543
FXUS61 KILN 251039
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
639 AM EDT Tue Jun 25 2024

.SYNOPSIS...
An unsettled pattern, with several chances for showers and
storms, will persist through Wednesday before drier conditions
briefly return for Thursday and Friday. However, rain and storm
chances return once again on Saturday, with drier conditions
favored for Sunday into early next week. Near to above normal
temperatures are expected for the foreseeable future.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Tranquil conditions will continue locally through daybreak,
although they won`t last too much long, unfortunately. As the
sfc high shifts to the E of the OH Vly through the morning,
abrupt moisture return will begin to nose back into the area
from the W into the afternoon hours. This will occur following
the S/W ejecting E through the Great Lakes region through
daybreak, which has prompted the development of a stout and
increasingly-well organized MCS now across WI, which will track
to the ESE into MI and far nrn IL/IN/OH through mid morning. As
this occurs, we may see a few WAA-induced WAA develop along a
N-S oriented axis across EC IN and WC OH, primarily between
about 13z-17z, but this should be of little consequence to the
convective evolution through the rest of the day.

The forecast later into the daytime becomes incredibly complex,
and will be largely dictated by convective evolution throughout
the time period. As the primary S/W pulls to the NE of the OH
Vly late morning into early evening, taking with it the better
forcing, the remnant outflow/boundary stretching back to the W
should serve as a focus for renewed convective development by
early afternoon across nrn IL/IN/OH. This will occur as activity
attempts to redevelop closer to the pool of better
moisture/instby collecting/advecting across IL/IN and far wrn
OH. Confidence continues to increase in the potential for
redevelopment, to a certain extent, of a E-W oriented axis of
TSRA along the stale MCS boundary. This reason for this is
partially because of the delayed timing (compared to previous
fcsts), which will allow /just enough/ time for a surge of
higher theta-e air (better LL moisture content) to nose into
areas near/W of I-75 into early afternoon. The latest guidance
suggests that a very narrow ribbon of SB-instby will develop
immediately ahead of the southward-progressing outflow-driven
storm activity into mid-afternoon, supporting locally gusty to
damaging winds with the strongest cores. This will especially be
the case for areas near/W of I-75 and especially near/W of I-71
with the better instby to work with than for locales in NE KY
or the lower Scioto Valley. The better SB instby should pinch
off with eastward extent.

The rapid jump in temps/humidity/SB instby early/mid afternoon
in the wrn third of the ILN FA may be enough to prompt and
maintain a more concerning severe threat into the local area
than was originally expected. At this juncture, it is likely
that additional clusters or complexes of storms will develop
within the trailing MCS boundary, spreading to the SSE through
the local area between about 17z-23z (N-S). Given the robust
destabilization efforts underway near/W of I-75/I-71 prior to
storm arrival, it is certainly worth mentioning the potential
for widespread gusty to locally damaging winds this afternoon
into early evening. A high DCAPE environment amidst favorable
LL/deep-layer thermodynamic fields and potential for aggressive
cold-pool driven processes suggests that these storms could be
locally intense and persist for quite a long time, even in the
absence of any synoptic-based forcing or source for lift. Feel
that the SPC slight risk on the SWODY1 in our west is well-
warranted and needed.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
The fcst for this evening through Wednesday following the
expectation for daytime convection becomes even muddier,
unfortunately. It seems plausible, given the latest data, that
there will be a several hour lull in pcpn locally following the
afternoon/early evening storms. This lull should stretch past
midnight into the middle of the night before additional loosely-
organized activity moves back in from the W by/after 06z-09z.
The storms tonight are likely to be much more disorganized and
not pose such a potential for strong/severe activity. However,
any of this activity will bring with it the potential for some
lightning and very heavy downpours/localized ponding of water.

Coverage of SHRA/TSRA should be on the increase toward daybreak
and beyond, but there are quite a few uncertainties in how
things will unfold on Wednesday in terms of a hazardous-weather
perspective.

There is likely to be better forcing moving E through the
region Wednesday morning through the daytime, potentially too
much so. In fact, in an uncapped environment, the focus for any
organized storms appears rather nebulous (except along the SE-
moving front very late in the day), potentially leading to a
somewhat "grungy" environment characterized by poor LL (and
midlevel) lapse rates. This would suggest that storms/updrafts
may struggle to become particularly intense, with much more in
the way of widespread storms, with only a few becoming strong to
severe briefly. There will be slightly better LL and deep-
layer flow fields to work with Wednesday, but the poor deep-
layer lapse rates and slightly less unstable environment cast
some doubt onto the coverage of /severe/ storms.

Rainfall through the period will be highly-variable, both in
time and space, but would expect that some spots will pick up
1-2 inches between now and Wednesday evening, especially with
the anomalously-high PWATs expected region-wide for the daytime
Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
The frontal boundary will be moving through the CWA at the start of
the extended period and any lingering showers/storms will be moving
southeast out of the region.

Post frontal air on Thursday indicates high temperatures in the low
80s with dew points in the lower 60s... will feel much drier than
previous days. Weak ridging and surface high pressure take over and
we`ll have mostly sunny skies with some CAA cu. Overnight lows in
the upper 50s/ low 60s as we head into Friday.

Friday we see yet another disturbance on the horizon and return
southerly flow helps pump warm, moist air back into the region. Mid
and upper level clouds increase and highs reach back into the upper
80s. Precip from this system looks to move into the region sometime
Friday into Saturday as the warm associated with this disturbance
lifts through the area. This keeps temperatures on the warmer side,
with highs in the upper 80s/ low 90s for Friday and Saturday. As of
right now, the cold front looks to push through Saturday sometime
and given the amount of moisture pumped up/ robust looking nature of
the parent low pressure, wouldn`t be surprised to see some stronger
storms move through, but time will tell.

Ridging and high pressure move into the region on the backside of
this system and Sunday we dry out again. Temperatures cool slightly
in the post cold-frontal air and highs reach the mid 80s. The high
looks to remain in control for at least another few days, so
anticipating dry conditions for the start of the working week.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Some mid/high clouds, courtesy of convective debris blowoff
upstream, are filtering in from the W, with thickening cloud
cover expected through early afternoon.

For the daytime, there continues to be quite a bit of
uncertainty in how things will unfold, especially when
attempting to focus on one specific location through time. More
specifically, there remain some uncertainties in both timing
and structural integrity of this axis of SHRA/TSRA which will
quickly move into the local area by early afternoon, especially
as the environment will be increasingly unfavorable for
maintenance of stronger/severe storms with further E/SE extent.
That being said, do think there will be a broken linear feature
that eventually migrates to the S through the local area
mid/late afternoon (17z-23z), bringing with it some SHRA/TSRA
and some gusty wind potential (as the storms will be outflow
dominant). But pinpointing impacts at one location through the
daytime will be somewhat challenging. The activity should weaken
with SE extent, with the best
organization/maintenance/intensity favored for KCVG/KLUK where
the better instby will be positioned by late day. Of course,
abrupt reductions in both VSBYs and CIGs and wind
speed/direction will be favored in the strongest activity.

After 00z, there may be a brief lull that evolves locally
before additional clusters/loosely-organized SHRA/TSRA move back
into the local area between 06z-12z Wednesday. Light southerly
winds will increase to 12-15kts as they go more out of the SW
by/past 15z, eventually subsiding toward the end of the period
as light (generally 5kts or less) southerly flow resumes.

OUTLOOK...Thunderstorms possible Wednesday and again on Saturday.

&&

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

&&

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