457
FXUS63 KMPX 010531
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1231 AM CDT Mon Sep 1 2025

.KEY MESSAGES...

- Quiet weather continues with patchy fog possible again
  tonight, favoring western WI.

- Isolated storms in western MN on Monday, with a cold front
  bringing widespread showers and a few storms Tuesday into
  Wednesday.

- Temperatures cool down significantly midweek, rebounding by
  next weekend.

&&

.DISCUSSION...
Issued at 239 PM CDT Sun Aug 31 2025

It would be difficult to imagine a better final day of August
and meteorological summer with temperatures in the low to mid
70s with fair weather cumulus the only clouds in the sky. The
expansive cu field over southern Minnesota especially will
gradually dwindle after around 5-6pm, with our daylight hours
being cut significantly as it has been over 2 months since the
summer solstice. We have lost approximately 85 minutes of
daylight over the course of August, and can expect to lose a
larger amount in September as the sun angle continues to
decrease as the Earth`s tilt migrates the sun towards the
equator by the Autumn equinox. For some additional context, in
the Twin Cities our average temperatures to start September are
a high of 78, low of 60, for an average of 69 degrees. By
September 30th, those averages are 67/48/57 respectively,
showing just how significant the lowering sun angle and daylight
hours are in terms of temperature.

Circling back to the upcoming forecast, we can expect a few
showers and storms across western Minnesota Monday
afternoon/evening on what will otherwise be a relatively quiet
day once again, as some localized vorticity circulates around an
upper level trough that will be diving southwards towards the
Great Lakes from the northern jet in Canada. A surface low will
develop as it digs southwards, with a cold front forming and
moving across the area Tuesday into Wednesday. Unlike most of
our synoptic level low pressure systems this summer, there will
be limited potential for northwards moisture advection and
warmth from the central plains, which will keep the vast
majority of activity as purely rain showers with some rumbles of
thunder. The lack of warm sector moisture will also keep PWATs
closer to 1 inch than the excessive 1.5+ inches we have seen
from a few systems this summer. In terms of percentiles for this
time of year, the 1-1.25`` PWATs are around the 90th for
northern Minnesota but within the 25th-75th expected range for
the southern half of the state and western Wisconsin. All of
this is to say, widespread showers and some rumbles of thunder
are expected along the cold front, but significant rainfall is
not expected with amounts generally ranging from 0.25-0.5
inches.

Temperatures cool down significantly Wednesday and Thursday with
-5 to -7C below normal 850mb temperatures behind the cold
front, with our coldest day likely to be Thursday with morning
temperatures in the upper 30s to low 40s and highs struggling to
break 60 depending on lingering cloud cover. This cool spell
will be a brief drop into more fall-like weather, however
temperatures will rebound back towards the mid to upper 60s by
the end of next weekend. Longer range guidance continues to show
less than 25% of ensemble membership favoring any sort of
shower activity beyond the 7 day forecast, with relatively dry
conditions expected to linger towards the middle of September.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1224 AM CDT Mon Sep 1 2025

Mostly clear skies and light winds are setting the stage for
another round of fog overnight. While more widespread fog is
expected across southwest Minnesota, pockets of dense fog are
possible elsewhere. KEAU is already seeing visibility impacts
early this TAF period. Fog will stick around through shortly
after daybreak. Another round of diurnal Cu develops tomorrow,
with increasing chances for scattered storms tomorrow afternoon
ahead of an approaching upper level trough. Confidence in the
extent and exact location is too low to include in the TAFs at
this time.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/
TUE...VFR. -SHRA likely, chc -TSRA/MVFR. Wind SW 5-15kts.
WED...Chc -SHRA/MVFR early. Wind NW 10-15G25kts.
THU...VFR. Wind NW 10-20kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.

&&

$$

DISCUSSION...TDH
AVIATION...BED