370
FXUS63 KLMK 262351
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
751 PM EDT Sun Jul 26 2026

.KEY MESSAGES...

* Sight risk for severe storms later tonight, mainly west of I-65,
  as a cluster of thunderstorms dive south out of IL/IN and into
  western KY. Damaging winds are the greatest concern tonight.

* Lower confidence forecast for temperatures and heat indices
  tomorrow due to the morning thunderstorms and potential cloud
  cover. A Heat Advisory is still being considered for Monday, but
  confidence remains low.

* Additional severe thunderstorms will be possible late Monday night
  and into Tuesday morning. This cluster of storms could be mainly
  for southern IN and northern KY, but the exact track of these
  storms remain unclear.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 338 PM EDT Sun Jul 26 2026

It has been a relatively quiet day across the region, with some rare
July drizzle earlier this morning, and still dealing with some pesky
low stratus over a large portion of the forecast area this
afternoon. This increase in cloud cover has slowed down the
temperature climb today, with some areas north of the WK/BG Pkwys
possibly underachieving on forecast temps today. However, more
sunshine has been able to break through in our south, and the KY
Mesonet clearly shows the warmer temps in the south. Heat index is
close to advisory in our southwest with upper 90s at some locations.
However, there is a notable spread of heat index across the state,
from the mid-70s in he Bluegrass to the upper 90s in the south.

We`ve got a very complicated forecast ahead, with multiple hazards
possible, with some hazards conditional on how other parts of the
forecast play out over time. We`ll break down the different
components of the forecast below.

===== Slight Risk for Severe Storms Tonight =====

SPC has upgraded the D1 outlook to a slight risk for half of the
forecast area, mainly for locations along and west of I-65 for
tonight. Multiple areas of strong to severe storms will be possible
this evening and throughout tonight from near the MS River into
IL/IN/KY/TN. This area has seen the best heating of the day, with
temps reaching the upper 80s to lower 90s, along with dewpoints
pushing into the lower 80s. This has allowed incredibly strong
destabilization to occur today, with SPC Mesoanalysis showing
upwards of 7000 J/kg SBCAPE across southeastern MO. Additional
convection developing later this afternoon will likely fully realize
the favorable thermodynamic environment (characterized by SCP values
of 8-12) draped across central IL into the lower OH Valley. Guidance
continues to depict relatively quick upscale growth into an
organized MCS by early evening with an attendant threat for severe
winds into western Kentucky overnight.

While damaging straight line winds are the primary concern tonight,
there could be a low end tornado threat as well. Some CAMs should
some enhancement of the 0-1km SRH over 100 m2/s2, though this remains
a lower confidence tonight. Timing of severe potential through our
area will be between 9pm to 5am, with the Slight Risk reasonably
placed in our area.

===== Potential for Heat Advisory Monday =====

Perhaps the lowest confidence of the overall forecast revolves
around the temperature forecast for Monday, which is also
conditional on how the thunderstorm activity plays out. There is
concern for temperatures to climb into the lower 90s tomorrow
afternoon, with dewpoints in the upper 70s west of I-65. This would
yield heat indices of 104-110 in our western third of the forecast
area, roughly from Allen (KY) to Washington (IN). However, the early
morning convection and possible cold pool could start the day off
cooler than currently forecast, leading to our afternoon temps to
never reach the forecast highs that are a concern. There is also
some potential for additional precip throughout the day as the CAMs
suggest additional weakening convective clusters to move into the
area from the north, would also add to the derailment of the
temperature forecast by adding more cloud cover and precip to the
area. With all that said, there was considerable debate on issuing a
Heat Advisory for the aforementioned area with this forecast, but
confidence just is not where it should be to issue one.
Considerations will continue through the evening and overnight as we
get more runs of the CAMs and hopefully better confidence.


===== Severe Risk for Monday =====

Another MCS may be possible Monday night into Tuesday morning, which
could cause additional damaging winds for a portion of the forecast
area. The RRFS appears to be initializing the best, and appears to
be favored based on the D2 SPC Outlook. We could see another
convective cluster develop over the Great Lakes and punch south-
southeast through the Ohio Valley late Monday night or early Tuesday
morning. Our northeast corner will have the best chance for severe
storms, as indicated by the Slight Risk in D2. Frequent lightning,
torrential rainfall, and localized flooding could become a concern
as storms roll through. Overall, the track of this MCS remains
conditional, but there is growing confidence on severe potential for
at least some part of our area for this time frame.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 338 PM EDT Sun Jul 26 2026

===== Tuesday - Thursday =====

The upper ridge remains in place to the west for the middle of the
week, with persistent NW flow across the Ohio Valley. Tuesday will
feature a sharper mid-level shortwave pivoting across the Great
Lakes and into the Northeast, and will influence a sfc low to follow
a similar track. A trailing frontal boundary will sweep through the
Ohio Valley, and will be the focus for additional showers and storms
on Tuesday, with the greatest severe risk just east of the forecast
area. Despite a lower confidence in forecast temps for Tuesday, we
should still be able to achieve some strong heating combined with
increased humidity to support strong destabilization through the
afternoon. PWATs near 2 inches are also expected, so heavy rain
rates along with some stronger thunderstorms are possible in the
afternoon. Steering flow should be slightly more by then, so storms
likely will be a bit more progressive to alleviate flooding concerns
some. Forecast temps have been knocked down from the NBM, but still
have upper 80s to lower 90s, combined with sfc dewpoints in the
upper 70s, which could yield heat indices around 100F. There could
be a need for a Heat Advisory, but confidence in that remains very
low given the precip forecast which could derail our temp forecast.

Our weather turns drier for the Wednesday-Thursday time frame as sfc
high pressure settles across the upper Midwest. However, the upper
ridge to the west will begin to show signs of weakening by then,
though we`ll still be in weak NW flow for the time being. Temps for
both days will be near normal in the upper 80s, with slightly lower
dewpoints.


===== Friday into the Weekend =====

Scattered showers and storms could make a return for Friday and into
the weekend as a compact upper low finally disrupts the upper ridge
and moves across the central US. There is decent agreement between
the GFS/ECMWF for the upper low to come spinning over the Wabash
Valley over the weekend, which could keep us slightly more active
over next weekend.

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 751 PM EDT Sun Jul 26 2026

A frontal boundary will serve as a focus for strong thunderstorms
across western Kentucky this evening, with additional activity
developing on their outflow and spreading east over portions of
central Kentucky and southern Indiana overnight. It`s unclear how
far northeast these storms will reach, but HNB, SDF, and especially
BWG will have the highest (40-60%) chances, so prob30 groups remain
at those airfields. The terminals further east, however, will be at
greatest risk for visibility reductions and MVFR/IFR ceilings during
the 08-13z timeframe. While gusty winds may accompany thunderstorms,
especially at BWG, winds outside of storms will be fickle but
generally light throughout the period.

&&

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

&&

$$

SHORT TERM...CJP
LONG TERM...CJP
AVIATION...JRB