884
FXUS61 KILN 180640
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
240 AM EDT Sat May 18 2024

.SYNOPSIS...
After the fog dissipates today, mainly quiet and seasonably warm
conditions are on tap. Cannot completely rule out a stray shower
or thunderstorm late afternoon through early evening, but most
spots should remain dry. Much above normal temperatures and
mainly dry conditions are expected for Sunday and Monday, with a
chance of showers and storms returning as early as Tuesday.
However, the next widespread chance for showers and storms is
likely to evolve midweek, with slightly cooler conditions for
the second half of the workweek.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Areas of fog, some dense, continue to expand about the ILN FA
early this morning, particularly near/S of the I-70 corridor,
with the greatest fog bank enveloping areas near the OH Rvr.
Visibility is being reduced to 1/4 mile or less at times in
these areas and expect that this will only continue to expand
through daybreak before lifting through the first few hours of
the daytime period. But until then, dense fog will prevail for
many spots S of I-70, so caution is encouraged if traveling
through about 13z-14z.

Temps have dipped into the upper 50s and lower 60s this morning,
but will rebound rather nicely once the fog/low stratus
lifts/scatters by late morning. Highs will top out a few degrees
either side of 80F this afternoon amidst some scattered
afternoon Cu. Cannot completely rule out a few spotty SHRA or
TSRA, especially beyond mid afternoon, although there`s really
not much in the way of forcing or lift to provide the nudge. Do
think that most spots remain dry today, but couldn`t really
reason going less than a 15 PoP given the potential for some
very spotty activity to sprout about late day, particularly near
I-70. But LL/deep-layer wind fields are incredibly weak, so
updraft strength/maintenance should be difficult to sustain.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Tranquil conditions are expected this evening/tonight once any
diurnally-driven spotty SHRA/TSRA activity wanes by about 02z.
Lows tonight dip into the upper 50s and lower 60s once again
amidst weak northerly sfc flow. Could see some fog develop in
area-river valleys and sheltered locales tonight, but the setup
for widespread fog development tonight appears to be less
favorable than is the case this morning.

Temps rebound nicely again on Sunday, topping out in the mid
80s with plentiful sunshine (and a few afternoon Cu) on tap.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
On Sunday evening, a narrow ridge of high pressure will extend from
the western Gulf Coast through the Ohio Valley, with an axis on a
southwest-to-northeast orientation. A surface high over the Great
Lakes will be moving off to the east, as the upper pattern shifts
into something a bit more progressive by Monday. Broader ridging
over the far southeastern CONUS will persist through the middle of
the week, but a more active WSW flow pattern will develop on the
periphery of the ridge, extending from the central plains through
the Ohio Valley.

Monday appears likely to be dry, with any forcing still upstream of
the area. By Tuesday, instability will be building into the region
from west to east, with deep-layer SSW flow and dewpoints getting
well into the 60s. However, forcing will still be mainly upstream of
the area, so convection will be limited -- though more likely to
occur in the northern and northwestern sections of the CWA, closer
to the forcing and further away from the stronger cap to the
southeast.

The most active stretch of the extended forecast will be some time
Tuesday night through Wednesday night. There is model agreement on a
compact upper low moving into the Lake Superior area, with an
associated cold front moving across the upper midwest and eventually
into the Ohio Valley. The timing forecast for the shortwave and the
surface front remain far from certain at this distance in the
forecast cycle. One notable change to recent model runs is further
displacement of the surface low from the Ohio Valley, which is
leading to a more southwest-to-northeast oriented frontal boundary.
This may not be as favorable from a forcing perspective, and winds
ahead of the front also appear rather veered (southwesterly) which
would limit directional shear if that were to verify. Nonetheless,
it is fair to say that instability and deep shear could support a
severe threat at some point in this time frame. A drier and cooler
air mass will follow the front to end the week, with very low
confidence on when the next progressive shortwave may move into the
area after Friday.

Monday and Tuesday will be the warmest days of the extended, with
highs possibly reaching the upper 80s on Tuesday. As convection and
a cold front move into the area, slightly cooler conditions are
expected for Wednesday and beyond.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
The earlier SHRA activity has waned locally, leaving in its
wake clearing skies amidst a very saturated/stagnant LL
environment. This is already allowing BR/FG to develop and
expand rather quickly, with VSBYs already trending to IFR/LIFR
for a few spots. Expect that the BR/FG will continue to expand
through daybreak, with the least favorable setup for central OH
sites of KCMH/KLCK where some lingering cloud cover may inhibit,
or at the very least delay, the onset of BR/FG development.
Elsewhere, expect LIFR/VLIFR VSBYs at the typical spots of
KLUK/KILN, with some IFR VSBYs eventually likely for KCVG/KDAY
as well closer to daybreak.

The BR/FG may evolve into a LIFR stratus deck/CIGs before
rapidly lifting to IFR, MVFR, and eventually VFR between about
13z-16z. SCT VFR Cu will prevail near/after 16z with a few
spotty SHRA/TSRA possible late afternoon into early evening.
Coverage of activity should be very spotty/ISO in nature, so
have kept terminals dry for now.

Light/VRB/calm winds will go more easterly and northeasterly
during the daytime before going back light/VRB/calm once again
toward the end of the period.

OUTLOOK...MVFR CIGs, along with thunderstorms, will be possible
Wednesday into Wednesday night.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ060>063-
     070>073-077>082-088.
KY...Dense Fog Advisory until 10 AM EDT this morning for KYZ089>100.
IN...Dense Fog Advisory until 10 AM EDT this morning for INZ050-058-
     059-066-073>075-080.

&&

$$
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...Hatzos
AVIATION...KC