577
FXUS63 KLMK 211823
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
123 PM EST Fri Feb 21 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Mostly dry weather through the weekend into early next week.
   Temperatures will rise above freezing today or Saturday, with
   above normal temps next week.

*  Next chance of rain arrives by the middle of next week.

&&

.UPDATE...
Issued at 1147 AM EST Fri Feb 21 2025

As high pressure continues to ease into the region, winds remain
light under mostly sunny skies for most in southern Indiana and
central Kentucky. However, a layer of status currently sits over
southeast Indiana and east of Louisville through the Bluegrass.
Throughout the day, this layer is expected to slowly move off to the
east. The forecast remains on track needing only slight adjustments.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 315 AM EST Fri Feb 21 2025

A large shield of clouds coming off the Great Lakes dropped south
across Indiana and Ohio overnight, slipping into northeastern
sections of Kentucky early this morning. These clouds should
generally persist over the Blue Grass through the morning, though
with some breaks. In temperatures this cold it`s not difficult to
squeeze a few flurries out of even a relatively thin stratus deck,
and indeed flurries have been reported and detected on radar
upstream, so have included a slight chance of flurries under the
clouds. Elsewhere scattered diurnal cu are expected to develop, but
still allow a decent amount of sunshine. The thicker clouds over the
Blue Grass this morning should become less pervasive this afternoon
as 925-850mb flow backs from northwest to westerly, cutting off the
moisture feed from the Lakes.

The center of a strong dome of high pressure will advance from
Kansas City to Louisville today, keeping winds light and
temperatures chilly. Afternoon readings should peak near the
freezing mark, though confidence in temperatures is slightly less
than normal due to questions of just how much cloud cover there will
be, especially in the Bluegrass.

Tonight the high will continue to push to the east into the
Appalachians. This will allow tonight to be a few degrees warmer,
with lows in the teens. A patch of mid-level clouds over Colorado
and Kansas this morning is expected to cross southern Indiana and
north central Kentucky late tonight, further preventing temperatures
from getting as cold as they did this morning.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 315 AM EST Fri Feb 21 2025

Synopsis...An Arctic surface high pressure along with rising mid-
level heights moving from the Central US will dominate through the
weekend resulting in dry weather and rising temperatures. Amplifying
mid-level ridge over the West CONUS will continue building eastward
with an overall split flow downstream as the polar jet flows across
the Northern Plains/Great Lakes and the subtropical jet remains over
the Gulf. Then, downstream pattern amplification is expected to take
place by the second half of next week as persistent action of
northern-stream shortwave energy carves a trough over the East
CONUS. Although confidence remains low for the latter portion of the
forecast, the forecast still reflects increasing rain chances and a
slight temperature cool down.

Model Evaluation/Confidence...As alluded to above, forecast
confidence considerably decreases towards the middle of next week
given high model variability handling the downstream pattern
amplification and shortwave energy phasing. The latest GFS and CMC
model runs have delayed the timing for the amplification and, as a
result, the attendant surface low is farther north and much weaker
which yields a much drier QPF signal Wednesday into Thursday. This
drier trend is also noted in the 20/0Z run of the ECMWF; however,
the UKMET and ICON deterministic guidance are on the wetter side of
the spectrum resembling previous runs of the GFS/CMC/ECMWF. Overall,
there is medium confidence (at best) in rain chances with low
confidence in amounts and location.

Saturday - Monday...Most notable change during this period will be
the highly anticipated temperature warm up with both lows and highs
going from double-digit below-normal values on Saturday to single
digit above-average values on Monday. Arctic surface high pressure
and building mid-level heights will foment dry and mostly sunny
weather even though Saturday will start off cloudy as a small
amplitude vort max crosses the Ohio Valley.

Tuesday - Friday...Surface high pressure will eventually move deeper
into the Southeast US while the Ohio Valley becomes more influenced
by the increasingly active northern-stream shortwaves and
accompanying low pressure systems. Although the richer moisture feed
from the Gulf will be blocked by the high pressure circulation,
modified Pacific airmass accompanying the westerlies will support
the introduction of light rain chances/sprinkles across the northern
extent of the forecast area on Tuesday. The Wednesday/Thursday
period still holds the best chance of measurable rainfall for the
region, but low confidence prevents delving into additional details
such as total QPF, timing of heaviest rainfall, or hydrological
impacts. Finally, a brief period of below-normal temperatures and
light frozen precipitation might follow the passage of the cold
front on Friday.

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
Issued at 123 PM EST Fri Feb 21 2025

Overall the period will remain quiet, but the area of stratus over
LEX and RGA is expected to last though the afternoon and evening
hours. The TAFs could be a little pessimistic in regard to the
ceiling at those two sites, but these layers tend to last longer
than expected. Winds at all the sites will remain light as high
pressure continues to move east towards the region. A passing wave
tomorrow will push some mid level clouds through the area.

&&

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

&&

$$

UPDATE...KDW
SHORT TERM...13
LONG TERM...ALL
AVIATION...KDW