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621
FXUS63 KARX 221136
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
636 AM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Shower and storms will continue to move across the area this
  morning, with up to an additional couple inches possible.
  Another round of storms moves through this afternoon/evening
  and could bring an additional quick 2-4 inches. Continue to
  monitor as more heavy rainfall may bring additional flooding
  issues, especially for those that saw heavy rain this morning
  as well as along area rivers.

- Severe thunderstorms remain another concern this
  afternoon/evening, with mainly a risk for damaging winds and
  heavy rain. However, a tornado or two cannot be ruled out.

- After a welcome respite from the rain Sunday and Monday,
  showers and thunderstorms return to the forecast Monday night
  and Tuesday. A Slight Risk (level 2 of 5) for severe storms
  has been included for parts of the area on Monday.

&&

.DISCUSSION...
Issued at 445 AM CDT Sat Jun 22 2024

Today`s Heavy Rain, Flooding, Severe Weather Details:

The busy stretch of weather continues! Latest (at time of writing 2
AM) surface analysis shows a surface low across northern Iowa with a
surface warm front out across northeast Iowa into southwest
Wisconsin. With the increasing moisture advection, current radar
shows a large area of showers and thunderstorms pushing generally
eastward into and across the forecast area... leaving a long line of
Flood and Flash Flood Warnings behind/with it. Higher rainfall
amounts within this system as of now have been between 1-2.5 inches
with a couple locations seeing amounts more towards 3 inches,
resulting in local reports of flooding. This system will continue
its trek across the area through the morning, with some areas
picking up an additional 0.5-1.5 inches. Though some locally higher
amounts may be possible.

As we move later into the day, model guidance suggests a shortwave
perturbation moving eastward across the region. Model guidance has
been fairly consistent on another round of showers and thunderstorms
developing and moving across portions of the forecast area. They
should be fairly progressive, but HREF 6-hr ensemble probability
matched mean (valid 00Z Sun) does highlight 2- inches across
portions of northeast Iowa and southwest Wisconsin, with again some
locally higher amounts. In turn, a moderate risk for excessive
rainfall was introduced across these areas and the Flood Watch was
also extended into the evening to account for this round of
rainfall.

In addition, the potential for severe storms will need to be
monitored with these storms this afternoon/evening. There are still
some uncertainties with how lingering impacts of this mornings
storms may influence storms this afternoon. However, hi-res model
guidance does suggest increasing instability values (MLCAPE 1500+
J/kg) along with strong southwesterly to westerly flow and moderate
shear values. Damaging winds appears to be the main threat with any
storms that develop. However, cannot rule out the potential for a
few tornadoes, with guidance showing sufficient clockwise-curved low
level hodographs. With this, portions of northeast Iowa and
southwest Wisconsin remain in a Slight Risk (level 2 of 5) for
severe weather.

Sunday - Monday:

After a busy start to the weekend, Sunday and Monday look to bring a
short respite from the very active weather. The upper level
shortwave trough will make its way down towards the Great Lakes,
with some scattered showers (15-30%) possible across portions of the
area Sunday. Surface high pressure is then forecast to move across
the region Sunday night into Monday bringing quieter conditions and
highs forecast in the 80s for most.

Monday night onward:

Model guidance continues to show an upper level shortwave trough and
surface low pressure moving generally eastward across parts of
Canada for the early part of the week. At the surface a warm front
is expected to move northeastward across parts of the region. This
looks to bring back chances for showers and thunderstorms to the
region Monday night into Tuesday, with chances for some storms to
also develop along a cold front on Tuesday. There still remains some
uncertainty in the development and evolution of these storms, but
with more favorable conditions looking possible SPC has introduced a
Slight Risk for severe weather for portions of the area (mainly
north of I-90) Monday. Will continue to monitor over the coming
days a details continue to be refined.

Upper level ridging looks to build to the west of the region with
surface high pressure building into our area towards mid-week. This
looks to bring another short break in shower and storms chances for
at least some bit of time mid to late week. However, model guidance
does hint towards a return of showers and storms late in the
extended period. Still plenty of spread in the ensemble solutions so
won`t try to get into too many details this far out.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
-- Changed Discussion --
Issued at 636 AM CDT Sat Jun 22 2024

Showers and storms continue to push eastward across the
forecast area this morning with some visibility and ceiling
restrictions remaining. There is some hint with upstream obs and
guidance that there could be a brief relief with ceilings
lifting some. However, this remains lower confidence and
adjustments may be needed in the short term if not realized.
Otherwise, chances remain for showers and thunderstorms to
develop this afternoon into the evening. As with the previous
forecast there is some uncertainty with how far north storms may
develop. Have maintained the previous thinking, but some
adjustments may be needed with the next issuance if a continued
push further south is noted. Otherwise, winds will turn more
southwest to west through the day and northwest into tonight.
-- End Changed Discussion --

&&

.HYDROLOGY...
-- Changed Discussion --
Issued at 636 AM CDT Fri Jun 21 2024

Have cancelled parts of the flood watch in southeast Minnesota
and west-central Wisconsin as the heavy rain threat appears
diminished for these areas. However, with additional heavy
rainfall possibly bringing another 2 to 4 inches this afternoon
across northeast Iowa and southwest Wisconsin, the flood watch
has been expanded into the evening for these areas.

River flooding concerns will last well into next week and
multiple rivers could exceed moderate flood stage if the
rainfall lines up correctly in their basins.
-- End Changed Discussion --

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
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WI...Flood Watch through this evening for WIZ043-044-053>055-061.
     Flood Watch until 1 PM CDT this afternoon for WIZ029-034-041-
     042.
MN...Flood Watch until 1 PM CDT this afternoon for MNZ088-094>096.
IA...Flood Watch through this evening for IAZ008>011-018-019-029-
     030.
-- End Changed Discussion --

&&

$$

DISCUSSION...EMS
AVIATION...EMS
HYDROLOGY...Skow