251
FXUS61 KILN 171025
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
625 AM EDT Tue Jun 17 2025

.SYNOPSIS...
Showers and thunderstorms will remain possible each day through
Thursday, and some strong to severe storms are possible Wednesday.
Drier weather is then expected on Friday and into the weekend, with
heat and humidity building through early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The main forecast concern for today is for continued rounds of
showers and thunderstorms, which could produce heavy rainfall and
flooding. A Flood Watch has been issued for the southeastern portion
of the ILN forecast area.

The 00Z KILN sounding recorded a precipitable water value of 1.73
inches. Projections from various models, including the SPC HREF,
suggest that a plume of precipitable water values from 1.8 to 2.0
inches (perhaps slightly greater than 2 inches) will advect northeast
into the area this afternoon and evening. The axis of this plume will
extend from Nashville to Lexington to Pittsburgh, so the highest
values over the ILN forecast area will be in the southeast -- with
slightly drier air further northwest. The main features that are
forcing the convective activity over the region will only be moving
very slowly eastward -- a shortwave at 500mb, some right entrance jet
support at 300mb, and continued theta-e advection in the boundary
layer. This suggests that after the early morning round of storms
occurring right now, there will likely be additional development
today, with some contribution from the diurnal cycle again. Model
soundings continue to support similar conditions to recent days, with
deep moisture, poor lapse rates, and wind flow that is not overly
strong. Thus, the severe risk remains very low, but heavy rain and
potential flooding will be the main concern. The Flood Watch was
issued for locations where there is highest confidence in storm
development and atmospheric moisture content, with some consideration
also given to terrain and antecedent conditions.

Clouds and occasional rain today will keep max temperatures in the
upper 70s to lower 80s -- very slightly cooler than Monday.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
The persistent (if somewhat unfocused) forcing over the past day or
two will finally be washing out and moving east by this evening,
leading to only low chances for precipitation heading through
Wednesday morning.

Severe weather will be the main concern through the Wednesday into
Wednesday Night time frame. The Storm Prediction Center has issued a
Day 2 ENH Risk for the northwestern corner of the ILN forecast area,
with SLGT and MRGL risks extending to the east and southeast.

Model soundings suggest that capping at around 800mb will be in
place for a good chunk of the day on Wednesday, and with forcing
still upstream, most locations should remain dry for the morning and
well into the afternoon. By mid to late afternoon, attention will
turn to a compact shortwave and surface low moving eastward through
the Great Lakes, with both features centered somewhere over the lower
peninsula of Michigan at 00Z. A trailing cold front will extend SSW
from the surface low, which may act as one source of forcing for
convective development, though there is the possibility of additional
forcing from a pre-frontal trough or forcing aloft from the shortwave
itself. With highs in the lower to mid 80s and dewpoints in the lower
to possibly mid 70s, SBCAPE values (per the SPC HREF) will reach
2000-2500 J/kg ahead of the forcing, and possibly higher over parts
of southern Indiana. While instability will be strongest with
southward extent, wind shear will be strongest with northward extent,
with deep-layer bulk shear of around 40kts across northern Indiana
and Ohio. There appears to be plenty of overlap between the favorable
instability and the favorable shear to support a severe risk. The
June 17 00Z model suite, compared to previous runs, has come in
slightly more favorable for severe weather -- and also slightly
earlier in terms of timing for the ILN CWA. This is not to say that
model timing is all aligned now, but the greatest severe threat seems
likely to fall in the 7PM to 2AM time frame. In terms of storm mode
and hazards, clusters and line segments seem most prevalent amongst
the 00Z CAMs. This makes sense given the forcing and shear profiles,
and also the fact that upstream convection (which may initially be
more discrete) will have time to congeal and grow upscale by the time
it reaches the ILN forecast area. The 0-1km shear and overall
directional shear do not appear overly concerning for tornadoes, but
there is enough to support some tornado risk, likely embedded within
lines rather than supercellular in nature. With that said, damaging
winds are clearly the main concern with this setup, as indicated by
the 30-percent wind-driven SPC ENH outlook.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
For Thursday, the trough continues is fairly slow progression
through the lower Great Lakes and Ohio Valley, with some variance
among ensemble model solutions of the progression of the surface
front through the day on Thursday. Areas near and southeast of the I-
71 corridor continue to have the greatest potential for a chance to
destabilize at least somewhat ahead of the progression of the frontal
boundary to allow for a greater chance of thunderstorms, with mostly
showers and an isolated thunderstorms to the NW. With limited time
for sufficient instability to form, chances for strong/severe storms
remain low. Temperatures a little cooler than Wednesday, with
dewpoints dropping to just the mid 60s behind the front.

Thursday night lows in the lower to mid 60s with clear skies and
lowering RH.

The break from the muggy conditions will be short-lived, as a deep
ridge builds into the Ohio Valley beginning Friday and expanding over
the weekend. Temperatures will climb to near 90 by Saturday, with
the potential for lower to even mid 90s for Sunday/Monday. With
increasing dewpoints, as well, will have to monitor for the potential
for heat advisory conditions especially Sunday and Monday.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Chances for rain will continue for the KCMH/KLCK TAF sites for
another couple hours. For the rest of the morning and into the early
afternoon, while a stray shower could occur, most locations will
remain dry. A period of MVFR ceilings is expected to settle into the
TAF sites through early afternoon, and some brief IFR conditions
could occur this morning as well.

MVFR ceilings are expected to lift by around 18Z. Additional showers
and storms will then develop during the afternoon. Coverage will be
spotty, so there is no guarantee on timing for any individual
airport, and a PROB30 group has been included with TSRA to cover this
possibility.

Tuesday night into Wednesday, precipitation chances should diminish,
but MVFR to IFR ceilings are expected to develop.

OUTLOOK...MVFR to IFR conditions are expected Wednesday morning.
Showers and thunderstorms will then be possible Wednesday afternoon
through Wednesday night, with MVFR to IFR conditions late Wednesday
night into Thursday morning.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Flood Watch from 11 AM EDT this morning through this evening for
     OHZ073-074-081-082-088.
KY...Flood Watch from 11 AM EDT this morning through this evening for
     KYZ098>100.
IN...None.

&&

$$

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