Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 261446
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1046 AM EDT Thu Apr 26 2018

.SYNOPSIS...
Fair conditions today will be followed by showers and a few
thunderstorms late tonight and early Friday, as a low pressure
system tracks from northern Georgia to southern Virginia
overnight. A stalled front inland, Friday and Saturday, will be
kicked offshore by Canadian high pressure before sunrise Sunday.
This will usher in a drying trend, with slight cooling Sunday
and Monday, followed by warming through mid week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1030 AM Thursday...Weak cold front has pushed offshore and
surface winds will gradually veer from NE to E to SE today. High
res guidance indicating a chance for some sea breeze showers
this aftn, and forecast soundings suggest some instability near
the surface, but a significant subsident cap near 700mb should
prevent this and have kept POP silent through the aftn. More
significant shower/tstm chances approach this evening, and that
is discussed below in the previous discussion:

As of 322 AM Thursday...Weak cold front moves across the area
around  daybreak, then stalls after moving off the coast.
Surface low developing over the southeast this morning, under a
5h shortwave trough moving through the large scale 5h trough,
moves east today, lifting the front back into the area as a warm
front this afternoon. Forecast soundings do show some surface
based instability during the day today, but weak mid-level
capping may prevent any showers until the environment becomes
more favorable late in the day and into the evening.

Approaching shortwave this evening increases divergence aloft
and  provides an increase in deep moisture. Mid-level lapse
rates steepen considerably late in the day with convection
seeming more likely, especially across portions of SC. Timing is
the biggest issue. The dynamics associated with the wave arrive
very late in the day, at which time diurnal instability will
have peaked and be starting to trend down. So while a few strong
updrafts cannot be ruled out, mainly across inland SC, the
potential for severe weather may be minimalized by the late
timing. SPC continues to carry a small area of marginal in the
day 1 outlook which covers most of Darlington and brushes
Florence and Marlboro counties. However, confidence in this is
low. Any convection that is able to persist overnight will be on
the weak side and will start winding down during the early
morning hours.

Varying amounts of cloud cover today, increasing in the late
morning  and afternoon due to heating, will keep highs confined
to the mid to upper 70s. Some areas across inland SC could hit
80 with an extended period of sunshine. Cloud cover coupled with
modest boundary layer winds will keep lows well above climo
overnight, mid to upper 50s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 322 AM Thursday...`Devolving` low complex dawn Friday is
over north-central NC, lifting north, swept then absorbed with
a northern stream low over the Great Lakes, leaving a dangling,
quasi-stationary frontal boundary waffling along the coastal
interior. Despite the shallow nature of moisture in vertical
profiles, lapse rates associated with the cool pool will prompt
moderate cumulus Friday afternoon, possibly isolated showers,
albeit low topped, capped by arid WSW aloft. This, diurnally
favored around peak heating and in proximity to the surface
boundary locality.

Saturday setting up to be a nice sunny and warm day, with 80s in
the cards, in a weak but impactful, dry, warm sector. FROPA late
Saturday night, offshore prior to daybreak Sunday will have a
passage without much consequence, aside from winds becoming N-NE
and slightly cooler min-T heading into early Sunday, middle 50s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 325 PM Wednesday...Cool high pressure at the surface
through the remainder of the weekend. Although temperatures will
be cooler than normal Sunday and Monday the weather will be
quite tolerable with highs generally in the lower 70s with clear
skies. A warm-up is expected by mid-week as the high moves off
the coast with as return flow develops.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
As of 12Z...VFR with cigs 3.5-10k this TAF valid period. Clouds
may be scattered at times at the coastal terminals. There could
be isolated showers this afternoon just inland of the coastal
terminals, but have omitted mention from all TAFs attm. Showers
will be more likely this evening at KFLO/KLBT and coastal
terminals overnight. Winds will be light this morning becoming
southeast to south by this afternoon.

Extended outlook...VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 322 AM Thursday...Have allowed NC Exercise Caution
headline to expire at 0300 with seas continuing to diminish.
Weak cold front moves off the coast this morning then stalls
just east of the waters. Front is quick to move back inland as a
warm front during the day with light and variable winds in the
morning becoming southeast this afternoon. Speeds stay under 10
kt into the evening before weak low approaching from the
southwest slowly increases the gradient. Southerly flow
increases to 10 to 15 kt overnight, becoming southwest late in
the period. Seas 3 to 4 ft this morning will slowly decrease
during the day, dropping to 2 to 3 ft by the afternoon. Slight
increase in winds overnight will push seas back to 3 to 4 ft
late in the period.


SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 322 AM Thursday...This will be a manageable marine
period, with Friday the breeziest and bumpiest day, SW winds
gusting between 20 and 25 kt in the afternoon inshore, aided by
the sea breeze circulation enhancement. Then another gusty
period Saturday night, winds veering to WSW-W, gusting to 20 kt
ahead of an approaching cold front. The front will bring a wind
shift to north before first light of Sunday, 15 kt or less. Seas
3-4 ft this period, so no Advisories appear to be needed. Seas
will be a mix of SW wind waves every 6 seconds, and SE waves
swell every 9 seconds. Isolated marine showers possible Friday
but drier Saturday.

LONG TERM /SUNDAY THROUGH MONDAY/...
As of 325 PM Wednesday...High pressure builds in from the
northwest through Sunday night. The high will build over the
waters during Monday. Northerly winds in the wake of the front
Sunday morning. Variable flow is expected Monday as the high
builds overhead. Seas of 3 to 4 ft are possible during Sunday,
otherwise they will subside to around 2 ft Monday with a weak
pressure gradient overhead.

&&

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

&&

$$
SYNOPSIS...MJC
NEAR TERM...III/JDW
SHORT TERM...MJC
LONG TERM...SRP
AVIATION...MRR
MARINE...



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