100
FXUS63 KLMK 230832
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
332 AM EST Tue Dec 23 2025

.KEY MESSAGES...

* Milder temperatures and intermittent light rain chances are
  expected during much of the upcoming week.

* Unseasonably warm temperatures are likely around Christmas, with
  temperatures expected to be 15-20 degrees above normal.

* Mild weather continues into the first part of the weekend, but
  will gradually trend cooler by Sunday with a series of reinforcing
  cold fronts. More substantial rainfall amounts, and potentially a
  few thunderstorms, are possible with the weekend cold front.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 331 AM EST Tue Dec 23 2025

This morning, a mild and muggy air mass is present over the region
as temperatures are 20-30 degrees warmer than this time Monday
morning. Widespread low clouds and southerly flow have helped to
keep temperatures fairly steady overnight, and temperatures should
remain steady or warm slightly between now and sunrise. Scattered
light rain showers have been persistent overnight thanks to a 50 kt
850 mb jet. While the core of this jet is now pushing to the east, a
secondary lower jet is nosing into the area from the SW, and should
continue to support scattered showers through mid-morning.

Later this morning, the plume of greatest moisture is expected to
shift southward into southern KY, with drier air attempting to work
into the area from the north. This should help to decrease the
coverage of scattered rain showers, especially along and north of I-
64. Still, model soundings show a 3-5 kft deep saturated layer,
which could lead to patchy drizzle and mist through the day. A sfc
cold front currently over the upper Midwest will sink southeast
later today, causing winds to gradually veer from S/SW to W/SW this
afternoon and evening. The cool advection behind the front shouldn`t
make it into our area today, and temperatures are expected to remain
mild, with highs in the upper 50s and low-to-mid 60s.

Tonight, building high pressure over the Great Lakes will give an
additional southward push to the decaying cold front. This surge
should send the boundary through much of our area, with most models
showing the front ending up near the KY/TN border Wednesday morning.
Light northerly winds will help temperatures to fall behind the
front tonight, which should result in a strong temperature gradient
across the region. The current forecast for lows tonight ranges from
the upper 30s across our northernmost counties to the mid-to-upper
50s along the KY/TN border, with confidence in temperatures at any
location being fairly low given the strong gradient. Drier air will
attempt to scour out clouds from the north late tonight. If this
occurs, patchy fog would develop Wednesday morning, though
confidence in this is pretty low.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 331 AM EST Tue Dec 23 2025

Christmas Eve through Friday Night...

Expansive upper level ridging will be present across the south
central US from Christmas Eve through the end of the week, and
southern IN and central KY should be on the northeast side of this
ridge. As a result, we`ll be in a NW upper flow pattern, with two
shortwaves transiting within this pattern expected to bring chances
for light precipitation.

Wednesday morning, the remnants of a sfc cold front will be draped
across the region, resulting in a strong north-south gradient in
temperatures. As the first of the two shortwaves approaches the
region from the NW Wednesday afternoon, the boundary is expected to
start to lift northeast as a warm front, continuing northeastward
into early Christmas morning. It is likely that the strong gradient
in temperatures will continue during the day on Wednesday, with the
current forecast featuring highs ranging from the mid 50s across
Jefferson County, IN and the northern KY Bluegrass to the mid-to-
upper 60s along the KY/TN border.

Strengthening 850 mb flow should bring another surge of low-level
moisture into the region Wednesday night, with the sfc boundary
serving as a focus for new development of light rain showers.
Wednesday night into Christmas morning should bring little drop in
temperatures with temperatures likely within a few degrees of
Wednesday afternoon. While PoPs are high Christmas morning,
especially across the KY Bluegrass, expected precipitation amounts
are light, generally 0.10" or less, so it shouldn`t be a washout.
Chances for rain should diminish later in the day on Christmas, but
mostly cloudy skies and pockets of mist and drizzle will linger
through the day. Highs Christmas Day are expected to be mild, in the
mid-to-upper 60s across the area, with slightly higher uncertainty
across our northernmost counties closer to the front.

A similar setup is expected on Friday as another upper shortwave
slides just to the north of the region. By this point, upper level
NW flow will become more zonal, which increases confidence that most
if not all of the region will be in the warm sector. Widespread mid
60s to low 70s are expected for highs on Friday, which will get us
close - but probably slightly below - record highs for the day.
Scattered showers are expected again on Friday, with best chances
the farther north and east you go, and precipitation amounts
remaining light. Mild temperatures and diminishing rain chances are
expected Friday night.

Saturday through Early Next Week...

A synoptic-scale trough which is expected to remain fairly static
along the west coast of North America through Christmas Day will
begin to eject to the east Friday night into Saturday. Initially,
this will shift the upper ridge axis over our area on Saturday,
resulting in the best chance for dry weather and what could be the
warmest temperatures of this stretch. For this forecast update,
highs on Saturday now range from the upper 60s to the mid 70s across
the area, which will again challenge daily high temperature records.

Saturday night into Sunday, a northern stream upper trough over
central Canada is expected to deepen and dig into the upper Midwest.
Low-level response to falling heights aloft should lead to the
development of a cold front across the Midwest and mid-Mississippi
Valley late Saturday night. While there is still quite a bit of
spread in how this system interacts with the energy ejecting out of
the western US, more recent model guidance has trended toward more
delayed phasing of the upper waves. As a result, moisture return and
instability ahead of this system is less concerning, but remains
marginally concerning for thunderstorm development Sunday. AI
probabilistic severe hazard guidance does show a weak signal during
this period, so we`ll have to keep watching in case model guidance
trends more unstable over the coming days.

Regardless, as the upper jet core moves into the Midwest on Sunday,
widespread precipitation is likely to develop along and ahead of the
front. Sunday should feature the best chance for more significant
precipitation over the next week given that the forcing mechanisms
at play will be stronger. Behind the front, strong cold advection
later Sunday into Sunday night will send temperatures tumbling from
well above normal to below normal. Exactly when that drop occurs is
uncertain, but it is increasingly likely that below normal
temperatures will return for the first half of next week. Drier
weather is also favored for next Monday and Tuesday as a cP air mass
settles across the region.

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1225 AM EST Tue Dec 23 2025

MVFR stratus is present across the region at this hour, with
ceilings gradually lowering as you go from east to west. There
should be a gradual lowering of CIGs between now and mid-morning,
with CIGs expected to settle in the IFR/low MVFR range for much of
the daytime hours on Tuesday. Will keep LLWS mention going as wind
profiles show winds at 2 kft approaching 40 kt at this time. At the
surface, we`ve mainly seen sustained winds in the 10-15 kt range,
with occasional 20 kt gusts. Think this should continue over the
next 3-6 hours, with gusts gradually subsiding later this morning as
the LLJ moves off to the east.

Through most of the current forecast, think that CIGs will be the
main driver of categories, though lower VIS is possible from
mist/drizzle as we get later into the forecast period. Winds will
continue to ease toward the end of the current forecast period, and
should eventually swing around to the NW as a cold front passes
through tonight.

&&

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

&&

$$

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