731
FXUS62 KILM 122012
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
412 PM EDT Sun May 12 2024

.SYNOPSIS...
Dry weather continues through Monday. High rain chances arrive
for Tuesday through Wednesday with an approaching storm system.
Dry weather and weak high pressure returns for Thursday and
Thursday night before rain chances return for Friday and beyond
with the next storm system.

&&

.NEAR TERM /THROUGH MONDAY/...
High pressure settles overhead this evening bringing calm winds and
clear skies. Weak return flow pushes inland early this evening as NW
winds relax. This additional surface moisture advection could lead
to a better chance of ground fog along the Grand Strand overnight.
Radiational cooling overnight will bring temperatures in the low 50s
with a few of our typical cold spots dropping into the upper 40s.
Swamps and low lying areas could see patchy ground fog inland as
well.

High pressure slides offshore throughout the day and southeasterly
winds become reestablished across the region. An ejecting shortwave
to our south and west will bring increasing upper level cloud cover.
Increased low level moisture advection will bring an afternoon
cumulus deck and within this deck, some afternoon showers will
develop across the southern Pee Dee through early evening. Showers
will be light initially with the best lift and heaviest precip
arriving after sunset. Highs in the lower 80s due to clouds and
onshore flow.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
The approach of a closed low from the central plains states will
send multiple shortwaves across the area during this period,
which should combine with increasing deep-layer moisture to
produce considerable rainfall totals by Wednesday morning,
particularly near the coast. With surface high pressure
offshore at the start of the period, increasing moisture aloft
and isentropic ascent over a warm front will yield
lowering/thickening clouds and perhaps some scattered light
showers during Monday night. As better forcing for ascent
arrives attendant to a lead shortwave in tandem with anomalous
pwats exceeding 1.75" (reaching or exceeding the 99th percentile
for this time of year), more widespread rain is expected to
overspread the region on Tuesday morning. With increasing
elevated instability as the warm front nears, convective
elements may enhance rainfall rates, leading to locally heavy
rainfall until the warm front lifts through, which is progged to
occur during the afternoon. Although the probability is low due
to showers and abundant cloud cover through most or all of the
daylight hours, a marginal risk for severe weather is outlooked
for most of our SC zones on Tuesday as there will be plenty of
wind shear available, but the limiting factor will be whether
much surface-based destabilization can occur.

With another shortwave hot on the heels of the first one, expect
showers and at least isolated thunderstorms to continue
affecting the area from Tuesday evening into the night without
much of a break in between. However, as this second shortwave
passes overhead and a surface cold front slides through from the
west, expect shower coverage to decrease considerably during
the latter half of Tuesday night.

Temperatures will be limited by thick cloud cover and shower
activity with advection primarily driving temperature changes.
Morning lows on Tuesday should fall into the middle 60s before
rebounding into the mid-upper 70s, warmest south. With only weak
cool advection arriving on WSWrly low-level flow behind the cold
front, morning lows on Wednesday should end up in the mid-upper
60s, mostly depending on how low dewpoints go behind the front.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
With the cold core associated with the closed mid-level low
tracking overhead on Wednesday, lapse rates will steepen and
should help to yield weak to moderate instability during the
afternoon, given enough surface heating occurs. With 30-40 kts
of effective shear in play and up to around 1000 J/kg of DCAPE
shown in forecast soundings, the severe weather risk is
certainly not zero. The key question is whether any organized
convection will come to fruition as multiple impulses rotating
about the low will likely yield scattered to perhaps widespread
shower activity, thereby keeping surface-based instability low.
Even if organized convection does not occur, showers may contain
gusty winds and small hail as wet-bulb zero heights fall
throughout the day. Highs should reach the middle 80s assuming
the cold core remains just far enough north to prevent
widespread cloudiness.

A second cold front is expected to drop southward as the mid-
level low and its associated surface reflection move offshore
over Wednesday night. Ridging quickly builds in and dry weather
ensues for Thursday and Thursday night before another collection
of shortwaves and vorticity impulses bring wet weather for the
weekend, although confidence in the timing and evolution of
these shortwaves is rather low at this time. Thus, PoPs for
Friday afternoon through Saturday are largely held in the 40-50%
range for now. Of course, temperatures will depend on the final
outcome of these shortwaves, but overall highs are expected to
reach the low-mid 80s from Thursday onward with morning lows in
the middle 60s, both of which are slightly above-normal.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
VFR. Sea breeze developing along the Grand Strand may bring more
southerly wind directions this afternoon as high pressure
settles overhead. Calm winds and clear skies overnight. Dew
points mixed into the mid 40s today, so most areas should stay
fog-free, however some of our radiative cold spots may see some
shallow morning ground fog. Keeping terminals VFR with lowest
confidence at CRE. VFR cumulus develops tomorrow afternoon and
high clouds begin to overspread the area. Flight restrictions
possible late tomorrow afternoon into tomorrow evening with
shower chances increasing.

Extended Outlook... Widespread VFR through Monday afternoon.
Flight restrictions may occur Monday night into Tuesday with the
next weather system moving in. Improving conditions into
Thursday. Another system approaches the area for next weekend.

&&

.MARINE...
Through Monday... High pressure overhead this evening will gradually
push offshore overnight. Light and variable winds will become SE
tomorrow morning. Winds increase to 10-15 knots during the afternoon
ahead of an ejecting shortwave from the Southeastern US. Showers
will develop ahead of this disturbance late tomorrow afternoon,
primarily in the SC nearshore waters. Showers and storms move
northward into tomorrow evening. Seas 1-2 feet.

Monday night through Friday:
A complex low pressure system will send a warm front through on
Tuesday with SSE flow turning to SSW behind it during the day.
Seas rapidly increase from 2 ft early in the period to 6+ ft
around midday Tuesday with wind gusts also peaking around 25
kts. Thus, SCA conditions are expected from midday Tuesday
through Tuesday night with conditions subsiding below SCA
criteria around midday Wednesday. A cold frontal passage early
on Wednesday will veer winds to WSWrly with gusts possibly
scraping 25 kts and seas hovering around 4-5 ft during the
afternoon, so while an SCA is not likely by definition,
conditions will be close to criteria. A second cold front is
expected to drop in from the north on Wednesday night into
Thursday morning with winds veering to northwesterly and
subsiding through the day while seas fall to around 2-3 ft. Weak
high pressure briefly takes control for Thursday night into
Friday, with variable flow at or below 10 kts ending up at
southeasterly ahead of the next system poised to affect the area
over the weekend.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Coastal Flood Advisory from 1 AM to 4 AM EDT Monday for NCZ107.
SC...None.
MARINE...None.

&&

$$

SYNOPSIS...ILM
NEAR TERM...21
SHORT TERM...ABW
LONG TERM...ABW
AVIATION...21
MARINE...21/ABW