textproduct: Twin Cities

KEY MESSAGES

- Best chance of rain comes late Tuesday night, followed by a low confidence precipitation forecast with multiple low chances for rain through Labor Day weekend.

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

DISCUSSION

Issued at 409 PM CDT Mon Aug 31 2026

There's an impressive bowling ball upper low over southern Saskatchewan and Manitoba this afternoon, which is driving a cold across western WI and far southeast MN. Our position south of this upper low puts us in its zone of subsidence and mid- level dry air, which means we get yet another dry cold front, which seems par for the course for an August that will see MSP finish the month with just 0.46" of rain (we average 4.34"), which is the 4th driest August on record and just the 8th out of 156 years where the Twin Cities failed to get at least 1" of rain in the month of August. With that said, we can't completely rule out rain in the MPX area this evening, but that chance is in Eau Claire and Chippewa counties, to the east of Chippewa Falls and Eau Claire. East of the cold front, it's oppressive for the last day of August, with temperatures in the upper 80s, dewpoints in the mid 70s, and heat index values in the mid 90s. All of this heat and humidity is translating into instability, with a pool of 3000+ j/kg of mlCAPE forecast develop ahead of the front. Although isolated storm chances look better east of the MPX area, the HRRR has been initiating storms in eastern Eau Claire county around 23z from the 15z run through its most current run (19z), so we will have to keep an eye on the storm potential out around Stanley and Augusta. After that, the rest of the night will be quiet, with drier air moving in limiting the fog potential in MN (where dewpoints are in the mid 50s across central MN). WI will still have radiational fog potential as they will hold on to dewpoints in the 60s through the night.

This drier airmass moving in today will stay with us through the day on Tuesday, with dewpoints in the upper 40s to lower 60s making highs Tuesday in the 80s more tolerable.

Tuesday night is when things start to turn more active as a shortwave coming out of the southwest monsoon travels across southern MN. Most guidance shows storms developing on the nose of the LLJ and riding the elevated CAPE gradient east Tuesday night. Looking at the HREF/REFS, the pool of high muCAPE (over 3000 j/kg) will remain near/north of the I-80 corridor in Iowa, with the LLJ nosing up into northern Iowa. This all points to the MN/IA border being the zone most conducive to seeing thunderstorms/heavy rain, with a lighter overrunning precipitation area getting about as far north as the Twin Cities metro, which will likely mean central MN into northwest WI misses out on this one. Based on where the large scale forcing is forecast to be, the NBM this morning looked to have displaced it's higher PoPs/QPF a bit too far north, so did nudge PoPs a bit south Tuesday night to get closer to where the forcing is.

Wednesday through Labor Day begins a period of high confidence in summer-like warmth and humidity for the first week of meteorological fall, but low confidence on precipitation. Figuring out severe weather potential comes down to figuring out where moisture (for said storms), forcing (something to provide large scale ascent for that moist air), instability (so that the ascending moist air goes up in a convective updraft), and wind shear (let's organize those storms!) all come together. The large scale weather pattern through the weekend will become amplified as a trough digs into the Pac NW. As it digs into the Pac NW, we see the ridge over the central CONUS amplify, with a westerly to southwest flow developing aloft locally. This setup will pump deep moisture into our region from the Gulf and southwest Monsoon. Looking at the 4 ingredients, we'll have plenty of moisture (mean EPS Pwats are 150% to 200% of normal through the weekend), given the heat and humidity, instability will be ample, and with the upper jet always overhead/nearby, we'll have ample wind shear as well. The big uncertainty through the weekend is the forcing variable. With the building upper ridge, forcing looks subtle, with precipitation chances tied to where the warm front is on a daily basis and where any weak waves move through in the upper flow. In other words, it's mesoscale features that will be driving our precipitations, which is hard to parse out more than 48 hours in advance. The result is what you get with this forecast, numerous low chances for precipitation through the holiday weekend. At this point, about the best we can say is whatever we get, it looks to be predominately nocturnal in nature. Will we manage to finally cash in on a potential active weather pattern? Maybe, but when it comes to forecasting precipitation in a drought, I like to live be the maxim of when in drought, leave it out.

AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 545 PM CDT Mon Aug 31 2026

VFR conditions expected throughout this duration. Behind the departing cold front, weak high pressure will breeze across the region tonight into tomorrow, resulting in diminishing winds from sunset through sunrise, along with mostly clear skies aside from passing high clouds. High clouds will increase in coverage during the day Tuesday, resulting in high ceilings from the afternoon onwards. After light/variable winds tonight, winds pick up from the W to NW under 10kts during the day tomorrow.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/ WED...VFR. Early AM -RA likely. Chc -TSRA late night. Wind SE 5 kts. THU...VFR. Chc TSRA morning and again overnight. Wind SE 5-10 kts. FRI...VFR. Wind S 5-10 kts.

MPX WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None.