Area Forecast Discussion
Issued by NWS Wilmington, NC-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KILM 261144
Area Forecast Discussion
National Weather Service Wilmington NC
744 AM EDT THU MAY 26 2016
Summer-like warmth will prevail today and Friday as an upper
ridge holds across the region. An area of low pressure organizing
near the Bahamas will drift west towards the southeast United
States coast this weekend. This slow moving feature will waver in
the vicinity through early next week bringing a good chance for
showers and thunderstorms.
.NEAR TERM /THROUGH TONIGHT/...
As of 620 AM Thursday...Movies from space on the vapor channel
show a pronounced and parched upper ridge maintaining a grip on
the eastern Carolinas, as tenuous cirrus spills southward. It does
not appear this slight veil of ice crystals will impact warm
maximum temperatures today of middle and upper 80s, but a few
sundogs are not out of the question this morning. Radar will begin
sensing the presence of sea breeze convergence around midday along
the coastal interior before lifting northward and losing identity
as the synoptic flow begins to match its vector. This alignment
will bring MAX-T `time of-occurrence` earlier in the day when
compared to deeper inland. Dryness aloft wins out, no mentionable
pop values today through tonight. Mild S-SSW winds overnight will
slow the late night temperatures drops, settling at 64-68 degrees
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 3 AM Thursday...Prime headline this period is arrival of
the leading edge of an elevated precipitable water surge onto the
Carolina coasts Friday night. This will set a trend of rising
dewpoints and layered absolute humidity. A continued trend of
deepening moisture through Saturday will deliver precipitable
water values near 2 inches and dewpoints around 70. By this time a
surface low will be positioned offshore somewhere between JAX and
CHS. One discernible consensus among the GFS/ECMWF/NAM solutions
is that despite exactly where...a slow drift landward toward the
NW is portrayed for Saturday into Sunday. Even given the abundant
vapor, forcing and details precludes likely or wash- out pops and
values were held in a 35-50 percent range Saturday. MAX-T Saturday
around 3-6 degrees cooler than Friday due to clouds and moisture,
but because of the elevated humidity Saturday, heat indices are
similar both days.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 AM Thursday...The forecast challenge for the extended
continues to be exclusively about a potential tropical/sub-tropical
low which will meander in the vicinity. Guidance remains in very
good agreement that a low pressure will be off the southeast coast
Saturday and then waver through the middle of next week - but any
fine details are still very far from being ironed out.
That being said...it does appear an unsettled period is becoming
more certain...although a 3-4 day washout is not expected. The
surface low will likely track WSW Sunday as the western Atlantic
ridge holds firm...before finally...and very slowly...moving NNE
through the remainder of the period. The steering flow is
exceedingly weak until a mid-level trough digs across the northern
tier states causing the ridge to open up and allowing the system to
move northward...but that may not happen until Tue. This suggests
all 4 days will be partly cloudy with periods of heavy rainfall
and thunderstorms in an environment characterized by increasing
PWATs on deep and moist easterly flow.
Still...timing when the heaviest rainfall is likely is challenging.
Sunday may actually be the quietest day as some subsidence moves
overhead as shown on time-heights and the low stays pretty far to
the south of the ILM CWA. As it starts to lift north...especially
Mon/Tue...850mb wind u-vectors reach -3 SD`s which combined with the
approach of the low will favor increasingly heavy rainfall
chances...and will try to show at least somewhat better certainty in
rainfall then. Even so...Sun/Wed will also likely feature periods of
showers/tstms in the moist/unstable environment...but the coverage
may be less on these days. Winds will likely not be too much of a
factor regardless of whether the system acquires tropical
characteristics as the STRONGEST of the guidance keeps min SLP well
above 1000mb with a weak PG otherwise. So heavy rainfall...as well
as strong rip currents...will be the primary hazards in the
timeframe surrounding Memorial Day.
It is important to note that all of this is dependent on a system
that has yet to develop so changes can and will likely occur. Once
the system begins to organize the finer details will become more
Temps will be warm but likely below climo due to clouds and
rainfall...but breaks would allow for short duration heating and
will show highs just below guidance...with lows struggling to fall
much below 70 each night.
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --As of 12Z...VFR this morning with generally scattered mid clouds
around 8k and thin high clouds. Patchy MVFR BR is occurring at the
After morning BR quickly burns off around 12Z, there is high
confidence VFR will continue through this evening. SW winds will
become S-SSW as the morning progresses, increasing to 12 kt by this
afternoon, highest at the coastal terminals. Scattered VFR level
cumulus will develop mid morning to late afternoon.
Winds decrease to light and variable this evening through overnight
with generally scattered skies. There is increasing confidence of
more widespread BR and lower vsbys towards the end of the TAF valid
period, but will address in later TAF issuance`s.
Extended Outlook...MVFR possible in scattered to numerous showers,
isolated TSTMS this weekend. Otherwise expect VFR.
-- End Changed Discussion --
-- Changed Discussion --NEAR TERM /THROUGH TONIGHT/...
As of 620 AM Thursday...Cooperative marine conditions today and
tonight as a high pressure cell off Cape Fear becomes absorbed by
a broader Bermuda anti-cyclonic circulation. This will result in
SW winds 10 kt becoming S 15 kt this afternoon, with a few higher
inshore gusts during the heart of the sea breeze middle to late
afternoon. Seas will be a composite of SE waves 2 FT every 8
seconds and a light to moderate S-SW chop. No TSTMS or VSBY
restrictions expected today through tonight.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 3 AM Thursday...Marine conditions will become more
challenging into the weekend as seas build due to growing wave
energy from the ESE in dominant periods of 8-9 seconds. An
advisory is not out of the question by Saturday as wave heights
approach 6 feet. Showers and isolated TSTMS can be expected
beginning Friday night and mariners should get a check on
conditions before heading out this holiday weekend, including a
look at radar trends. E winds 10 kt Friday will ramp up to NE 15
kt gusts to 20 kt Friday night into Saturday. The National
Hurricane Center is monitoring low pressure from the Bahamas for
potential development into the weekend, please stay tuned.
LONG TERM /SUNDAY THROUGH MONDAY/...
As of 300 AM Thursday...Marine conditions will be significantly
dependent on a low pressure system progged to move out of the
Bahamas and towards the coast this weekend. Guidance still differs
on the exact timing...placement...and strength of this
feature...but it is most likely a weak low pressure will move
across the coastal waters Sunday and Monday. Although the low
pressure will be weak...prolonged easterly fetch will build a long
period swell to 4- 7ft at 8 sec...creating seas of 3-5 ft...with 6
footers possible. Most of the contribution to the sea spectrum
will be from this swell...as winds are forecast to remain rather
light...from the E/SE at 10-15 kts...barring any unforeseen
strengthening of the low pressure.
-- End Changed Discussion --