Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 271350
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
950 AM EDT FRI MAY 27 2016

.SYNOPSIS...
Sunny and warm conditions will prevail today before clouds and
showers increase into the weekend. Low pressure from the Bahamas
will organize and approach the South Carolina coast Sunday. This
low will meander near the coast through the middle of next week
maintaining unsettled weather and slightly cooler temperatures.
Periods of heavy rain and strong rip currents are possible at
times throughout the holiday weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 945 AM Friday...Day is starting out sunny most locations and
warming quickly, with temperatures now in the mid to upper 70s
most locations. No changes to the forecast were needed with the
latest update. Previous discussion follows:

Sunshine minutes today reaching the moderate to high category as
subsidence aloft is injected into the western lobe of the overhead
upper ridge, by the approach of the broad upper gyre hosting the
tropical wave below it. A few clouds into daybreak near 6-8 KFT
will erode through morning. There may be some afternoon cumulus
but sea- breeze convergence is expected to remain weak today since
the synoptic and sea breeze flow remain similar to northwest.
Debris clouds from convection well west of the region may increase
later in the day generally above 20 thousand feet. The overnight
period will remain quiet and it is not until daybreak Saturday
that we see significant column moisture brought onshore. Maximums
for today middle and upper 80s and warmest deeper inland, minimums
near 70 at the coast and middle 60s inland in light northeast
wind.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 3 AM Friday...A consensus can be seen in the PMSL plots from
the GFS/NAM/ECMWF/SREF solutions showing a 1009-1013 MB low moving
near or onshore into the Charleston area sometime Sunday afternoon
or evening. This consensus was used to generate pop distribution and
construct the QPF layout for Saturday and Sunday. The rainfall
expectation at present is 1 to 1.25 inch totals SAT/SUN for coastal
SC and around a half inch on areal average across SE NC. Winds at
least for now do not appear to pose a hazard concern. Convection
embedded in the tropical moisture however could cause locally heavy
rain because precipitable waters in excess of 2 inches will edge
onshore by Saturday afternoon. Low-level winds are not strong so any
TSTMS should remain below severe limits barring no enhanced low
level helicity. The National Hurricane Center will be sending out a
plane today to investigate the offshore system. Maximums both days
near average for this time of year, low and middle 80s. Minimums
will be slightly above overage due to clouds and abundant
moisture.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 AM Friday...Lots of uncertainty remains in the extended as
what could very well be Topical/Sub-tropical storm Bonnie drifts
across the area. Other than the GFS which is a clear outlier (00z/27
guidance) - the majority of the models develop a weak closed low
moving onshore in SC and then drifting slowly before lifting NE at
the start of the extended. The difference in the GFS vs the other
guidance is how the surface low interacts with a shortwave moving
through the Great Lakes and into New England. This shortwave is the
one currently across TX...and this should break down the ridge
enough to allow the surface low pressure to move NE and out of the
area mid-week around the offshore high. The GFS does not have this
happen and therefore spins the weak low across SC through all of
next week.

That being said...will favor a non GFS forecast for next week. This
suggests increasing rain and thunderstorm chances...mostly Mon/Tue
as the weak low meanders NE across the ILM CWA. The combination of
the weak low moving slowly overhead and the deep easterly tropical
fetch angling into the area will produce widespread showers and
thunderstorms early next week. Still uncertainty exists about QPF
due to the showery nature of the precip and weakening 850mb
wind/moist transport...but with PWATS around 2 inches there is at
least the potential for periods of heavy rainfall. Beyond
Tuesday...anticipating the slow departure of the remnants of the low
pressure...the area will remain unsettled but with at least somewhat
decreasing shower chances and warming temperatures as ridging begins
to blossom across the SE.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
As of 12Z...Kind of in a holding pattern for the next 24 hours until
low pressure moves near the coast by Saturday afternoon. Fairly
decent subsidence on the west side of low pressure...which should
keep skies fairly clear for much of the day. A southeast gradient
and resultant is expected this afternoon. Overnight...increasing
clouds in advance of the offshore low. Scattered showers will break
out toward the end of the forecast period.

Extended Outlook...OCNL MVFR in scattered to numerous showers,
isolated TSTMS this weekend. Otherwise expect VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 945 AM Thursday...Conditions remain benign over the waters
with seas of right around 2 ft and winds of less than 10 kts.
forecast good to go with no changes anticipated for the near term.
Previous discussion from this afternoon follows:

Another fine marine-weather day but waves will begin to grow
tonight as swell from an approaching tropical wave fans ashore,
reaching 3 to 4 feet every 8-9 seconds from the SE by daybreak
Saturday. As a result no advisory is expected through the near
term period, but showers will begin to increase in coverage
offshore, and waves will continue to grow in size into Saturday.
Light southerly winds this morning will become more onshore ESE-
ENE in the afternoon but no higher than 15 kt with seas holding
2-3 ft every 8-9 seconds.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 3 AM Friday...The weekend will not be ideal for offshore
boating ventures as elevated seas in SE swell and scattered to
numerous showers and isolated TSTMS will troll the waters. Seas 4
to 6 feet every 9 seconds accompanied by a moderate onshore chop
will characterize the sea- spectrum. The National Hurricane Center
is sending a plane out this afternoon to investigate the system
for tropical development and potential. Mariners should remain
closely briefed on the weather as there is a possibility a
`tropical storm watch` may be posted.

LONG TERM /MONDAY THROUGH TUESDAY/...
As of 300 AM Friday...Meandering low pressure will remain the
primary story this period as it moves slowly across or just inland
of the coastal waters. The gradient around this feature will be
weak...so wind speeds are forecast to be just around 10 kts...with a
S/SE or S/SW direction both days. Wave heights will be dependent
primarily on continuing 8 sec E swell from the weekend...with some 6
fters still possible Monday before falling to 3-4 ft Monday night
and Tuesday. Still some uncertainty into the track and strength of
this low pressure...which could impact this forecast
considerably...but attm it appears the worst of the marine
conditions may occur before this period.

&&

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

&&

$$

SYNOPSIS...JDW
NEAR TERM...MJC/REK
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...DL
MARINE...MJC/REK/JDW



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