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499
FXUS61 KILN 221902
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
302 PM EDT Sun Sep 22 2024

.SYNOPSIS...
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Several upper level disturbances moving through the Ohio Valley
will bring occasional chances for showers and a few
thunderstorms tonight through Tuesday. Warm conditions are
expected through Tuesday before more seasonable temperatures
return to the region by midweek. There is the potential for
additional rainfall toward the end of the workweek into next
weekend, but the details of the pattern at these extended ranges
are still somewhat uncertain.
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&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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Mostly clear skies from this morning have been replaced by
expansive cloud cover moving in from the W as a midlevel S/W
moves in through this evening. The drier air currently
entrenched across the region is quickly being shunted to the E,
with a fairly pronounced dewpoint gradient along the leading
edge of the better moisture. While it will take some time to
truly moisten the profile, a narrow ribbon of instby extending
from S to N through the wrn/central parts of the area may
provide a brief opportunity for the continuation of ISO/SCT
TSRA through the afternoon. Deeper-layer moisture and shear are
lacking along this N-S axis stretching near and parallel to the
I-75 corridor as of 19z, but enough heating on the periphery of
the thicker cloud shield and along an advancing/decaying outflow
boundary from near KDAY to KILN will provide just enough
overlap of lift and instby to generate some renewed updrafts
from time to time. This axis of ISO convection should move into
central/south-central OH and perhaps NE KY late afternoon, but
will be outrunning a more favorable environment back to the W
and will likely wane with time and eastward extent.

A large, but diminishing, shield of RA moving in from the W
through the middle of the afternoon will provide a shield of
stability across the srn half of the ILN FA from late afternoon
through early evening, representing perhaps a minimum in overall
coverage of activity from about 21z-00z or so. However,
additional activity is likely to move back into SE/EC IN/WC OH
around or shortly after 00z, moving W to E through the wrn
quarter of the ILN FA through about 03z or so. Overall, coverage
will transition from SCT to ISO in nature past 06z, with
a trend toward drier conditions expected for the remainder of
the night.

Temps tonight will range from the mid to upper 60s amidst
overcast conditions. Some patchy fog will also be possible
amidst the increasingly-saturated LL environment, but
indications point to more favorable stratus conditions opposed
to widespread or dense fog.
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&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
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A weak frontal boundary will drift to the S across the ILN FA
during the predawn hours, lining up to near the I-71 corridor by
daybreak. The front`s southward progression will slow into the
afternoon before eventually stalling across KY/TN. The front
itself, along with renewed mid/upper level forcing, will
provide a focus for renewed convection during the day Monday
across parts of KY, but certainly there is enough uncertainty
in the exact placement of the E-W oriented boundary that some
SCT SHRA will continue to be possible near/S of the OH Rvr
through the afternoon, with ISO activity possible N of the OH
Rvr and N of the diffuse baroclinic zone. This will especially
be the case during the afternoon hours. It shouldn`t be a
washout for any one location, but it may not be completely dry,
either. This being said, locales near/S of the OH Rvr will have
the most favorable setup for soaking rain with one or more clusters
of storms Monday afternoon.

A more potent S/W and attendant surface system will approach
from the SW overnight Monday into early Tuesday morning,
bringing renewed/more widespread chances for SHRA/TSRA into the
Tri-State and wrn parts of the local area by daybreak Tuesday.
Still some uncertainty in just how far N the warm front advances
into the day Tuesday, with the warm sector favored to get to at
least near the OH Rvr.
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&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
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Breezy and wet conditions are expected to start out the long term
period for the day on Tuesday.  That system will begin to then push
to the east with a decrease in precipitation chances Tuesday night
into Wednesday.

Beyond Wednesday, for Thursday through Saturday, there continues to
be a lot of run to run consistency issues and model variability and
therefore confidence is lower during that time.  By Sunday however,
models come back into better agreement and focus precipitation
chances more across southwestern portions of the region near the tri-
state.

Temperatures will be cooler in the long term than we have been
seeing with high temperatures in the 70s Tuesday and Wednesday.
Thursday through Sunday will have high temperatures in the 70s to
lower 80s.  Low temperatures during the long term will generally be
in the upper 50s to lower 60s.
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&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
The river valley BR/FG has long dissipated, leaving mostly sunny
skies through the morning hours. However, deeper-layer moisture
is on the increase from the west as moisture advection works its
way E into the region. This will promote ISO/SCT SHRA/TSRA
through the first part of the TAF period, especially for wrn
sites through this evening. Given the expected evolution of the
activity, it is difficult to pinpoint one particular favored
location or time window for the greatest coverage, although did
attempt to highlight the afternoon round with TEMPOs as best
possible.

Do think there will be additional redevelopment near/after 00z,
which will move back into the local area between about 00z and
06z. As such, decided to broad brush a VCSH, even recognizing
that there will be large portions of the first 12 hours where
there is not SHRA or TSRA particularly close to a specific
terminal. There should be a decrease in overall coverage of pcpn
locally by 06z, with MVFR, and even IFR, CIGs settling in
during the predawn hours, especially for nrn sites. KDAY/KILN
will have most favorable conditions for IFR CIGs, but certainly
it may briefly be possible elsewhere, too.

SW winds around 10-12kts this afternoon will go more westerly at
around 5-7kts past 21z through the remainder of the period. CIGs
will gradually lift/scatter toward/past 18z Monday.

OUTLOOK...Thunderstorms possible Tuesday. MVFR CIGs possible
Tuesday into Wednesday.

&&

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

&&

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