536
FXUS63 KARX 291738
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1238 PM CDT Mon Apr 29 2024

.KEY MESSAGES...

- Cooler weather today, with a rebound to above average
  temperatures for Tuesday and Wednesday. Seasonal temperatures
  for the remainder of the week.

- Several more rounds of showers and storms are lined up for
  Tuesday and late Wednesday through Friday. Overall severe
  threat looks low at this time, however the likelihood of
  widespread rainfall is high (between 60 and 90%) with these
  systems.

&&

.DISCUSSION...
Issued at 337 AM CDT Mon Apr 29 2024

Today through Tuesday:

The surface low continues to move off to the northeast during
the day. The progression of the low slows a little bit, allowing
for some showers to be possible for areas along and north of
I-94 through the day. Shortwave ridging will move over the area,
however with low stratus hanging around for most of the day,
temperatures will be on the cooler side. Heading into Tuesday, a
compact shortwave trough will dip down into the Central Plains.
This will be our next chance at seeing some precipitation.
Accompanying this shortwave will be dewpoints ranging from
around 50F to the low 50s, especially in northeast Iowa and
southeast Minnesota, a 50kt low- level jet, and good shear. The
one ingredient that is missing is instability. The greatest
instability lies west of the area in northwestern Iowa. There is
still some uncertainty in how far north the instability and
moisture transport gets. This will help in determining if severe
weather will be possible across the area. Combining the above
ingredients with recent model guidance that has a few hundred
joules of SBCAPE across northeastern Iowa and southeastern
Minnesota, SPC has gone with a Marginal risk (level 1 of 5) in
this area. Even though the severe threat is low, general showers
and thunderstorms seem likely during the evening and early
overnight hours on Tuesday into Wednesday.

Active Pattern Continues:

By Wednesday, a longwave trough shifts eastward. This will allow for
deeper moisture transport and warm sector spreading northward.
Periodic precipitation will be possible given this regime through
the end of the week. It is too early to tell if severe weather will
be possible, however the current guidance gives the Central Plains
the best chance at seeing severe weather through the week. That
being said, rainfall probabilities continue to increase. They
have increased slightly from the previous forecast. The Grand
Ensemble gives a 50% to 70% chance of at least 0.5" and 25% to
40% of at least an 1" occurring Thursday into early Friday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1236 PM CDT Mon Apr 29 2024

Scattered to overcast MVFR ceilings persist across the forecast
area today until clearing arrives from southwest to northeast
late this evening. Scattered sprinkles/light rain showers have
developed periodically with a low pressure center nearby. Brief
reductions in visibility may result. Winds will primarily be out
of the southwest with gusts up to 25-30 knots, especially west
of the Mississippi River.

&&

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

&&

$$

DISCUSSION...Cecava
AVIATION...KAA