-- Discussion containing changed information from previous version are highlighted. --
716
FXUS61 KILN 221826
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
226 PM EDT Sat Jun 22 2024

.SYNOPSIS...
Hot conditions continue today before a brief respite arrives
Sunday into Monday with slightly cooler and drier air,
especially on Monday. A few showers and storms are expected on
Sunday, especially during the morning into mid afternoon. By
late Tuesday, warmer and much more humid air will quickly build
back into the region, with chances for storms returning Tuesday
night through Wednesday. Drier and cooler conditions will then
return for the last part of the workweek.

&&

.NEAR TERM /THROUGH SUNDAY/...
Heat wave continues across the area today. Mid and upper level
ridge stretches from the Southern Plains across the Ohio Valley
into the Mid Atlantic.

Expect thin high level clouds with few to scattered cumulus
clouds. With a lack of forcing coverage of convection should be
north of ILN/s area where the more favorable mid level flow is
located. Can not rule out a rogue storm - mainly across the far
north during peak heating but with such limited coverage have
maintained a dry forecast.

Highs in the mid and upper 90s are likely again today, with
dewpoints generally in the mid 60s during peak heating, yielding
max heat index values around 100 degrees. Max WBGT values top
out in the mid and upper 80s today which is similar to yesterday.
This is in the top of the red heat stress category - which is
category 4 out 5.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH 6 PM SUNDAY/...
Thickening mid/high level clouds will be moving into the local
area toward/beyond sunset, with the first real "change" of wx
pattern upon us that we`ve seen within the past week. The
increase in cloud cover and LL moisture content late in the
night will translate to a /very/ warm night tonight as lows
only dip into the mid 70s for many areas. A few showers or
storms may survive into WC OH late tonight on a weakening trend.

Broad-scale height falls will already be underway by late today
as the center of the ridge gets shunted to the SW into the lower
MS Rvr Vly as troughing amplifies a bit into the Great Lakes
region. The main S/W energy will pass us well to the NE across
the interior NE, with the trailing cold front back to the SW
across the wrn OH Vly by daybreak Sunday. Latest guidance
continues to show a slightly faster progression of the front
into (and through) the local area than had previously been
indicated, with the best LL and deep-layer moisture and LL wind
flow now positioning itself near/SE of I-71 early in the day.
The core of the LLJ will already be pulling E of the local area
by 15z, with some trailing LL moisture lingering back to the SW
across the SE 2/3 of the local area by early afternoon.
However, the front should continue to drift to the SE somewhat
quickly, with some drier/well-mixed air already filtering into
WC OH by late afternoon.

All of this paints a picture of a somewhat meager potential for
organized strong to severe storms locally, despite some
moderate instability (owing to ample LL moisture). The only real
source for lift will be convergence along the front itself, but
even the wind shift will be fairly gradual/subtle from one side
of the front to the other. Currently, the best potential for a
few strong to severe storms will reside near/SE of I-71 through
mid afternoon before storm chances gradually diminish from NW to
SE late in the day as drier air filters in from the NW toward
Sunday evening. The main threat with the activity will be
locally strong to damaging winds, with some small hail also
possible. But, given recent data, the coverage of strong/severe
storms should remain somewhat isolated.

Forecasting high temps on Sunday will be a challenge given the
prospect of the front bisecting the ILN FA by mid afternoon.
Clouds and SCT storms may keep locales SE of I-71 a bit cooler
than spots further to the NW, where there should be ample late
day sun as some drier air filters in. Either way it is sliced,
most locales will top out in the mid to upper 80s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
The cold front will be working its way through our CWA at the start
of the extended period, most notable by the decrease in dew points/
moisture as it moves through. Overnight lows into Monday drop to the
low 60s in the north and upper 60s along the Ohio River- quite a
reprieve from what we`ve been experiencing.

Post frontal subsidence helps clear the clouds out for Monday and
we`ll wake to sunny skies. High temperatures reach the mid to upper
80s with much less moisture in the air. Overnight lows drop into the
mid/upper 60s. However, this respite is short lived, as we quickly
rebound on Tuesday with another surge of theta-e into the region
ahead of the next system... a rather potent low are of low pressure
that is carving its way through Canada.

In fact, Tuesday looks to be downright uncomfortable, with heat
indicies sky rocketing back into the upper 90s, particularly for
western Ohio and the Tri-State region, as this system works in from
the west. Following this furnace blast of heat, a cold front will be
slowly moving toward the Ohio Valley, moving through sometime
Wednesday. With this being said, showers and storms forced out ahead
of this front Tuesday overnight into sometime on Wednesday will have
quite a bit of instability to work with. Already, some deterministic
runs hint at a MCS somewhere near the Great Lakes region. Colorado
State machine learning highlight Tuesday night with a 30 prob for
organized severe weather for the ILN CWA and a prob 15 for
Wednesday. For now, have maintained PoPs through the overnight hours
Tuesday night and most of Wednesday as the front moves through the
region.

Thursday and Friday we should dry out again and, possibly, have
another respite from the heat in the cooler post-frontal air,
particularly on Thursday. Box and whiskers plots for the NBM
indicate a range from 80 to 88 for the high. While this forecaster
would prefer the 80, have stuck with the blend for now and gone in
the middle.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
Mid level ridge remains across the Ohio Valley today which will
inhibit the development of widespread convection. VFR conditions
this afternoon into tonight with scattered to bkn cumulus
clouds around 5000 feet. A renegade shower or storm can not be
ruled out - mainly east of I-71 but coverage would be so low and
short lived that no mention is in the TAF forecast at this time.
Cumulus clouds will dissipate with the loss of heating this
evening with some mid/high level clouds overspreading the area
after 06Z tonight.

Progressive mid level shortwave to track thru the Great Lakes
overnight and Sunday. This will drive a surface cold front thru
the area Sunday afternoon. Pre-frontal showers and embedded
thunder from a mid deck will be possible toward sunrise Sunday.
This pcpn activity should be in a weakening trend as it moves
across the area. Have included a VCSH mention to account for
this threat toward 12Z.

An increased threat for thunderstorms will develop during the
late morning into the afternoon with the approach of the cold
front. At this time have included a mention of VCTS with
continued VFR ceilings but can not rule out the possibility of
MVFR ceilings or lower in storms.

Southwest winds at 10-12kts this afternoon will drop to less
than 10 kts this evening and then gradually increase toward
sunrise Sunday as the pressure gradient tightens with the
approach of the front. Expect southwest winds 10-15 kts with
gusts up to 22 KTs Sunday before shifting to the northwest late
in the day.

OUTLOOK...Thunderstorms possible on Sunday afternoon and late
Tuesday through Wednesday.
-- End Changed Discussion --

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Heat Advisory until 8 PM EDT this evening for OHZ026-034-035-
     042>046-051>056-060>065-070>074-077>082-088.
KY...Heat Advisory until 8 PM EDT this evening for KYZ089>100.
IN...Heat Advisory until 8 PM EDT this evening for INZ050-058-059-
     066-073>075-080.

&&

$$
SYNOPSIS...KC
NEAR TERM...AR
SHORT TERM...KC
LONG TERM...CA
AVIATION...AR