994
FXUS63 KARX 061112
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
612 AM CDT Sun Apr 6 2025

.KEY MESSAGES...

- Band of rain and snow showers drops south through mainly
  Wisconsin tonight (60% chance). Snow showers may briefly lead
  to localized reduced visibility, but little to no accumulation
  expected.

- Colder and blustery on Monday with scattered daytime
  flurries/sprinkles.

- Temperatures rebound Tuesday into next weekend. Rain chances
  (40-50%) return Wednesday-Thursday, especially south of I-90.

&&

.DISCUSSION...
Issued at 207 AM CDT Sun Apr 6 2025

Another dry day with on tap today with southwest flow induced warm
air advection yielding a noticeable bump in temperatures compared to
Saturday. Highs are expected to rise into the 50s with a decent
amount of sunshine despite a gradual increase in clouds, especially
late this afternoon.

Band of Rain and Snow Showers Drops South Tonight:

Tonight a sharp shortwave trough will drop south through the western
Great Lakes region, driving a strong cold front southward through
the area. The strongest QG forcing with this trough will graze our
far eastern forecast area, which is also where RAP guidance shows a
deep layer of frontogenesis associated with the front. While this
system has respectable forcing, it will be lacking in moisture.
Forecast soundings only show a 2-3 hour window for deeper saturation
from near the surface to about 600mb as the front pushes through.
Precipitation should initially take the form of rain with low level
temperatures still above freezing, but dynamic cooling behind the
front will lead to a quick changeover to snow showers. These snow
showers may briefly turn a little vigorous as the fgen band drops
south through central Wisconsin, with the strongest lift becoming
coincident with the dendritic growth zone for a short time. Several
CAMs support this, but there is less agreement on how far west the
precip band will extend. Greatest likelihood for any snow impacts
will be east of the Mississippi River, particularly our eastern
counties. But "impact" is an overstatement, as those areas only
carry a 40-60% chance for greater than 0.1" snow accumulation.
Reduced visibility would likely be the main story within the band of
snow showers (if only for a short time), especially with the band
being co-located with gustier northerly winds behind the front.

Colder with Lingering Flurries and Sprinkles on Monday:

Cyclonic flow and lingering cold air advection producing steep low
level lapse rates on Monday will support scattered daytime
flurries/sprinkles as the RAP/HRRR depict. With greater forcing just
off to our east and drying low levels, opted to go with
flurry/sprinkle chances during the day as opposed to anything
measurable. It will definitely feel like a raw, blustery April day
with highs only in the 30s to around 40 and gusty northerly winds.

Warming Temperatures Rest of the Week:

Temperatures will gradually rebound for Tuesday and beyond, with 60s
likely by the weekend as an amplified upper ridge builds into the
central CONUS. The next chance of precipitation arrives Wednesday
into Thursday as a couple developing shortwave troughs drop through
the region. While the main developing surface low and higher precip
chances are still progged to track just south of our area, there
remains a decent (~50%) chance for rain south of I-90, with lesser
chances further north.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 611 AM CDT Sun Apr 6 2025

VFR conditions expected for the next 24 hours. Light winds will
pick up out of the west later this morning with some gusts to
20-25 kts possible this afternoon. Gusts will taper off by this
evening with sustained speeds briefly coming down as well. A
cold front is expected to move through the area overnight which
will bring low chances for showers. Have added PROB30 groupings
at both LSE and RST as some MVFR visibilities and CIGs will be
possible with that precipitation. Winds will shift to the north
behind the front with speeds increasing in its wake. Did not
have enough confidence to add gusts along/behind the front for
either terminal at the time but this is something that will need
to be monitored with future package updates.

&&

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

&&

$$

DISCUSSION...Kurz
AVIATION...Barendse