258
FXUS63 KLMK 040511
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
111 AM EDT Fri Sep 4 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Heat Advisory continues for all counties in the forecast area
  through Friday.

* Daily afternoon temperatures in the mid to upper 90s Friday. Heat
  index values will be over 100 and up to 107.

* Warm overnight temps in the mid to upper 70s will provide little
  relief during the nighttime hours. Practice heat safety by
  remaining hydrated and limit time outdoors if possible.

* A weak cold front could bring scattered showers and storms to the
  area late Friday and Saturday, ending our stretch of hotter
  conditions across the region.

&&

.UPDATE...
Issued at 900 PM EDT Thu Sep 3 2026

At this hour, most of central Kentucky and southern Indiana is under
mostly clear skies while continuing to cool down from sweltering
afternoon temperatures in the mid-to-upper 90s and low 100s. I say
most of the area is clear as we were able to get a few showers to
develop mainly along and south of the Parkways this afternoon. A few
showers continue at this hour across portions of Allen and Barren
County, though given the weak forcing and decreasing sfc-based
instability, these showers should dissipate over the next hour or
two. There is also a band of showers and thunderstorms over southern
Ohio at this time; however, these are not expected to make it into
our northeast Bluegrass counties.

For the rest of this evening and tonight, temperatures should slowly
drop through the 80s and into the mid-to-upper 70s by early Friday
morning. May have to watch out for patchy fog in the few areas which
have received rain this afternoon and evening, though most should
remain fog free. Just tweaked PoPs over the next few hours with this
forecast update; otherwise, the forecast remains on track at this
time.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 340 PM EDT Thu Sep 3 2026

It`s another hot day across central Kentucky and northern Indiana,
as temperatures across the region are in the mid to upper 90s. With
a few more hours of peak heating still to come, some places reaching
100 cannot be ruled out. This stretch of hot weather is thanks to
an upper-level ridge overspreading the eastern 2/3 of the CONUS. A
Heat Advisory is still in place through Friday evening with heat
indices of 100-107 expected. A few very brief and isolated showers
have developed this afternoon, but with very weak wind shear present
(<15 kt of 0-6 km shear), convective activity will remain quite
limited for the remainder of the afternoon. For tonight, the hot air
mass will again limit our overnight temperature recovery, with lows
in the mid 70s forecast.

For Friday, A surface frontal boundary currently over the upper
Midwest will push southward towards central Indiana and Ohio by the
evening hours. Slight (~20%) chances for showers and storms will be
possible tomorrow afternoon, with the SPC placing the northern
portions of the area under a Marginal Risk for severe weather. While
SBCAPE will be near 2000 J/kg during the afternoon, weak wind shear
(<20 kt) will again limit the potential for more robust development.
The main concern with the strongest storms would be gusty winds, but
confidence in severe weather occurring is low.

The frontal boundary will begin to move through the area on
Saturday, with elevated chances for showers and scattered storms (30-
50%) mainly east of I-65. There is some model disagreement as to how
much convection occurs ahead of the front, but this does present
the highest chance for precipitation for the next several days. A
Marginal Risk is again in place for most of the area for gusty
winds, but the continued presence of weaker wind shear will again
limit the severe potential on Saturday. Temperatures will still be
on the hotter end, with highs in the low to mid 90s. While
confidence was not high enough to extend the Heat Advisory into
Saturday, further consideration may be needed in future forecast
packages.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 340 PM EDT Thu Sep 3 2026

With the cold front departing off to our south by Sunday morning,
surface high pressure and drier air will fill in over the region.
Looking broadly at the upper-levels, an omega block tries to take
shape as two upper-level lows flank both sides of a well-amplified
ridge over the central CONUS. Central Kentucky and southern Indiana
will be placed just to the east of the ridge, with northerly flow
aloft persisting into the early portions of next week. Temperatures
to close off the weekend and start the following workweek will be
closer to normal for this time of year, with highs ranging from the
mid 80s to around 90. The biggest benefit from this pattern change
will be the increase in drier air, allowing dew points during the
overnight hours to drop into the 60s. This will help with overnight
temperature recovery, allowing for lows to also be in the 60s Sunday
and Monday night.

As the workweek progresses, the previously mentioned omega blocking
pattern quickly breaks down, causing the upper ridge to move
eastward towards the Ohio Valley. While the upper-level flow will
continue to be northerly over the region, lower-level and surface
flow will shift to the south, allowing warmer air to fill back in.
Widespread afternoon highs in the 90s will return Tuesday, lasting
through the rest of the forecast period. A few weak perturbations
passing over the region could allow for a few isolated diurnally-
driven showers and storms to develop, but with limited moisture and
weak wind shear in place, chances will remain rather low through
Wednesday (<20% chance).

The end of the forecast period on Thursday becomes more uncertain as
another pattern shift looks to take shape. Most deterministic and
ensemble guidance picks up on a robust upper level low moving from
central Canada towards the NE CONUS while a surface cold front
passes over the Ohio Valley. The uncertainty lies in the timing and
progression of these features, but it does appear that this could be
the next chance for more appreciable precipitation across the region.

&&

.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 110 AM EDT Fri Sep 4 2026

Ridging aloft and sfc high pressure continue to influence our
forecast through the 06z TAF forecast period. Overall we remain VFR
but here are the potential impacts during this forecast:

Through the rest of the overnight and morning we will remain quiet
with light winds and clear skies. Some patchy fog is possible in
spots but I think terminal sites remain unaffected.

As has been the trend the last couple of days, with the heat and
humidity we have the chance of isolated showers or storms with a
scattered Cu field in the afternoon. The chance of showers is under
20 percent so no mention of a Prob30 but it is possible an isolated
storm could hit a site tomorrow afternoon/evening but confidence is
generally low.

Mixing winds are again possible as we go late afternoon and evening
with some isolated gusts of 10-15kts.

Once the sun sets, skies clear and winds become light but a sfc cold
front to our northeast will start to track into the region late
tomorrow and Saturday. Think this is slow to arrive but as it gets
closer we could see more increased clouds and PoP chances late
Friday into Saturday.

&&

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

&&

$$

UPDATE...CSG
SHORT TERM...BEN
LONG TERM...BEN
AVIATION...BTN