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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 141040
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
640 AM EDT Sun Apr 14 2024

.SYNOPSIS...
The ridge of high pressure has moved east of the region, allowing
for return flow to begin to usher in much warmer air to the
region. A few storms will be possible in central Ohio this
evening into overnight and then again in parts of northern
Kentucky on Monday. Much above normal temperatures are expected
through most of the week, with episodic showers and storms
through at least midweek. Cooler and drier conditions should
return by next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As the ridge of sfc high pressure moves to the E of the OH Vly,
southerly flow has once again become established, with stronger
SW flow at the sfc evolving through the daytime today. This
will help usher in /much/ warmer air to the area, with highs
expected to reach into the mid to upper 70s. A few 80-degree
readings may even be possible, especially near the OH Rvr where
ample midday sunshine is expected amidst a well-mixed BL.

A few cirrus and midlevel clouds are expected from time-to-time
through early afternoon, with breezy conditions developing late
morning into early afternoon. SW winds of 15-20kts, with gusts
25-30kts, are expected mid morning and beyond, promoting
increasingly-deep mixing into the afternoon. The amount in which
LL moisture (sfc DPs) mix out during the afternoon into early
evening will undoubtedly play /some/ role in dictating the
coverage of storms into the evening/overnight, even with the
expectation that LL moisture/pooling immediately ahead of the
sagging frontal boundary (near/N of I-70) will be better than
points further to the S (removed from the front). Removed from
the front, diurnal mixing should decrease sfc DPs and limit SB-
destabilization efforts rather notably through the daytime,
most of which will be unable to rebound or respond much by the
time the front approaches overnight.

Synoptically-speaking, a midlevel S/W will dig into the
interior NE CONUS, with an attendant weak sfc low darting E from
MI into the ern Great Lakes through late morning. On the srn
flank of the low, back to the SW toward the OH Vly, an enhanced
LLJ will nose to the NE through the region as stronger SW flow
near the sfc will help usher in some better moisture in the
lower part of the profile, some of which will be eroded during
the afternoon due to BL mixing. As this occurs, a plume of
drier air aloft will also move E into the region, helping
steepen midlevel lapse rates quite considerably and increase
deeper-layer instby. The stout/impressive EML should allow for
midlevel lapse rates greater than 8C/km to overspread from the W
during the day amidst an attempt to moisten the LL profile. All
of this points to the likelihood of SBCAPE of ~1000 J/kg
developing, mainly for locales near/N of I-70 in the region of
better LL moisture availability immediately along/ahead of the
southward-sagging front.

There are several questions that remain today, especially as it
relates to overall convective coverage -- most notably a
pronounced cap that may hold through most of the daytime until
inhibition wanes close to and beyond sunset. This will act to
delay CI until perhaps early evening (or even beyond), focusing
activity in a /very/ narrow spatial and temporal scale
immediately ahead of the front itself (pushing into central OH
between 00z-04z).

Looking at the specifics, although LL wind profiles should be
largely veered, there should be some deep-layer directional and
speed shear to work with, creating elongated and slightly curved
hodographs. This, combined with decreasing CIN very late in the
day into early tonight (near/N of I-70) and the front sagging S
through the nrn/ern OH Vly, should provide enough of a combo of
instby/shear/lift to initiate some clusters of TSRA this
evening, primarily near I-70 in the ern half of OH. Current data
suggests the best forcing should exist in far ern OH, with much
weaker forcing further to the WSW toward WC/SW OH, even this
evening. So... there are considerable uncertainties regarding
convective coverage with westward extent during this time period
(especially if the pronounced cap is able to hold through early
evening as expected), with the greatest coverage of storms
likely to focus during the evening in central and EC OH,
eventually drifting further to the S toward midnight and beyond.
However, as this occurs later into the evening/night, instby
should begin to wane with southward extent, as should the
already-meager LL forcing, as the front slows to a southward
crawl through the night. So the time period of concern, as it
relates to a few strong to severe storms, appears to be
relatively small at this juncture (mainly in the several hour
period around/after sunset), with more of an isolated
storm/severe potential persisting past midnight. There is
enough of a signal for /some/ overlap of moderate instby,
erosion of the cap, and sufficient deep-layer shear (and LL
directional shear) to suggest that a few strong to severe storms
(with strong/damaging winds (owing to a favorable DCAPE
environment) and large hail (owing to /very/ steep midlevel
lapse rates) being the primary threats) are going to be
possible. This is mainly the case between about 8 PM and
midnight in the ern half of Ohio. The most-favorable area
locally for this would be in central OH (near I-70 and near/E of
SR 23), although certainly it cannot be ruled out in WC or
south-central OH later in the evening. Although a tornado cannot
be completely ruled out, do feel that the relatively high LCLs
and dry BL should help limit tornadic potential locally. Expect
that locales near/S of the OH Rvr in parts of N KY and SE IN may
not see much (if any at all) as the front finally makes it to
these areas much later in the night toward daybreak Monday.

Despite the uncertainties regarding both convective initiation
and coverage, will continue to highlight the potential for a
few strong to severe storms in central OH and points near I-70
for this evening into early tonight in the HWO.

&&

.SHORT TERM /MONDAY/...
The aforementioned sagging frontal boundary will continue its
southward crawl early Monday morning, eventually making it into
N KY or near the OH Rvr. S of the front, the presence of more
ample LL moisture amidst daytime heating should allow for
robust diurnally-driven destabilization and perhaps for the
development of ISO TSRA in central KY, potentially grazing the
far srn parts of the ILN FA during the afternoon. It is worth
noting that on Monday, the LL wind fields should be much weaker
than will be the case today. The question that remains, once
again, is the presence of a cap and relatively meager
forcing/lift, both of which may limit TSRA development/coverage
to more of an isolated or spotty nature. But... if a few storms
are able to develop/mature Monday afternoon, a
conditional/localized severe threat (hail/wind) may evolve in
parts of central/N KY.

Highs Monday will range from the mid 70s in WC and central oH to
the lower 80s in N KY. Extensive early day cloud cover is
expected near the OH Rvr close to the front, with some
scattering and more sunshine expected by the afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A northwest to southeast oriented warm front will move northeast
through the Ohio Valley overnight and early Tuesday. GFS is the most
robust generator of shower and tstorm activity under this feature.
Only the ECMWF in a reasonable agreement, and this just for Tuesday
during the day. Forecast builder is and has been the strongest
supporter of this solution. As this incorporates a significant
amount of ensemble data, the lack of a deterministic unification is
not terribly significant at this time.

Showers and some thunderstorms will move northeast during the day
and quickly give way to drier air in its wake. That is until later
overnight when deep layer moisture gets advected in on strong
southerly winds, particularly in the western half of the CWA between
midnight and daybreak. Activity wanes in the early morning, then
ramps up Wednesday afternoon as the cold front approaches exiting to
the east by midnight with the frontal passage. Stronger storms and
heavy rainfall will be found with the storms on Wednesday.

Forecast builder seems to be too generous with regard to rainfall
Thursday evening and overnight. This does not seem to be supported
by the evolution of the models over the past few nights. While a
lower confidence regarding occurrence of showers/storms during this
time, still left the higher chance pops given.

Pops on Friday and overnight remain possible, though the GFS and
European are significantly different in how any weather is generated
given the mass fields. They do come in line on Saturday with colder
air on northwest winds, clearing out any precip.

Highs in the 70s Tues and Wed will drop to the mid 60s and low 70s
Thursday, upper 50s to mid 60s Friday, and slightly below climo in
the 55-60 range Saturday. Overnight lows will follow a similar
trend. 50s Monday night rising to low 60s Tues night. Dropping to
low 50s Wed night, near 50 Thurs night, and low 40s Fri night. While
forecast doesn`t go out to the next period, current guidance shows
mid to upper 30s for overnight Saturday.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A FEW/SCT mid clouds will move through the area during the
heart of the morning hours. Some Cu development is expected very
late in the day near/N of I-70 for KDAY/KCMH/KLCK close to 00z
as a front sags S into the area during the evening hours. Still
some uncertainties regarding convective coverage along the front
itself, but data continues to suggest the best potential for a
few TSRA will be near KDAY/KCMH/KLCK between about 01z-06z. But
certainly some activity may be possible near KILN between
03z-06z as well. Did not have confidence to go beyond a VCTS at
this point, but a TEMPO TSRA may eventually be warranted,
especially at KCMH/KLCK, should trends indicate slightly better
coverage of TSRA.

VFR CIGs will be maintained until close to 12z Monday where some
MVFR CIGs will be possible as the front continues to shift S.
The best potential for MVFR CIGs will be near KILN/KCVG/KLUK
between about 11z-15z.

Light southerly flow early in the TAF period will abruptly increase
through the morning hours, becoming gusty after about 14z-15z
or so. SW winds of 15-20kts, with gusts of 25-30kts, are
expected late morning through mid afternoon before slowly
subsiding a bit into early evening. Light/VRB winds should exist
near the front itself around 06z before winds go out of the NE
at 5-10kts by 12z Monday (progressively from N to S).

OUTLOOK...Thunderstorms possible Tuesday into Wednesday night.
Brief MVFR CIGs possible Monday morning. MVFR conditions are
also possible Thursday.
-- End Changed Discussion --

&&

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

&&

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