955
FXUS63 KARX 270344
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1044 PM CDT Wed Mar 26 2025

.KEY MESSAGES...

- Light rain chances for parts of the area tonight. Light
  accumulations, if any.

- Warm temperatures for Friday, some locations flirting with
  records. Cooler to below normal temperatures for next week.

- Widespread rain chances (70-90%) and possibly a few rumbles of
  thunder late this week and this weekend. A transition to
  snow/ice/wintry mix is possible Saturday night into Sunday,
  especially north of I-94.

&&

.DISCUSSION...
Issued at 229 PM CDT Wed Mar 26 2025

Tonights Rain Chances

Forecast looks on track for tonight. Early this afternoon,
regional radars are showing echoes over the Dakotas shifting
rapidly southeast toward the area. Surface observations are
showing sprinkles at best and generally 5-8kft cloud bases. This
is indicative of the fairly dry sub-cloud layer out there and
struggles to get lighter intensity showers to the surface. These
showers are stemming from frontogenetical forcing from
600-800mb in a nicely confluent wind flow at that level per the
latest RAP comparisons to radar. Also in play is a nice 700mb
warm advection signal. This forcing traverses the area in the
late evening and overnight from west to east providing lift for
showers. When this occurs, convective upright instability
[MUCAPE>100 J/Kg] remains over IA southwest of the area per RAP.
The challenge in the absence of better instability is the
degree of saturation and how much if any rain will occur outside
of sprinkles. Have kept most of the forecast as it was with a
60-70% max band of rain chances centered on about the Miss river
decreasing west and east to 40%. Areas north of I-94 should
remain dry. The forcing will shift southeast in the morning with
clearing skies again and highs near 60.

Warm Temperatures Friday, Cooler Next Week

Friday continues to look warm with some areas flirting with
record high temperatures as a warm front moves northward through
the region. Higher confidence in the high temperature forecast
exists south of I-90 while confidence decreases further north
owing to remaining variations in the northward extent of said
warm front. Regardless, above normal temperatures are expected
across much of the area on Friday. Please see the climate
section for more details.

Greater variability in the temperature forecast comes this
weekend as a mid-latitude cyclone moves through the region. The
speed of this system`s propagation will have a great impact on
the high and low temperatures, especially Saturday afternoon
into Sunday as the 24.06z GEFS/EPS indicate a roughly 10 degree
spread in the 25th-75th percentiles for both. This spread
decreases into early next week, but a cooling trend and below
normal temperatures are currently expected.

Widespread Rain And Winter Precipitation Chances This Weekend

As the aforementioned warm front moves northward through the
region Thursday night into Friday, chances for showers and
perhaps some storms increase (30-50%) along an area of 850hPa
warm air advection, 850hPa moisture transport, and 800-700hPa
frontogenesis associated with said front. Anything that develops
is expected to be elevated given low-level stability, but there
is the indication of a few hundred J/kg of MUCAPE which
combined with mid-level lapse rates of 7-8 C/km would be
supportive of thunderstorm development. Better storm chances
lie across northern Wisconsin Friday afternoon where greater
instability and stronger effective shear is able to develop.

To revisit this somewhat persistent topic, widespread rain is
expected across the Upper Midwest this weekend (70-90%),
generally from Friday night into Sunday. Some models do suggest
a bit of a lull during the day Saturday, mainly areas along and
south of I-90, before the main 500hPa trough and associated
surface wave propagate through the region.

Thankfully, ensemble guidance continues to show improving,
although still varied, agreement regarding the development of
this system and placement of the highest axis of QPF. The 24.06z
EPS/GEFS suggest 50-70% probabilities of 1/2" or greater QPF
along a line generally from Wausau to Sioux Falls, suggestive
that this may be where the axis of highest QPF ends up. While
amounts do remain uncertain, most ensembles depict means around
1/2"-3/4" with a 25th-75th spread of 1/4"-1 1/4", respectively.
Overall, confident everyone will see rain this weekend, but just
how much and where remains in question.

Concern is increasing regarding a wintry mix and/or icing
potential Saturday night into Sunday for areas in the vicinity
and just north of the warm front, especially for areas north of
Hwy 29. Warm air advection ahead of the surface warm front with
cooler air underneath leads to a good set-up for
freezing/refreezing hydrometeors and thus freezing precipitation
potential. The 26.00z LREF and 26.13z NBM have begun to show
better probabilities regarding ice accumulations, both
suggesting 30-50% for greater than or equal to 0.1" in 24 hours,
primarily across northern Wisconsin. Uncertainty remains
regarding the ultimate placement of the warm front during this
time frame and thus the precipitation type and impacts to our
area, but the increasing signal for this messy scenario has
begun to pique our interest.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1039 PM CDT Wed Mar 26 2025

A few spotty showers may occur over the next 6 hours, but
operational visibility and ceiling reductions have yet to occur
with this activity either in our region or upstream so, while
spotty light rain could very well occur, have kept things VFR
and free of any flavor of MVFR mention. Moving ahead to this
afternoon and evening, while statistical guidance suggests MVFR
ceilings will hold off until after 06z, multiple individual
models strongly suggest these will spread north across the area
after 21z. Have therefore introduced new MVFR mentions at both
RST/LSE this afternoon with this continuing through the end of
the period. As for winds, these should generally be out of the
southeast after light and variable conditions occur overnight
tonight.

&&

.CLIMATE...
Issued at 214 PM CDT Wed Mar 26 2025

Unusual warmth will bring the possibility of breaking these records:

Fri March 28 Temperature Records

LSE High      80F/1986
LSE Warm Low  52F/1879
RST High      76F/1946
RST Warm Low  49F/1977

Sat March 29 Temperature Records

RST Warm Low 45F/1976

&&

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

&&

$$

DISCUSSION...Baumgardt/Falkinham
AVIATION...Ferguson
CLIMATE...Baumgardt