saturday night. Still too much uncertainty
with coverage and duration to issue any flood watch products.

With the front stalled near the coast Sunday another round of
scattered showers and storms should develop during the day.
Precipitable water values should return to "normal" wet-summer
conditions around 2.0 inches. As the longwave trough takes shape to
our west Sunday night, increasingly westerly wind directions should
begin to advect drier air into the Carolinas, leading to a reduction
in precipitable water values and eventually pushing the stalled cold
front off the coast late Sunday night.


&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 PM Thursday...Cold front will be stalled along the
coast Monday before being pushed offshore and out of the area
by Tuesday. The stalled boundary combined with deep SW flow
aloft and residual moisture from the departing remnants of TS
Cindy will create a good chance for showers and thunderstorms
the into Monday. The GFS has been consistent with widespread
activity mainly near or along the coast on Monday, and now the
latest ECM/CMC have trended in that direction as well. PWATs
fall on Monday from west to east, so the highest POP will be at
the coast on Monday, but an unsettled period is expected until
a secondary front beneath an anomalously deep trough clears
everything out by Tuesday.

This secondary front will usher in much cooler air for the remainder
of the period. 850mb temps crash towards +10C, near the bottom 10th
percentile for late June, and highs will likely remain at least 5
degrees below climo Tue/Wed with dewpoints potentially falling into
the 50s! This will feel quite refreshing, especially after the high
humidity of Sunday. By Thursday the surface high shifts offshore and
height rises begin again, so temps and humidity will increase, but
remain below seasonable norms into late week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 06Z...Moisture streaming north mainly in the way of mid
to high clouds with bkn ceilings between 15k and 25k but expect
some bkn to ovc stratus developing mainly inland between 800 ft and
1500 ft, lifting shortly after daybreak. Therefore LBT and FLO
should have IFR ceilings this morning. Expect mostly VFR along
the coast through the period, but added some SCT lower ceilings
and some SHRA/TSRA possible mainly just inland from coastal
terminals this afternoon with possible deck of strato cu mixing
in with some AC/CI. Included VCSH to acct for that. Southwest
winds around 5 to 7 kts should keep fog out of the forecast
although guidance shows it possible in FLO and LBT right around
daybreak.

Extended Outlook...MVFR ceilings/vsbys Saturday as tropical
moisture associated with Cindy remnants traverse the region.
More MVFR/IFR conditions possible in SHRA/TSRA with cold front
late Saturday through Sunday possibly again on Monday

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Friday..Atlantic ridge reaching back westward into
the Southeast coastal waters will maintain a S to SW flow over
the local waters through tonight. The remnant low from Cindy
moving up from the western Gulf coast will combine with a cold
front marching east toward the Carolinas, tightening the
gradient flow through today. Therefore expect increasing
southerly flow from 10 to 15 kts up to 15 to 20 kts through this
afternoon into tonight. Expect especially gusty winds near the
coast in afternoon sea breeze.

This persistent southerly flow will push seas up from 2 to 4 ft
early to 3 to 5 ft by midnight and increasing further to 4 to 6
ft overnight into early Saturday.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM Friday...The remnants of former Tropical Storm Cindy
will race off the Mid-Atlantic coast Saturday morning just ahead of
a cold front advancing toward the East Coast. This front will slow
as it moves into the Carolinas Saturday night, stalling just inland
from the beaches Sunday. Several waves of thunderstorms are expected
to develop across the area, especially Saturday Night and again
Sunday afternoon. The front should finally begin to move out across
the coastal waters very late Sunday night with winds shifting to the
north.

Breezy conditions are expected Saturday into Saturday evening as the
pressure gradient should tighten between Bermuda High pressure
offshore and the cold front approaching from the west. Add the
seabreeze in and wind gusts could easily exceed 25 knots Saturday
afternoon. A Small Craft Advisory will remain in effect through
Saturday night for these winds and seas in the 4-6 foot range.

LONG TERM /MONDAY THROUGH TUESDAY/...
As of 300 PM Thursday...Stalled cold front along coast will
waver in the vicinity Monday before a secondary front pushes
everything out to sea and clears the waters on Tuesday. Winds
will fluctuate between S to the east of front and W behind it on
Monday, but the weak gradient immediately near the front will
keep winds at 10 kts or less regardless of direction. As the
second front kicks everything off to the east on Tuesday, winds
will become northerly, with speeds around 10 kts. A 2 ft/8sec SE
swell will exist in the spectrum each day, and thanks to light
winds on Mon, it will likely be the predominant wave group
despite a present S/SW wind-wave. Seas will be 2-3 ft most of
Mon, and then fall further to 1-2 ft Tuesday as the winds turn
offshore.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from midnight tonight to 6 AM EDT Sunday
     for AMZ250-252-254-256.

&&

$$

NEAR TERM...RGZ
SHORT TERM...TRA
LONG TERM...JDW
AVIATION...RGZ



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