744
FXUS63 KLMK 020445
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1145 PM EST Mon Dec 1 2025

.KEY MESSAGES...

* Weather systems will come together over the region tonight and
  Tuesday morning, bringing a wintry mix and impactful snow
  accumulations.

* Snow accumulations of 1 to 3 inches are likely across southern
  Indiana and most of central Kentucky. Brief periods of freezing
  rain/sleet are possible, and a glaze of ice is possible before
  changing to snow.

* The heaviest snow accumulations of 2-3+ inches are most likely
  across southeastern Indiana and portions of north-central
  Kentucky. Localized, persistent banding of moderate to heavy
  snowfall could result in narrow swaths of up to 4 inches.

* Impacts to travel are likely Tuesday morning.

&&

.UPDATE...
Issued at 1145 PM EST Mon Dec 1 2025

Still a good signal in model data for banded precip over the next
several hours. NAM and GFS both show broad areas of frontogenesis
with instability above it...especially in the 06-09Z window.  Seeing
MRMS upstream reflectivity at -15C increase in coverage across
western TN and KY...and this moist airmass will get into central KY
and parts of southern IN in that window with the best potential for
banding. Current freezing line roughly runs along the I-64 corridor
from Louisville to Lexington and then arcs southwest from SDF.
Anticipate this eventually dropping south and east, but it is
interesting to note with latest ACARS soundings that a pretty good
warm nose exists over KSDF...2-2.5C at 800 mb. Still a bit of dry
air to overcome in those soundings and the wetbulb zero line is
farther south into central KY, compared to the freezing line.

All that to say we expect a narrow corridor with the best banding
potential, moisture, and freezing temperatures to occur roughly
along a line from Hartford to Louisville and then steadily
progressing eastward toward daybreak. Warm ground temps will help to
lower overall snowfall totals...though with broad scale lift in
place these next several hours, the winter weather advisory still
looks placed well with at least an inch. The heavier snow banded
area(s) will see more in the 2-3" range, with 4" not out of the
question in isolated swaths.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 414 PM EST Mon Dec 1 2025

An upper level trough is over the Upper Midwest and Plains this
afternoon, with a potent mid-level vorticity maximum noted over
TX/OK. We are already seeing low-level warm, moist air advect
northeast over the Lower MS Valley ahead of this wave. Dry low-level
air remains in place over KY and southern IN, and sfc high pressure
continues to shift across the Northeast. Temperatures have been able
to warm into the mid 30s to low 40s under partly to mostly sunny
skies this afternoon. However, the dry air at the sfc is especially
noteworthy heading into tonight with sfc dewpoints solidly below
freezing. Expect fairly steady temps until after sunset with mid and
upper clouds spreading in from the west ahead of the upstream
trough.

Tonight, the upper level trough will swing ENE over the Lower OH
Valley, with potent mid-level vorticity advection providing
increasing large scale ascent. In the lower levels, strengthening SW
LLJ winds will draw warm, moist air northeast through TN and central
KY. Weak low pressure at the sfc will evolve northeast across the
Gulf, with an inverted sfc trough setting up through eastern KY/TN.

Strong, deep forcing provided by the above factors, in addition to
robust frontogenetical lift, will yield widespread wintry
precipitation late this evening through Tuesday morning. The
heaviest precipitation is expected late tonight through the early
morning hours of Tuesday, when forecast soundings show deep moisture
overlapping with the strong lift. PW values will increase into the
0.6-0.9 inch range, certainly above normal for early December. Model
soundings and cross sections reveal weak stability in the mid-levels
(including the DGZ), above an isothermal layer extending up through
about 750 mb. Given the fairly strong fgen forcing expected and
sharp mid-level trough rotating in, this environment will likely
support heavier banded precipitation. Narrow, heavier bands could
easily boost snowfall totals in localized swaths.

Both QPF and snowfall amounts have been increased slightly with this
forecast update. The low-level warm advection is still expected to
pull a warm nose aloft northeast across central KY tonight,
complicating the precipitation type evolution/transition zone. The
latest available model guidance remains fairly consistent in
bringing that warm nose/p-type transition zone over roughly the
southeastern half of the forecast area. In other words, a transition
zone consisting of a wintry mix is likely to setup from
Morgantown/Bowling Green areas northeast into the Bluegrass Region
late this evening and early tonight. Southeast of that line, a plain
cold rain is likely for at least a few hours (lasting several hours
in the Lake Cumberland region). Northwest of that line,
predominantly snow is expected but QPF is relatively lighter further
to the northwest. The narrow transition zone from rain to snow will
then sweep fairly quickly southeast across all of central KY during
the early morning hours tomorrow. Precip will then taper off from
west to east as all snow during the mid to late morning hours.

Due to increased QPF and a slightly faster transition to snow as the
dominant p-type, the snowfall forecast has been increased slightly.
Snow accumulation of 1 to 3 inches is likely across southern IN and
most of central KY. Amounts of an inch or less are most likely
across southern KY, including the Lake Cumberland region. The
heaviest totals of 2-3+ inches are expected across southeastern
Indiana, northern KY, and parts of the Bluegrass Region. Some
locally enhanced snowfall totals are also possible immediately to
the northwest of the evolving p-type transition zone. Localized 4
inch amounts are certainly possible underneath more persistent
mesoscale banding.

Based on the updated forecast, the Winter Weather Advisory was
expanded slightly to the southeast to include Bowling Green,
Campbellsville, and Richmond. Regardless of the exact snowfall
accumulation in any one spot, slick and hazardous travel will be
possible Tuesday morning. Temperatures are forecast to dip into the
upper 20s to right around 32 degrees early Tuesday morning. Even in
south-central KY where snow amounts will be lighter, slick spots
will be likely (especially elevated surfaces) during the Tue morning
commute. Light snow could also end as freezing drizzle during the
mid to late morning hours Tue as drier air advects into the region
aloft. Skies will remain mostly cloudy through Tue afternoon, with
highs only in the low to mid 30s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 414 PM EST Mon Dec 1 2025

A cold high pressure system builds into the region for the midweek
time frame. Wednesday morning, in particular, will be quite cold
with lows in the mid teens to around 20 degrees. Temperatures should
rebound into the mid 30s to low 40s Wednesday afternoon under mostly
sunny skies.

Yet another cold front is forecast to drop through the area
Wednesday night and early Thursday, bringing another quick shot of
cold air. Look for lows in the 20s and highs in the 30s. This front
looks to pass through dry, with only an increase in cloud cover.
Another sfc high quickly builds east across the Ohio Valley late in
the week as another weak low pressure system sets up across the Gulf
Coast. A southern stream wave could bring us some light precip on
Friday, but most of the moisture could also pass to our south.
Forecast confidence is fairly low Friday and beyond.

&&

.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 709 PM EST Mon Dec 1 2025

The forecast remains on track as a system approaches the region
tonight. Between 4-7z all area TAF site ceilings are expected to
fall into IFR levels, and snow showers will drop visibilities into
IFR levels.

Currently, SDF and HNB are expected to see snow for most of the
event. LEX could see short period of a mix as rain begins falling
before changing to all snow around 6-8z. RGA expect all rain until
changing to snow around 8-9z. BWG can expect all rain until changing
to snow around 7-8z.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Winter Weather Advisory until 10 AM EST /9 AM CST/ Tuesday for
     KYZ023>043-045>049-053>057-061>067-070>072.
IN...Winter Weather Advisory until 10 AM EST /9 AM CST/ Tuesday for
     INZ076>079-083-084-089>092.

&&

$$

UPDATE...RJS
SHORT TERM...EBW
LONG TERM...EBW
AVIATION...KDW