773
FXUS61 KILN 031500
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1100 AM EDT Wed Jul 3 2024

.SYNOPSIS...
Hot and humid conditions are expected today along with
increasing chances for showers and thunderstorms as a cold front
approaches from the northwest. This boundary will then remain
in the area on the Fourth of July. Embedded mid level
disturbances will interact with this boundary, resulting in
multiple rounds of showers and thunderstorms. A stronger weather
system is expected to move into the Great Lakes and Ohio region
Friday into Friday night, continuing the threat for showers and
thunderstorms.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
The previously discussed MCS across southern Illinois is notably
weakening at the time of this writing, with its outflow boundary
surging out ahead of it, evident via satellite imagery. Timing
for this afternoon`s CI still looks to be between 2-5 PM in this
relatively weakly sheared, moderate CAPE environment. Recent
ACARS depicts very skinny CAPE at CMH and CVG, but this is
forecast to get /slightly/ more robust as the day continues on.
Forecast soundings also indicate that some heavy rain producers
may move through later today. Any storms that train over the
same area may produce localized flooding or a quick burst of
flash flooding.

Previous discussion--> A cold front was located from the
western Great Lakes, southwest across the middle Mississippi
River Valley, then into the southern Plains. This front will
make its way southeast toward our region today. For this morning
into early afternoon, we should see a mix of high clouds
(spilling in from the west from upstream convection) and
scattered cumuliform clouds. Winds will increase from the south
and southwest between 10 and 15 mph with gusts up to 25 mph.
This low level flow will bring higher dewpoints into the region.
In fact, dewpoints are forecast to peak this afternoon into the
lower to mid 70s. This will combine with forecast highs in the
upper 80s to the lower 90s. As a result, heat indicies will
range from the upper 90s to the lower 100s. Where heat indicies
are expected to approach 100 or above, a Heat Advisory has been
issued, which is mainly along and south of the I-70 corridor.
Elsewhere, mid and upper 90s heat indices are expected, and this
will be mentioned in the HWO. With the heat and humidity, the
airmass will become unstable with moderate instability forecast.
This will be occurring in an environment with weak to low end
moderate deep layer shear. The big question of the day will be
how showers and thunderstorms will be triggered. Well, perusing
the various CAMs and models, it appears that either an outflow
boundary/MCV will rotate east into our area by late afternoon,
or perhaps a low level prefrontal trof in advance of the cold
front. This forcing should be enough to produce scattered to
numerous showers and thunderstorms in an uncapped sounding
regime. There is some uncertainty on how fast convective
initiation will start, ranging from 2 pm to 5 pm or later. As a
result, have taken a blended/broad brush approach for this
afternoon. We will likely see multicellular clusters or small
bowing segments of convection. With pwats 2+ inches, pcpn
loading in the strongest updrafts will likely lead to some
strong to damaging winds as the the cores descend back to the
surface. In addition, there should be some DCAPE values between
500 and 900 negative J/kg for wet microburst potential. Poor mid
level lapse rates and overall thin CAPE soundings indicate that
large hail is not a big concern. Heavy rainfall will be
possible which could lead to localized flooding. Will mention
the strong to damaging winds and localized flooding in the HWO.
As we head into tonight, the cold front will eventually move
into our northern CWFA where it will become quasi-stationary.
Ongoing convection will undergo a weakening trend as instability
wanes some and overall forcing weakens. It will be warm and
muggy with lows in the lower 70s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Quasi-frontal boundary will remain across our northern forecast
area on Thursday. In a very moist airmass (pwats still 2+
inches), a mid level disturbance (perhaps convectively induced)
is forecast to ripple west to east across our region during the
day. This feature will couple with a modest 850 mb low level jet
to result in the likelihood of showers and thunderstorms,
particularly across our southern two thirds CWFA. With marginal
low end moderate instability, can not rule out isolated strong
to severe convection. Strong to damaging winds will continue to
be the main concern. In addition, heavy rainfall will still be a
concern as well, which may result in localized flooding. Will
mention these threats in the HWO. Clouds and the threat for
additional pcpn will keep highs in the lower to mid 80s. So a
little cooler but still humid.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Weather will be unsettled to start the period as a cluster of
showers and thunderstorms forming under a disturbed westerly mid
level flow is likely to be affecting much of the area on
Thursday night. Threat for thunderstorms continues through
Friday when a cold front trailing Canadian low pressure pushes
through from the west. Strong to severe storms and heavy rain
cannot be ruled out from an environment containing ample
moisture, instability, and winds aloft.

For Saturday and Sunday, high pressure is expected to provide
tranquil weather. The threat for showers and storms returns
Monday and Tuesday as moisture and lift increase ahead of an
upper trough and weak surface boundary.

Temperatures should remain relatively consistent and close to
normal, with highs generally in the 80s each day, and lows
mainly in the 60s.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
For today, Focus will be on the potential for showers and
thunderstorms. A cold front will approach our region from the
northwest late in the day. It will become hot and humid ahead of
this front, leading to moderate instability. Convection
allowing models show varying convective initiation timing and
coverage, so a blended approach will have to be used at this
time. It appears that showers/storms will become induced by
either a remnant outflow boundary/mid level weak disturbance or
subtle prefrontal trof convergence. Have showers/storms
developing in the 18Z to 00Z time frame. Given very moist
airmass, MVFR ceilings and IFR or less visibilities will be
possible in the stronger storms. For now, will put some MVFR
visibilities in the terminals with a period of -TSRA. Gusty
south/southwest winds will gust between 20 and 25 knots this
morning into the afternoon hours, but they should then diminish
between 22Z and 00Z.

For tonight, showers/storms should gradually decrease in
coverage overnight as the cold front pushes south into our
northern forecast area weakens and becomes more diffuse. The
recent rainfall, if it comes to pass, may help to develop some
MVFR ceilings late tonight.

OUTLOOK...MVFR ceilings possible Thursday morning.
Thunderstorms possible Thursday through Friday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Heat Advisory until 8 PM EDT this evening for OHZ053>056-
     060>065-070>074-077>082-088.
KY...Heat Advisory until 8 PM EDT this evening for KYZ089>100.
IN...Heat Advisory until 8 PM EDT this evening for INZ050-058-059-
     066-073>075-080.

&&

$$
SYNOPSIS...Hickman
NEAR TERM...CA/Hickman
SHORT TERM...Hickman
LONG TERM...Coniglio
AVIATION...Hickman