651
FXUS61 KILN 051855
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
255 PM EDT Sun May 5 2024

.SYNOPSIS...
A warm and moist airmass will remain in place across the region
through at least midweek, leading to occasional periods of
showers and thunderstorms into Thursday. Drier air will return
by the end of the week, although rain chances may persist at
times into next weekend as below normal temperatures settle in
for next weekend.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As expected, ISO/SCT SHRA/TSRA activity is sprouting about the
uncapped environment, with SBCAPE on the order of 1000-1500
J/kg near/E of I-71. The forcing and lift remain very weak, so
expect that coverage should remain generally scattered in
nature, eventually focusing mainly in central/south-central OH
and NE KY by about 20z or so. The best coverage will likely be
from Franklin/Licking/Madison Cos OH to Lewis Co KY between
about 20z-23z before activity becomes more ISO toward sunset and
beyond as it shifts out of the local area.

There may be some very brief clustering/training of cells from
time-to-time, but the overall potential for either severe
weather or flooding appears to be rather low. Still cannot rule
out some very isolated gusty winds, small hail, or brief heavy
rain with any of the strongest activity (especially in central
OH between about 20z-23z), but this potential should remain
isolated/spotty in nature. Will maintain HWO for now even if the
threat appears to be somewhat lower than originally anticipated
(given a few lingering uncertainties in terms of coverage).

Elsewhere, it will continue to feel like an early-summer day
with a healthy Cu field and temps in the mid 70s (WC OH) around
80 degrees (elsewhere) and dewpoints generally in the upper 50s
(WC OH) to lower 60s (elsewhere). Drier air is going to attempt
to filter in from the NW this evening and from the N overnight,
but the push for a more significant airmass change is just not
there. In fact, the boundary should lay out somewhere in the
vicinity of the OH Rvr overnight (with sfc DPs in the mid 50s
near I-70 to the lower 60s in N KY). The E-W oriented boundary
will gradually pivot back N toward/beyond daybreak Monday as
another S/W moves in from the SW during the morning.

More widespread SHRA/TSRA activity will move back in from the SW
late tonight as a weakening S/W moves NE through the wrn TN/OH
Vlys. This should lead to a wet AM commute for parts of the Tri-
State, with drier conditions further N toward the
Dayton/Columbus metro areas around daybreak. Before that occurs,
some patchy fog will be possible across the area where clearing
is able to occur through the first part of the night,
particularly in areas that received quite a bit of rain over the
past several days.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
A pivoting axis of SHRA/TSRA will overspread the srn 2/3 of the
ILN FA during the daytime Monday, with the greatest coverage
focusing S of I-70 during the heart of the daytime. The
aforementioned front will also pivot back N, allowing for
richer LL moisture to expand back N through the daytime, with
PWATs once again exceeding 1.5 inches (175% of seasonal norms).
This, combined with slowing/erratic cell motions (owing to a
developing W-E oriented LL convergence zone (with stretching
along it)), may once again create isolated heavy rain/flooding
concerns, especially in a tier or two of counties either side of
the OH Rvr. This setup, on top of already-saturated ground for
many spots, lends itself to at least some concern for more than
a spotty/ISO hydro concern during the afternoon/early evening.
So have added mention in the HWO for the areas of greatest
potential for high water/flooding concerns Monday
afternoon/evening, even recognizing the threat should still be
fairly isolated.

With quite a bit of cloud cover and SHRA/TSRA activity about the
region during the day, forecast highs were trimmed several
degrees, with highs generally in the lower/mid 70s and sfc DPs
nudging back into the mid 60s for most spots. SHRA/TSRA activity
should become more ISO in coverage toward the evening/beyond,
but may not shut off completely through Monday night as the
weakly-convergent axis continues to crawl to the N. An
unseasonably warm night is on tap for Monday as lows only dip
into the lower/mid 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Broad upper level troughing over the western two thirds of the
CONUS will shift slowly east through mid week, keeping the Ohio
Valley in persistent west to southwest flow aloft. This will allow
for a series of embedded mid level short waves to move through the
region Tuesday through Thursday. At the surface, a frontal boundary
along the Ohio River will lift north across the area through the day
on Tuesday with afternoon highs climbing into the upper 70s to lower
80s. This will combine with surface dewpoints in the mid 60s to
produce surface based capes into the 1500-2000 J/kg range. This will
result in fairly widespread shower and thunderstorm development
Tuesday into Tuesday evening and with strong deep layer shear
develop through the day, some severe storms can be expected.

A trailing cold front will push southeast across our area Tuesday
night before stalling out heading into Wednesday morning. There is
then some uncertainty as to how far back to the north the front will
lift through the day on Wednesday ahead of an approaching low
pressure system. Along and south of the boundary, good instability
will develop with fairly widespread showers and thunderstorms
possible once again. With strong deep layer shear persisting and the
approach of a surface low, severe storms will again be possible.
Highs on Wednesday will be in the upper 70s to lower 80s.

A cold front will then push off to our southeast later Wednesday
night into Thursday, leading to lower pcpn chances and slightly
cooler temperatures. Highs on Thursday will be in the mid to upper
70s. Additional short wave energy dropping down across the Great
Lakes will help deepen the trough over the Great Lakes and Ohio
Valley Friday through Sunday. This will keep us in a cooler airmass
with daytime highs in the 60s to lower 70s. This will also keep some
lingering lower end chances for showers and a few thunderstorms
through the weekend.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
A mix of MVFR/VFR diurnally-enhanced Cu has expanded with
daytime heating, but expect that CIGs should gradually
transition to more VFR within the first hour or so of the TAF
period (if they haven`t already done so).

For early in the TAF period, still expecting a few SHRA/TSRA to
develop near KCMH/KLCK through about 22z or so before the
activity pushes further to the E. Confidence is somewhat low
regarding coverage, but there seems to be enough of a signal for
a few SHRA/TSRA around central OH to add a TEMPO. Elsewhere, a
stray SHRA/TSRA cannot be completely ruled out at KILN, but
would expect that activity should focus a bit further E of the
site.

Conditions will trend dry area-wide by/past 00z before more
widespread SHRA/TSRA moves in from the SW past 09z, impacting
KCVG/KLUK by daybreak. But until we get to that, some BR/FG will
be possible once again tonight, especially as mainly skies
(except for some cirrus) should evolve from 00z through about
09z. With ample rainfall in recent days and mostly clear skies
and relatively light/variable/calm winds, the potential for
some patchy fog/VSBY reductions exists, especially for
KILN/KCVG/KLUK.

MVFR CIGs and VSBYs coincident with pcpn are expected to spread
in from the SW past daybreak. A few uncertainties in just how
far N the activity spreads, with a sharp cutoff likely near
KCMH/KLCK by the end of the period. Fairly widespread pcpn is
expected further S toward KILN/KCVG/KLUK between 12z-18z.

Light WNW winds will become more northerly (at ~3-5kts) around
00z before going easterly by daybreak and eventually out of the
ESE by Monday afternoon. Winds should remain 10kts or less
through the period.

OUTLOOK...Thunderstorms are possible at times each day through
Thursday. MVFR conditions are possible Tuesday morning.

&&

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

&&

$$
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...Coniglio
AVIATION...KC