549
FXUS63 KLMK 020520
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
120 AM EDT Sat Aug 2 2025

.KEY MESSAGES...

* Cooler and less humid for most of 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.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 354 PM EDT Fri Aug 1 2025

This afternoon, expansive 1030+ mb sfc high pressure is sinking
south over Wisconsin, bringing drier NE near-sfc winds into the
lower Ohio Valley. Lingering moisture in the 925-850 mb layer has
supported continued stratus and stratocu for areas along the I-64
corridor and south which has kept temperatures very mild, with
several sites still in the mid-70s as of 19Z. Where more sunshine
has broken out, temperatures have warmed into the upper 70s to
around 80. As the low-level moisture continues to mix out from north
to south this afternoon and evening, would expect more areas to
reach the upper 70s and lower 80s before cooling after sunset. Areas
which mix more deeply could see a few 20-25 mph wind gusts, with
breezy NE winds continuing until around sunset.

Tonight, the sfc high will remain centered over the Great Lakes,
with the pressure gradient remaining strong enough to limit boundary-
layer decoupling in most areas. A light N/NE wind is expected to
continue overnight, with dewpoints expected to continue to fall
overnight. This should limit the potential for any valley fog
Saturday morning, though if any location did see it, it would be in
the river valleys across far southern KY. While scattered mid-level
clouds and the aforementioned NE breezes may somewhat hinder
radiational cooling, we are still expecting temperatures Saturday
morning to be the coolest in well over a month. Lows in many areas
will fall into the low 60s, with rural areas in north central KY and
southern IN expected to cool into the upper 50s.

Tomorrow should feature very pleasant conditions for early August,
with high temperatures continuing to run 5-10 degrees below climo.
As the high pressure over the Great Lakes starts to weaken, moisture
will start to creep back into portions of east central KY from the
east and southeast. This should primarily manifest as scattered to
broken cumulus clouds during peak heating, though a stray shower
cannot be ruled out across Lake Cumberland. Highs Saturday afternoon
should reach the low-to-mid 80s in most locations.

By Saturday night, greater low-level moisture will continue to
spread from SE to NW as an inverted sfc pressure trough develops
over eastern KY. This should support additional clouds and isolated
showers over eastern KY, some of which may spill over into central
KY by Sunday morning. Given the increasing moisture, temperatures
will likely be slightly milder Sunday morning, with lows expected to
range from near 60 across southern IN to the mid-to-upper 60s across
southern KY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 354 PM EDT Fri Aug 1 2025

By Sunday, the high pressure which is bringing us the cooler weather
over the next few days will shift east of the Appalachians, setting
up a CAD/wedge pattern over the Carolinas. Given the low-level
easterly flow, this setup will help to develop an inverted pressure
trough on our side (lee side) of the Appalachians. This pressure
trough should provide enough convergence, combined with increasing
moisture, for scattered showers and storms to develop across the
area on Sunday. With extra cloud cover in place, temperatures should
remain steady or possibly cool by a degree or two on Sunday, with
highs expected in the upper 70s and low 80s.

For the first half of next week, the synoptic pattern will be
relatively static as a blocking upper high sets up over central
Canada. Upper ridging over the southwest US will gradually build and
spread to the east by the second half of the week, which will start
to kick out a weak upper trough which sets up early in the week over
the mid-Mississippi and lower Ohio Valley. With the upper trough and
weak inverted sfc trough still over the region, there should be
enough support for daily afternoon and evening shower and storm
chances. Temperatures will very gradually warm, approaching
climatological normals in the upper 80s by late next week.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 120 AM EDT Sat Aug 2 2025

Strong high pressure parked over the Great Lakes continues to
dominate the weather pattern. Look for NNE winds to persist through
the TAF period, staying up just shy of 10 kt overnight, and gusting
near 20 kt during the peak heating of the day. Less diurnal Cu is
expected compared to Friday, with a sct deck around 6K feet in BWG
and nothing more than cirrus at SDF and LEX. Winds will decouple in
the evening but the boundary-layer is dry enough that fog is not a
concern heading into Sunday morning.

&&

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

&&

$$

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