988
FXUS61 KILN 041723
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
123 PM EDT Sat May 4 2024

.SYNOPSIS...
A warm and moist airmass will remain in place across the region
into the middle part of next week, leading to occasional
periods of showers and thunderstorms.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
Fcst was updated a bit to increase PoPs this morning into this
afternoon as there is already quite a bit of SHRA/TSRA activity
in various pockets throughout the ILN FA. Although the severe
threat remains very low, very heavy downpours and frequent
lightning is occurring with some of this activity. Isolated
heavy rain/ponding of water has already occurred, with some
stations from Owen to Boone Cos KY picking up more than an inch
of rain in ~30 minutes. Brief ponding of water can be expected
with these rates, with isolated flooding due to 1.5 to 2 inches
possible in the more persistent bands.

PREVIOUS DISCUSSION...
Mid level short wave energy will lift northeast across the mid
Ohio Valley through the day. Forcing isn`t terribly great, but
in a moist airmass, this has been enough to maintain scattered
shower activity across southeast portions of our area so far
this morning. Flow aloft is very light, so this activity will
very slowly pivot up across mainly eastern portions of our area
through mid morning.

As we head through late morning and into this afternoon, some
weak instability will develop as afternoon highs push into the mid
to possibly upper 70s. This will allow for a continuation of
occasional showers along with a chance for thunderstorms. Given
the light flow and general lack of deeper shear, the overall
severe threat will be low. However, with PWs up around 1.5
inches and the slow storm movement, some heavier downpours will
be possible today.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SUNDAY/...
As we lose the daytime heating and the mid level short wave
moves off to our northeast, expect an overall decreasing trend
in pcpn this evening and into the overnight hours. Lows tonight
will mostly be in the lower 60s.

Another mid level short wave will move east across the Great
Lakes region on Sunday. An associated weak surface wave will
move across the southern Great Lakes while a trailing weak cold
front moves east across our area during the day on Sunday. This
will lead to additional chances for showers and thunderstorms,
especially across eastern portions of our fa Sunday afternoon.
With a little better deep layer shear, a few strong to severe
storms may be possible across our eastern areas Sunday
afternoon. The main severe threat would be damaging winds.
Highs on Sunday will range from the mid 70s northwest to around
80 degrees in our southeast.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A strong surface high over MI will push drier air into the northern
Ohio Valley behind a departing cold front.  A s/w undercutting a
mean H5 ridge will move east and into the Ohio Valley on Monday. The
earlier cold front will have draped w-e through southern CWA Monday,
and then begin to lift northeastward as a warm front overnight. The
region will be warm-sectored on Tuesday with scattered showers and
thunderstorms expected with daytime heating. Earlier showers with
embedded thunderstorms on Monday/overnight look to be triggered by
the surface front.

Tuesday night, warm sector showers will scatter out as a convective
line works in from the west ahead of a H5 s/w and trailing the
exiting upper ridge. This looks to be behaving as a cold front, but
the only front mildly shown in guidance is a shift from the highest
moisture on Tuesday to slightly drier air (back to what has been
seen) overnight.

A brief drying on Wednesday will change after daytime as strong
southwest flow brings a continued feed of deep moisture that will be
wrung out overnight. This will be the most prominent rainfall period
in the extended forecast. While some showers may linger into
Thursday/Thursday evening ahead of a H5 trough, the region should be
fairly worked-over enough to where upper level lift will not
overcome an expected stable airmass behind Wed night`s rain.

Low chance pops continue through the forecast but the overall end of
the period beginning Thursday evening looks to be dry and cooler.
Cooler to the extent that from Thursday night through Saturday it
will be near seasonal normals. Beginning with a brief cooling on
Monday, temperatures will warm through Wednesday and cool through
the remainder of the period.

&&

.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/...
Following the AM SHRA/TSRA activity, additional (albeit very
disorganized) redevelopment is underway, especially NE of
KCVG/KLUK. This cellular activity will continue to slowly drift
to the NNE, remaining incredibly disorganized and "popcorn-
like," perhaps transitioning to one or more clusters as we
progress late into the afternoon/evening. Nevertheless,
attempting to time out impacts at any one site is incredibly
challenging given the nature of the activity. So, decided to
broad-brush a VC for KDAY/KILN/KCMH/KLCK, with a TEMPO for time
windows of greatest expected coverage. Sudden reductions in
VSBYs will be the primary concern with any of the activity.
Certainly a brief SHRA/TSRA could once again meander near/over
KCVG/KLUK after about 21z, but confidence in this occurring was
too low to include in the fcst at this juncture.

A mix of VFR/MVFR/IFR CIGs continue to linger about, with a
gradual transition to mainly VFR/MVFR through the first hour or
so of the TAF period. Numerous SHRA/TSRA will slowly wane in
coverage from W to E past 00z, with drier conditions evolving
locally toward/beyond 03z. CIGs may trend back to, or below,
2000ft past 06z or so, but there are uncertainties in just how
widespread the MVFR (or even IFR) CIGs may be after 06z through
mid morning Sunday. There also could be some VSBY reductions
develop tonight due to BR/FG as well, particularly at KCVG/KLUK
where more widespread rain occurred this morning. A stray SHRA
cannot be ruled out at KCVG/KLUK/KDAY between about 07z-09z as a
decaying patch of pcpn moves in from the W.

A front will move into/through the local area on Sunday,
allowing for winds to go more westerly late in the period. Until
then, light SW winds at 7-9kts or less are expected.

OUTLOOK...Thunderstorms are possible at times each day from through
Wednesday. MVFR or IFR conditions are possible Monday morning.

&&

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

&&

$$
SYNOPSIS...JGL
NEAR TERM...KC/JGL
SHORT TERM...JGL
LONG TERM...Franks
AVIATION...KC