765
FXUS63 KARX 231122
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
522 AM CST Sun Feb 23 2025

.KEY MESSAGES...

- This week will feature intermittent light precipitation
  chances (20-55%). While rain will be the more common
  precipitation type early in the week, some snow may mix in at
  times, with a very low (15%) chance for a bit of freezing rain
  Tuesday night north of I-94.

- Seasonably mild temperatures throughout much of the upcoming
  week with highs in the upper 30s to 40s areawide with
  potential for 50 degrees Monday and Friday.

&&

.DISCUSSION...
Issued at 348 AM CST Sun Feb 23 2025

Periodic potential for precip:

Northwesterly flow aloft looks to occur over the next week with a
series of upper waves bringing multiple chances for precipitation to
the region. Best potential looks to focus on Monday night, Tuesday
night into Wednesday morning, and Friday into Friday night.

This morning and again tonight, could presumably get a stray flurry
or sprinkle as upper disturbances currently over southwestern
Minnesota and the Canadian Rockies advance downstream, providing a
bit of lift through a briefly saturated DGZ. Enthusiasm for precip
is greatly muted by struggles with moisture, particularly in the low
levels, as seen in 23.00z MPX/INL RAOBs. Additionally, while radar
returns are seen upstream ahead of this morning`s wave, have yet to
see any reports of snow reaching the surface. Given these struggles
and the lack of flurries upstream, have limited mentions of
flurries to the slight chance (15%) category.

Monday into Monday night, good agreement that a robust wave will
eject over the CWA, most likely over SE MN/NE IA. Quick forward
motion of this feature and progged dry antecedent conditions int he
750-900mb layer will limit precip potential, but have nonetheless
nudged PoPs upward in our southwestern zones in deference to the
strength of the wave. As for precip type, progged soundings and
23.01z NBM probabilities both strongly suggest rain would occur with
this round.

Looking ahead to the Tuesday night round, guidance has trended
toward a stronger wave aloft over the past day and is now suggesting
that a zonal upper jet will advance over the central Plains, driving
surface cyclogenesis somewhere in Iowa or southern Minnesota. While
available moisture remains a limiting factor, plentiful forcing for
ascent suggests going above NBM PoPs would be prudent. Depending on
where exactly the surface low develops, warm advection could lead to
a modest warm nose developing in central WI, with 23.00z LREF joint
probabilities pointing toward a low (15%) chance for supportive
thermal profiles for freezing rain as precip falls. Have therefore
introduced slight chance mentions for freezing rain north of I-94
Tuesday night. All that said, rain and/or snow remain the more
probable outcomes with this round of precip.

Next wave arrives Friday night with an associated surface low
favored to pass to our northeast. In contrast to earlier in the week
when low level dryness looks to limit potential, dry air intrusion
around 700mb may keep precip to our northeast as well. Have
therefore kept the low 10-20% NBM PoPs as is during this period.
While rain would be the more likely precip type, should precip occur
late Friday night, strong CAA west of the departing surface low
would to thermodynamic profiles that favor snow.

Above normal temperatures ahead:

General trend toward ridging over the western half of the CONUS
should lead to above normal temperatures in our neck of the woods as
low level winds will tend to carry a westerly component most days,
helping to advect warmer air to the region. 23.01z interquartile
ranges for highs tend to be about 5-7 degrees Monday through
Thursday so am fairly confident most locations will reach and
remain in the 40s each of those afternoons. Before Monday,
uncertainty for this afternoon is higher with interquartile ranges
of 8-9, likely courtesy of uncertainty surrounding how much of a
role snow cover will continue to play. Current thinking is that
temperatures will reach 40 this afternoon as southwesterly winds
help temps overachieve. Either way, we should (80%+) reach 40 Monday
through Thursday afternoons with a decent chance (40%) to reach 50
in the Mississippi River Valley Monday afternoon.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 519 AM CST Sun Feb 23 2025

VFR conditions expected for the next 24 hours. Ceilings generally
around FL100 will continue for the next few hours before scattering
out later this morning. Ceilings will return again tonight mainly
around FL200 and should continue into tomorrow morning. Winds out of
the south to southeast will continue into the afternoon hours with
speeds generally between 6-12 kts. As a low-level trough passes
through tonight, we could see the development of a westerly LLJ
which could lead to some LLWS during the overnight period. Surface
winds are also expected to increase during the overnight periods,
especially at KRST, where gusts to around 25 kts will be possible.

&&

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

&&

$$

DISCUSSION...Ferguson
AVIATION...Barendse