Granger, Minnesota Weather Forecast Discussion

707
FXUS63 KARX 212327
AFDARX
Area Forecast Discussion
National Weather Service La Crosse WI
627 PM CDT Sun Sep 21 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms through Monday with
  localized heavy rain at times. Some storms may become strong,
  bringing primarily a risk for hail.
- Temperatures stay near normal with highs in the low to mid
  70s through much of next week.
&&
.DISCUSSION...
Issued at 131 PM CDT Sun Sep 21 2025
Storm Potential Today and Monday:
An upper level low will make its way southeastward from North Dakota
this afternoon to northern Wisconsin by this evening. At the
700mb level, a wave moves through this afternoon giving the
area, mostly Wisconsin, a low chance (20 to 40%) for showers and
storms to form. With only around 1000 J/kg of MLCAPE and
limited shear (up to 20kts of 0-3km shear) these showers and
storms will be scattered in nature and pulse up and down.
Heading into the evening, another wave and frontal boundary
moves into southern Minnesota. This will be the focus for more
widespread shower and storm development through the overnight.
While there are some differences between CAMs as far how
widespread the convection is, they are all mostly suggesting the
front stays near our common border with Minneapolis`s CWA
throughout the overnight period. With the incoming boundary,
there is slightly better shear than the past few days (around 25
to 30 kts of 0-1km and 0-3km shear). Instability is expected to
linger through the overnight with up to 1000 J/kg of MLCAPE, so
some thunderstorms will be possible and with lapse rates around
6 to 6.5 C/km lingering through the evening, can`t rule out
that a storm could be strong to even severe, particularly in
southeast Minnesota. The better chances are along and west of
the I-35 corridor in southern Minnesota, northern Iowa.
This boundary will shift southeastward through our CWA on Monday
during the day. With a little better instability and shear
parameters as today, showers and storms are expected along the front
with a low chance of a strong to severe storm possible all along the
boundary as it moves through, however the strong to severe threat
will be quite isolated. Any stronger storm that does develop, the
main threats would be hail and damaging winds. Rainfall amounts are
generally between 0.20 and 0.5". Looking at HREF LPMM, there a
couple pockets of 1 to 1.25" in portions of southeast Minnesota,
northeast Iowa, and north central Wisconsin.
Storm Potential From Tuesday into the Weekend:
Heading into Tuesday, the upper level low continues to move off to
the east while another trough digs down into the Central CONUS from
the Intermountain West. This trough is expected to close off and
merge with the current upper level low near the Great Lakes region
around the midweek timeframe. While some lingering showers and
storms will be possible (low chances around 15 to 25%) for portions
of northeast Iowa and southern Wisconsin, the lows will stay far
enough away causing most of the CWA to be dry from midweek through
the weekend. There is some disagreement in how these lows interact
and where exactly they merge. About 40% of EPS members suggest that
the low coming up from the south will be closer in proximity to our
CWA increasing our precipitation chances into the weekend, while
almost every member of the GEFS has a dry solution for the same
period. Regardless of rain chances, high temperatures into next
weekend look to largely stay in the low to mid 70s while the lows
are generally in the low to mid 50s.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 626 PM CDT Sun Sep 21 2025
Scattered showers and storms are expected to be ongoing through
much of the TAF period, initially across southeast Minnesota
into north-central Wisconsin this evening into the overnight
hours (40-60%). Brief heavy downpours can be expected with any
storms resulting in pockets of MVFR/IFR visibilities. MVFR
ceilings remain possible (30-40%) Monday morning into the
afternoon hours, mainly over southeast Minnesota into north-
central Wisconsin.
Additional showers/storms develop by Monday afternoon (20-40%),
expected generally along I-90 currently, but the ultimate
location will be largely dependent on storm evolution overnight
and where a surface boundary sets up across the region.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Cecava
AVIATION...Falkinham

NWS ARX Office Area Forecast Discussion