Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 230645

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

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 tonight into Saturday with an increasing chance of showers
and thunderstorms heading into and 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


As of 730 PM Thursday...Only subtle changes to the forecast this
evening with some very near term tweaks to cloud cover and
temperature trends. Most guidance has showers ending almost
completely over the next few hours and even though we aren`t
carrying much I resisted removing pops completely as any
outflow or residual boundary could trigger some activity. No
other changes. Previous discussion follows:

Plenty of tropically-sourced moisture in
the column now with soundings showing P/W values in the 2 inch
range. This will change in the early morning hours of Friday as
dryer air at the mid-levels moves in. High-res guidance handling
present convection well with a focus along the coast and
secondary activity well inland. Have relied on this guidance
for the very near term, with pops dropping to slight chance
overnight and only isolated convection for Friday. Temperatures
will remain very seasonally-correct and do expect warmer
readings on Friday as we will see more breaks on the cloud
cover. We will be seeing the beginnings of a pattern shift
during the Near Term, with the Bermuda ridge pushing east as the
upper H/5 ridge breaks down as a broad upper trough descends
upon eastern CONUS.


As of 3 PM Thursday...The upper ridging extending across the
Southeast States, including the ILM CWA, will peak Fri evening.
This will help keep the remnants of Cindy west and north of the
FA Friday night with models taking it off the DELMARVA Coast
during Saturday morning. The flow aloft will suppress the upper
ridging during Saturday with models indicating the upper
longwave trof expanding southward as a result of weak mid-level
s/w trofs/vorts rotating thru it. The wavelength of this upper
trof is quite extensive, affecting a good chunk of U.S. real
estate by and during this upcoming weekend.

At the sfc, the remnants of Cindy will hook up with a cold
front Fri night. The cold front is progged to be oriented NE to
SW across the western Carolinas early Saturday and will slowly
sink toward the southeast Saturday and likely across portions of
the FA Sat night. Any leftover diurnally induced convection Fri
evening should become pop-less Fri night into early Sat.
Convection will fire up by mid to late Sat morning inland and
extend to and off the Carolina coasts during Sat and Sat night.
Will have forcing from the front, pinned sea breeze,
differential heating and very weak but effective perturbations
in the mid-level flow. Pops will be ramped up to Good Chance
just shy of likely, for Sat aftn and night.

The sfc pg will remain tightened thruout this period except
come Sat night when the cold front itself will be nearly
overhead. As for winds, expecting SSW-SW 10 to 15 mph, except up
to 20 mph at the coast, winds will become SW-WSW 10-20 mph
during Sat then finally decrease Sat night as the sfc pg


As of 3 PM Thursday...Cold front will be stalled along the coast
Sunday and Monday before being pushed offshore and out of the area
during 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 first
half of the extended. The GFS has been consistent with widespread
activity Sunday and Monday, and now the latest ECM/CMC have trended
in that direction as well. PWATs climb towards 2.25 inches Sunday
before slowly falling Monday, so the highest POP will be Sunday, but
an unsettled period is expected until a secondary front beneath an
anomalously deep trough clears everything out on 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.


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


As of 730 PM Thursday...No changes to the coastal waters
forecast with the evening update. Previous discussion follows:

Persistent S to SWly winds will persist
over the waters around the back-side of the Bermuda High through
the Near Term. Main change will be a gradual tightening of the
gradient with winds increasing from present 5 to 10 kt range to
10 to 15 kts tonight and 15 to 20 kts by Friday afternoon. Seas
will likewise increase, from around 2 ft this afternoon to 2 to
3 ft tonight and up to 4 ft on friday. Winds and seas will be
higher in the vicinity of thunderstorms this afternoon.

As of 3 PM Thursday...SCA conditions Fri night thru Saturday.
Dropping back to SCEC conditions during Sat night.

Bermuda high pressure centered off the Southeast U.S. Coast
will lose a portion of its grip across the local waters this
period. This in response to a sfc cold front dropping southeast
and becoming oriented NE-SW just inland from the Atl waters by
late Sat night. At the start of this period, a well tightened
sfc pg will exist across the local waters, which will continue
thru Fri night and daytime Sat. During Sat night, models finally
and slowly relax the pg across the area waters. Wind directions
will basically run from the SSW-SW Fri night and SW-WSW Sat
into Sat night. Significant seas will be elevated thruout this
period, peaking Fri night thru early Sat evening. Locally
produced wind driven waves at 3 to 5 second periods will
dominate this period. The SW-WSW winds will result in a limited
fetch for the seas to develop off of. Scattered to widespread
convection Sat afternoon and night will pose the usual hazards
to mariners.

As of 3 PM Thursday...Cold front will stall along the coast and
waver in the vicinity Sunday and Monday before a secondary
front pushes everything out the sea and clears the waters on
Tuesday. Winds will fluctuate between S and W Sunday/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
northerly, with speeds around 10 kts. A 2 ft/8sec SE swell will
exist in the spectrum each day, and thanks to light winds
Sun/Mon will likely be the predominant wave group despite a
present S/SW wind-wave. Seas will be 3-4 ft very early Sunday
before falling to 2-3 ft most of Sun/Mon, and then fall further
to 1-2 ft Tuesday as the winds turn offshore.


MARINE...Small Craft Advisory from midnight Friday night to 6 AM EDT
     Sunday for AMZ250-252-254-256.


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