Chaska, Minnesota Weather Forecast Discussion

189
FXUS63 KMPX 221153
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
653 AM CDT Mon Sep 22 2025
.KEY MESSAGES...
- Ongoing showers and storms exit to the east this morning.
  Another round of showers and storms is expected along I-90
  this afternoon through early Tuesday.
- Quiet weather for the rest of the week with temperatures in
  the 70s.
&&
.DISCUSSION...
Issued at 254 AM CDT Mon Sep 22 2025
Showers and storms continue primarily in eastern MN and western
WI this morning with storm strength having decreased from
yesterday evening where we saw some reports of hail up to around
2 inches in diameter in a few locations. The main risk has
transitioned to localized flooding tonight as multiple rounds of
showers have moved through a few areas, with the highest amount
of 3-4 inches over the last 12 hours being observed in portions
of northern Dakota and Pierce counties. The upper level low
which has been the primary driver behind the last few days of
weather is parked over Lake Superior and will weaken further
throughout the day today as flow aloft becomes westerly by early
Tuesday morning before shifting northerly for the rest of the
week. A pseudo stationary boundary and increase low level jet
later this evening will set the stage for one final round of
showers and storms favoring southern Minnesota along I-90 as the
boundary slides southwards into early tomorrow morning, with a
few stronger storms possible as SPC has introduced a SWODY1
marginal including 5% hail/wind risks. Storms are expected to be
isolated in coverage but keep refiring over the same locations
such that localized flooding could also be a concern, however
PWATs are somewhat limited around 1.25`` so multiple rounds of
training storms will be required to see impacts. As the boundary
slides southwards into Iowa overnight, active weather will
cease within the bounds of the MPX CWA and will begin a period
of quiet weather.
Flow aloft will favor northerly with some wobbles to
northwest/northeast over the rest of the week, alongside weak
surface high pressure bringing general subsidence across the
region. Fair weather cloud cover is still expected as dew
points remain in the 50s and we should mix fairly well, which
will also mean chances for overnight fog become possible as
temperatures fall to dew points with efficient radiation cooling
and weak surface winds underneath high pressure. The fog will
be the most dense earlier in the week behind the showers, with
gradually drying conditions as we head towards next weekend
resulting in fog that is overall patchier and less of an issue.
Other than the fog chance, there is little in the way of
sensible weather expected with a lack of synoptic or mesoscale
lifting mechanisms as well as moisture. It looks to be a fairly
warm but overall quiet end to September, with predictability
lower as we head into October due to a lack of longer scale
indicators. For now, enjoy the warm weather while it lasts as
October also brings the autumnal equinox, marking the trend of
rapidly losing daylight as we slide closer to the winter months.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 648 AM CDT Mon Sep 22 2025
Precipitation has ended for all TAF sites, but there is some
potential for re-development over far southern MN into southwest
WI. Precip looks to remain far enough south to not impact MKT
but also be quite close to EAU so have only included afternoon
precip mention there. Otherwise, through mid-to-late afternoon
the main concern will be ceilings. MVFR ceilings will be quite
prevalent, with brief periods of IFR possible through midday.
KMSP...No precipitation is expected but MVFR ceilings will
prevail through late afternoon. By late morning, ceilings also
look to drop sub-1700ft for much of the day. VFR conditions are
expected this evening into the early morning hours, but another
round of low-range MVFR ceilings is looking likely around
sunrise Tuesday morning.
/OUTLOOK FOR KMSP/
WED...VFR. Wind NE 5-10 kts.
THU...VFR. Wind NW 5-10 kts.
FRI...VFR. Wind SW 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...TDH
AVIATION...JPC

NWS MPX Office Area Forecast Discussion