041
FXUS61 KILN 070216
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1016 PM EDT Mon May 6 2024

.SYNOPSIS...
Several rounds of showers and storms are expected through
Thursday amidst a continued warm and humid pattern. Slightly
cooler air will filter into the region late in the week, with
slightly drier conditions also expected. However, periodic
chances for showers will likely linger into the weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Evening update...
Scattered showers continue to spiral counter-clockwise around
the remnant MCV which resulted in more widespread showers and
thunderstorms this afternoon. Expecting this activity to linger
for a few more hours across southern Ohio and northern Kentucky.

Given the saturated low-level flow, still anticipate the
development of fog, focusing along the Ohio River and south of
I-70. Can`t rule out the potential for dense fog for the morning
commute, focused around the Ohio River and tri-state areas. The
one limiting factor could be the development of stratus,
preventing more favorable boundary layer cooling.

No changes made to the forecast for the band of showers and
thunderstorms expected to arrive from the west during the late
morning/early afternoon hours.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
Midlevel ridging briefly moves through the OH Vly tonight as a
tremendously large/broad low migrates into the upper Midwest. On
the SE flank of this stacked/occluding low, S/W energy pivoting
around the basal portion of the longwave trof will eject NE
into the OH Vly by Tuesday afternoon/evening. This will provide
the focus for an active short-term period, with the details
discussed below.

Bottom line up front... the setup for severe storms appears to
have increased and become a bit more concerning given recent
data trends. The main time period for severe potential locally
appears to be somewhere in the vicinity of the 4 PM to 11 PM EDT
window, likely maximizing between 6 PM and 10 PM.

Diving a bit further into the details, expect that a (somewhat
decaying) band of convection will move into the region by
mid/late morning Tuesday. This activity represents "convective
leftovers" from the central plains severe weather episode
expected later today. Although the activity /should/ be on a
weakening trend with eastward progression closer to/into the ILN
FA around/after noontime, a slightly slower arrival may mean
that sufficient diurnal destabilization could occur /ahead/ of
this activity, lending itself to at least some potential of SB-
convection and redevelopment along the eastward-moving arc. Do
think that the activity should survive long enough to enter the
local area, potentially providing a focus for some redevelopment
along it`s trajectory through the ILN FA between about 12 PM and
4 PM. Certainly a few strong/severe storms may develop
associated with this feature (providing it holds together
enough), with strong/damaging winds and some small hail being
the primary threat through the first half of the afternoon.

Once we get past about 3-4 PM or so, the environment is going to
become increasingly conducive to redevelopment of convection
(initially back to the W in IL/IN), with a conditionally-
volatile setup very possible given rapid destabilization in the
wake of early afternoon activity. There are still a few
uncertainties in just /how much/ redevelopment occurs across
IL/IN mid/late afternoon before it overspreads the local area
late afternoon through the evening. Nevertheless, a strongly
unstable environment (courtesy of SB/MLCAPE in excess of
2000J/kg) should develop within a decently-wide corridor
(nudging in from the SW past 21z). This will occur amidst an
environment with plenty of forcing and ascent, good midlevel
lapse rates (supporting robust updraft development/strength),
and good deep- layer speed shear. A H5 jet speed max will nose
to the NE into the OH Vly by late afternoon/evening, eliciting
an elongated and subtly-curved hodograph from the sfc to about
H5. There is some directional shear in the BL as well, but the
"fly-in-the-ointment," so to speak, is the backing of winds in
the upper levels within the H2-H5 layer, producing an
anticyclonic curvature to the end of the hodograph. This depicts
a likely scenario that is conducive to discrete/cellular
activity (perhaps with splitting supercells), with some
clustering possible. In addition to the large to very large hail
threat, the primary concern would be if sfc winds are able to
back immediately ahead of the convection, especially between
about 21z-03z, creating local enhancements to the 0-1km/0-3km
SRH fields. This backing appears most probable/favorable near/N
of I-70, suggesting the tornado potential is slightly greater in
these areas than further S toward/S of the OH Rvr with the LL
flow remains more veered. Given the sufficient overlap between a
strongly-unstable environment, good forcing/ascent, and good
deep-layer shear, all hazards are in-play Tuesday late
afternoon/evening, with the greatest tornado threat likely to
focus near/N of I-70 in a slightly more conducive environment
with the somewhat backed LL/sfc flow. And although storm
motions should be fairly quick, cannot completely rule out some
brief heavy rain/flooding, especially in areas that have
received significant rain over the past few days. Have adjusted
HWO wording to reflect this latest thinking.

The coverage of storms should be on a decreasing trend from W to
E toward midnight/beyond, with quieter conditions briefly
returning late Tuesday night in the wake of evening convection.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Forecast calls for active weather as numerous moisture-laden systems
are expected on a southwest to west upper flow.

Period begins Wednesday with a strengthening cluster of short wave
energy triggering a surface low that will move toward Ohio from the
west. Favorable moisture and lift will aid convective development,
while a tight pressure gradient causes breezy conditions.
Thunderstorms are nearly certain during Wednesday afternoon and
evening, continuing Wednesday night as the low progresses to
Northern Ohio. Organized and enhanced by the strong wind fields and
supported by ample instability, some storms may be severe and
produce heavy rain. As the low moves east on Thursday, coverage of
convection will decrease along with the severe threat.

A few showers may occur in residual moisture on Friday. A fast
moving low tracking to the Great Lakes could trigger more showers
and storms on Saturday. Low chances for showers and storms will be
maintained Sunday and Monday as weak short waves encounter a
marginally unstable environment.

Temperatures will exhibit fluctuations that will follow changes in
geopotential heights and low level advection and insolation patterns.
Highs are forecast to remain above normal on Wednesday in warm
advection ahead of the first low, with highs ranging from the upper
70s to mid 80s. As geopotential heights drop and the low level flow
turns northwest, readings slide to the upper 60s to around 80 on
Thursday. Further reduction in geopotential heights and continued
cold advection will provide highs mainly in the 60s Friday through
Sunday, with lows in the 40s. A rebound to the 70s is indicated for
Monday under rising heights and increasing insolation.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Still some scattered shower activity around the area this
evening. Brief MVFR VIS/CIGs will be possible with these
showers. This activity will continue to become more isolated
over the first few hours of the TAF.

Overnight, low-level flow will saturate and winds will be weak,
supporting descending CIGs from VFR to IFR/LIFR into 12Z. Given
the weak winds, IFR VIS is also likely, especially where rain
occurred earlier today.

Light/variable flow overnight will calm before going more
southerly and increasing to around 10-15kts past 15z Tuesday. A
band of SHRA/TSRA should approach from the W toward 18z
(CVG/LUK/DAY/ILN) Tuesday and continue eastward toward CMH/LCK
by around 20Z. Additional showers and thunderstorms are expected
behind this line through the remainder of the TAF.

OUTLOOK...Thunderstorms will be possible Tuesday afternoon and
evening and then again late Wednesday into Wednesday night.
MVFR/IFR CIGs are possible Wednesday night into early Thursday
and again on Friday.

&&

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

&&

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