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218
FXUS63 KARX 141140
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
640 AM CDT Fri Jun 14 2024

.KEY MESSAGES...

- Quiet and seasonable today.

- Becoming more active with multiple chances for showers and
  thunderstorms Saturday into next week. Best chances (40 to
  90%) for widespread precipitation is Saturday through Saturday
  night.

- Becoming hot and humid Sunday through Tuesday with max temps
  near 90 and dewpoints in the 60s to low 70s.

&&

.DISCUSSION...
Issued at 309 AM CDT Fri Jun 14 2024

Today and Tonight: Seasonable and Quiet

Weak high pressure will transit the area today bringing quiet and
calm conditions across the area. Expect ample sunshine with highs in
the mid 70s to low 80s as diurnal cumulus develops by mid day. High
pressure shifts east to the Great Lakes tonight with low-level SErly
winds on the back side of the exiting high. Temperatures may
initially drop off before increasing late in the night as winds
increase west of the river. Typical cool/sandy soil spots could dip
as low as 50, otherwise expect mid 50s to low 60s.

Saturday through Saturday night: Heavy Rain Potential in MN and
northern/central WI

Behind the exiting high pressure, weak ridging builds across the
Upper Midwest with increasing moisture and warm air advection into
the region. Look for increasing clouds early through the day on
Saturday, with shower chances (20 to 60%), mostly west of the river,
through the day.

Moisture and warm air advection continues to build and brings in
instability Saturday night as a wave shifts west to east across the
area. PWATs climb into the 1.75 to near 2.00 range along the I35
corridor into central MN, which is near climatological max for MPX
sounding, with freezing levels climbing into the 3.5km range. While
the best chances for the heaviest rain exists along and to the NW of
our local area, WPC will retain a slight (risk level 2 out of 4)
excessive rainfall outlook along a line from roughly Decorah to
Wisconsin Rapids northwestward for Saturday night`s heavy rainfall
threat. A 100-member ensemble (30 GEFS, 20 GEM, 50 ECMWF) shows a
20% chance of exceeding 1.0 inches of precipitation in 24 hours from
7am Sat to 7am Sun at Rochester, but those chances increase to over
50% for the Twin Cities. It`s important to note the aforementioned
models are not convective-allowing, meaning they make assumptions on
how thunderstorms develop, so expect some changes to these
probabilities with the 12Z Friday HREF.

Sunday into next week: Hot, Humid, Continued Precipitation Chances

The pattern over the CONUS will evolve into a western CONUS trough
with an amplified ridge building across the eastern CONUS. The
result will bring our local area in the persistent SW flow with
elevated dewpoints/humidity and continued precipitation chances
throughout the week. The entire forecast period in the longer term
will feature some chance of precipitation as there is some
uncertainty in the upper level height pattern...and in turn, where
the best moisture/forcing slides north along the trough/ridge axis.
A weaker ridge would favor a slightly more southern track for the
best precipitation chances, which roughly 30% of the GEFS/EC/GEM
members suggest; however, roughly 70% of their combined members
suggest the best storm track remains just off to our NW, where
central MN would see the best chances throughout the week.

Expect some variability in temperatures throughout the week
depending on thunderstorm development/evolution, but a favored
eastern CONUS ridge should support above-normal temperatures through
the period.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
-- Changed Discussion --
Issued at 640 AM CDT Fri Jun 14 2024

VFR conditions through the TAF period.
-- End Changed Discussion --

&&

.HYDROLOGY...
Issued at 309 AM CDT Fri Jun 14 2024

An active period of weather is expected over the next week with
chances of precipitation across the region expected virtually
every day beyond Saturday. While the best chances of heavy
precipitation remain off to our NW, there are still small
chances of heavy rainfall across our area Saturday night (best
chances along and north of an Austin, MN to Medford, WI line).

Mean precipitation amounts through Wednesday range from around
2.5 to 3.5 inches to our NW across central MN and around 0.75 to
2.0 inches across our local area. While much of this
precipitation is expected across multiple rounds, it will
eventually route into the Mississippi River, which will likely
keep the river elevated through at least the next two weeks.
There is a 10% chance that the Mississippi River reaches Minor
Flood Stage over the next 10 days through Winona (and roughly 25
to 30% chance at Wabasha).

&&

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

&&

$$

DISCUSSION...JAW
AVIATION...Zapotocny
HYDROLOGY...JAW