textproduct: Twin Cities

KEY MESSAGES

- Isolated thunderstorms possible this morning, favoring southern Minnesota. Heavy rain and gusty winds are the primary threats.

- Another round of storms possible tonight, heavy rain and gusty winds as the primary risks.

- A lull in storm chances early in the week, returning midweek. Warm and muggy conditions otherwise continue.

DISCUSSION

Issued at 258 AM CDT Fri Jul 3 2026

IR satellite imagery shows a significant plume of cold cloud tops above a cluster of storms moving across western Iowa as of around 230am, with the northern edge of the storms just sliding across the southern state border into southwest Minnesota. The northern edge will be the thing to watch this morning as our chance for storms is largely tied to the ongoing storms and remnant outflow boundaries, with forcing generally weak across the area aside from this. High resolution guidance has generally struggled to fully capture the thunderstorm threat for the morning with some like the HRRR showing far too widespread coverage amidst what is mostly capped upper level instability, with others such as the RRFS showing next to nothing even across southern Minnesota this morning. The vertical displacement of the stationary front is one of the key components that has resulted in a tricky forecast, with the surface boundary slowly creeping northwards as it continues to produce the storms in Iowa, however aloft the boundary is much farther north. This leaves our southern coverage area wedged between the more bountiful instability which is more closely tied to the surface to our south, but leaves enough instability aloft to be concerned for storm chances. The grid philosophy this morning has been to broad brush slight chance to chance thunderstorm chances as there is lower confidence in the overall spread of storms this far north. The surface boundary is expected to stall over the area today with some isolated cells possible, but generally we expect to remain dry throughout the daylight hours with our next chances for storms arriving later in the evening and overnight once again.

The storm chances tomorrow night could take multiple different forms as there is zero consensus as to how the overnight hours will go. The HRRR/RRFS produce some isolated storms along the stationary boundary, but generally keep the overall activity muted as we end up with another -200 CIN layer cutting off surface instability, with MUCAPE ranging from 1500-2500 within various models generally above 800-750mb. The NAM suite tries to produce a pair of MCS complexes over Nodak/Nebraska which bisect the area, however this seems less likely given our prominent capping inversion. No matter the shape, the overnight hours tomorrow look to primarily be a heavy rain, thunder, and isolated gusty wind threat due to the cap, with heavy rain over already rain soaked southern Minnesota being the best chance for isolated flooding concerns. Not to be outdone, the global guidance also shows a chance for an MCS type feature overnight, with both the GEFS/EPS suites showing decent chances. Until we actually see storm formation to our west, this will remain a low confidence forecast, but do not be surprised to be woken up by some heavy rain or thunder tomorrow night as the thermodynamics generally support elevated storms. After any morning storms roll through, the surface low and associated boundary is expected to push southeast, which should open up conditions to be gradually clearing out during the afternoon and evening on the 4th of July. We cannot completely rule out some further airmass pulse type storms as we still maintain some instability, however without the forcing from the boundary it seems unlikely that coverage will be very high. SPC seems to agree with this forecast given the area-wide general thunder for the entire states of Minnesota and Wisconsin for the holiday.

Behind the departing boundary into Sunday and to start the week, brief surface high pressure builds as our upper level flow takes a more northerly tilt. Our next chance for showers and storms arrives later in the day on Tuesday into Wednesday as our flow becomes zonal once again, with further potential for shortwaves within the base flow. Another weak surface low could produce yet another broad surface front that lingers in the area for the second half of next week, however confidence is low in individual storm systems and timing. The main impact of said boundary would be a continued warm and humid airmass, with highs generally in the 80s and dew points in the 60s. So while we are not looking at another stretch of heat indices in the 100s, it will be slightly above normal temperature wise for this time in July.

AVIATION /06Z TAFS THROUGH 12Z SATURDAY/

Issued at 1249 AM CDT Fri Jul 3 2026

This period, the surface boundary is expected to remain in Iowa, with the elevated CAPE gradient across northern MN. This leaves us stuck in between with adequate moisture/instability for deep convection, but no real focus for said convection. The last couple of runs of the HRRR really want to blow up a cluster of storms over southern MN before sunrise, but we're having trouble buying that given what we're seeing with the convection currently out by Yankton and the fact that the surface front stays in Iowa and there really is no good push of southerly flow in the 850-700mb layer to really help spark another round of storms. Only held on to a TS mention (prob30) at MKT as possibly we see some convection sneak out of Iowa, but for now, will keep things optimistic when it comes to convection. Where we will likely have some issues again in central MN and western WI is fog/stratus development, though that will come down to how much convective cloud debris we see through the night. For Friday, we could see some scattered afternoon convection, but with no real forcing mechanism to hang our hats on, we kept any additional TS mention out of the TAFs for now. In summary, if you were looking for high confidence TAFs, you came to the wrong CWA!

KMSP...As mentioned above, we're having trouble buying into the convective blowup the HRRR has toward sunrise (which the AWC leaned heavily into for the 11z convective forecast they have), so we continued to the trend of no TS mention in the MSP TAF. Bigger concern for Friday morning may end up being fog/stratus in the region possibly bringing some reduced vis/cigs in around sunrise. You really can't rule out TS potential at any point in this period, but until we have higher confidence on when/where storms will be near MSP, we've opted to keep that mention out of the TAF.

/OUTLOOK FOR KMSP/ SAT...Chc MVFR/TSRA. Winds SE bcmg NW 5-10 knots. SUN...VFR. Winds N 5-10 knots. MON...VFR. Winds SE 5-10 knots.

MPX WATCHES/WARNINGS/ADVISORIES

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