textproduct: Twin Cities

KEY MESSAGES

- Quiet and dry weather begins, with a warmer day today followed by cooler temperatures for the rest of the period.

- Isolated showers possible Saturday afternoon/evening, otherwise a dry forecast. Amounts generally less than a tenth of an inch, most remain dry.

DISCUSSION

Issued at 305 AM CDT Wed Sep 30 2026

Most mornings we bring up the nighttime microphysics RGB as the product to look at, mainly because it helps us pick out areas of low level cloud cover and fog, and while that is also the case today I'd like to put some focus on the Differential Water Vapor RGB. There is a tremendous signal between the clouds and moisture flowing southeast of the area down where there are still showers ongoing in eastern Iowa through southern WI and northern IL and where there is a bit of dry air just northwest of the this line as evident by the tan/brown. Northwest of the thin line of dry air is air that once again contains a bit more moisture despite the lack of cloud cover, mainly due to the subsidence as high pressure moves in. Our lower level temperatures from the surface to around 850mb continues to be on the warmer side, especially for this time of year, which will allow temperatures to reach into the mid 70s this afternoon with some 80s in western MN possible in our normal warm spots. This will be relatively short lived as after today we should drop back into the 60s for high for the rest of the period, with lows likewise dropping from near 60 this morning to mid to upper 50s tomorrow morning down to the upper 40s by Friday morning. Keep in mind that for Sep 30th for the Twin Cities, our normal high is 67 and low is 48; these numbers will only continue to fall into the first week of October so we will be essentially near normal temperature wise despite it seeming colder simply due to having been warmer than normal recently. Taking another queue from climatology, our average first 32 or colder day in the Twin Cities is October 12th and the longer range guidance favors continued 60s for highs and 40s for lows through the first half of October, meaning we probably end up on the later side for a first hard freeze. Whether or not we make a run at the latest on record being Nov 18th back in 2016 remains to be seen.

The main thing to look at besides the temperatures moving forward will be a chance for showers on Saturday evening as a shortwave quickly sweeps through the region, with accumulation generally a tenth of an inch or less with the current forecast. The GFS suite is much drier than the ECMWF, however even the most bullish EPS members only show a couple tenths of an inch at the most with duration of precip only 3 to 4 hours as the shortwave rapidly moves through. GFS forecast soundings show a classic inverted V lower level profile, although lapse rates become poor above 850mb such that instability is minimized. We could still manage to squeeze out some thunder given the degree of surface instability that would be possible, with the main question being how well we can saturate the lower levels to overcome the weak lapse rates. For now, don't expect much in the way of thunder, with some isolated to scattered light showers being the expectation. After Saturday we resume our dry pattern as a broad area of high pressure drops down into the northern plains and into the Great Lakes to start next week.

AVIATION /18Z TAFS THROUGH 00Z FRIDAY/

Issued at 1240 PM CDT Wed Sep 30 2026

LIFR/IFR cigs continue to persist over southern/eastern MN and parts of WI. The bank is eroding from west to east and expecting the rest of it to scatter out by mid afternoon. High clouds will remain to the south for much of the afternoon, but will spread north tonight. More fog may develop tonight across southern MN, but a cold front will bring drier air and increasing northwest winds overnight which should lead to improvement by morning.

KMSP...IFR cigs are expected to persist through about 20Z, then should scatter out. Some additional fog and low stratus can't be ruled out late tonight just ahead of the cold front, but the better chances of this occurring will be to the south.

/OUTLOOK FOR KMSP/ THU...VFR. Wind NW 10-15G25 kts. FRI...VFR. Wind variable 5 kts. SAT...VFR. Chc MVFR SHRA. S bcmg SW Winds 5-10kts.

MPX WATCHES/WARNINGS/ADVISORIES

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