235
FXUS63 KLMK 011057
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
657 AM EDT Mon Jun 1 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* An organized cluster of strong storms will move across the lower
  Ohio and Tennessee Valleys later this morning into the early
  afternoon. There is a low-to-medium probability (20-30%
  confidence) in this cluster impacting counties south and west of
  Bowling Green.

* Isolated showers and storms may develop this afternoon and evening
  mainly south and west of Louisville.

* Dry weather and seasonable temperatures is expected from Tuesday
  through most of the week. Storm chances and warmer temperatures
  return this coming weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 324 AM EDT Mon Jun 1 2026

Now through Early Afternoon...

Early this morning, mostly calm and dry conditions are present
across central KY and southern IN. Over the past few hours, there
have been a few isolated radar returns popping up on composite
reflectivity as a band of enhanced mid-level moisture streams from
NW to SE over the area. However, most of this outside of the
strongest reflectivity cores is evaporating thanks to dry air
between the top of the PBL and about 8 kft aloft. With that being
said, we could see a few sprinkles across the area through the early
morning hours.

The other thing we`re watching over the next few hours is a pool of
low-level moisture mainly concentrated over the Cumberland Plateau.
Some hi-res guidance shows this moisture developing into a fog or
low stratus layer across our southern and southeastern zones. We`ll
keep patchy fog in the forecast for now and see how things evolve.

Looking upstream from our area, scattered storms have developed over
eastern MO and southern IL over the past hour or so, with strong to
severe storms present to the west in MO and KS. The expectation in
hi-res guidance is that this activity will congeal into an MCS over
the next 3-6 hours, eventually turning SE and following the
instability gradient. The main forecast uncertainty for later this
morning is if the CAPE gradient will be close enough to our SW
counties (i.e., Logan, Butler, Warren, Simpson) for the MCS to track
more to the east and impact these areas. With the 0Z HREF guidance,
the majority of 40+ dBZ swaths track to the southwest of our
counties; however, certain models like the HRRR favor a more
northeast track. The new Day 1 SPC Marginal Risk continues to clip a
portion of Logan County, so we`ll have to watch this activity later
this morning to see how it evolves. The main severe threat (if any
exists) will be strong to severe winds, and the main timing for this
system to pass would be between 10 AM and 2 PM CDT.

For the northeastern three-fourths of the CWA (roughly NE of a line
from Hartford to Burkesville) a mix of sun and mid-level clouds is
expected this morning into the afternoon. As has been the case in
recent days, it will be more muggy the farther south and west you
go. As the convective system mentioned above approaches the region
later this morning, some showers may develop on the northeast flank
of this activity, with rain becoming more unlikely the farther NE
you go. Temperatures should warm into the mid-to-upper 70s by
midday, with heating tempered by any convection in our southwest
counties.

Mid Afternoon through Tonight...

Once the morning/early afternoon wave clears into the TN Valley,
there is expected to be a resurgence in instability, with 0Z HREF
progs showing 500-1000 J/kg SBCAPE across the southwestern half of
the CWA by mid-to-late afternoon. With that being said, a trigger
for re-development of storms is unclear, though this may come as a
backdoor cold front begins to impinge from the NE later this
afternoon into the evening. This could bring a second chance for
isolated storms, again mainly in the southwest half of the CWA.
There is a low threat that these storms could bring strong gusty
winds; however, the main severe threat should be with the first wave
of storms.

Temperatures this afternoon should warm into the upper 70s and low
80s across the area. As the backdoor front starts to move into the
area, winds, which should be light/variable through the first half
of the day, should swing around and become fairly steady out of the
NE. While it may take until later tonight, the effects of the cold
front will come by Tuesday morning as dewpoints are expected to fall
precipitously through the overnight hours. Skies will begin to clear
from NE to SW overnight, with low temperatures expected to range
from the low-to-mid 50s to around 60 Tuesday morning.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 324 AM EDT Mon Jun 1 2026

Tuesday through Friday...

During the middle of the upcoming week, an expansive ridge of upper-
level high pressure over Canada is expected to break down and eject
to the south-southeast across the Great Lakes and into the southeast
US. The upper-level pattern transition will force an area of surface
high pressure near Hudson Bay southeastward in a similar fashion to
the upper ridge. While the sfc high should weaken somewhat as it
drops south, ECMWF ensemble mean MSLP values are expected to exceed
the 99th percentile of model climatology for early June Tuesday into
Wednesday. The approaching high will cause enough of a pressure
gradient over the region on Tuesday to lead to a breezy day for
June, with NE winds of 10-15 mph and gusts of 15-25 mph expected.

This unusually strong high moving across the region will bring
unseasonably dry air with it, with ensemble mean PW dropping to 0.50-
0.70" for Tuesday into Wednesday, or roughly the 10th percentile of
climo. With scant moisture and large-scale subsidence present, dry
weather is expected region-wide from Tuesday through the end of the
week. Temperatures will initially be slightly below normal Tuesday
into Wednesday, with the dry air mass allowing morning lows to cool
into the 50s for most areas Wednesday and Thursday morning. The
typical cool spots in valleys may even see lows in the upper 40s.

By the end of the week, with the sfc high expected to be over GA,
we`ll start to see modest return S/SW flow Thursday into Friday.
While this flow regime will allow temperatures to warm back to near
or slightly above normal levels, the bulk of the moisture return
should remain just west of our area, allowing dry weather to
continue.

Saturday and Sunday...

For the upcoming weekend, a return to a more active and muggy
pattern is favored in medium-range guidance. As the upper-level
ridge settles into the southeast US, a baggy upper trough over the
Four Corners region will try to nudge eastward into the southern
Plains. As the trough gradually encroaches on the southeast ridge,
the flow pattern will become more favorable for moisture advection
out of the Gulf. By the latter half of the weekend, ECMWF/GFS
ensemble mean PW values are expected to exceed the 90th percentile
of climatology across the region, suggesting a shift to a much more
tropical air mass.

The return of said tropical air mass should bring diurnally-driven
chances for showers and thunderstorms, as current medium-range
guidance suggests fairly weak synoptic forcing. Since the forcing
mechanisms are unclear at this lead time, the current forecast of 30-
50% chances of showers and storms peaking in the afternoon and
evening seems appropriate. At this time, the weekend doesn`t appear
to be a washout, although Sunday should feature better chances for
rain than Saturday.

High temperatures over the weekend should remain fairly steady, with
most areas in the 83-87 degree range, though this is dependent on
coverage of afternoon clouds and precipitation. Low temperatures
would be more likely to increase as richer moisture should suppress
nighttime radiative cooling effects.

All in all, most medium-to-long range guidance features a
continuation of a relatively stagnant, muggy pattern as we head into
next week, with no strong signals for systems which would either
bring enhanced precipitation chances or cooler/drier air.

&&

.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 657 AM EDT Mon Jun 1 2026

Lingering mist at BWG should dissipate over the next hour or two,
with VFR conditions expected at all sites later this morning. The
main forecast concern today will be the potential for showers and
possibly storms at BWG. Due to low confidence in storms, we`ll leave
TSRA out of the forecast and mention SHRA since confidence is
higher. At other sites, light rain showers could impact the
terminals later today, but impacts to CIG/VIS are unlikely as
showers should be weakening. There will be additional chances for
SHRA/TSRA later today, mainly at HNB/BWG, but due to low confidence
will leave this out of the forecast as well.

Otherwise, mid-level clouds and light and variable winds are
expected through much of the day, with winds increasing out of the
NE this evening before weakening after sunset. Skies should clear
late tonight with VFR conditions expected into Tuesday.

&&

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

&&

$$

SHORT TERM...CSG
LONG TERM...CSG
AVIATION...CSG