855
FXUS61 KILN 241910
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
310 PM EDT Tue Sep 24 2024

.SYNOPSIS...
A wave of low pressure will bring showers and thunderstorms to
the Ohio Valley today. An upper level low and remnants of
Tropical Cyclone Helene provides chances of rainfall through
the week and into the weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Severe Update:
Severe Thunderstorm Watch has been issued for a portion of the
area until 8 pm. Over the last few hours, enough clearing has
allowed for temperatures in northern Kentucky and southwest Ohio
to climb into the upper 70s. As better synoptic lift arrives
this afternoon, thunderstorms coverage is expected to continue
increasing across the watch area, with the severe threat focused
on the potential for damaging winds and large hail. Can`t rule
out a tornado or two where conditions come together to support
it. This briefly occurred northeast of Louisville, KY, but the
rotation did not persist.

Outside the watch area, locations across eastern Indiana and
west-central Ohio will still experience thunderstorms later this
afternoon as the surface low pressure passes to the north. Still
can`t rule a tornado here, but overall storm coverage and
severity is expected to be lower. East of the watch (Scioto
Valley), convective intensity should decrease into the evening
hours, likely reducing the potential for severe thunderstorms.
Thunderstorms and rain are still forecast, and if needed, the
watch will be extended farther east.

Rest of tonight:
As thunderstorms decrease in coverage this evening, low clouds
and some fog potential become the main focus. The upper level
trough digging southward out of the Midwest prevents the frontal
boundary from moving through the area, keeping the area in moist
southerly flow. Mid and upper level clouds increase within the
divergent flow aloft, but closer to the Indiana and Ohio border,
there will be a better chance for less cloud cover, helping fog
to develop. Confidence is still quite low on if stratus will be
the dominating feature.

Across the Scioto Valley and northeast Kentucky, the better
divergent flow and mid- level moisture advection overnight
night supports rainfall mentions into the early morning hours.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Quite the complex upper level pattern throughout the short term
and then eventually the long term periods with an elongated
trough stretching southward from Canada all the way to the lower
Mississippi Valley. A closed low in the middle Mississippi
Valley provides constant mid and upper level moisture advection
as it stalls Wednesday night. While overall rainfall amounts are
expected to be light, there is a long duration of shower or
light rain chances throughout the entire day, especially east of
the I-75 corridor.

A weak surface boundary moving slowly southeastward into
eastern Indiana and western Ohio may spark a few showers into
the area during the afternoon, but the boundary will dissolve as
high pressure builds in across the lower Midwest Wednesday
evening.

By late Wednesday night, the combination of the now cut-off upper
level low and Tropical Cyclone Helene results in a pressure
pattern where a weak high pressure is positioned across the
Great Lakes and Midwest with the low pressure to the south.
Upper level diffluent flow still persists over southeast
portions of the area primarily along and south of the I-71
corridor. As a result, mentions for rain persist, but overall
rainfall amounts remain light.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Our region will be wedged between two mid level closed lows on
Thursday. One will be spinning over the lower Mississippi River
Valley while the other low will be pivoting east across
southeast Canada and New England. Clouds and a chance of showers
will persist, with the highest PoPs along and south of the Ohio
River. Highs will range from the mid 70s to the lower 80s.

The track of Helene is coming into better focus, which it has
now shifted more east into the middle Ohio Valley than the
previous track which was more west into Missouri. That brings
the remnants across our area Thursday night into Friday, with
the system weakening and becoming absorbed into the mid level
closed low to our southwest Friday night. This should bring a
good chance of needed rain to our drought stricken region.
Temperatures will be warm at night, in the 60s, with highs on
Friday in the mid 70s to the lower 80s. Winds will be gusty on
Friday, 25 mph to 25 mph due to a tightening pressure gradient.

For the upcoming weekend, a chance of showers/slight chance of
thunderstorms, will continue as the center of the mid level
closed low slowly meanders east across the Ohio Valley.
Temperatures will be persistent, lows in the 60s, and highs in
the mid 70s to the lower 80s.

The mid level closed low is forecast to be pushed east by
Monday/Tuesday as another large scale mid level trough digs
southeast into the Great Lakes. Chance of rain will be lower as
the first low moves away. Temperatures will cool some. Lows in
the upper 50s to the lower 60s will be followed by highs in the
lower to mid 70s.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Thunderstorm activity lull early this afternoon, but development
is already beginning again across southern & western Indiana as
well as western Kentucky. This activity will quickly move
northeast, impacting CVG/LUK first, then ILN. DAY may see
additional development moving east out of Indiana in the next
few hours. Maintained TEMPOs for all sites, including CMH/LCK
with a later arrival time there. This thunderstorm activity
decreases in coverage quickly this evening, with a few remnant
showers around after 00Z.

During the overnight, low level clouds are forecast to develop,
as well as pocket of fog. IFR/MVFR forecast as all sites, with
timing adjusted slight faster (~07 to 08Z) from previous
forecast. Conditions gradually improve between 14Z and 18Z
Wednesday.

OUTLOOK...MVFR ceilings possible Wednesday night. Wind gusts
between 30 to 35 mph possible Friday.

&&

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

&&

$$
SYNOPSIS...McGinnis
NEAR TERM...McGinnis
SHORT TERM...McGinnis
LONG TERM...Hickman
AVIATION...McGinnis