971
FXUS63 KARX 221819
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
119 PM CDT Sat Mar 22 2025

.KEY MESSAGES...

- Rain chances and wind for most late tonight into Sunday. Higher
threat for snow and a short period of freezing rain north of I-94.
Snow accumulations of a few inches and light icing could be
realized.

- Warming moving through the new week. Increasing precipitation
chances for the latter half.

&&

.DISCUSSION...
Issued at 305 AM CDT Sat Mar 22 2025

- TONIGHT/SUNDAY: rain and wind for most, snow to wintry mix more
likely north of I-94.

Upper level shortwave set to move from the PAC NW to the northern
plains this afternoon. The mix of embedded bits of energy then move
eastward across the upper mississippi river valley tonight and
Sunday. Decent QG response all the way through the atmospheric
column later tonight into Sun morning. Left exit region of a 300 mb
jet streak will help deepen the overall lift tonight. Add a couple
sfc fronts and associated Fgen to the mix and there is ample lift to
support widespread precipitation generation.

Saturation could be a limiting factor initially for this
afternoon/evening as initial warm air advective band will only have
mid level RH to play with - per time/height x-sections and bufkit
soundings. The saturation does deepen overnight and the column will
stay relatively moist moving through Sunday.

Expectation is for a band of north-south running pcpn ahead of cold
front to become more expansive overnight, quickly shifting into
eastern WI by Sun afternoon. Slug of cold air will increase 1000:850
mb lapse rates to 8+ C/km with Bufkit soundings also depicting
instability below mid level inversion. A good setup for shower
development. All in all, several rounds/areas of pcpn looking likely
with I-94 northward the favored location to take the brunt of it.

For precipitation type, temperature profiles favors rain for the
bulk of the forecast area. However, north of I-94 looks like it
could harbor a variety of ptypes. Warm layer a loft and colder near
sfc temps leans into a freezing rain potential overnight tonight.
This has support from the HREF/SREF with RAP/HRRR also showing this
possibility. This would transition to mainly snow Sunday morning.
Ice accums of a trace with a few inches of snow would be possible in
this setup - but a lot of questions in how quickly the warm layer a
loft would erode, along with any potential for loss of ice in cloud.
If current forecast continues to bear out, a winter weather advisory
could/would be needed for Taylor, possibly Clark county in north-
central WI for overnight-Sun morning (maybe lingering into Sunday
evening).

Winds will be on the increase late tonight, continuing through
Sunday afternoon/evening. GEFS and EPS means suggest gusts of 40+
mph possible - more so Sunday into Sunday night. So do a few of the
short range models. The NBM is underdone and have increased several
mph above. Might need to do more if these wind trends also continue.
Looks sub-wind advisory at this time.

- NEXT WEEK: warming, widespread rains looking possible for the
following weekend.

The longwave upper level trough will continue to influence the
region for the start of the new week, and a perturbation or two
could ripple across the area as a result. Long range models aren`t
enthused about any shortwave in particular at this time - only a
smattering of low end chances (20-30%) for precipitation.

Upper level ridging starts to build in from the west as we move into
the middle part of the new week, with solid support from all 4 of
the WPC clusters. GEFS and EPS mean temps for highs suggest we could
warm into the 60s by next weekend...but with a 30+ degrees spread in
the 10-90% of potential outcomes, confidence not high in how the
numbers will shake out. That said, as long as the ridge continues to
slide in, above normal temps should follow.

With the milder airmass could come increased precipitation chances.
The bulk of the EPS and GEFS members edge the ridge axis east on
Friday, allowing a few bits of shortwave energy to spin across/near
the region. Widespread rains could/would result. A lot of unknowns
with overall development, any phasing, etc with the shortwaves - not
to mention timing. But the good agreement between the 2 model suites
pegs this period as one to watch.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1250 PM CDT Sat Mar 22 2025

VFR conditions this afternoon with increasing mid and high level
clouds. Deteriorating conditions tonight and Sunday with
increasing winds and showers developing especially after 03-05Z
at both KRST/KLSE with MVFR/patchy IFR conditions. Periodic
showers will continue through the TAF period. Cannot rule out
thunder with the showers Sunday morning. With the cold air in
place, a wintry mix is expected along and east/north of I94
Sunday morning. Some areas (Taylor Co.) could stay with periodic
light snow through the day. Farther south, rain is favored or a
mix for Clark Co. Surface winds vary from light and variable to
increasing 10 to 20 mph for parts of southeast MN and northeast
IA today. Winds strengthen areawide tonight into Sunday 10 to
20kts with gusts 20 to 30kts Sunday morning. Did mention low
level wind shear at KLSE tonight and Sunday morning.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.

&&

$$

DISCUSSION...Rieck
AVIATION...Zapotocny