289
FXUS63 KARX 091929
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
229 PM CDT Sun Mar 9 2025

.KEY MESSAGES...

- Warm weather continues into Monday as high temperatures reach
  the 60s with some areas flirting with 70F. Some fire weather
  concerns Monday afternoon given warm temperatures and breezy
  winds.

- Brief cool down Tuesday, then another warming trend through
  late this week. Some areas may reach the low 70s by Friday.

- Dry weather is expected until a stout low pressure system
  develops across the Great Plains late this week, tracking into
  the Midwest on Friday. Potential for thunderstorm development
  (20-40%), but uncertainty remains for severe weather.

&&

.DISCUSSION...
Issued at 229 PM CDT Sun Mar 9 2025

Warm Weather Continues

A 500hPa ridge continues building into the region today into
Monday, which combined with southwesterly low level flow sets up
a warm air advection regime across our area. We have been able
to overachieve on temperatures again this afternoon and as such,
expecting to do so again Monday, especially in valley locations
where downsloping and adiabatic warming can play a roll in
increasing temperatures above model guidance. Thinking these
areas have a good shot at reaching above 70F on Monday. Record
high temperatures for 3/10 at both RST and LSE remain in
jeopardy as the current records are 67 (1894) at LSE and 63
(1977) at RST.

There is some fire weather concern Monday afternoon, mainly east
of the Mississippi River. Breezy winds develop again, generally
20 to 30 mph with some gusts to 35 mph. Dewpoints are also
expected to mix out more than model guidance suggests, so have
trended towards the 10th percentile of the NBM to account for
this and lower RHs. However, the wet ground should help
alleviate some of the risk.

Still expect a brief cool down Tuesday following the passage of a
surface cold front before southerly flow sets up on Wednesday,
allowing for warm air advection and subsequent warming through
the end of the week.

Dry Weather Before a Stout Low Moves Into The Region Friday

With little in the way of forcing and ample dry air in place through
the next several days, dry weather is expected across the region
until the system expected late this week moves into the Midwest. Not
many changes regarding the system in the ensemble guidance is noted
over the past 24 hours, as the 09.06z EPS, GEFS, and GEPS look
fairly similar to their previous runs. There still remains some
discontinuity between the various ensembles, as well as between
their individual members, regarding placement and depth. The GEFS
remains the deeper and farther north solution, keeping the low
mostly to our northwest whereas the EPS/GEPS are a little further
south, dragging the low nearly on top of our area, but overall the
various ensembles and their members look to be in good agreement for
an event this far out.

All three solutions do put us within the warm sector of this system,
but how far into said warm sector is still uncertain given
variations in the track. Probabilities for temperatures above 70F
have increased in the EPS slightly since the 09.00z run, now showing
20-70% probabilities with the highest probabilities south of I-90,
closer to the Wisconsin/Illinois border. The 09.06z GEFS remains
less confident in this outcome, keeping probabilities of >= 70F
temperatures south of the Wisconsin/Illinois border. Given warm
near surface temperatures and an above freezing column, the
dominant precipitation type appears to be rain.

Deterministic solutions tend towards a high shear environment
associated with this system as a strong 700-500hPa jet streak
and 850hPa low-level jet pivot around the base of the
trough/low. Instability will still be something to watch over
the coming days as the ultimate track of the low will dictate
how warm we are able to get and how much moisture return we
receive, influencing how much instability develops. Current
deterministic solutions do depict 500-1000 J/kg of MUCAPE across
our area Friday afternoon and evening which is similar to the
09.13z NBM 25th-75th spread in surface based CAPE. Based upon
these variations of instability combined with the uncertainty in
the track of the low as mentioned previously leads to low
confidence in the overall severe threat across our area.
However, it is important to note that this threat is not zero as
the CSU severe probabilities continue to show a 15-30% chance
of severe weather in our area with the SPC Day 6 outlook
highlighting a 15% risk just south of our area.

A transition to snow appears plausible as the low begins to exit
late Saturday. Probabilities for 850hPa and surface temps falling
below freezing begin to increase to 40-70% and 20-50%
respectively by Saturday evening. Any snow accumulation will be
largely dependent on how fast this possible transition takes to
occur and how warm the surface is after a week of warm
temperatures and the preceding rainfall.

In summary, ensemble guidance appears to be in good agreement
regarding the overall development of this system at such a long lead
time. The dominant precipitation type appears to be rain with a
possible transition to snow as the low exits the region.
Thunderstorms also appear possible, but the extent of any severe
threat across our area remains challenging to pin down this far
out.


&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1250 PM CDT Sun Mar 9 2025

Breezy west to southwest winds have begun this afternoon, but
will begin to wane as the sun sets, falling below 10KT
overnight. VFR conditions will continue with SCT to BKN high
clouds continuing to move through the region this afternoon,
decreasing in coverage this evening and overnight. Southwest
gusts begin again Monday afternoon as diurnal mixing increases.

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Falkinham