891
FXUS63 KLMK 082340
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
740 PM EDT Tue Jul 8 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Isolated to scattered thunderstorms could produce locally gusty
  winds and brief torrential rainfall this afternoon. Storm coverage
  will diminish by this evening.

* Warm and humid all week, with scattered showers and thunderstorms
  expected each day. Organized severe weather is not expected.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 319 PM EDT Tue Jul 8 2025

Weak sfc boundary is along the Ohio River today, with sfc temps in
the upper 80s and low 90s across the forecast area, and dewpoints in
the upper 60s and lower 70s. A cluster of thunderstorms is noted
across western KY, being driven by a pocket of deep moisture
convergence and upper level divergence. Despite marginal
instability, little to no wind shear is keeping any convection
unorganized. PWATs above 1.5" will support some heavy rain rates
near the BWG area. Overall, this cluster of storms is expected to
continue to weaken as it pushes east this afternoon. CAMs have
performed poorly today, so confidence in additional precip outside
of this cluster remains low.

By this evening, the loss of daytime heating will promote a decease
in precip activity. Overnight, mid-level clouds will linger overhead
as we remain under the influence of general troughiness and the weak
frontal boundary. Before sunrise, some patchy fog may develop,
especially in our valleys and any areas that do pick up some rain
this afternoon.

For tomorrow, the weak boundary is expected to dissipate, though we
will remain in a warm and muggy airmass. Stacked shortwave energy is
supporting a sfc low over the Great Lakes, with a trailing cold
front through the Midwest. This front will shift southeastward by
tomorrow, and will be cutting across central IN and IL by the end of
the day. The combination of warm daytime heating and muggy airmass,
along with marginal instability ahead of the front, will support
additional isolated to scattered shower and storm development across
the region tomorrow, especially in the afternoon. Model soundings
suggest PWATS to be above 1.7", suggesting heavy rain possible. Wind
shear will be weak, leading to another day of messy garden variety
storms, with slower storm motions.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 319 PM EDT Tue Jul 8 2025

Upper level troughing will remain over the region for Wednesday
night and into Thursday, with upper ridging centered over the
southwestern US. A second weak cold front will be shifting southward
through the upper Ohio Valley on Thursday, driven by a sfc low
passing over the Great Lakes. Additional showers and storms will be
possible Wednesday night and Thursday as we remain in a warm and
humid airmass. The front is not expected to pass through the
forecast area, likely getting stalled out north of the Ohio River on
Thursday and Friday. This will keep our forecast area in the warm
side of the boundary, with muggy dewpoints and above average PWATs
available for afternoon destabilization as we warm into the upper
80s and lower 90s. Diurnally-driven storms will fire off in a
marginally unstable environment, but weak flow in the column will
keep wind shear weak. This will promote storms to be unorganized,
though should be capable of producing heavy downpours and gusty
winds.

As we get into the weekend, the frontal boundary will lift north of
the region, though additional shortwave energy will lead to another
sfc low to track across the Great Lakes, and trail an associated
cold front through the Midwest. We will remain warm and muggy, with
highs both Saturday and Sunday in the upper 80s and lower 90s, and
dewpoints in the lower 70s during peak heating. Shower and storm
chances will continue each afternoon for the weekend and into early
next week. Precip coverage is expected to diminish into the
nighttime hours as we lose heating each day.

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 739 PM EDT Tue Jul 8 2025

Most of the shower and storm activity has pushed to the south and
east of the region at this hour, and dry, VFR conditions are
expected through the evening and early overnight hours. Mid- and
upper-level cloud debris from convection to the west and southwest
will move over the region later tonight, though this may not be
enough to keep the typically foggy spots (i.e., HNB and BWG) from
seeing visibility drops before dawn Wednesday. Winds should be light
and variable overnight. For the day on Wednesday, predominantly VFR
conditions are expected. Brief MVFR ceilings are possible depending
on how much mixing occurs before the cu field develops. Otherwise,
the main thing to look out for will be isolated TSRA during the
afternoon and evening hours.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

$$

SHORT TERM...CJP
LONG TERM...CJP
AVIATION...CSG