423
FXUS61 KILN 162323
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
723 PM EDT Thu Jul 16 2026

.WHAT HAS CHANGED...
No significant changes

&&

.KEY MESSAGES...
1) Hot, humid, and hazy conditions continue.

2) Showers and thunderstorms are forecast to develop Friday and
continue into the weekend, bringing a risk for localized flash
flooding and gusty winds.

&&

.DISCUSSION...
KEY MESSAGE 1)

Mid level ridge axis situated northwest to southeast across the
region will sag slowly south tonight and break down/ weaken. As such,
a very moist airmass has begun to encroach into the Ohio Valley
region on Thursday. This has acted to raise Tds even more so than
yesterday, resulting in some very muggy conditions. Have continued
the Special Weather Statement for hot and humid conditions through
Thursday evening. CAMs still indicate some isolated thunderstorm
activity primarily south of I-70 today, so have kept a low end PoP in
the grids.

Wildfire smoke from the northern US/Canada will continue to wrap
through the larger flow and into the Ohio Valley. HRRR smoke modeling
suggests that near surface smoke will primarily remain across
northern Ohio today before percolating southward on Friday. It`s not
unheard of for temperatures to be impacted a couple of degrees from a
thick column of smoke, as insolation is inhibited, so have tweaked
daily highs down a couple degrees accordingly for Friday, though kept
Tds as is, given the moist airmass.

Even with the smoke and increasing cloud cover, muggy conditions are
expected to continue through the weekend with scattered
thunderstorms.

KEY MESSAGE 2)
Showers and thunderstorm chances are reintroduced to the forecast on
Friday and Saturday as midlevel flow becomes more northwesterly and
shortwaves move through the larger flow. As previously mentioned,
moisture from the Gulf will surge into the Ohio Valley, increasing
PWATs to 2+ inches, which is well above the 90% percentile and
nearing climatological maximums. This moist airmass will be present
both Friday and Saturday, allowing for a saturated column as well as
surface Tds in the low to mid 70s.

On Friday, the first weak shortwave will move through the flow,
sparking showers and thunderstorms Friday afternoon into late
evening. An instability gradient will exist from west to east, with
more robust instability building in from the west southwest.
Scattered thunderstorms are expected to develop beginning Friday
afternoon and continuing through the evening hours. Shear is nearly
non-existant but DCAPE will be over 900 J/kg and MLCAPE will 1500
J/kg+. Given that and the high PWATs, storm motions will be very slow
and water loaded storms may quickly collapse, producing instances of
gusty winds. Localized heavy rainfall may result in isolated flooding
issues.

A larger shortwave will then pivot through the flow Saturday into
Sunday, dragging a surface low pressure system through the northern
Great Lakes region. The associated cold front will sag into our area
Saturday afternoon into the overnight hours, bringing additional
thunderstorm chances.

Given the larger shortwave, around 30 knots of bulk shear will swing
through, which (while not overly robust) may be able to help support
more organized thunderstorm development and propagation. In addition
to this, instability looks to build in area wide with with various
guidance suggesting anywhere between 2000-3000 J/kg of SBCAPE
available during the late afternoon, getting pinched off as we head
into the evening and overnight. Main concerns right now are damaging
wind gusts with stronger storms and would not rule out some large
hail, especially during the afternoon hours.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Although some spotty SHRA may linger through the first hour or so of
the TAF period (especially near KLCK), mainly dry conditions are
expected through at least daybreak. Coverage of activity through 12z
is too limited to include in the fcst at this time.

VFR Cu will slowly wane in coverage with loss of daytime heating, but
may linger a bit. Nevertheless, still expecting some river valley BR
development and corresponding MVFR VSBY restriction at KLUK. Suppose
that IFR VSBY cannot be completely ruled out during the several
hours around daybreak at the site.

The other item of interest will be the infiltration of some near-
surface smoke from northern/eastern OH into parts of west-central and
central Ohio past 06z. The latest data suggests that surface-based
VSBY reductions due to smoke will be most pronounced between about
08z-16z, particularly at central OH sites of KCMH/KLCK where some
brief IFR VSBYs will be possible, particularly between about
12z-15z. As the sfc high pushes off to the E of the region by early
afternoon, the low-level wind flow will quickly become southerly and
eventually southwesterly, shunting the smoke back to the NE by 18z.

After 18z, the focus will shift to the expected development of SCT
to numerous SHRA/TSRA, initially for wrn sites of
KDAY/KCVG/KLUK/KILN. This activity will be disorganized in nature,
slowly drifting to the E later into the afternoon/evening. Some ISO
activity may eventually reach central OH sites of KCMH/KLCK late in
the period, but have opted to keep the sites dry for now given lack
of confidence of eastward extent of the best coverage. Have
maintained PROB30 for other sites, which may require a TEMPO at some
point once confidence increases enough in a more focused time window
for potential impact. Sudden reductions in VSBY and changes in wind
speed/direction can be expected in the strongest cells.

Light/VRB winds early in the period will go more out of the NE by
09z, eventually go easterly by 12z and southerly by 15z. SW winds
around 8-10kts are expected past 18z. SCT/BKN VFR Cu is expected
area-wide by/past 18z.

OUTLOOK...Thunderstorms possible Saturday afternoon into the
overnight.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Air Quality Alert until midnight EDT Friday night for OHZ026-034-
     035-042>046-051>056-060>065-070>074-077>082-088.
KY...Air Quality Alert until midnight EDT Friday night for KYZ091>093.
IN...Air Quality Alert from midnight tonight to midnight EDT Friday
     night for INZ050-058-059-066.
     Air Quality Alert until midnight EDT Friday night for INZ074.

&&

$$

DISCUSSION...Aiena
AVIATION...KC