325
FXUS63 KLMK 142346
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
746 PM EDT Fri Aug 14 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Hot and humid conditions into the weekend with highs in the
  low/mid 90s with heat index values up to 108 degrees both days.
  Heat Advisory is in effect this weekend for a large portion of
  southern IN, central and southern KY.

* Isolated thunderstorm chances this afternoon and evening (20-30%
  chance). There is a low end chance of any storms being strong to
  severe with gusty winds the main threat.

* Additional storms are possible (20-30% chance) across areas mainly
  east of a Salem, Indiana to Richmond, Kentucky line tomorrow
  afternoon and evening. Any storms that form could be severe with
  damaging winds and large hail.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 325 PM EDT Fri Aug 14 2026

The bulk of the rain and thunderstorm activity today has been mainly
across central Indiana along a stalled frontal boundary. But we`ve
seen a few isolated showers and thunderstorms try to develop along a
lingering outflow boundary that is currently cutting across the CWA
along and near both the Western Kentucky and Bluegrass Parkways.
There is also a second outflow boundary closer to the KY/TN border.
Both of these boundaries can be seen on the visible satellite
imagery. While SPC has the area under a marginal risk for severe
weather (level 1 of 5) the dynamics are marginal at best. Wind shear
is to the north along the boundary and the cloud cover to the north
has created a west to east instability gradient across the county
warning area (CWA). Isolated convection is expected through the
remainder of the afternoon and evening which is in general agreement
with most of the CAMs and short range model guidance.

The other story today has been the heat and humidity as a Heat
Advisory will continue through the afternoon and early evening
before being allowed to expire around 9pm EDT/8pm CDT. Many
locations in the Heat Advisory have had heat index values above 105
degrees with areas to the north within the cloud cover in the
low/mid 90s for heat indices.

As we go overnight, any convection that develops in the evening will
be diminishing and we should mostly clear conditions. It will remain
warm and muggy with lows in the low/mid 70s.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 325 PM EDT Fri Aug 14 2026

***** HEAT AND HUMIDITY THROUGH THE WEEKEND *****

The main weather impact for the weekend will be temperatures warming
into the mid/upper 90s as upper level ridging expands northward over
the Ohio Valley into the Great Lakes and the stalled frontal
boundary currently over central IN lifts northward towards northern
IN and southern MI tomorrow. Because of this, a second Heat Advisory
was issued for Saturday morning into Sunday evening for most of the
CWA with heat index values up 108 degrees when you factor in
dewpoint values into the mid/upper 70s both Saturday and Sunday.

The main limiting factor to the heat, especially across the
Bluegrass and our far eastern CWA will be cloud cover and the
potential for showers and thunderstorms especially on Saturday.
Models continue to highlight an MCS over IA and northern IL at the
start of the day tomorrow. This activity is then forecast to work
along the boundary and dive southward out of eastern IN towards
Cincinnati in the afternoon extending into the far northeastern
portion of our CWA. The other thing we would need to watch will be
any outflow boundaries that form and work southward into southern
IN. These boundaries could be enough lift to fire off some limited
convection. SPC does have portions of our CWA, Harrison and Nicholas
counties under a Slight Risk or level 2 out of 5 for severe weather
as there will be a little better bulk shear for possible gusty winds
and hail with a Marginal risk extending back to the west from
Louisville down to Somerset. Overall confidence in severe and even
storm threat remains low.

The next potential threat for storms will come with an approaching
boundary Sunday night into early Monday morning. Timing is still in
question but we do have an SPC Day 3 Marginal Outlook for central KY
and southern IN with the main threat being strong gusty winds. Due
to the timing questions, confidence is rather low at this time but
does need to be monitored as we go through the first part of the
weekend.

***** LESS HOT, MORE STORMY TO KICK OFF NEXT WORK WEEK *****

A shortwave trough looks to flatten the ridge late Sunday into
Monday, bringing better (40-70%) chances for storms as early as
Sunday night, and perhaps offering at least limited relief from the
oppressive heat and humidity Monday into Tuesday. WPC Cluster
analysis suggests that, by midweek, the highest source of
uncertainty among long range ensembles (given by PC1 for EOF1) is in
the east-west placement of h5 ridging building over the central US
and hence: whether our area sees (outcome 1) oppressive heat return
or (outcome 2) remains far enough northeast of the ridge to instead
see more seasonable temperatures and waves of "ridge-riding"
thunderstorms. About 50% of models favor each scenario.

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 744 PM EDT Fri Aug 14 2026

VFR conditions are likely through this TAF period. Conditions will
remain mainly dry overnight, with FEW-SCT high clouds and very light
winds. SW winds of 5-8 kts will develop after 15Z Saturday. Saturday
looks to be mainly hot and dry, though there is a 20% chance for an
isolated storm near and northeast of LEX during the afternoon and
evening hours. However, coverage looks too low to include in the TAF
at this time.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory from 11 AM EDT /10 AM CDT/ Saturday to 9 PM EDT
     /8 PM CDT/ Sunday for KYZ023>031-034-038-039-045-046-053-
     054-061>065-070>077-081.
     Heat Advisory until 9 PM EDT /8 PM CDT/ this evening for
     KYZ023-024-026>028-053-054-061>065-070>077-081.
IN...Heat Advisory from 11 AM EDT /10 AM CDT/ Saturday to 9 PM EDT
     /8 PM CDT/ Sunday for INZ076>078-083-084-089>092.

&&

$$

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