625
FXUS63 KLMK 311901
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
301 PM EDT Sun Aug 31 2025

.KEY MESSAGES...

* Isolated daytime shower and thunderstorm chances return across
  southern KY for Labor Day, and then all other locations through
  mid to late week.

* Best chance for .5" to 1" of rainfall will be across southern
  and eastern KY.

* A strong front will bring another shot of cool and dry air to the
  region late week through the weekend.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 300 PM EDT Sun Aug 31 2025

Quiet rest of the day and into the overnight this stretch of
pleasant temperatures and dry conditions continues. Highs peak in
the upper 70s and low 80s for most today, although southern KY will
see a few mid 80s. Look for overnight lows in the low to mid 50s
with a light NE surface wind and occasional periods of upper sky
cover.

Monday starts off dry, however we do have some scattered chances for
afternoon/evening showers and storms developing south of the
Parkways where a well-advertised inverted surface trough will set
up. This feature will act as focus for PM convective development as
HREF probabilities of at least 500 J/KG of ML CAPE appear to set up
south of the boundary. Not a lot of instability, so expect anything
that fires to be mostly showers, with a few storms possible. Not a
lot of deep layer shear, so storm motions will be pretty slow. Areas
north of the Parkways will likely stay dry with slightly warmer
temperatures more solidly in the lower 80s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 300 PM EDT Sun Aug 31 2025

Monday Night - Thursday...

The upper pattern will feature troughing over the eastern half of
the CWA through mid week, with individual shortwaves rotating
through the mean flow and bringing rounds of showers (and perhaps a
few storms) to our area. At the surface, a well-advertised inverted
surface trough will be in position over our SE CWA Monday night, and
will lift to the NW a bit through Tuesday. This feature, along with
one of the subtle shortwaves embedded in the flow will provide the
focus/trigger for some scattered showers and perhaps a few storms
Tuesday through Wednesday. Overall, coverage likely won`t get past
scattered, and temps will remain below normal mostly in the 75 to 80
degree range for highs.

By later Wednesday night into Thursday, an intense shortwave (trop
fold down to 550mb!) will dig into the parent trough over the upper
Great Lakes region, closing off into anomalously deep sub-540 H5
heights. H5 anomalies are in the -4 to -5 standard deviation range!
Ahead of this more impressive shortwave trough axis, we`ll see
better forcing and better deep moisture return. The positive tilt of
this shortwave won`t allow the deepest moisture return for a truly
substantial rainfall, but at the very least we should see numerous
to widespread showers and a few storms. For context, PWATs look to
rise around 1.5 to 1.6" through the column, which is about 60-75th
percentile for this time of year.

Best coverage now looks to be through the day on Thursday, where
rainfall totals through the week look to cap off around .5" to 1"
along and south of the Western Kentucky/Bluegrass Parkways, and
likely less than a half of an inch north of that line. Given these
values, drought conditions will likely maintain or worsen this week
given the several days of dry we`ve had since the last outlook
update. The overall deep layer shear profile does improve ahead of
this impressive trough and its associated cold front, but really
won`t see the instability needed to be too concerned about any
strong storms at this point. Something we`ll monitor. Highs on
Thursday likely only reach into the low to mid 80s for most.

Thursday Night - Friday Night...

The cold front passes by Thursday evening/night with steady cool
advection in its wake. Recently, this late week period had looked
dry, but now models suggest that another shortwave could quickly
race into our area depending on how the closed low wobbles/fujiwaras
with it as it digs. This is technically a clipper system that will
bring a final and reinforcing shot of cool (cold for this time of
year) air behind it. We`ll keep a dry forecast for now, until we see
exactly how that interaction will take place. The bigger story will
be the cooler air. At the moment, it doesn`t look like we`ll break
records, although we could flirt with a few of them Friday and
Saturday mornings.

Saturday - Sunday...

Canadian high pressure builds into the area for the heart of the
weekend with with dry NW flow aloft holding. This will be a dry
pattern with initially cool temperatures trying to moderate. After
highs on Saturday only around 75 to 80, temps on Sunday recover to
the low and mid 80s for most. Still a touch below normal.

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 148 PM EDT Sun Aug 31 2025

VFR conditions are expected to continue through the forecast
period as strong high pressure centers to our north. Look for steady
NE surface winds again today mostly between 5 and 10 mph. A few
gusts up around 15 to 20 mph will be possible through the afternoon.
Winds slacken a bit overnight, but will remain light out of the NE.
Surface winds on Monday take on a more ENE to E component and
overall lighter between 5 and 10 mph. Look for a few periods of
upper sky cover at times over the next 24 hours.

&&

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

&&

$$

SHORT TERM...BJS
LONG TERM...BJS
AVIATION...BJS