789
FXUS63 KLMK 081708
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
108 PM EDT Mon Jun 8 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Unsettled weather with localized areas of heavy rainfall and flash
  flooding are possible in KY and southern IN Monday - Tuesday
  midday. Localized amounts of 3-6" of rain will be possible in the
  heaviest swaths.

* Despite some morning showers and weak storms on Wednesday, hot
  temperatures and mugginess are expected Wednesday and Thursday,
  with peak afternoon heat index values between 90-100.

* An approaching cold front later in the week provide more
  opportunity for rain and some strong storms Thursday evening
  through Friday, though timing is still uncertain.

&&

.UPDATE...
Issued at 1248 PM EDT Mon Jun 8 2026

First wave of widespread precipitation is working northeast across
the LMK Forecast area.  The heaviest rainfall thus far, has been
across Logan and into Warren counties.  Seeing some 2-3 inch
rainfall measurements from personal weather stations here. Currently
have a flood advisory out for the Russellville to Bowling Green
corridor.  However, rainfall is quickly moving out with an upcoming
break, but some scattered convection is likely to fire across SW KY
over the next few hours.

Further north, widespread light to moderate rain will push across
north-central Kentucky and into southern Indiana.  Some heavier
pockets of rainfall may impact our far western IN counties
(Perry/Dubois).  Some additional convection is developing in the I-
75 corridor down toward Richmond which will also work northward into
the Bluegrass this afternoon.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 339 AM EDT Mon Jun 8 2026

The upper ridge axis stretching from the Gulf Coast up through the
Great Lakes region will slide east today. Meanwhile, a slow moving
shortwave trough will begin to slide into our region. As this
occurs, ample deep moisture will move into our area ahead of the
shortwave trough axis. The meandering upper disturbance then hangs
around through Tuesday, before departing as we head into mid week.

PWATs will surge into the 2-2.25" range today which is above the
daily max climatology. In addition to the high moisture content
through the atmospheric column, we will likely develop some modest
to moderate instability today with HREF probs for 1000 J/KG of ML
CAPE in the 20-40% range, and in the 60-70% range for at least 500
J/KG. The end result will be a tall/skinny CAPE profile more
indicative of a tropical airmass. The freezing level will also be
above 14k feet, which will allow for more efficient rainfall
processes thanks to collision and coalescence. Fully expect to see
low centroid radar presentation on the stronger showers/storms. The
final piece of the puzzle will be deep layer flow, which will be
pretty weak with 0-6 km bulk shear magnitudes only in the 15-20 knot
range. The slow storm movement combined with all of the factors
creating efficient/intense rainfall rates will result in pockets of
locally heavy rainfall through Tuesday.

There has been a consistent signal in the HREF PMM and LPMM data for
these pockets of intense rainfall, including some localized 5+"
amounts showing up. Given that pretty much all of the boxes for
heavy rain are checked, do think that this is reasonable. WPC also
agrees and has our area in a higher end Slight Risk for Excessive
Rainfall today (25% probs of exceedance over western CWA), and again
tomorrow. As a result, have lifted a Flood Watch (Flash Flooding due
to intense rates) in coordination with several surrounding offices
for our western two-thirds of the CWA where the heaviest rain is
anticipated to fall. This will go through early Tuesday evening when
things should start to improve with the departing upper shortwave.
It is worth noting that we only expect isolated instances of
flooding, however given the setup and some of the data suggesting
localized big amounts, some of those isolated areas could see some
notable impacts from flash flooding. 1,3, and 6 hour Flash Flood
Guidance is running quite robust (3-5" for 6 hour FFG across the
area), however short term hourly rates could exceed 2 or 3 inches
per hour over shorter spurts, and 1 hour FFG values are more around
2".

The other thing we will have to keep an eye on is for a localized
wet microburst wind threat with any stronger cell as a water-loaded
downburst could occur in this environment. Especially, if we realize
some of the stronger instability values offered by the Nam (not
likely given its low level moisture and instability bias). SPC did
add a Marginal Risk for wind across our western tier of counties,
but will have to monitor other storms as well. Given what has
occurred upstream closer to the center of the upper low the past 2
days, we will also have to be vigilant of a few rotating storms
across our west later this evening. Overall, the deep layer shear
profile does not look that favorable for any rotating storms/tornado
potential, but also don`t want to ignore what occurred upstream.
Therefore, can`t completely take it off the table.

Overall, will be messaging a more widespread 1 to 2" of basin
average QPF now through late Tuesday, but again those localized
rainfall amounts over 3"+ are also expected. Some more extreme
amounts of 5"+ also seem feasible given the setup. Best chance for
the higher amounts are expected west of I-65. Flood Watch begins at
2 PM EDT today, and will run through 8 PM EDT on Tuesday. Another
noteworthy portion of this forecast will be the humidity as dew
points in the lower 70s combine with temps in the 80s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 339 AM EDT Mon Jun 8 2026

Wednesday - Wednesday Night...

Beginning Wednesday morning, temperatures will be warm for this time
of year in the low to mid 70s. Continued SW flow will dominate as
the shortwave causing all the rain earlier this week will slowly
exit towards the northeast. However, as the previous discussion had
mentioned, there is a continued signal of an MCS in deterministic
long range model guidance descending from central IL/IN. With
continually weak shear Wednesday morning, low instability and high
PWATs, the main threat would be a line of heavy downpours Wednesday
morning more in our NE counties and lightning with any embedded
storms. Long range ensemble mean rainfall totals for Wednesday
morning paint an additional T to near 0.5" of rain for areas north
and east of Louisville. Otherwise, rain clears as an advancing ridge
from our southwest moves over the Ohio Valley.

During the day on Wednesday, a deepening ridge from the surface
through 500 mb moves overhead. This will clear skies and increase
high temperatures into the upper 80s to low 90s. Dew points
throughout the day with continued SW flow remain in the low to mid
70s. With this in mind, muggy summer weather is expected Wednesday
afternoon and for as long as this tropical air mass lingers over KY.
Feels like temperatures will max out in the upper 90s to low 100s at
times. Should consider checking on those without A/C and take breaks
should you work outdoors for extended periods of time Wednesday.
Confidence is high in oppressive heat from the high dew points and
the potential to mix air temperatures at 850 mb to the surface
that`s expected to be 96-99th percentiles. After sunset, the ridge
axis slowly shifts to the east, albeit with continued warm SW flow
from the Gulf keeping dew points and temperatures high overnight.
Need to monitor record warm lows for Thursday morning with this
synoptic pattern. EFI tables indicate anomalously warm lows are
possible in the low to mid 70s.

Thursday - Sunday...

Thursday morning is warm and will continue to be warm throughout the
afternoon. Synoptic setup begins to shift Thursday as SW flow gets
amplified from an impending trough swinging through the plains. With
a strong high to our SE and the incoming trough, a tightening
pressure gradient at low to mid levels is expected, mixing down
breezy winds towards the surface with afternoon heating. Latest
ensemble guidance suggests gusts of 25-30 MPH is possible on
average, though this will be monitored as Thursday draws closer.
With the amplified SW flow, dew points remain high and PWATs may
raise closer to 1.8-1.9" again, meaning pop up storms in the
afternoon are possible, though confidence in rainfall amounts is
low. For now, an isolated shower or storm can`t be ruled out with
prime time afternoon heating. Highs on Thursday will be hot once
again in the upper 80s to low 90s, with feels like temperatures
maxing out in the mid 90s to low 100s once again.

Beyond the afternoon hours, the trough swinging through the central
plains will create a trailing cold front that will move towards KY,
albeit slowing and weakening as it does so. Timing of this front`s
arrival is uncertain, but may hold off until overnight Thursday into
Friday morning. Should this occur, then any severe risk would be
muted but will deserve to be watched as the event draws closer.
Regardless, increased rain chances for later this week are expected
until the timing of this front can be determined.

From Friday through the rest of the weekend, an unsettled pattern
with passing shortwaves drawing close enough to bring more rain
chances through Sunday is the current trend. Some guidance tries to
bring in a more pronounced trough through and dry the area out,
though that does not happen often this time of year. For now,
continued highs in the 80s and low 90s will continue through Sunday.

&&

.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 108 PM EDT Mon Jun 8 2026

Mix of MVFR/IFR conditions are expected through the afternoon hours
as an area of rich moisture will surge into the region from the
south.  A band of showers with embedded storms will move northward
through southern IN and north-central/east-central KY this
afternoon.  Behind this wave, we`ll just see isolated-scattered
convection in the late afternoon.  Cigs could improve once this
first wave of convection pulls through.  Secondary surge of
showers/storms expected to come in later this evening and into the
overnight.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch through Tuesday evening for KYZ023>031-034-038-045-
     046-053-054-061>065-070>078-081-082.
IN...Flood Watch through Tuesday evening for INZ076>078-083-084-
     089>092.

&&

$$

UPDATE.......MJ
SHORT TERM...BJS
LONG TERM....BKF
AVIATION.....MJ