745
FXUS63 KARX 300001
AFDARX

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

.KEY MESSAGES...

- Round of showers and thunderstorms expected going into Tuesday
  evening, with a higher risk of severe weather just west of area.

- More showers and storms expected Wednesday night into Thursday.
  Likelihood is high /70-90%/ for pockets of heavy rain with
  chance for a few stronger storms at times.

&&

.DISCUSSION...
Issued at 200 PM CDT Mon Apr 29 2024

Tonight:

If you include the current, passing trough, there are no less than 6
systems to impact region over the next 10 days...so yes...active
pattern continues.

Current upper low, with large area of wrap around stratus, continues
to make good progress northeastward. Precipitation associated with
this will remain very light with trend towards cloud cover clearing
going into early Tuesday from south to north. Although winds will
diminish overnight as well, temperatures should remain warm enough
to prevent any widespread frost or freeze outside of favored
Wisconsin bogs.

Tuesday and Tuesday Night:

Attention quickly turns to next mid level wave which will move out
of the northern Rockies into the northern Plains on Tuesday. Bulk of
day will be quiet for us in between systems but will have to watch
convective risk with some moisture return ahead of this wave and
stronger mid level flow suggesting some shear to work with.

Question for us centers on how far east this modest instability will
translate and if stronger/severe storms to the west can keep their
strength east of Interstate 35. At first glance it almost appears
any instability gets pinched out to the south as wave moves through,
but trends in the RAP outcomes suggest there still could be enough,
mainly elevated, instability and 0-3km shear to sustain a small risk
/10-20%/ for a severe storm or two. Seems like any threat would be
in our far west with storms weakening and/or losing their
organization as they move east. Examining soundings, hail and gusty
winds would be our threats IF any severe storms work into the west
during the 6-9pm TUE time frame.

Wednesday Night into Thursday:

One could say rinse and repeat with next approaching wave late
Wednesday into Thursday, but there are subtle differences. Larger
trough digs through central Rockies and as it ejects into the
Plains, better /deeper/ poleward moisture transport expected.
Convection will likely be ongoing at start of day Thursday and as
trough ejects into the upper Mississippi River valley could see a
ramp up in storm strength as the day goes on. While bouts of heavy
rain seem likely /70%/ given deeper moisture and high precipitable
water, details on severe weather risk are unclear given how storms
could be impacting setup through a big part of the day. Instability
could be limiting factor once again. This will be another period
worth keeping an eye on as details get worked out.

Although still several days out, looks like front would clear the
area on Friday with another in-between day and seasonal
temperatures. Yet another wave could bring showers back into the
picture on Saturday but by then, low level moisture will be lower
keeping any storm threat a bay.

If you are counting, we still have more systems to track the
following week, but one week at a time.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 645 PM CDT Mon Apr 29 2024

MVFR/VFR ceilings fl020-035 across the region with a little
light rain in the area this evening. Look for improvement in the
ceilings later tonight tonight VFR, then clearing Tuesday
morning. Clouds will thicken during the afternoon with showers
and thunderstorms developing. Unsure how far east the elevated
showers will make it; could be some at RST by 21 or 22Z with
increasing storm chances 23Z and thereafter. West winds diminish
and become southwest and south with time. Southeast wind
increase at RST Tuesday afternoon 10 to 18kts with gusts 20 to
30 kts.

&&

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

&&

$$

DISCUSSION...Shea
AVIATION...Zapotocny