802
FXUS63 KLMK 010745
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
345 AM EDT Tue Sep 1 2026

.KEY MESSAGES...

* Highs in the low to mid 90s continue Tuesday as heat builds this
  week. Chances for heat indices above 100 degrees are highest
  within the Heat Advisory Tuesday through Thursday, being near a 60-
  90% chance of occurring.

* Major Heat Risk is expected from Tuesday through at least
  Thursday. Depending on possible lack of storms, Friday may be
  included in this as well.

* A deepening trough will try to push chances for storms into our
  area Friday evening and Sunday as well.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 344 AM EDT Tue Sep 1 2026

Heat Advisory is in effect today and will continue through at least
Thursday and may need to be extended until Friday.  Currently, the
Heat Advisory includes all areas along and west of I-65 and
locations along and north of I-64 up to Franklin County. It does not
include Lexington or areas along and east of the I-75 corridor.
Depending on how temperatures warm today, we may need to expand the
Heat Advisory further to the east.

Our prolonged heat wave continues as the strong 594 upper ridge
positions itself right over the Ohio Valley and the Commonwealth of
KY. Highs have gradually increased over the last couple of days and
we expect that trend to continue with highs into the mid to upper
90s today into the middle of the week. It`s not out of the realm of
possibility we could have a few locations by Wednesday, Thursday or
even Friday hit 100.  Dew points continue to be in the upper 60s to
low 70s but the expectation remains, as it has been the past couple
of days, that as we approach peak afternoon heating we will start to
see dry air mixing which will help lower dew points into the mid
60s. Even with the mixing, as temperatures continue to gradually
increase, heat index values will start to reach 100 degrees and
could start to see more heat index values climb to near 105.

The other aspect of this heat advisory is the wet bulb globe
temperature. Unlike heat index that only accounts for the moisture
in the air and air temperatures in the shade, the wet bulb globe
temperature or WBGT also factors in sun intensity. These values
start to reach the upper 80s which means that working or exercising
in direct sunlight will stress your body after 20 to 30 minutes. It
is also possible that by Thursday and Friday we could see some
locations get to 90 or above which lowers the time your body is
stressed in direct sunlight to around 15 minutes.

Lows will also remain very warm each night with light winds and
temperatures remaining in the 70s. It is likely some of our more
urban areas could see lows each night now until Friday morning in
the upper 70s to near 80. This is also factored into issuing the
Heat Advisory. With dew points each night still in the low 70s to
upper 60s and nearly calm winds, you get very little relief from the
heat.

Take time to stay hydrated, taking frequent breaks should you be
outdoors for prolonged periods of time. Check on your neighbor as
well, especially if their A/C doesn`t work well or if they have
none. SCT cumulus will return, but skies should remain dry still.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Issued at 344 AM EDT Tue Sep 1 2026

===== Friday - Weekend =====

Trend in forecast guidance has been slower on shifting the upper
ridge back to the west as an upper trough deepens over eastern
Canada. While the upper ridge is expected to weaken some by the end
of the week, the ridge axis is expected to remain over the Ohio
Valley on Friday. If this trend continues, it is not out of the
question that that temperatures remain hot in the afternoon, current
forecast is picking up on this slow transition with highs on Friday
now remaining in the upper 90s and heat index values ranging from
102 to 107 or higher. While confidence is growing, it still remain
on the lower side. This is due to where we could see a weak sfc
boundary set up over the region for Friday and where potential
convective complexes move through the Ohio Valley Friday afternoon
into Friday night. This placement of the boundary and potential
convective activity will play a role on how much clouds we could see
as well as rain/storm chances.

By Saturday and heading into Sunday, the deepening upper trough and
associated upper low will slowly work southward into New England and
the Canadian Maritimes. This will allow the upper ridge to continue
to retrograde further to the west and allow for slightly "cooler"
air to advect in from the north-northeast. While we could be nearly
10 degrees cooler this weekend than Thursday and Friday, that still
means we would have highs in the 90s and upper 80s. We will also see
an increase in shower and storm chances for Saturday into Sunday as
the aforementioned sfc boundary is expected to be somewhere over the
area during this time. Due to the temporal and spatial difference in
current guidance, confidence remains low on the finer details for
this weekend.

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 209 AM EDT Tue Sep 1 2026

Very little change in the weather pattern over the region for the
next several days. Strong upper ridging combined with sfc high
pressure off to our east and southeast will continue to provide VFR
flight categories. Like we`ve seen the past several days, after
light to calm winds overnight and early morning, daytime heating
will result in mixing with occasional gusts between 15-20kts and
afternoon Cu develop. Once we lose the daytime heating, skies will
clear and winds will diminish and become light to nearly calm. This
pattern is expected to repeat the next several days.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory from 1 PM EDT /noon CDT/ this afternoon to 8 PM
     EDT /7 PM CDT/ Thursday for KYZ023>035-038-061-062-
     070>072.
IN...Heat Advisory from 1 PM EDT /noon CDT/ this afternoon to 8 PM
     EDT /7 PM CDT/ Thursday for INZ076>079-083-084-089>092.

&&

$$

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