959
FXUS61 KILN 121018
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
618 AM EDT Mon May 12 2025

.SYNOPSIS...
An area of upper level low pressure will move northeast through the
region from today through Wednesday. This system will bring showers
and storms to the area on occasion. Warmer temperatures are expected
by the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A closed upper low is currently located over the lower Mississippi
Valley. This low is beginning a slow journey to the northeast, where
it will eventually traverse the Ohio Valley over the course of the
next couple days. The main story for the ILN CWA today will be some
bands or clusters of showers (with embedded thunderstorms) moving
northward through the region. This appears to be associated with a
surge of theta-e at 850mb-700mb, well ahead of the closed low. There
is some dry air to contend with initially, so PoPs will increase more
significantly after 16Z, with some diurnal component to the
development expected as well. Forecast soundings today suggest
profiles will be moist, with poor lapse rates, but precipitable water
values somewhere around 1.3 to 1.5 inches. Strong storms are
unlikely in this sort of environment, but some heavy rain will be
possible. While steering flow is weak, there should be enough
northward movement to keep flooding concerns isolated to instances of
training or repeated storms over the same area.

Clouds and afternoon rain will keep temperatures cooler than
yesterday, with highs in the upper 60s to lower 70s.

&&

.SHORT TERM /TUESDAY/...
A diurnal minimum in precipitation is expected Monday night, so PoPs
will be kept limited. A few isolated showers will still be possible.

Showers and storms are expected again on Tuesday. Compared to Monday,
the approaching upper low will be closer to the area -- in a more
favorable position for broad, deep-layer forcing over the ILN CWA.
This means that both the coverage and intensity of storms could be a
little greater on Tuesday than on Monday, and slightly warmer
boundary layer conditions will support a little more instability as
well. With that said, it is interesting that CAM projections for
Tuesday are very tied to the diurnal cycle -- keeping the forecast
area mainly dry until after 17Z. Thus, PoPs have been heavily focused
on peak diurnal timing for Tuesday.

The overall situation for Tuesday in terms of hazards looks similar
to Monday, with perhaps a little bit of a greater chance for heavy
rain and isolated flooding. Precipitable water values will be
similar, but slightly weaker flow aloft will mean storm motions will
be a little slower. Overall, the concern for flooding should still
remain isolated. The severe threat, once again, looks minimal.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The closed low is directly over the local area to start the long
term. Lingering showers and thunderstorms are likely ongoing in the
evening hours, before gradual weakening and dissipation takes place
overnight. Locally heavy downpours leading to rainfall amounts of 1-
2+ inches leading to localized flooding concerns is the primary
threat expected with any thunderstorms.

The closed low begins to interact with the trough digging into the
central and northern Plains, causing it to shift northeastward
through the day on Wednesday. A diurnally driven increase of showers
and thunderstorms is forecast during the afternoon with the greatest
coverage across the Scioto River Valley region due to the trough axis
shifting northeast.

Temperatures are much warmer Thursday (mid 80s) with mid-level
ridging building over the Ohio Valley. Heights begin to fall during
the evening, due to the trough shifting into the region. These height
falls may be enough to trigger elevated convection late Thursday
evening and night. Thermodynamically, mid-level lapse rates are very
steep due to the EML shifting eastward into the Ohio Valley, however,
a capping inversion likely limits the potential for widespread
thunderstorms. Still, if thunderstorms do form, strong shear and
steep mid-level lapse rates would support the possibility for large
hail.

Through the overnight into Friday morning, a cold front will attempt
to move through the area, but there are at least some indications it
may stall with a shortwave trough ejecting eastward out of the
central Plains. This shortwave results in another round of showers
and thunderstorms Friday afternoon and evening. In these types of
situations, the instability pool is typically favored south of the
local area due to tendency for convectively driven cold-pools to move
southward. Ultimately, it will depend on the strength of the cold
front as it moves through the area Friday morning.

Saturday and Sunday feature mostly zonal jet stream flow as trough
passes to the north of the region. Lower-end PoPs/t-storm chances
remains but are focused to southern areas as a weak system propagates
along the northern periphery of a ridge over the Gulf Coast. At this
time, temperatures are likely a few degrees cooler during the
weekend in comparison to Thursday and Friday.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
VFR conditions are expected for the start of the TAF period, with
ESE winds of 10 knots or less.

Chances for rain will gradually increase today. A few very light
showers have already begun to move into the area, but with little
impact to aviation expected during the morning. Initially, these
showers will be scattered and light. However, some heavier showers
(and possibly thunderstorms) will occur during the afternoon. Most of
the showers and storms will dissipate after 23Z, with just a low-end
chance of some light showers through the overnight hours. The TAFs
will be kept dry after 23Z.

In addition, MVFR ceilings will also move into the area from south
to north this afternoon. Some IFR ceilings are possible later in the
evening, and this has been included for the Columbus and Dayton TAF
sites, but confidence is a little lower for the other airports.

OUTLOOK...Thunderstorms are possible at times through Wednesday, then
again on Thursday night. MVFR ceilings are expected Tuesday morning,
and then possible again Wednesday morning.

&&

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

&&

$$

SYNOPSIS...Hatzos
NEAR TERM...Hatzos
SHORT TERM...Hatzos
LONG TERM...McGinnis
AVIATION...Hatzos