394
FXUS63 KLMK 310801
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
401 AM EDT Mon Aug 31 2026

.KEY MESSAGES...

* Highs in the upper 80s and low 90s continue Monday with a stray
  shower possible.

* Major Heat Risk is expected this week due to the multi-day
  duration of hot temperatures with little overnight relief.  Anyone
  without effective cooling or adequate hydration will be
  susceptible to heat illness.

* The upper level pattern may break down toward the end of the week
  as the heat ridge moves west and back into the central Plains.
  This may bring an increased risk of showers and storms for Friday
  and through the weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 358 AM EDT Mon Aug 31 2026

A few high clouds may be around this morning for parts of southern
IN and north central KY as a weak system passes by to our north.
Forecast today will be very similar to what we saw yesterday with
very warm temperatures getting into the 90s. Scattered afternoon Cu
will develop once again and while dew points will start off this
morning in the upper 60s to low 70s, afternoon mixing will help
lower dew points down into the mid to low 60s keeping heat index
values in the upper 90s to just near 100 degrees.

Any clouds that form will diminish with the setting sun and winds
will also diminish becoming light to calm. Lows will remain warm in
the low 70s with mid/upper 70s for more urban locations. Dew points
will also creep back up into the upper 60s to near 70 overnight and
can`t rule out some patchy ground/valley fog by early Tuesday
morning.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 358 AM EDT Mon Aug 31 2026

Tuesday through Thursday Night...

The overall forecast has remained very consistent with the heat
peaking for the middle of the week. Guidance continues to show the
large 594 mid-level ridge building over the Ohio Valley over the
next couple of days. This will keep our weather mainly dry, with
daily highs gradually increasing into the upper 90s with a few
locations possibly reaching the triple digits by Wednesday or
Thursday. Along with the increased in heat, we will see dew points
climb into the upper 60s with a few 70s but we still anticipate dry
air mixing each afternoon and even some scattered mid-level Cu to
also develop. Heat index values will start to get into the low 100s
then near and above Heat Advisory criteria for Wednesday and
Thursday where confidence is growing we will likely need a heat
headline for Tuesday into Wednesday.

Thinking also remains that the hottest temperatures will be in areas
along and west of the I-65 corridor with slightly lower temperatures
as you work east to northeast in the CWA into the Bluegrass and I-75
corridors. LREF heat index probabilities have been pretty consistent
run to run with the probabilities of exceeding 100F at between 40-
60% on Wednesday and 50-70% on Thursday along and west of I-65 with
lower values as you go east and northeast.

What elevates the heat risk with this current heatwave is not only
the duration of several days but the lack of relief of cooling
overnight. Lows will be in the low/mid 70s for most location with
many urban areas only dropping into the upper 70s to near 80
overnight.

Friday through Sunday...

Moving into the late week and into the weekend, the upper air
pattern will start to change slightly.  A large upper trough/closed
low is forecast to plow into the Pacific northwest while the mid-
level ridge over the OV/SE US starts to flatten out and retrograde
slightly to the west.  If this were to occur, our flow will become
northwesterly and we`ll have to watch for perturbations riding
around the ridge which may bring MCSs back into the forecast.  A
fair amount of spread remains in the long range ensembles here
indicating that not all the members are suggesting the ridge
retrograding.  The OP Euro trends have been stronger with the ridge
retrograding and bringing some relief to the region.  For now, 20-
30% POPs out in the Fri-Sun period look reasonable at this time. The
tropics will become more active in this time period and may end up
influencing the pattern than other synoptic scale features.  As such,
the forecast confidence here is lower than average.  For now, we`ll
likely see low-mid 90s on Friday for highs, but things may cool back
into the upper 80s/lower 90s for Sat/Sun, especially if we get
convection back into the forecast.

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 131 AM EDT Mon Aug 31 2026

A weak upper level system passing across northern and central IN
could bring some high cloud over HNB to SDF in the pre-dawn hours
but we will remain VFR for the forecast period. As we continue to be
locked under a persistent pattern featuring strong ridging aloft we
will see nearly identical weather setups each day through the middle
of the week. It remains dry with winds generally out of the south to
southwest. As we heat up, air will mix and increase some of the
winds near the surface so occasionally we could see a few gusts
around SDF/LEX of 15-20 kts in the afternoon and the development of
scattered mid-level Cu in the afternoon before we return to mostly
clear skies and light winds overnight and remaining VFR.

&&

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

&&

$$

SHORT TERM...BTN
LONG TERM...BTN
AVIATION...BTN