903
FXUS63 KLMK 110953
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
553 AM EDT Fri Sep 11 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Rounds of showers and thunderstorms will continue today and
  Saturday. Any storm will be capable of brief intense rainfall
  where localized flooding concerns could develop. Most folks can
  expect .5" to 1" additional rainfall, however localized amounts
  over 2-3"+ are possible.

* Overall drier and hotter conditions arrive early next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 247 AM EDT Fri Sep 11 2026

Deep moisture with PWATs in the 2-2.25" range continues to pool
along a nearly stationary WSW - ENE oriented surface boundary
stretching from the Red River Valley up through the mid Atlantic
states. The boundary currently bisects our CWA with clusters of
showers and storms in the vicinity. Overall deep layer shear is
pretty weak on the order of 15-20 knots through the 0-6 km layer.
However there is moderate instability evident on forecast soundings.
A near-surface stable layer should keep the storms elevated and
limit any damaging wind threat, although did see one storm over
western KY recently develop a hail threat. Outside of that, the main
concern early this morning will be for locally heavy rainfall thanks
to efficient rainfall rates in this moist and unstable atmosphere.
The bulk of the activity should stay across southern and central KY.

We`ll keep isolated to widely scattered chances for showers and
storms in the forecast for today high moisture content combines with
moderate instability. Tough to define any strong triggers for today
so there will likely be extended periods of dry between bouts with a
few showers and storms. Should be a decent temperature gradient from
the low 80s across the northern CWA to the upper 80s across southern
CWA.

By tonight, a shortwave is expected to slowly eject out of the mid
Mississippi River Valley, and this could contribute to an uptick in
convective coverage from W-E as we go through the overnight.
Confidence is lowered a bit by the loss of daytime heating, however
there will still be elevated instability to work with based on
forecast soundings. There could be a continued locally heavy rain
threat with any of these showers and storms.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 247 AM EDT Fri Sep 11 2026

Saturday - Saturday Night...

Another slow-moving shortwave will cross the Ohio Valley region on
Saturday. Ahead of the feature, deep moisture with ~2" PWATs will
pool over our area, along with moderate instability spread through a
tall/skinny CAPE profile. As a result, look for scattered to
numerous slow moving heavy showers and storms on Saturday. The slow
storm movement, high moisture content, and freezing levels over 15 K
feet will create efficient rainfall rates which will result in some
localized precipitation totals of 2"+ possible. 11/00z HREF data
continues to suggest some PMM/LPMM data closer to the 48hr QPF max
which suggests that higher end of the QPF envelope withing the
ensemble is possible. Something to keep an eye on. Highs on Saturday
look to range in the low to mid 80s.

The shortwave trough axis will push eastward Saturday night,
shutting off the deeper moisture. Convection will diminish with a
dry rest of the overnight expected. Lows should fall off into the mid
and upper 60s.

Sunday - Tuesday...

Strong upper ridging from the southern CONUS will re-center eastward
over the SE CONUS through early next week, with increasing upper
ridging influence over the Ohio Valley as well. This will trend our
forecast much drier along with increasing temperature back above
normal. Highs in the mid and upper 80s on Sunday will give way to
highs in the upper 80s and low 90s by Tuesday. Will also go with dry
Pops during this time.

Wednesday - Thursday...

Upper ridging will stay centered over the SE CONUS through mid week,
however this is a bit of uncertainty whether it will hold influence
over our area, or weather it breaks down a bit allowing a surface
front to sink southward toward our region. The trend has been
stronger with the ridge, and overall drier/hotter conditions
continuing through mid week. However there is some data that
suggests the front drops close enough to us that we are able to
spark some showers and storms over southern Indiana and perhaps
northern KY. Will play the middle ground here and mention some
isolated shower and storm chances across our northern CWA, but will
also keep pretty warm temperatures in around 90 degrees. If the
drier trend prevails, look for hotter temperature more solidly into
the 90s.

Extended Forecast Discussion...

The month of September is off to a hot start.  Thus far we`re
running about +8.5F above normal at SDF, +8.6F at BWG, and +7.6F at
LEX.  We`re likely to keep those above average temperatures going
due to the expected warm period of weather for much of next week.

Looking at the hemispheric scale, we`re starting to see some
interesting changes on the horizon.  Quite a few of the extended
models and ensembles are indicating a cool down for our area as we
enter late September, probably after the 20th or so.  The forcing
mechanism behind that appears to be a combination of factors that
may come together.  The Euro and its ensembles have been fairly
intent on developing a strong area of high pressure over western
Asia just north of the Himalayas.  If this occurs, we`ll get a
strong pressure gradient there which will result in a good amount of
momentum transfer into the atmosphere.  Global atmospheric angular
momentum charts really ramp up over the next 2 weeks and this should
lead to a Asian jet enhancement and eventually a Pacific jet
extension and enhancement.  The downstream affects here would lead
to a stronger ridge over AK and a +PNA pattern.  Downstream, decent
troughing looks to develop across the eastern CONUS.  Interestingly
enough, the west Pacific looks to be favorable for continued typhoon
activity and we`ll be watching for any typhoons that recurve and
merge into the Pacific Jet which could yield stronger impacts to the
flow over the CONUS later this month. Considerable uncertainty
remains as to how much the pattern will flex, but confidence is
increasing that seasonal fall air will be possible across our area
for late September into October.

&&

.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 553 AM EDT Fri Sep 11 2026

Clusters of showers and storms continue to ride along a WSW to ENE
surface front this morning, with most of the activity expected to
stay along and south of the Ohio River. Ceilings should steadily
improve by late morning into midday, however a few sporadic showers
and storms could be around this afternoon and  at times overnight.
Used Prob30s to message these. VFR does prevail from afternoon
onward, outside of any rogue shower or storm activity. Winds are
tricky through this period and will be light and variable at times.
The SE surface will be most likely to prevail early in the period.

&&

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

&&

$$

SHORT TERM...BJS
LONG TERM...BJS/MJ
AVIATION...BJS