textproduct: Twin Cities

KEY MESSAGES

- Isolated storms possible this afternoon over eastern MN and far western WI.

- Increasing signal for a potential MCS and attendant severe weather and heavy rain risk late Tuesday into Wednesday.

- Dry weather with near normal temperatures expected Thursday through Saturday.

DISCUSSION

Issued at 332 AM CDT Sun Jul 5 2026

What's left of the July 4th storms we saw are falling apart as they approach I-80 in Iowa. The only thing that has kept us going hard into fog/stratus mode this morning is the presence of remnant convective debris, but if we see any sort of substantive clearing before sunrise, we should see dense fog develop pretty quick given the light winds and rainfall we saw Saturday afternoon/evening. After that, we'll see upper heights build as a ridge axis from the Black Hills to Lake of the Woods early this morning shifts east through the day. This will keep most of us dry, but deterministic and hi-res guidance continues to show a plume of deeper moisture remaining stuck across eastern MN and far western WI. This looks to promote the development of some isolated showers and storms with diurnal heating, basically east of a Mankato to Cambridge line and west of Menomonie in WI. CAPE on the 4th was up between 2000-2500 j/kg, which was enough to give us a few stronger updrafts. Today, we'll take 1000 j/kg off that CAPE, which means updrafts today will be weak, with only the strongest updrafts able to just produce some lightning.

Monday will start dry with that ridge overhead, but as it flattens out during day, we'll see a cold front move across NoDak into northwest MN. HREF shows mlCAPE values along the front pushing 3000 j/kg, which will likely promote the development of thunderstorms in the afternoon across eastern NoDak into northwest MN. There will likely be a line of storms making a run for northwest portions of the MPX area Monday night, but with no LLJ to help sustain them with the loss of daytime heating, this line should be falling apart as it moves into the MPX area Monday night. What it will do is likely leave a boundary draped across central MN that could be the focus of some scattered diurnal acitivity Tuesday afternoon. However, this is not the concern for the Tuesday/Tuesday night time frame. The concern is convection that will fire Tuesday afternoon on the nose of a weak LLJ back over the Dakotas. There's a strong signal from all deterministic models that this activity will become a forward propagating MCS with some back building across MN Tuesday night. There are latitudinal differences on where this MCS would track, but from the synoptic scale, this is a pretty classic summer severe MCS setup. There will be modest westerly mid-level flow, with a weak, but sufficient southwesterly LLJ feeding into the right entrance region of an upper jet streak. It will be interesting to see how this gets handled by the CAMS as they come into play, but the "double slight" (Slight Risk of severe weather from the SPC and Slight Risk of excessive Rainfall from the WPC) for the Day 3 period looks warranted and will be something to keep track of over the next couple of days.

Behind this system, we'll get a bit of a reprieve from the oppressive humidity Thursday and Friday, with dewpoints falling back into the upper 50s/lower 60s and highs in the lower 80s. After that, the next big atmospheric feature to watch will be the developing ridge over the central US next weekend. Just how far east this develops will determine how uncomfortable we'll get to start the week of July 13th, but the ECMWF AIFS has h5 heights in excess of 600 dm over southern MN to start that week. If we see something like that, then we will be looking at another round of dangerous heat in that 8-10 day period, with that heat starting to build back in here at the end of this forecast period, which is Sunday of next weekend.

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/

Issued at 1156 AM CDT Sun Jul 5 2026

Most sites will see VFR conditions through the period, with limited cloud cover under weak surface high pressure today. There is a pool of higher moisture stretching from eastern IA up through southeast MN and western WI, where isolated thunderstorm development is possible this afternoon and evening. KEAU and KRNH are the most likely to see any impacts, though confidence is low.

Winds remain light through the period as well, generally out of the east today and shifting more southerly by tomorrow afternoon.

KMSP...Latest satellite trends suggest that any thunderstorm development should remain east of the terminal today. At the same time, thunderstorm coverage is expected to be fairly isolated, so confidence is low in general. To reflect this, the Prob30 group of -TSRA this afternoon was removed.

/OUTLOOK FOR KMSP/ TUE...VFR, chc pm -SHRA. Wind SW 5-10kts. WED...MVFR/-SHRA likely, chance IFR/-TSRA. Wind SW 10-15kts. THU...VFR. Wind E 5-10kts.

MPX WATCHES/WARNINGS/ADVISORIES

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