411
FXUS63 KLMK 211034
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
634 AM EDT Thu Aug 21 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Near normal temperatures and drier conditions today through
  Saturday.

* Below normal temperatures expected for the second half of the
  weekend into next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 256 AM EDT Thu Aug 21 2025

Strong ridging is centered over the desert southwest and extends
into the north Plains and upper Midwest. Over the eastern CONUS,
troughing aloft will weaken and exit the region. At the surface, the
cold front has push through Kentucky and remains stationary over the
Appalachians as Hurricane Erin passes just off the mid-Atlantic
coast. Broad high pressure to the north of the region is allowing
for northerly and north-northeasterly flow into the Ohio Valley.
Moisture trapped in the 925-850mb layer and aided moisture transport
from Erin has allowed for a low stratus layer to develop over the
northeastern CONUS. The southern extent of these clouds are just now
entering the lower Ohio Valley. Through the morning, broken-overcast
low clouds will be the main feature. With weak LLJ winds along the
Ohio River and ample moisutre, there is a signal for very light,
weak showers to pass through southern Indiana around sunrise. This
is low confidence, but have a 10% PoP in the forecast for this
reason.

By the afternoon, these clouds will lift and thin allowing for
better sunshine and heating. Though, high temperatures will remain
below normal for the day in the low-mid 80s.

Tonight, Hurricane Erin will pass just off the northern Atlantic
coast and surface high pressure will remain over the Ohio Valley.
Upper ridging will begin to stretch over the Midwest and mid-
Mississippi Valley regions. Due to these conditions, skies will
remain mostly clear overnight and winds will be light out of the
north-northeast. Low temperatures Friday morning are expected to be
in the mid-upper 60s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 256 AM EDT Thu Aug 21 2025

Friday - Saturday Night...

Upper ridging will continue to extend towards the Ohio Valley, which
will increase heights and temperatures over the region. On Friday,
high temperatures will warm to near normal in the mid-upper 80s.
Friday will be warm and sunny, likely being the warmest day in the
long term.

On Saturday, a more impressive low pressure system will move through
southern Canada and into the Great Lakes region. This system will
work to weaken the ridging in place over the Ohio Valley and force
it to retreat back to the west. The cold front of this system will
move into the lower Ohio Valley late Saturday afternoon and evening.
With additional cloud coverage, retreating ridging, and potential
timing of the front, high temperatures on Saturday will likely stay
in the mid 80s. Though, upper 80s are not out of the question if the
front slows and clouds hold off. With modest moisture present over
the southern portion of the region, could see some isolated to
scattered showers and storms in the late afternoon and evening as
the front approaches.

Sunday - Tuesday...

The front will exit the region by Sunday morning bringing showers
and storms with it. Deep troughing will remain over the region
through mid next week. This will help to keep below normal
temperatures through the long term. Surface high pressure will build
in behind the front, helping conditions to remain dry. Looks like a
really good glimpse of fall is forecasted for the end of August. A
few weak shortwaves riding along the broader troughing will
reinforce the cooler air through the long term. Temperatures look to
be in the mid-upper 70s for highs and 50s for lows Monday through
mid next week.

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 634 AM EDT Thu Aug 21 2025

A low stratus layer continues to overspread the region this
morning bringing MVFR CIGs to the northern terminals over the next
few hours. Steady winds continue out of the north and north-
northeast. CIGs will steadily lift and thin into the afternoon where
we will break out and see VFR conditions through the remainder of
the forecast.

&&

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

&&

$$

SHORT TERM...SRW
LONG TERM...SRW
AVIATION...SRW