433
FXUS63 KLMK 282325
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
625 PM EST Fri Nov 28 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* A storm system will work into the region Saturday afternoon
  through Sunday morning. Expected snow amounts continue to trend
  down across the area, with most of the precipitation falling as
  rain Saturday night. Impacts with this system are expected to be
  limited by light precipitation amounts and marginal temperatures.

* Wintry weather is likely Monday night and Tuesday with some areas
  receiving an accumulation of snowfall.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 335 PM EST Fri Nov 28 2025

High pressure is moving across the region this afternoon, resulting
in mostly sunny skies and cool temperatures in the mid-to-upper 30s.
A band of mid-level dry air over the area has cleared out much of
the stratocu field this afternoon, with some of that dry air mixing
down to the ground, as 20-25 degree dewpoint depressions are
currently noted in obs. The first signs of our weekend system are on
our doorstep as scattered high clouds are pushing into western KY at
this hour. With that being said, nothing more than dry and cold
weather are expected this afternoon and evening, with west winds
becoming light and variable tonight.

Tonight, an upper-level shortwave will amplify as it ejects out of
the northern US Rockies and into the central Plains. At the sfc, a
Colorado Low will develop and get picked up by the upper wave,
ejecting across KS and MO during the day on Saturday. Mid- and upper-
level moisture will overspread our area tonight from west to east,
with high clouds increasing in coverage through the night. With
winds expected to remain light tonight and limited low-level sky
cover, temperatures should drop once again into the low-to-mid 20s,
with some upper teens likely along and east of US 127.

Tomorrow morning, greater low-level moisture will begin to surge
into the region from the west on the leading edge of a strengthening
S/SW LLJ. This should begin the process of top-down saturation, with
mid-level stratus increasing from west to east during the morning
hours. A band of precipitation, likely in the form of snow, should
develop across eastern MO during the pre-dawn hours before moving
across southern IL and approaching the Wabash Valley later in the
morning. As this precipitation moves into SW and southern IN, it is
likely that much of the snow will sublimate as it encounters very
dry air in the lowest 5-10k feet. While radars will likely show
precipitation across southern IN during the late morning and early
afternoon hours, much of this may end up being virga, or could only
reach the ground as light snow or flurries. Differences in the
strength of the low-level dry air appears to be a key reason why
certain hi-res models (e.g. NAM 3 km) show heavier precipitation
amounts, as they erode the dry air faster than the drier models
(e.g. HRRR). Would lean toward the drier models being closer to
perfect prog, as the best forcing and moisture advection should
remain to the NW of the area until late Saturday afternoon.

Initially, model soundings would support snow across northern KY and
southern IN as sublimation and associated wet-bulbing effects keep
temperatures aloft below freezing. However, as the WAA (and moisture
advection) strengthens over our area late Saturday afternoon into
Saturday evening, precipitation types should transition to all rain
as most of the sub-freezing air between the sfc and 700 mb is
scoured out. In short, if precipitation onset is faster tomorrow
morning, there would be better potential for accumulating snow
across southern IN, and potentially along and north of I-64 in
central KY. However, the increasingly likely outcome is that delayed
precipitation onset tomorrow will result in a less favorable thermal
profile for snow once precipitation begins.

In terms of amounts and impacts, this forecast has continued the
downward trend of the past 24 hours. Along and north of a line from
Jasper to Madison, a quick burst of around 1/2" of snow is expected,
with localized amounts up to 1" possible. Between the Jasper-Madison
line and areas along the Ohio River, a quick dusting is possible,
though many areas may remain dry until precipitation begins as rain
Saturday evening. All in all, marginal snow amounts and ground
temperatures should lead to minimal impacts in southern IN, though
there could be brief slick spots if any heavier snowfall rates
develop.

Saturday night into Sunday morning, temperatures should remain
steady or even warm into the upper 30s and low 40s in the warm
advection regime ahead of the cold front. Light to moderate rain
showers are expected to move across the area along and just ahead of
the cold front, though rain amounts will be light (generally 0.25"
or less). With the LLJ overhead, breezy conditions are likely
Saturday night, with southerly winds of 10 to 20 mph and gusts of 20
to 30 mph expected.

Sunday morning, the sfc cold front will quickly push across the
region, with winds veering around to the west with cold FROPA.
Behind the front, strong CAA is expected during the day on Sunday,
and given continued mostly cloudy skies limiting heating from
insolation, temperatures will either remain steady or fall through
the 30s during the daytime hours Sunday. Wind chill values will
likely be stuck in the 20s during the day on Sunday given the
blustery conditions. Sunday night, winds will steadily ease as high
pressure noses into the region from the NW. By Monday morning,
temperatures should bottom out in the low-to-mid 20s across the area
under mostly cloudy skies.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 335 PM EST Fri Nov 28 2025

Monday through Tuesday Night...

An active period of weather is expected for late Monday and into the
day on Tuesday as a mid-latitude wave ejects out of the southern
Rockies and into the Plains while amplifying slightly as it reaches
the MS river.  At the same time, surface cyclogenesis is expected
across LA with the surface low taking a track across the SE US
states before ending up in the Carolinas/Mid-Atlantic region by
Tuesday afternoon.

A decent fetch of Gulf moisture will be advected northward into the
region late Monday afternoon, which will be come more than
sufficient for widespread precipitation production.  Synoptic scale
forcing will increase across the region as a h5 jet streak moves
into the region in tandem with the aforementioned wave coming out of
the Plains.  A secondary jet streak is expected to be in place from
western NY into ME.  If this configuration evolves like this, we`ll
be in the left exit region of the approaching souther jet streak
while also being in the right entrance region of the NY-ME jet
streak.  As a result a band of moderate to potentially heavy
precipitation is expected to develop across the region.

While this is generally a classic setup for an Ohio Valley winter
storm, we are lacking an important ingredient here, which is the
existence of a deep/cold airmass in place prior to the system`s
arrival to offset the usual warm air advection that occurs with such
systems.  Both the GFS and Euro ensembles contain a considerable
amount of spread with p-type for the event, which is not surprise at
this forecast time range.  The general consensus of the models
suggests at least a wintry mix of rain/freezing rain/snow developing
across the region Monday night before ending as all snow Tuesday
morning.  Impactful accumulations will be possible for portions of
the region.  Probabilistic ensemble guidance as of this writing
suggests the highest probabilities of impactful accumulations would
likely be north of the WK/BG Parkways.  A continued spread in the
model solutions is expected to continue into the weekend, but
increasing forecast convergence should allow us to start to narrow
down the threat areas as we get deeper into the weekend.  At this
time, it is simply way to early to speculate on specific ice/snow
accumulations.

Wednesday through Friday...

By mid-week split flow pattern is expected to be in place across the
CONUS with an upper level low remaining out across CA and downstream
convergent zonal flow from the Plains through the Ohio Valley.  High
pressure at the surface looks to bring drier conditions to the
region, however, temperatures will remain below normal through the
period.  The flow across the western CONUS is expected to become
more amplified with stronger ridging building across the western US
Coast.  This will lead to height falls and a broad trough developing
across the east.  This will result in cold weather continuing with
smaller perturbations moving within the flow.  One of these
perturbations looks to arrive in the Fri/Sat period which could
bring another round of wintry weather to the region.

Extended Forecast Discussion...

Looking beyond the period, the overall hemispheric driver will
continue to be the MJO with lesser contributions from the normal
teleconnection (AO/PNA/NAO/EPO) patterns.  Currently, the MJO remain
in phase 6 and an orbit into phase 7 is expected as we enter into
the first part of December.  Within a weak -ENSO pattern, this will
lead to a gradual expansion of colder weather from Canada, into the
Plains and down into the OV and eventually the east Coast.  Most
modeling shows a pause in the orbit of the MJO as we approach the
10th of December.  However, the MJO pulse then looks to orbit out
into Phase 8 which will likely lead to a much colder pattern taking
shape across much of the eastern US as we head into mid-late
December.  Updated signal analysis shows a rather active pattern
with multiple signal crossings in our area through December.  Many
of them are close together, but the strongest ones are around 12/6,
12/8, 12/10, and 12/14.

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 625 PM EST Fri Nov 28 2025

For this evening, VFR conditions are expected with light westerly
winds.  Expect winds to become light and variable later this evening
with high clouds moving into the region from the west.  By Saturday
morning, winds will swing around to the southeast with cigs lowering
through the day.  Light snow will likely impact KHNB after 15Z
Saturday.  Light precipitation, perhaps mixed with a little
snow/sleet will be possible at KSDF/KLEX after 29/20Z or so.

&&

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

&&

$$

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