828
FXUS63 KLMK 172325
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
725 PM EDT Sun Aug 17 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Hot and humid Monday 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 next week.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 344 PM EDT Sun Aug 17 2025

Outflow boundary associated with the overnight MCS that worked out
of central IN has worked into northern TN and took most of the
convective activity with it. While there is still a small chance of
an isolated shower or storm this afternoon, most will remain dry the
rest of the afternoon and through the overnight. It remains hot and
humid with temperatures this afternoon ranging from the upper 80s
thanks to the rain and clouds from earlier to some places in the
low/mid 90s. Behind the outflow boundary, the atmosphere was able to
mix allowing for a little better northerly breeze which helped to
also knock dewpoint temperatures down into the low 70s and upper
60s. While still hot, heat index values have ranged from the
mid/upper 90s across northern/central KY and southern IN to low 100s
across south central KY. Skies will clear overnight and winds will
diminish some but remain warm with lows in the upper 60s/low 70s
except in our urban heat island locations.

Upper ridge axis expands more eastward over the Ohio Valley. This
looks to be the driest and hottest day during this stretch. We will
lack any real trigger with no lingering outflow boundary and expect
to be mostly sunny. Dewpoints will be in the low 70s and with highs
again in the mid to upper 80s, we will see heat index values between
100-105. A few isolated locations could see heat index values over
105 but confidence was not high that we would see widespread
criteria heat index values. Decided to not issue any heat headlines
at this time.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 344 PM EDT Sun Aug 17 2025

Our hot and humid weather continues for one more day as we go into
Tuesday. With Hurricane Erin working northward over the western
Atlantic, and a shortwave trough working over the top of the ridge,
and dropping southeast across the Great Lakes into the Northeast US,
we will start to see a change in our hot and humid weather pattern.
As the trough moves through the region on Tuesday into Wednesday, a
sfc cold front will work out of the Upper Midwest and into the Ohio
Valley Tuesday night into Wednesday, resulting in slightly "cooler"
temperatures for the second half of the week with daily highs closer
to seasonable normals near 90.

Tuesday will feature highs once again in the low/mid 90s with heat
index values ranging between 100 to 105 in the afternoon. As the
aforementioned cold front approaches from the northwest, we will
see an increase in showers and storms mainly across southern IN and
western KY with better shower and storm coverage on Wednesday as the
cold front works across the Commonwealth.


Tuesday that ridge gives way to a shortwave diving southeast across
the Midwest. This trough should allow better coverage of later
afternoon/evening storms. Ahead of those storms, we`ll see another
hot day, potentially with some areas into Heat Advisory range. Rain
chances continue into Wednesday. resulting in slightly "cooler"
temperatures

Seasonably warm, late summer temperatures are expected through the
end of the week and with mostly dry weather. Can`t completely rule
out a chance of an isolated or scattered afternoon showers or storm
during the heating of the day, but for now, most of the forecast
beyond Wednesday into the weekend looks dry.

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 725 PM EDT Sun Aug 17 2025

VFR conditions are expected through this TAF period. Light and
mostly variable winds overnight. Convective debris clouds will
stream overhead before thinning out in the early morning hours. Some
patchy fog development is possible, though confidence is low given
light winds. Therefore, fog has not been mentioned in the TAFs.
Monday, winds will pick up out of the northeast between 5-8kts.

&&

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

&&

$$

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