Area Forecast Discussion
Issued by NWS Wilmington, NC

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455
FXUS62 KILM 231915
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
315 PM EDT Fri Jun 23 2017

.SYNOPSIS...
Deep moisture will become increasingly squeezed by an
approaching cold front through Sunday morning. Some drier air
should move in later Sunday. More seasonable weather will return
next week with isolated mainly afternoon thunderstorms.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 300 PM Friday...The KLTX 88D continues to be relatively echo
free across the ILM CWA. The relatively pinned sea breeze is
identifiable to a degree via the KLTX 88D. From hence on out thru
sunset, would not be surprised for isolated convection to break out
especially across the ILM SC CWA where the NVA aloft is not as
strong or prevalent like across the ILM NC CWA. Will only carry
isolated to widely scattered 15-25 POPs thru sunset followed by no
POPs for the night-time period.

Relatively oppressive, heat-wise, with sfc dewpoints in the mid and
upper 70s and temps around 90 this aftn and evening. Only saving
grace, is that the sfc winds will stay active this aftn thru
tonight, and likely continue thruout the day on Saturday. The sfc pg
will remain tightened thruout this period and will only show some
signs of relaxing well inland during late Sat due to the approaching
frontal boundary. With some decent forcing now avbl, will ramp POPS
up big-time during Sat aftn which will mesh nicely with the even
higher POPs slated for Sat night. With PWS back well over 2 inches
by Sat aftn, heavy rainfall will be the primary tstorm parameter to
affect the ILM CWA. If enough precip loading occurs, then wet
microbursts may become an issue.

As for max/min temps, just stayed with the meshing of the various
Model MOS Guidance which gives widespread 70s for tonights lows and
lower 90s for Sat highs and only mid-upper 80s along the immediate
coast given local SSTS are in the 80-85 range now.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 3 PM Friday...Slow moving cold front will move into the region
as the period begins with showers and thunderstorms likely ongoing.
There will be an abundance of deep moisture for much of the period.
Precipitable water values rise to almost 2.25 inches Sat night into
Sun. Surface based instability will be lacking Sat night but
convergence along the weak surface boundary as well as the presence
of outflows in a moist, conditionally unstable environment should
maintain at least some nocturnal convection. In addition there will
be a little bit of shortwave energy approaching from the southwest
which should lead to an increase in PVA after midnight. Storm
coverage will be highest along the coast but everywhere will have at
least a chance of showers and thunderstorms overnight.

Front and deep moisture remain in the area Sun, although the 5h
trough and drier air to the northwest start moving into northwestern
portions of the forecast area later in the day. This will likely
curtail convection in these areas but closer to the coast coverage
will be higher. There will be another in a stream of shortwaves
within the vorticity channel that spreads some PVA into the area on
Sun. Combined with surface heating this should light off another
round of convection. Storm motion will be around 15 kt which should
prevent any 1 storm from posing a flooding risk however, training
storms could pose a problem. Storms that develop will be very
efficient at producing rainfall having warm cloud layers on the
order of 13k-14k ft deep. While severe weather is unlikely given
vertical profiles/limited shear a wet microburst from a storm cannot
be ruled out. Still the main concern Sun will be flooding and not
strong to severe storms.

Dry air spreads in from the northwest late Sun and Sun night with
most if not all convection shifting off the coast by midnight. Push
of dry air is significant with pwats forecast to drop over an inch
from 18Z Sun to 06Z Sun night. Some convection just off the coast
cannot be ruled out late Sun night but wind direction/storm motion
would tend to push any activity off the coast and thus pop after
midnight is unlikely. Temperatures Sat night will run well above
climo while temps Sun and Sun night will be near climo.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...Mid level troughiness Monday sharpens through
Tuesday or Wednesday. Initially this will be a dry westerly flow
Monday but a slightly more moisture-laden WSW flow Tuesday. Daytime
temperatures will be held a bit below climatology through this time
frame. The trough axis appears to swing through on Wednesday
bringing a more decided drying. The rest of the period will be
characterized by a building upper ridge over the Southeast and
Bahamas. This will mark a transition back towards seasonable
temperatures and isolated convection mainly during the diurnal
maximum.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 18Z...For the remainder of this aftn and evening, NVA and
Subsidence aloft will keep convection from firing and/or
developing. The pinned sea breeze may have enough forcing to
overcome the subsidence aloft and result in isolated convection.
Once the days insolation ceases, so will the threat for any
tstrm formation. Have indicated thunderstorm threat by midday
Sat as upper levels become more conducive for convection
chances ie. no longer debilitating NVA present overhead.

The sfc pg will remain tightened this aftn thru tonight and
well into daytime Sat. The inland terminals will see SW-WSW
10g15 kt thru this period with the exception of possibly going
SSW 10g15kt this evening. The coastal terminals will run SSW-SW
10-15g20+ kt this aftn thru tonight and likely continuing thru
midday Sat.

Extended Outlook...Local MVFR/IFR conditions are possible in
thunderstorms Saturday afternoon through Sunday afternoon.
Thunderstorms are anticipated to be most widespread Saturday
evening thru the overnight.

&&

.MARINE...

NEAR TERM /THROUGH Saturday/...

As of 300 PM Friday...Marine conditions will continue to erode
thruout this period with SCEC conditions developing this evening and
further eroding to SCA conditions after midnight tonight. This a
result of the sfc pg, that continues to tighten as a sfc cold front
drops southeast into the western Carolinas late tonight. At the same
time, the Cindy remnants, will move along this cold front, reaching
the DELMARVA coast Sat morning. Wind directions will run SSW-SW at
10 to 20 kt speeds thru this evening and veer slightly to SW-WSW at
15 to 25 kt speeds toward daybreak Sat and continue thru daylight
Sat and into Sat Evening. Wind driven waves at 3 to 5 second periods
will dominate the significant seas and should peak in the 3 to 6
foot range with a few 7 footers off Cape Fear and Romain
respectively. Moderate to strong longshore currents will become
apparent, especially south of Cape Fear to Murrells Inlet.


SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...

As of 300 PM Friday...As of 3 PM Friday... Will continue to
carry small craft advisory headline Sat night but hazard will be
marginal at best. Front moving into the area combined with
Bermuda High will tighten the gradient and speeds will increase
to a solid 20 kt. Sustained 25 kt may be hard to come by and
highest seas may end up closer to 5 ft than 6 ft but given at
least some uncertainty with respect to the strength of the
surface features will maintain the headline unchanged. Bermuda
High remains in control Sun with southwest winds continuing,
though in a weaker state as the front slowly moves closer and
the high retreats east. Winds and seas will gradually decrease
Sun into Sun night with flow becoming offshore late in the
period as the surface boundary slips east of the waters.


LONG TERM /MONDAY THROUGH WEDNESDAY/...

As of 300 PM Friday...Not a typical summertime pattern in place for
most of the period. A sharpening mid level trough will be in place.
A series of weak surface boundaries may come through but with only
very minor fluctuations of wind direction, though a northerly
component will dominate. Wind speeds never really look to exceed
10kt by much though a few higher gusts will be possible. Seas will
average 2 to occasionally 3 ft with near shore wave shadowing much
more pronounced than usual this time of year where SW winds much
more common.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Beach Hazards Statement until 8 PM EDT this evening for SCZ054-
     056.
NC...Beach Hazards Statement until 8 PM EDT this evening for NCZ106-
     108.
MARINE...Small Craft Advisory from midnight tonight to 6 AM EDT Sunday
     for AMZ250-252-254-256.

&&

$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...III
AVIATION...DCH



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