396
FXUS63 KLMK 140000
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
800 PM EDT Thu Aug 13 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Hot and humid conditions continue this afternoon, with heat index
  values near 100 for most. A few isolated showers and storms remain
  possible through the afternoon and evening.

* Thunderstorms are most likely across Indiana and Ohio tonight, and
  could see some storms sneak into our southern IN areas tonight and
  tomorrow morning. Confidence remains low, and overall severe risk
  is low for our area.

* Outside of storms, heat indices are likely (60-80% chance) to
  surpass 100 degrees west of I-75 again tomorrow. The heat and
  humidity peaks Saturday and Sunday, when HeatRisk is forecast to
  reach the Major category area-wide.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 336 PM EDT Thu Aug 13 2026

It is fairly warm and muggy across the region today, with KY Mesonet
stations showing temps reaching the upper 80s and low 90s. The Heat
Advisory still appears to be well placed, with the more consistent
100+ heat indices in our southwest, though there are many locations
hovering right around 100 this afternoon. The advisory will continue
as is and is planned to expire on time at 01z this evening. Due to
the heat and humidity in place, we have been able to become quite
unstable today, with SBCAPE up to 5000 J/kg according to SPC
Mesoanalysis. We`ll continue to see some isolated showers and storms
through the afternoon, though weak shear and a lack of a trigger
mechanism for our area should keep convection isolated and somewhat
unorganized.

For tonight, will be keeping a close eye on the convection moving
across IL/IN as it progresses eastward by tomorrow morning. There is
better agreement from most CAMs that the main axis of heaviest
convection and precip will be across IN and southwest OH into
tomorrow morning, though some of our northeast CWA could get clipped
by this. The HREF LPMM shows this axis of precip well, and shows the
main axis stretching from Davenport, IA to Cincinnati, OH, remaining
just to our north. For our area specifically, Jefferson County IN
would have the greatest chance for any hydro issues, but currently
not expecting enough to warrant a Flood Watch at this time. This
could change with how the evening evolves, but there is not enough
confidence we will end up seeing that much precip. Our FFG numbers
are lower, with 1-hr FFG around 1.25" for areas east of I-65. Not
going to rule out the possibility of a flooding issue tonight, but
again the confidence is higher to our northeast. We talked with WPC
about the moderate risk in the D1 ERO, and we both agreed that it
should probably be trimmed back from our area. However, they are not
planning to update this outlook again until this evening.

Heat and humidity continue to build tomorrow, with highs in the mid-
90s possible, along with uncomfortable dewpoints potentially
reaching 80 in some spots. This set up will yield heat indices well
above 100, possibly peaking over 110 in some areas as well. The one
caveat to this is if we do end up seeing more morning convection and
lingering cloud debris than forecast, that could possibly derail the
temp/heat index forecast tomorrow. We`ll let the current Heat
Advisory run as is this evening, but will likely need to issue a new
one for tomorrow if the forecast remains on track. Tomorrow`s
potential headline will need to cover much more of the area too.

A stationary boundary will be situated across the Ohio River through
tomorrow, and could be the focus for redevelopment tomorrow
afternoon. We`ll have another day of very strong instability, though
shear will likely be very weak.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 336 PM EDT Thu Aug 13 2026

===== Drier Trend This Weekend, But Hotter Temperatures =====

Upper ridging will build across the US over the weekend, leading to
a drier trend for our area. However, this will also lead to much
hotter temps, with daily highs in the 90s both days. With dewpoints
reaching the mid 70s, that will easily yield heat indices between
105-110 both Saturday and Sunday. There is high confidence that
we`ll need a heat headline for the weekend.

===== Precip Chances Return Early Next Week =====

A frontal boundary will shift southward through the Ohio Valley
Sunday night and into Monday, and will likely bring a round of
showers and storms to the area. Any overnight convection Sunday
night will be elevated, but redevelopment Monday afternoon would be
sfc based in a highly unstable airmass. Not a lot of shear expected
then to limit organization, but certainly could see scattered
thunderstorms on Monday.

Tuesday and Wednesday appear mostly dry, with mainly isolated chances
east of I-65 both days. Sfc high pressure will be centered to our
north then, so not going to expect much activity for the mid-week.

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 759 PM EDT Thu Aug 13 2026

Deep convection is sagging southeast over northeastern and eastern
KY this evening. One stronger storm further west is moving over RGA
at the start of the TAF period. Other than brief TSRA impacts at
RGA, the rest of the overnight period looks mostly dry. We could
have a couple showers north of SDF linger for another hour or two
before diminishing.

On Friday, weakening convection diving southeast across central IN
may send out an outflow boundary into southern IN by mid-morning.
Scattered showers and storms appear possible, especially along and
north of I-64, through the mid to late morning hours. However,
confidence is somewhat low in the convective evolution tomorrow.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory until 8 PM CDT this evening for KYZ023-026-061-
     070>073.
IN...None.

&&

$$

SHORT TERM...CJP
LONG TERM...CJP
AVIATION...EBW