375
FXUS61 KILN 150642
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
242 AM EDT Tue Sep 15 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...
1) Warm and humid conditions move in on Tuesday, with an initial
chance of storms on Tuesday night.

2) Heat and humidity continue through the week, with occasional
chances for storms through the forecast period.

&&

.DISCUSSION...

KEY MESSAGE 1)

Surface high pressure is drifting off the east coast. Meanwhile, a
closed mid-level high is setting up over the southeastern states.
This will result in a pattern change and deep-layer theta-e advection
coming into the Ohio Valley starting today. This change in air mass
will result in highs in the mid 80s to lower 90s, and dewpoints
reaching the upper 60s to around 70. Not out of the question that
head indices could briefly approach 100 in the far southwestern ILN
CWA.

While an initial shortwave today will remain well north of the
region, a frontal zone will set up over the Great Lakes, eventually
leading to increasing precipitation chances across the ILN forecast
area. For tonight into Wednesday morning, the convective forecast for
the ILN CWA is not particularly high confidence. Storms are expected
to initiate over Illinois and northern Indiana during the evening,
moving east toward the northwestern corner of the ILN CWA in the late
evening through the overnight hours. The SPC Day 1 MRGL risk area
indicates the area where this may occur. It is not entirely sure if
the storms will hold together -- some CAMs are quite spotty with
coverage. If they do, while parameters are not overly impressive,
there appears to be just enough CAPE and shear to support a marginal
severe threat.

KEY MESSAGE 2)

Most of the rest of the week will be characterized by high theta-e
values (with heat and humidity) on the northern periphery of the
ridge, with convective chances initiating from the frontal zone on
the northern edge of the warm sector. Timing on convective chances
remains somewhat uncertain, as antecedent convection may play a role,
as will fast-moving shortwaves moving through the westerly upper
flow.

Although convection could disrupt the temperature forecast, as of now
it appears both Wednesday and Thursday will feature highs in the mid
80s to lower 90s. With dewpoints getting into the lower 70s, some
areas in the southern half of the forecast area may approach heat
advisory criteria (100 degree heat indices).

As of now, it appears heavy rain will be the main convective threat.
Shear will be marginal, though a strong storm or two could not be
totally discounted given the expected instability (SBCAPE of
1000-2000 J/kg). Rather, it will be the potential for repeated rounds
of storms that create greater concern for flooding -- especially in
an environment with precipitable water values of around 2 inches.

Might have some additional storm chances on Friday and into the
weekend, but confidence in the forecast decreases considerably once
the ridge begins to break down. Slightly cooler temperatures look
likely for Friday, Saturday, and Sunday, compared to the middle of
the week.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR conditions are expected through the TAF period, with the
exception of some fog at KLUK.

Winds today will be out of the SSW, generally 10 knots or less. High
and mid clouds will thicken up during the overnight into early
Wednesday morning. As of now, it looks like precipitation chances
will remain outside of the TAF sites through the valid forecast
period.

OUTLOOK...Thunderstorms are possible in some locations at times from
Wednesday through Friday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$

DISCUSSION...Hatzos
AVIATION...Hatzos