675
FXUS63 KLMK 261809
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
209 PM EDT Thu Jun 26 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Heat and oppressive humidity continue, with a Heat Advisory in
  effect at least through today.

* Increasing coverage of afternoon thunderstorms Friday through the
  weekend.

* Very warm temperatures continue well into next week, but a weak
  cold front brings lower humidity by Wednesday.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 336 AM EDT Thu Jun 26 2025

Heat and humidity will remain in full force today as the upper ridge
axis still sits east to west across Kentucky. Forecast is largely
"rinse and repeat" with isolated diurnal convection and max temps
perhaps falling a degree or two short of Wednesday`s highs. That is
still enough for the 5th or 6th consecutive day (depending on which
part of the area) of triple-digit heat index values. Heat Advisory
looks good through at least the end of today. Still no relief
tonight outside of late-day storms, with Friday morning lows mainly
in the lower/mid 70s, while urban Louisville struggles to drop below
80.

By Friday the upper low currently between Florida and the Bahamas
lifts across the Okefenokee Swamp, and a shortwave trof pushes
across Wisconsin, both of which will serve to pinch off the upper
ridge. We`ll still be quite hot and humid Friday, but with the ridge
starting to break down we`ll see increased coverage and earlier
development of diurnal convection. This limits confidence in
maintaining triple-digit heat index values for enough of the day to
warrant extending the advisory at this time. That being said, later
shifts may need to carry the advisory into Friday for at least part
of the area.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 336 AM EDT Thu Jun 26 2025

The weekend will feature what is best described as a weakness in the
upper ridging, which will allow for scattered, mainly diurnally-
driven convection each day. While it won`t be as oppressively hot as
most of the week has been, highs could still top 90 any place that
manages to avoid convection through the peak heating of the day.

Tuesday, model agreement continues to look fairly good as the
global models begin to form a ridge over the Rockies and a trough
over the East Coast. Northwest flow over the Lower Ohio Valley will
push a cold front through the CWA, bringing a line of showers and
thunderstorms with it. Shear continues to be weak, but stronger wind
gusts become more likely during the afternoon and evening hours. By
Wednesday a broad upper trof over the eastern CONUS and a sfc high
building SE from the Upper Midwest will bring temperaturss near
normal, but more importantly manageable dewpoints in the mid 60s.

&&

.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 209 PM EDT Thu Jun 26 2025

Mostly VFR conditions will continue as upper ridging and surface
high pressure remain over the Lower Ohio Valley. The exception could
be if one of the isolated to scattered storms directly hit an
airfield this afternoon/evening. Coverage remains limited, but we
continue to see these storms develop over urban heat and propagate
along outflow boundaries. Winds are generally out of the southwest
and are expected to back towards the south tonight.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory until 8 PM EDT /7 PM CDT/ Friday for KYZ023>043-
     045>049-053>057-061>067-070>078-081-082.
IN...Heat Advisory until 8 PM EDT /7 PM CDT/ Friday for INZ076>079-
     083-084-089>092.

&&

$$

SHORT TERM...RAS
LONG TERM...RAS
AVIATION...KDW