474
FXUS61 KILN 030610
AFDILN

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

.SYNOPSIS...
Hot and humid conditions are expected on Wednesday 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 /THROUGH TONIGHT/...
Ongoing fcst remains on track this evening as /mainly/ clear
skies, aside from a few 4-5kft clouds from time-to-time, evolve
through the near term period. Temps are running about 10-12
degrees above 24 hours ago and this pattern will maintain itself
through the night as better LL moisture works its way into the
local area. Expect conditions will remain dry locally through
sunrise, with southerly winds increasing subtly toward daybreak.

PREVIOUS DISCUSSION... Weather remains quiet across the area
this afternoon with temperatures topping out in the upper 80s to
lower 90s.

A weak, low-level trough is moving northward on the western
periphery of the surface high pressure to the east, pumping
better boundary layer moisture northward through
central/northern Kentucky. Most dewpoints in the area are in the
50s, but mesonet stations across Kentucky are already
indicating mid to upper 60s dewpoints entering the local area.
Light southerly flow will continue to usher in this better
moisture over the next few hours before flow becomes more
southeasterly this evening. This tongue of moisture will be
directed northwestward, combining with the better surface
moisture ahead of the approaching front. This moisture will be
critical for humidity and thunderstorm development tomorrow
afternoon.

Even with the better moisture entering the area this evening,
no rainfall is expected with forcing remaining quite weak. After
the afternoon cumulus dissipates, a few scattered upper level
cloud linger into the early evening. Eventually, skies will
clear with temperatures dropping into the upper 60s and lower
70s.

&&

.SHORT TERM /THURSDAY/...
There is some potential for showers and thunderstorms to be
ongoing early Wednesday morning across central Indiana. Whatever
remnant activity moves into central Indiana will struggle to
survive into the local area due to the corridor of lower
dewpoint values across eastern Indiana and western Ohio. Even if
the thunderstorms weaken, outflow boundaries and cloud debris
will play a role in temperature and rainfall forecasts later in
the day. At the same time, low level moisture will continue to
improve (low 70s and perhaps mid 70s) as the convergence
increases along the boundary. The increasing moisture and
forcing along the front/other boundaries will ultimately lead to
thunderstorm development during the afternoon and through the
evening. All three of the below impacts remain noted in the
HWO...

Heat: Confidence is fairly high that cloud debris will enter
the area through mid-morning. Depending on how quickly this
clears, some disruption to heating will be possible.
Additionally, low- level moisture will be increasing during the
day. Given this uncertainty, local heat conditions may rapidly
change from the mid-morning hours into the early afternoon.
Then, developing thunderstorms may quickly erode heat advisory
conditions that have ultimately developed. The most likely area
for a short- fused heat advisory would be across northern
Kentucky, southwest Ohio, and southeast Indiana.

Severe: Day 2 Slight Risk (Level 2 of 5). With the heating and
increasing boundary layer moisture, clusters of strong to severe
storms are possible Wednesday afternoon and evening. Damaging
wind gusts are the main threat with some hail possible if an
updraft split is able to change mean storm motion. At this time,
downburst winds appear to be the more likely storm mode with
limited ability for organization into bowing segments.

Heavy Rain/Flooding: While much of the area remains quite dry,
stalled boundaries situated in a very moist atmosphere, in July,
should always be viewed as potential heavy rain producers.
Ultimately, storm mode and boundary orientation remain the key
factors. The latest 18Z HRRR shows how some back-building
activity could provide isolated corridors of 2-3"+ into the
evening hours. This would be beneficial rain for the abnormally
dry conditions, but a few flood advisories may be possible in
the heavier/more flood prone areas.

Thunderstorm coverage is expected to decrease a little during
the overnight activity, but continue mid-level forcing and
remnant instability will keep the threat lingering into Thursday
morning.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
East-west oriented front will extend across the area at the
beginning of the period. High precipitable water and deep warm
cloud depths will extend along this same corridor. As a short
wave moves across the area, showers and thunderstorms will occur
with heavy rain potential and perhaps some damaging winds being
the concern. Exactly where that boundary sets up, which latest
data suggests will be near I-70, will have a greatest threat of
heavy rain with the possibility of training and backbuilding.

As that impulse moves off to the east, there will be a relative
lull in showers and any storms through late Thursday night.
During this time the boundary will lift north. More showers and
storms will occur Friday, especially in the afternoon in part
due to a pre- frontal trough pushing through the area. Airmass
will be the same as on Thursday, so locally heavy rainfall will
remain possible although convective elements will be progressive
and less prone to training. Damaging wind threat will also
persist.

The cold front will not move through until Friday evening with
the chance of showers and thunderstorms lingering until that
passes. High pressure will build in for the weekend and still be
influencing the region into Monday. The next cold front will
approach and move through the area Monday night into Tuesday
bringing the next chance of showers and thunderstorms.

Warm, muggy airmass ahead of the first cold front will get
replaced by something more seasonal for the weekend. But
temperatures and dew points will be rising again early next week
ahead of the next system.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are expected overnight as a mixture of a FEW-SCT
cumliform clouds mix with high level convective debris blow off
from storms upstream in the middle Mississippi River Valley.
Southerly winds will increase some overnight to 10 to 12 knots
with gusts up to 20 knots possible by 12Z. There will be a brief
period of LLWS at KDAY/KILN/KCVG/KLUK where south/southwest
winds of 40 knots at 2000 feet will be possible by a transient
low level jet.

For today, LLWS threat will end around 12Z. Otherwise, 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
predominant showers with a VCTS/CB until timing can be better
pinpointed. Gusty south/southwest winds between 20 and 25 knots
will continue into the afternoon, then diminish between 22Z and
00Z.

For tonight, showers/storms should gradually decrease in
coverage overnight as the cold front pushing 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 and visibilities late tonight.

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

&&

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

&&

$$
SYNOPSIS...Hickman
NEAR TERM...KC/McGinnis
SHORT TERM...McGinnis
LONG TERM...
AVIATION...Hickman