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112
FXUS63 KARX 260353
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1053 PM CDT Sat May 25 2024

.KEY MESSAGES...

- Widespread rain with perhaps an embedded thunderstorm is
  expected Sunday. While some rises on area rivers may occur as
  a result, ingredients do not appear conducive for flash
  flooding or anything more than brief minor flooding on a few
  rivers. A stray severe storm could occur in far southern Grant
  County.

- Additional shower and storm chances Monday/Tuesday, but
  quieter conditions return for mid-week.

&&

.DISCUSSION...
Issued at 221 PM CDT Sat May 25 2024

Sunday rain:

Shortwave trough, located over the Front Ranges as of 19z, will
translate downstream in the west-southwesterly flow aloft, reaching
the CWA by around 09z Sunday. Ahead of this wave, plume of 700/850mb
moisture looks to reach us just in time for this wave to generate
numerous showers. As the day goes on, southern stream jet looks to
advance eastward over the south central Plains, with a surface low
developing to our south under the left exit region of this feature.
This should serve to enhance moist advection, allowing for a period
with widespread rainfall during the late morning and early afternoon
before the wave begins to shift eastward and precip begins to taper
off west to east accordingly. Progged instability is modest with the
vast majority of the area seeing low (<10%) HREF probabilities of at
least 250 J/kg of CAPE. Have therefore held thunder mentions to a
slight chance or less. Exception may be Grant County, where some
guidance suggests 750 J/kg of MLCAPE could be present in the
presence of sfc-6km bulk shear values of 35 knots, so cannot
totally rule out a stray severe thunderstorm there. As for heavy
rain, probabilities suggest a less than 10 percent chance for
greater than 2 inches of rain over 24 hours and ensemble PWAT values
are below the 90th percentile of climatology, so am not overly
concerned about the flooding threat. Latest river forecasts from
NCRFC also suggest a low level of concern, with top end
ensemble QPF yielding minor flooding only at a couple locations,
mainly in the Turkey River basin. In summary, will need to keep
an eye on how things develop in the far southern CWA, but
otherwise widespread impacts - aside from postponing outdoor
activities - are favored to be minimal.

Sunday Night through the Week:

The surface low will continue to track northeastward towards the
Great Lakes Sunday night into Monday, with an upper level trough
remaining generally over the Great Lakes through the early week.
Multiple shortwaves are forecast to dive down across the area
keeping additional shower and storm chances in the forecast Monday
(~30-60%) and perhaps again Tuesday (~20-40%).

Mid-week looks to bring the potential for drier conditions as high
pressure moves in across the region ahead of upper level ridging
building in over the central U.S. Though spread does increase some
in ensemble solutions there is a suggestion towards an increasing
trend in temperatures from early in week. For now, forecast temps
return to more seasonable, with highs in the 70s for much of the
area to end the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
-- Changed Discussion --
Issued at 1050 PM CDT Sat May 25 2024

VFR conditions overnight will deteriorate to low-end MVFR to
high-end IFR late Sunday morning as a broad area of rain and
associated low pressure system lift into the area. There`s a 70
to 90% of IFR conditions at RST, with a 40 to 60% chance of IFR
at LSE. Opted for a OVC010 at LSE as conditions there are
expected to be on either side of the MVFR/IFR thresholds.
There`s a slight chance (10-20%) of an embedded thunderstorm
with these showers, but will leave out of the TAFs at this time.
-- End Changed Discussion --


&&

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

&&

$$

DISCUSSION...Ferguson/EMS
AVIATION...JAW