893
FXUS63 KLMK 011739
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
139 PM EDT Fri Aug 1 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Cooler and less humid today into the weekend with temperatures
  more typical of early fall.

* Chances for isolated to scattered showers and storms return
  Sunday, continuing into early-to-mid next week.

&&

.UPDATE...
Issued at 1134 AM EDT Fri Aug 1 2025

1030 mb sfc high pressure is slowly sagging to the south over the
upper Midwest this morning, with the cold front which passed through
the area on Thursday now over the lower Tennessee valley. Drier air
continues to filter into the region within breezy north and
northeasterly winds, with upper 50s and lower 60s dewpoints moving
into north central KY and southern IN at this hour. Daytime heating
has been slowed so far today by a stratus layer, mainly along and
south of the Ohio River. Where the densest cloud cover is located,
temps have remained in the upper 60s as of 15Z, with low-to-mid 70s
observed in areas which have seen more sunshine. Looping visible
satellite imagery reveals that this stratus layer is mixing out from
north to south, and should continue to do so through the afternoon
hours. It may take until around sunset for stratus to scatter out
along the TN border, so temps may struggle to reach forecast highs
in the low 80s.

Otherwise, the forecast remains on track at this time, with dry
conditions and unseasonably cool temperatures expected across the
area today.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 417 AM EDT Fri Aug 1 2025

An all too rare summertime intrusion of a cP air mass is underway as
a 1030mb sfc high over northern Minnesota continues to build into
the Great Lakes. The cold front is well into the Tennessee Valley
and we have a good NNE wind surge behind it, keeping gusts up close
to 20 kt at SDF through the night, but the lower dewpoints have been
slow to filter in thus far. Still expecting dewpoints to drop into
the 50s today, with max temps in the lower to mid 80s (just barely
where the cloud cover is most persistent over south central
Kentucky). Even after clearing is underway, sunshine could be
filtered by elevated wildfire smoke drifting overhead from the West,
but near-sfc smoke concentrations remain low.

Northeast winds will drop off slightly after sunset, but not
completely decouple, which is the only negative on an otherwise
favorable radiational cooling night. Min temps will run solidly
below normal in the lower/mid 60s, with a few sheltered valleys
having a chance to drop into the upper 50s. Bottom line, it will be
the coolest night since the Summer Solstice for most of the area. If
you like today`s weather, you`ll also like Saturday as it`s very
close to a persistence forecast with the slowly-modifying sfc high
to our north.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 417 AM EDT Fri Aug 1 2025

Over the weekend, a fairly static synoptic pattern is expected
across North America as upper-level ridging gradually retreats
toward Baja California while troughing continues over the Canadian
Maritimes. Surface high pressure will remain centered over the
Midwest and Great Lakes region, with NE low-level flow keeping
temperatures and dewpoints suppressed. Seasonably cool temperatures
are expected Saturday night, with lows expected to fall into the
upper 50s and low-to-mid 60s. Highs Sunday will also be below
normal, ranging from the upper 70s to the mid 80s. By Sunday, the
center of sfc high pressure will shift east of the Appalachians,
setting up a wedge pattern for the Carolinas up into the mid-
Atlantic. This pattern will start to bring moisture back into the
area via east-southeasterly low-level flow, particularly across
south central KY. With moisture expected to increase, chances for
afternoon showers and storms will also return on Sunday, with the
best chances across south central KY.

Over the first half of next week, medium-range guidance shows a weak
upper low drifting from the upper Midwest toward the Ohio Valley as
upper ridging strengthens over the southwestern US. While the
pattern will be somewhat supportive for increased shower and storm
chances, the air mass is not expected to be particularly moist,
especially for early August (PW 1.4-1.6"). As a result, the current
expectation would be for isolated to scattered afternoon and evening
showers and storms. No rapid warm up is expected through the first
half of next week, though temperatures should gradually approach
climatological normals, with highs in the mid-80s and lows in the
60s.

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
Issued at 139 PM EDT Fri Aug 1 2025

MVFR stratus and stratocu has scattered out at SDF and is expected
to scatter out at LEX/RGA/BWG in the next few hours. VFR conditions
are expected through the remainder of the current TAF period once
stratus lifts this afternoon. Winds should be gusty this afternoon,
particularly once low clouds lift, with N/NE winds gusting up to
around 15-20 kt.

Tonight, wind gusts should subside, though most areas are not
expected to completely decouple as a steady N/NE wind of 5-10 kt
continues overnight. Tomorrow, another stratocu layer with bases
around 3-5 kft should develop during the late morning hours. Winds
will veer slightly toward the NE and should be somewhat less gusty
than today.

&&

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

&&

$$

UPDATE...CSG
SHORT TERM...RAS
LONG TERM...CSG
AVIATION...CSG