Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
843 PM CDT Tue Sep 1 2026

.KEY MESSAGES...

- Multiple clusters of storms are expected across southern MN
  tonight to the north of a warm front. There is a level 2 of 5
  risk of severe weather, with damaging winds being the highest
  risk.

- A low confidence precipitation forecast through Labor Day
  weekend, with multiple low chances for rain.

- Summer-like temperatures and humidity continue through Labor
  Day weekend.

&&

.UPDATE...
Issued at 836 PM CDT Tue Sep 1 2026

Regional radar and satellite imagery shows the incoming cluster
of showers and storms focused primarily over the monster
supercell thunderstorm ongoing over the southeast South
Dakota/northeast Nebraska border. The trajectory of this
individual storm looks to take it eastwards into Iowa and should
remain south of our area for now, however we will keep a close
eye on some further development out ahead of it over north-
central Iowa that is moving northeast towards our southernmost
counties along I-90. The expectation as the night continues to
progress is for this cluster of showers and storms to focus
along the leading edge of a developing low level jet, which you
can see via the SPC mesoanalysis page within the MLCAPE gradient
focused over southern Minnesota, and this gradient is where we
expect any potential stronger storms or MCS/bowing line segment
to favor moving across. This would place the area from roughly
Redwood Falls through Mankato and southwards within the most
likely area to see a stronger thunderstorm with the potential
for severe level wind gusts, especially if it takes on the
classic bowing shape indicative of stronger winds. The CAM
guidance has been waffling on the pacing of the storms since the
afternoon, with each run either speeding or slowing the pace of
the line segment as it moves through. At slowest, it is still
moving eastwards at around 40-50mph, so some severe level winds
up to 60mph are possible despite lower level inversion building
underneath the low level jet, with even higher gusts possible
mainly within any potential bowing segment. The more recent HRRR
runs have favored the bowing shape to occur as it passes through
Mankato and approach Rochester in southeastern MN, which mimics
the location of the MLCAPE gradient as of 0130z. With the Twin
Cities at least 2 tiers of counties north of the gradient, it is
looking less favorable to see the stronger portion of the
storms, however there is still at least some activity expected
north of gradient in the form of some scattered rain showers.
These showers look to persist into the mid morning tomorrow
before dissipating, and could contain some intermittent
lightning but are not expected to be strong whatsoever. For now,
we keep a watchful eye on the radar and satellite as we await
whatever storms reach us later tonight and into the morning.

&&

.DISCUSSION...
Issued at 112 PM CDT Tue Sep 1 2026

Water vapor imagery this afternoon shows a subtropical ridge
centered over the bootheel of MO, with a monsoon shortwave coming
out of Wyoming that will run around the north side of the ridge
through the night. At the surface, there's a stationary front a
little north of the I-80 corridor in Iowa, with dewpoints pooling up
into the upper 70s along it. As we go through the night, the WY
shortwave and IA warm front will work together to support an
overrunning convective event over southern MN. Current expectations
are that storms will develop this afternoon in the Dakotas
associated with the shortwave, with elevated storms developing north
of the warm front near the MN/IA border shortly after sunset as the
LLJ over IA starts to ramp up (eventually getting up into the 35-40
kt range). We're seeing the idea from the HRRR and other CAMS that
we could see multiple clusters of storms develop on the nose of the
LLJ, with the convection in the Dakotas that develops this afternoon
eventually sweeping up any clusters ahead of it late tonight. The
favored zone for heavy rain and severe potential will be on the nose
of the LLJ and along the MUCAPE gradient. The HREF/REFS continue to
show these two features lining up along the MN/IA, with the southern
two or three tiers of counties in MN being most at risk for storms,
heavy rain, and severe weather tonight, which matches up well with
the Day 1 Slight Risk from the SPC. From the severe weather
perspective, instability (muCAPE > 3000 j/kg) and deep shear (over
40 kts) are certainly favorable for severe weather, but weak mid-
level lapse rates and overnight timing/nocturnal stabilization will
be limiting factors that will put a ceiling on this being a
significant severe weather setup.

For the rest of Wednesday, we're expected to be dry as the
atmosphere recovers from the early morning convection. We'll have
height rises through the day, with easterly low level winds, so we
may have to battle some morning stratus as the low level moisture
gets trapped beneath a building inversion. Those easterly winds and
potential for morning clouds will result in Wednesday being the
"coolest" day of the work week, with highs generally in the low to
mid 80s, with ever increasing dewpoints, as tropical dewpoints in
the 70s begin spreading back north across southern and southwest MN.

Going into Wednesday night, we'll begin to see the stationary/warm
front lifting back north across the area. The LLJ will not be as
strong as what we see Tuesday night, but WAA will still be present.
HREF shows over 2000 j/kg of muCAPE coming up with that warm front
and the presence of the weak WAA will give us a chance of storms,
but it's highly uncertain if we'll get storms to fire with our
subsidence and building cap. This uncertainty is why we ended up
with pretty broad 20-40 PoPs across the area Wednesday night as we
await some hopefully better clarity on where mesoscale features will
be.

Answering the question of where mesoscale features will be will
continue to be a headache as we go through Labor Day weekend. We'll
see a ridge axis centered over us by Saturday, that shifts to our
west Sunday into early next week. That ridge will come with strong
capping, along with a rather uncomfortable airmass, as we see highs
near 90 Friday and Saturday, with dewpoints in the low to mid 70s
sending heat index values both days up into the mid to upper 90s,
welcome to Augtember! That ridging will also result in capping.
However, given how unstable the atmosphere is, it's not taking much
for convective parameterization schemes in the deterministic models
to start firing off convection. There is lots of spread with QPF in
the ensembles, so the on/off, mostly low chances for PoPs makes
sense. Again, where any weak shortwaves happen to meetup with a
surface boundary, chaos could ensue, but where that may happen is
still uncertain given the capping and weak forcing.

For Sunday into early next week, the ridge axis shifts to our west,
with MN/WI transitioning into northwest flow. This is why you'll
notice temperatures in the forecast taking a step back after
Saturday. We'll still be placed within the northern stream and
susceptible to mesoscale shenanigans though. At the moment, it looks
like Sunday night through Monday night would be a period with
increased storm potential, but there's still time for this to change
in the coming days.

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 623 PM CDT Tue Sep 1 2026

The primary factor within the TAF period is the potential for
-SHRA/TSRA moving in after 02z from west to east with a cluster
 of storms over southeastern South Dakota the feature to watch.
 CAM guidance shows this cluster moving towards southern MN by
 02-03z and continuing eastwards before becoming linear and
 moving across southeastern Minnesota and western WI. The most
 likely sites to see -TSRA or TSRA are RWF/MKT/EAU, with MSP/RNH
 having a lower but non-zero chance, and STC/AXN being too far
 north to get hit with the main band of -TSRA and instead
 relying on some weaker -SHRA with embedded TS. Winds will
 become light outside of -TSRA and variable in direction,
 eventually favoring 120-150 at 5kts. By the 06z issuance,
 storms should be ongoing and we can pinpoint the timing which
 for now is based off the most recent runs of the HRRR which
 have generally captured the storms in South Dakota better than
 other guidance. Outside of TSRA, VFR is expected. As the TSRA
 moves through, strong gusts in excess of 40kts are possible
 mainly for RWF/MKT/EAU alongside a drop to IFR/MVFR as they
 pass.

KMSP...Kept the prob30 for -TSRA but added some prevailing -SHRA
as CAM guidance shows lingering -SHRA after the -TSRA passes.
MSP is still on the very northern edge of the potential track of
the stronger line of storms, with the line more likely moving
along the southern MN border/I-90.

/OUTLOOK FOR KMSP/
THU...VFR, early MVFR/-SHRA possible. Wind SE 5-10 kts.
FRI...VFR. Sl chc -TSRA. Wind S 5-10 kts.
SAT...VFR. Wind SE 5-10 kts.

&&

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

&&

UPDATE...TDH
DISCUSSION...MPG
AVIATION...TDH

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
117 PM CDT Tue Sep 1 2026

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
021830-
Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns-
Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa-
Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington-
Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota-
Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth-
Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk-
St. Croix-Pierce-Dunn-Pepin-Eau Claire-
117 PM CDT Tue Sep 1 2026

This Hazardous Weather Outlook is for portions of central and
southern Minnesota, and west central Wisconsin.

.DAY ONE...This Afternoon and Tonight.

Thunderstorms are expected to move across the area tonight. A few
storms could produce damaging wind, mainly across southern
Minnesota.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation will not be needed.

JRB

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
938 PM CDT Tue Sep 1 2026

MNZ091-092-020315-
Martin MN-Faribault MN-
938 PM CDT Tue Sep 1 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN FARIBAULT AND EAST
CENTRAL MARTIN COUNTIES THROUGH 1015 PM CDT...

At 937 PM CDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Blue Earth, or 10 miles east of Fairmont, moving
northeast at 25 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Blue Earth, East Chain, Huntley, and Guckeen.

This includes the following highways...
 Interstate 90 between mile markers 109 and 125.
 U.S. Highway 169 between mile markers 7 and 16.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4350 9425 4358 9438 4377 9425 4366 9398
TIME...MOT...LOC 0237Z 213DEG 22KT 4360 9427

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

CTG

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1018 PM CDT Tue Sep 1 2026

MNZ083-084-092-020415-
Blue Earth MN-Faribault MN-Waseca MN-
1018 PM CDT Tue Sep 1 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN FARIBAULT...
SOUTHEASTERN BLUE EARTH AND SOUTHWESTERN WASECA COUNTIES UNTIL 1115
PM CDT...

At 1018 PM CDT, Doppler radar was tracking a strong thunderstorm over
Delavan, or 23 miles northeast of Fairmont, moving northeast at 30
mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Delavan, Mapleton, Minnesota Lake, Pemberton and Waldorf.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 4385 9414 4408 9390 4391 9362 4373 9405
      4380 9419
TIME...MOT...LOC 0317Z 225DEG 24KT 4379 9406

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

TDH