342
FXUS63 KLMK 181029
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
629 AM EDT Mon Aug 18 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Hot and humid today and Tuesday. Heat index values of 100-105 are
  likely mainly along and west of the I-65 corridor.

* A cold front will likely bring relief from the heat, along with
  increasing thunderstorm chances, by the middle of the week.

* Below normal temps on the horizon, expected by late this coming
  weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 300 AM EDT Mon Aug 18 2025

Pretty quiet morning across the area with some variable upper sky
cover and a few patches of fog. Most of the fog should stay
contained to the river valleys, but will continue monitor through
the early morning.

Upper ridging extends eastward and establishes more in our region
today. As a result, looking for a hot and dry day with max temps
surging into the low and mid 90s for many. Skies should be mostly
sunny, with the only slightly limiting factor for max heating being
a light NE surface wind. Won`t give those light winds much credit,
and went between the 50-90th percentile NBM for most locations. Dew
points will be highest (low to mid 70s) west of I-65 and this is
where we could yield a few hours of max heat indices around 105 this
afternoon. Decided to go ahead with a Heat Advisory headline along
and west of a line from Scottsville, KY up through Jasper, IN.

Will have to keep an eye on our NW CWA this afternoon where some
lingering surface convergence along a boundary may exist. Forecast
models mostly suggest any activity would be NW of our area across
the Wabash River Valley and into northern IL. As a result, will keep
a dry forecast going but will also monitor that boundary.

Overnight tonight also looks quiet. Looking for more mild conditions
with lows bottoming out in the upper 60s and low 70s for most. Will
have more potential for fog, perhaps a bit more widespread east of I-
65.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 300 AM EDT Mon Aug 18 2025

Tuesday - Thursday...

Upper ridging will begin to lose a bit of influence over our area by
Tuesday as shortwave energy and a weak surface low move through the
Great Lakes region. Looks like we stay warm and dry for most of the
day ahead of an approaching cold front, but do like the idea of
isolated to widely scattered shower and storm chances across our NW
CWA by Tuesday PM, especially the evening hours. Given the expected
mostly dry or dry conditions through peak heating Tuesday, we should
see another hot afternoon with max T`s in the low to mid 90s. Best
chance for dew points above 70F will be along and west of I-65,
where some 100 to 105 max heat indices will be possible. Chance for
a Heat Advisory headline somewhere across our western third to half
of the CWA, but will likely take a wait and see approach as values
look fairly marginal for a headline. Any t-storms developing early
could also play spoiler, but again expecting development to be
fairly late in the day.

The shortwave pushes into New England by Wednesday, with the weak
cold front trailing into our region by this time. This will likely
continue to serve as a triggering mechanism across our area,
carrying over from Tuesday PM. Will continue to carry scattered
chances for the whole CWA on Wednesday. Overall, deep layer shear
looks to be very weak both days, so not expecting any organized
severe threat. Bigger concern would be locally gusty winds from
collapsing storms, and high rainfall amounts given efficient
rainfall and slow storm movement. The good news is that this feature
does provide some "relief from the heat as highs settle back down
into the upper 80s and low 90s.

The frontal boundary is slow to move through, but should be mostly
dry across the area by Thursday. A few showers and storm chances
will have to continue across our SE CWA closer to the front, but
overall not as active as Wednesday. Looking for highs mostly in the
upper 80s by this time as we are more established on the "cooler"
side of the boundary.

Friday - Sunday...

The Friday forecast should be fairly similar to Thursday as we
continue to hold onto some small shower and storm chances across our
SE CWA both from the stalled frontal boundary hanging up down there,
and from a very weak mid level disturbance hanging out across the
TN/mid MS River Valley. By Saturday and Sunday, broad troughing
looks to envelope much of the eastern CONUS, helping to drag a
secondary and much more effective cool front through our region.
Possible that we see a few showers or storms ahead of this feature
as it passes, but overall it looks to be a fairly quiet fropa, with
the benefit of cooler temps behind it. By Sunday, highs look to top
out in the low to mid 80s. Sunday morning lows should feel nice in
the low and mid 60s for most.

&&

.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 628 AM EDT Mon Aug 18 2025

VFR conditions are expected to continue through this TAF period,
although could have some brief visibility restrictions in fog at HNB
for an hour or two this morning. Otherwise, the trickiest part of
the forecast will be surface wind direction. For the most part,
winds should mostly be out of the NE between 5 and 10 mph, but may
have some periods where they vary more toward the E or N. Will
likely see some few-sct cu development this afternoon between 5-6 k
feet, with a few upper clouds also possible at times. Another fog
signal is showing up for tonight for our eastern TAF sites, so
included some MVFR mention at LEX/RGA for this issuance.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory from noon today to 7 PM CDT this evening for
     KYZ023-026-061-070>073.
IN...Heat Advisory from 1 PM EDT /noon CDT/ this afternoon to 8 PM
     EDT /7 PM CDT/ this evening for INZ083-089.

&&

$$

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