446
FXUS63 KLMK 021600
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1100 AM EST Tue Dec 2 2025

.KEY MESSAGES...

* Hazardous travel expected Tuesday morning as moderate to briefly
  heavy snow moves east across the region. Additional snow amounts
  up to 1-3 inches possible.

* Snow is expected to taper off from west to east this morning.
  Winter Weather Advisory in effect until 10 AM EST.

* Drier weather expected later today, though with temperatures
  struggling to get above freezing. Patchy freezing fog is possible
  tonight.

&&

.UPDATE...
Issued at 1057 AM EST Tue Dec 2 2025

Snow has ended across the area, and the Winter Weather Advisory has
been cancelled. Some roads, especially lesser traveled side streets
or rural roads, may remain slick into the afternoon.

Upper troughing lingers over the Ohio Valley this morning, but will
quickly swing east this afternoon. High pressure at the surface will
build in from the west this evening. An expansive stratus deck
blankets the region, extending west across Illinois and the eastern
half of Missouri. While the mid-levels continue to quickly dry out,
the low-level moisture trapped beneath an inversion will allow the
low clouds to stick around the rest of the day.

The low clouds are currently expected to slowly scatter out from
west to east this evening and overnight. However, as skies begin to
clear, there is a signal for fog late tonight and early Wednesday.
The fog could become dense, and areas of freezing fog may result in
slick/icy spots on roads tonight and Wednesday morning. Temperatures
are forecast to drop into the upper teens to lower 20s by the
Wednesday morning commute.

.MESOSCALE...
Issued at 539 AM EST Tue Dec 2 2025

Snowfall is tapering off from west to east this morning as the
primary 850mb frontogenesis axis, upper level divergence, and deeper
moisture convergence shift east of the forecast area. However, we
are allowing the Winter Weather Advisory to continue to help
increase awareness for the hazardous road conditions ongoing across
the forecast area. The headline may be allowed to be trimmed or
cancelled entirely before 10 AM EST if road conditions improve.

Radar currently shows light returns east of a line from Allen county
to Harrison county (KY), with light snow falling in our eastern CWA.
The back edge of the precip shield should exit our forecast area by
12z or so.


Issued at 328 AM EST Tue Dec 2 2025

===== Moderate to Heavy Snow Bands Causing Travel Impacts =====

Heavy snow rates around or exceeding 1 in/hr are ongoing across a
considerable portion of the forecast areas this morning, leading to
hazardous travel impacts. Area traffic cameras and snowplow cameras
show snow-covered roads, even on treated surfaces.

A belt of 120+kt southwesterly flow in the upper levels has
overspread the entire region just ahead of the upper trough axis,
with strong upper level divergence and mid-level vorticity providing
large-scale forcing. Per Mesoanalysis, 850mb layer frontogenesis is
quite strong, aiding in the large-scale forcing and a well-saturated
airmass with PWATs noted to be 0.6-0.9", which is certainly above
the daily mean based off sounding climo, and exceeding the 75th
percentile across our southern half of the CWA. Strong lift,
evidently maximized in the mid-levels by the frontogenetical
forcing, will continue to support large dendritic ice crystal growth
within these saturated profiles.

We have been watching MRMS Reflectivity at -15C, which has been a
good indicator of where heavier snow bands are moving across the
region. This reflectivity shows a drier slot now working into
portions of Hancock/Ohio/Perry counties, with another band of snow
following behind. If this feature holds, expect a brief lull in
snow activity followed by one final burst of snow. However, it
appears that secondary snow band may be weakening, and could
completely dissipate before reaching the I-65 corridor. If so, then
the back edge of the snow band may already be approaching I-65 and
some areas such as Ohio/Hancock may be close to being done with the
snow.

We have measured a total 2.4" of snow at the Weather Forecast Office
so far, with the -15C reflectivity showing perhaps the last of the
heavier bands working east of Louisville now. Correlation
Coefficient and sfc obs show that LEX has finally switched over to
snow, but a dry slot on radar over Anderson/Woodford should move
over LEX and give them another break in snow accums.

Generally speaking, an additional 1-3 inches will remain possible
before 12z this morning, which could lead to some isolated 4+ inches
of snow when it`s all done.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 328 AM EST Tue Dec 2 2025

The main snow shield is expected to be pushing east of the area by
the beginning of the forecast period at 12z today as forcing shifts
toward the mid-Atlantic, with the 120Kt 300 mb jet and vort max
clearing our area. Model soundings indicate we could see some patchy
freezing drizzle in the wake of the departing sfc low and inverted
trough as we deal with some lingering low level moisture, but
confidence remains limited on this. Overall, a drier trend is
expected as the day progresses, though temps will struggle to get
above freezing for majority of the area as clouds linger region-
wide.

By tonight, we will eventually begin to see clouds slowly clear from
west to east as the upper shortwave axis pivots east and we take on
a more zonal flow regime. However, cloud cover will likely remain
overhead for areas east of the I-65 corridor, and we won`t complete
clear out. With fresh snowcover, and sfc high pressure setting up
directly over us, our sfc temps are forecast to drop into the upper
teens to low 20s. However, lingering low level moisture trapped
underneath a very stout nocturnal inversion combined with weak WAA
regime and fresh snowcover could lead to a higher chance for fog
developing tonight, as indicated by hi-res guidance. Given the
forecast lows in the upper teens to lower 20s, we could see patchy
freezing fog across the forecast area.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 328 AM EST Tue Dec 2 2025

===== Wednesday - Thursday =====

Zonal flow in the upper pattern takes over for Wednesday, with sfc
high pressure situated over the Ohio Valley. Temps are forecast to
be well below normal for early December, with temps to start off our
Wednesday in the upper teens to low 20s, and with temps struggling
to hit the low 40s by the afternoon hours. Despite the cold temps,
should have plenty of sunshine for the daytime hours. Mid-level and
high-level clouds will begin to increase by Wednesday evening ahead
of an approaching cold front.

A weak impulse within the primary westerly flow aloft will aid in a
weak cold front to drop into the region on Thursday, which will
likely bring a reinforcing shot of cold air due to the associated
CAA flow. We could see some light snow to our north, but lingering
dry air below 700 mb and meager saturation in the DGZ should lead to
a dry frontal passage in our area. Best chance for any light snow
would be across southern IN Wednesday night ahead of the front,
though we only have a 15-20% chance drawn for now. Temps on Thursday
will be even colder, with highs ranging from low 30s across souther
IN to upper 30s across south-central KY.

Temps for Thursday night and into early Friday morning are expected
to be the coldest of the long term period, with temps dropping into
the low teens for areas north of I-64, upper teens for areas north
of the KY Pkwys, and low 20s to the south.

===== Friday - Weekend =====

Confidence for Friday and into the weekend falls considerably as
deterministic guidance diverges. Temps each day are forecast to
reach the upper 30s to low 40s, but confidence in precip chances
remain low. While there is a bit more agreement on Friday of seeing
a sfc low move across the Gulf Coast, there remains considerable
spread within the ensembles for QPF on Friday.

More uncertainty plays into the weekend, and whether we see a quick-
hitting clipper system or not that could bring another shot of snow
to the region. The GFS deterministic believes so, but the ensembles
are not as convinced. Will be worth watching, but keep in mind the
low confidence for now.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 615 AM EST Tue Dec 2 2025

Snow is ending this morning, but low cigs will continue throughout
the entire period. IFR cigs are expected through this morning, with
slight improvements to MVFR by the afternoon. Otherwise, drier
weather is expected for today and tonight. Patchy freezing fog may
be possible tonight, but did not include mention in TAFs at this
time.

&&

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

&&

$$

UPDATE...EBW
MESOSCALE...CJP
SHORT TERM...CJP
LONG TERM...CJP
AVIATION...CJP