140
FXUS63 KLSX 262012
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
212 PM CST Wed Nov 26 2025

.KEY MESSAGES...

-Cool and dry conditions will continue through Friday afternoon.

-Confidence is increasing in impactful snow moving through the
region Friday night through Saturday with greatest probabilities (50-
60%) for significant snowfall (4+ inches) across northeast Missouri
and west-central Illinois.

-Uncertainty in impactful snow is highest around the I-70 corridor
where slight changes in the transition of snow to rain will greatly
impact snowfall totals.

&&

.SHORT TERM...  (Through Late Thursday Night)
Issued at 212 PM CST Wed Nov 26 2025

Winds gusting into the 20s to 30s across the region, combined with
highs in the 40s has resulted in a blustery day despite the
increasing sunshine. The surface pressure gradient will continue to
loosen this afternoon and evening as the surface low across the
Great Lakes continues to lift northeast and a surface high pushes
into the mid-Mississippi Valley. Between the slackening gradient and
the loss of deep mixing with sunset, gusts will diminish late this
afternoon. Overnight temperatures will drop into the 20s to low 30s
across our far south, the low-level cold air advection mitigated by
incoming mid to high clouds and elevated winds.

Thanksgiving day will be a few degrees cooler than today given a
slightly cooler start and continued cold air advection, with highs
in the upper 30s to low 40s area wide under a mostly clear sky.
Overnight lows into Friday will be cooler than tonight as winds are
calmer with less cloud cover allowing for temperatures to cool well
into the 20s.

Delia

&&

.LONG TERM...  (Friday through Next Wednesday)
Issued at 212 PM CST Wed Nov 26 2025

The trough that will dive this weekend`s wintry weather is still
over the northern Pacific Ocean, and will come onshore Thursday over
the Pacific Northwest. As this feature slides southeast into the
CONUS, a surface low will develop across the northern Plains and
push southeast into the mid-Mississippi Valley. Precipitation will
start Friday evening, aided by a 45-55 kt low-level jet that will
persist into the day Saturday. Precipitation is expect to start
falling as snow as low-level dry air causes wetbulbing across the
region. As snow continues overnight the very strong low-level jet
will persists, prompting robust warm air advection as well.
Precipitation will continue Saturday as the low pushes across the
region, aided by the low-level jet and mid-level trough. Snow will
transition over to rain at some point on Saturday for many locations
as the warm air advection eventually wins out and overwhelms the
dynamic cooling. Across southeast Missouri and southern Illinois
this change over will happen soonest, while for portions of far
northeast Missouri and west-central Illinois, snow may not
transition at all. In between, across central and east-central
Missouri, is where a great amount of uncertainty exists in the
timing of the change over to rain.

Ensemble guidance shows a spectrum of options in how the details
listed above play out together. On the coldest/snowiest end of the
spectrum, the strong low-level jet produces more QPF than previously
forecast from the combination of strong dynamics and strong lift
within the dendritic growth zone. This results in higher snowfall
rates, keeping near surface temperatures cooler and snowfall lasting
longer into Saturday areawide. In this scenario, high snowfall rates
(up to 1"/hr) would also be able to overcome warm ground
temperatures to produce snowfall accumulation on all surfaces even
where snowfall amounts remain low (1-2 inches). Impacts would be
expected wherever snow falls.

Meanwhile, the warmer/rainy side shows warm air advection winning
out over the dynamics of falling snow keeping the near surface
atmosphere cold. This would change snow over to rain quicker than
currently forecast, limiting snowfall accumulation overall. Snowfall
would end in many locations before producing higher snowfall rates,
meaning that impacts would be limited to grassy and elevated
surfaces.

The most likely solution falls between these two extremes, as does
our current forecast. The official forecast has trended cooler,
however, showing a slightly slower transition to rain than 24 hours
ago, producing more snow across more of the forecast area. Both
deterministic and ensemble guidance are coming into agreement in a
stronger, colder system. LREF and NBM QPF have increased over the
past 12 hours, and is now more representative of what we expect from
the dynamics with the low-level jet. With the overall trend toward a
cooler and wetter forecast, the probability of exceedance products
from the NBM and LREF for 1, 2, and 4 inches of snow have increased
30-40% over the past 24 hours. This brings more confidence to a
middle ground solution that leans towards a cooler, snowier forecast.

Another surge of Arctic air will push into the region Sunday behind
the exiting winter system. More surges of cold air will push into
the area as multiple mid-level shortwaves push through the region
during the first half of next week. These will help keep 850 mb
temperatures in the negative single digits Sunday through Tuesday,
resulting in high temperatures in the 20s to 30s before ensemble
guidance hints at a warming trend starting up mid-week. Near
freezing temperatures and multiple shortwaves mean that any
precipitation that is squeaked out of the cold air will fall as
snow, though confidence in this occurring is low at this point.
Delia

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1030 AM CST Wed Nov 26 2025

While all terminals are at VFR flight conditions, winds are
gusting into the 30s at most terminals. Between a tight surface
pressure gradient and mixing stronger winds down to the surface,
gusty winds will continue at largely the same magnitude through
the late afternoon. As we lose daytime mixing late this afternoon
and the surface pressure gradient loosens winds will diminish,
though will still remain near 10kts sustained overnight.

Otherwise, dry and VFR conditions will continue through the rest
of the TAF period.

Delia

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX