512
FXUS63 KARX 272007
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
207 PM CST Thu Nov 27 2025

.KEY MESSAGES...

- A winter storm moves through the Midwest Friday night through
  Saturday night, providing a prolonged period of snowfall.
  Probabilities for 6+" of snow are 25-95%, highest (70-95%)
  along and south of I-90.

- Cold temperatures remain through next week with highs in the
  upper teens to mid 20s. Overnight lows fall into the single
  digits above and below zero by the beginning of next week.

&&

.DISCUSSION...
Issued at 159 PM CST Thu Nov 27 2025

Winter storm Saturday:

All eyes are on an upper disturbance off the Pacific Northwest coast
this afternoon. Broad agreement across guidance that this feature
will dive southeast toward the southern High Plains as an upper jet
advances to the equatorward side of this feature as it approaches
the Front Ranges of CO. This will result in lee surface cyclogenesis
where CO/NM/KS/OK/TX meet Friday evening. As this occurs, upper low
over the Great Lakes will shift eastward and an upper jet currently
on the westward side of this low over the northern and central
Plains will become oriented over roughly a MN to NYC axis.
Additionally, broad surface ridge will build in the TN/OH Valley in
the wake of this upper low with this shifting to the Piedmont on
Saturday. With the right entrance region of the MN to NYC jet
located over IA/MO, southern High Plains surface low should rapidly
advance northeastward toward NE MO. Given the surface high to the
east, southerly moist advection will be sufficient for widespread
precipitation to develop as isentropic lift occurs on the 275-285K
surfaces. Thermal profiles across the CWA are solidly below
freezing, so any precipitation will fall as snow.

While snow is a certainty for areas along and south of I-90,
remaining questions surround both how far north snow shield will
extend and exactly how much will fall. Mesoscale features that tend
to be needed to reach a foot of snow in this part of the country -
frontogenetic banding or a persistent TROWAL - are conspicuously
lacking in guidance outside of a frontogenetic band moving northward
with the initial warm advection regime. Therefore, am expecting an
extended period of light to moderate snow and have gone with the
more conservative WPC numbers, which line up better with 27.12z
modeled snow depth change, rather than the more aggressive NBM.

Due to collaboration concerns, have upgraded all counties within
the Winter Storm Watch to a Winter Storm Warning west of the
Mississippi and issued a Winter Weather Advisory for Wabasha
County.

Cold week ahead:

A week of cold weather is expected in the wake of Saturday`s winter
storm. Based on the timing of when the surface high builds into the
region, Sunday night should be the coldest of the bunch. Indeed, NBM
highs are in the single digits above and below zero and would not be
surprised to see all locations end up below zero once all is said
and done. Silver lining is that breezy winds appear improbable
during the cold snap so wind chills are favored to remain above
-15.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1128 AM CST Thu Nov 27 2025

Scattered to overcast cigs at low-VFR to MVFR heights will be the
primary aviation concern throughout the afternoon and into the
evening. In addition, steeper low-level lapse rates and some weak
instability will allow for some snow showers to develop near and
east of the Mississippi River that could result in isolated category
vsby reductions. However, confidence was too low (10-20% chance in
the recent HREF) in the to include at KLSE at this time with
higher probabilities further east. RAP/HRRR soundings indicate
some drier air tries to sneak in overnight which may raise cigs
somewhat before additional scattered to perhaps broken MVFR cigs
return for the early part of the day on Friday. Northwest winds
will slowly diminish throughout the TAF period beginning at
around 12-18 kts at 18z and falling below 10 kts overnight.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Watch from late Friday night through late
     Saturday night for WIZ041>044-053>055-061.
MN...Winter Storm Warning from midnight Friday night to 6 AM CST
     Sunday for MNZ086>088-094>096.
     Winter Weather Advisory from midnight Friday night to 6 AM CST
     Sunday for MNZ079.
IA...Winter Storm Warning from midnight Friday night to 6 AM CST
     Sunday for IAZ008>011-018-019-029-030.

&&

$$

DISCUSSION...Ferguson
AVIATION...Naylor