239
FXUS63 KLMK 081033
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
633 AM EDT Tue Sep 8 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Mostly dry and warmer today. A few light showers possible later
  this morning through the daylight hours. No T-storms expected.

* The hottest day of the week will be Wednesday with highs in the
  low to mid 90s and peak heat indices in the low 100s along and
  west of I-65.

* A cold front arrives Thursday morning with 80-90% chance of
  showers and a few storms possible. Fairly widespread rainfall
  between .25" - .75" is expected with locally higher amounts over
  1" possible, especially along and north of I-64.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 254 AM EDT Tue Sep 8 2026

Strong upper ridging continues to dominate the southern CONUS today,
with plenty of influence extending through the Ohio River Valley.
Surface high pressure will be centering over the mid Atlantic, which
will allow a steady SSW wind to develop this afternoon. Given the
upper ridge and a steady warm advection component, temps are
expected to be warmer than yesterday as they climb back to the upper
80s and lower 90s. Fairly rich low level moisture could contribute
to a bit more cloud cover than anticipated this afternoon, and that
would be the only limiting factor to realizing these above average
temps.

We should be mostly dry under this pattern, however we`ll still be
dealing with the inverted surface trough lingering from yesterday.
This feature will continue to contribute to an axis of ~70F Tds
stretching SW-NE through the area which will allow for a roughly
~500 J/KG instability axis along with some weak but persistent
surface convergence. This will likely be enough to trigger some
isolated showers later this morning into the afternoon, however
forecast soundings show a notable H7 inversion, which is supported
by the upper ridge pattern. Given that feature, any vertical
development will only make it a few thousand feet. As a result, will
only carry the shower mention without any thunder forecast. Most
will stay dry with the most likely area for a few showers across our
southern or SW CWA. Any showers will die off with the loss of
heating tonight. Lows will find their way down to the upper 60s and
low 70s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 254 AM EDT Tue Sep 8 2026

Wednesday - Thursday Night...

Elongated upper ridging will be in control across the southern half
of the CONUS on Wednesday, with a belt of zonal westerlies
controlling the northern half of the CONUS. At the surface, a
notably strong pressure gradient will exist across the Ohio River
Valley between surface high pressure anchored off the mid-Atlantic
coast and a strong surface low over eastern Canada. This will give
us a steady to occasionally gusty SW flow with peak gusts likely in
the 20-25 mph range through the afternoon. This will be the hottest
day of the period with temps warming into the low and mid 90s across
the area. Dew points are also expected to "pool" across our NW CWA a
bit ahead of the approaching cold front, but this will also be the
area closes to upstream convection and afternoon cloud cover could
play a limiting role. Regardless, max heat index values will be into
the triple digits along and west of I-65 at some point Wednesday
afternoon. For now, looks like we`ll stay just short of any headline
criteria for most of the area, but will continue to monitor T/Td
trends as it will be close in our NW CWA.

As we move into later Wednesday evening through Thursday, we`ll deal
with fairly widespread convective activity along a cold front
trailing from the aforementioned eastern Canada surface low. Fairly
impressive late summer speed shear profile (25-35 knots) will be in
place across our northern CWA thanks to strong mid to upper level
jetting, and a decent low level jet response. If we do get a
stronger updraft, then this would be sufficient for some
organization, and perhaps an isolated strong to severe threat. Main
problem is that instability looks pretty meager later Wednesday
evening into Wednesday night. By the time modest instability
develops on Thursday, the overall shear profile is a bit weaker
across central and southern KY. Can`t rule out a few strong to
severe storms later Wednesday evening into Thursday, but overall not
real impressed with the overall scenario, and SPC Marginal Risk
seems appropriate.

Will also have to watch for the potential for a few swaths of
heavier rain through Thursday night, even if it might be welcome in
most locations. The overall orientation of the deep layer shear
profile will be roughly parallel to the surface frontal boundary,
and this could allow for some training/repeated rounds of showers or
storms. 07/12z LREF data did increase probabilities of over 1" of
rain from 10-15% to 20-40% along and north of the I-64 corridor.
This is a notable increase, and have also noted that a few of the
deterministic models show some isolated swaths of 2-3". These values
still aren`t overly concerning given how dry we`ve been, but
nevertheless something to monitor for trends.

Friday - Monday...

The late week into the weekend time frame now looks a lot more
active than it did 24 hours ago as the overall frontal progression
has slowed, and now lingers across KY into the weekend. In addition,
a slow moving shortwave on the southern end of the stronger belt of
westerlies looks to meander out of the southern Plains into the
Tennessee Valley, and could be a spark for additional diurnally driven
showers and storms through the weekend mainly across central and
southern KY. Will keep lingering iso-sct chance pops in the forecast
through the weekend to account for this.

After a brief cool down with temps in the low and mid 80s behind the
front on Friday, max T`s should quickly recover to the upper 80s to
around 90 through the weekend.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 633 AM EDT Tue Sep 8 2026

VFR is expected to prevail through this forecast cycle, although a
couple of minor weather impacts worth noting. Expect Sct-Bkn clouds
around 4-5 K feet to increase through the morning as a weak surface
boundary focuses low level moisture over the area. Light SE winds
early this morning will give way to more steady SSW winds later
morning into the afternoon. A few gusts up between 15 and 20 mph may
be possible. In addition, a few isolated showers could develop from
late morning into the afternoon, although confidence and coverage
are too low to include mention. Ceilings gradually rise and scatter
out through late afternoon and early evening, however VFR conditions
continue to prevail.

&&

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

&&

$$

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