textproduct: Twin Cities

KEY MESSAGES

- Widespread steady soaking rain is expected Friday into early Saturday.

- The highest amounts will be near I-90, where heavy rain and flooding are possible, mainly Friday evening.

- Looking ahead into next week, temperature remain near to slightly below normal, with a few small chances for rain.

DISCUSSION

Issued at 157 PM CDT Thu Sep 17 2026

TONIGHT THROUGH FRIDAY NIGHT...The main concern is the potential for heavy rain and flooding across southern Minnesota. Latest guidance supports the greatest risk for thunderstorms Friday evening along and near I-90. These storms will have abundant moisture, and could be slow moving and/or back building. Hourly rainfall rates of 2 to 3 inches would be possible, so any areas that see a couple hours of storms have a potential for rainfall totals of 4, 5, 6 inches, or more. No flood watches have been issued, but these would be needed later if the trends continue to highlight southeast Minnesota. Generally in the area of Owatonna and Albert Lea and points east.

Elsewhere, widespread, soaking rain is still expected, but the rainfall rates will be much less given the lack of instability. Forecast soundings off the RRFS and HRRR for MSP only have about 0.25 inches in any given hour, so even though total amounts of 1 to 2 inches of rain seems likely by the time the rain ends Friday night, the risk for flooding across central MN and west central MN is pretty low, especially considering the dry antecedent conditions.

The set up for all of this ties back to a shortwave that will lift up from the southwest later tonight. A stationary boundary that was laid out west-to-east along the I-80 corridor will lift northward as a warm front. Precipitable water values are in excess of 2 inches along this warm front, and strong southeast winds along the front will lead to widespread rain and storms in the Dakotas overnight. These will move eastward into Minnesota and Wisconsin on Friday, but weaken as they run out of instability. This will lead to lower rainfall rates, generally around 0.25 inches per hour. The lone exception could be an enhancement of FGEN/rain along an elevated front, but even then it would be tough to get rates over an inch per hour given the lack of instability.

Farther south however is a different story. Forecast soundings show elevated instability building near I-90, and some HiRes guidance show thunderstorms developing Friday evening. This is the main area of concern for flooding, generally after 6pm, and ending by midnight.

SATURDAY, SUNDAY AND NEXT WEEK...Rain will exit the region Friday night as the warm front pushes south, leaving low clouds behind. A few showers could redevelop on Saturday, main to the south along I- 90 again. Given the clouds, northeast winds, and cooler airmass, afternoon highs will be in the mid 60s, giving a fall-like feel to the weekend.

Looking ahead, the aforementioned warm front will stall out across Iowa and Illinois, keeping the rain chances to the south. There are a few small chances for rain (10 to 20 percent) at times, but overall drier ensemble guidance shows drier weather for next week.

AVIATION /00Z TAFS THROUGH 06Z FRIDAY/

Issued at 624 PM CDT Thu Sep 17 2026

Mostly VFR with some MVFR CIGS across southern Minnesota this evening. This will continue into the early overnight until Friday's rain moves in from west to east. As the rain arrives going with a prevailing MVFR impact with more of a TEMPO IFR. As the lower atmosphere continues to saturate a more prevailing IFR will take hold for much of the rest of the period. Thunderstorms are possible, but outside of MKT confidence in their occurrence was not high enough for PROB30 inclusion. Winds will be light from a northeast direction this evening into tonight becoming gusty from the east up to 20 knots tomorrow.

KMSP... Our just VFR cloud deck will remain with us this evening. Tomorrow morning we will see the arrival of an all day rain chance. This rain should remain MVFR with periods of heavier IFR throughout the day. Winds will continue this evening from a crosswind direction for the parallels, but should remain 10 knots or less. Winds will shift to the east as the rain arrives overnight and into tomorrow morning.

/OUTLOOK FOR KMSP/ SAT...VFR. Chc -SHRA. Wind NE 10-20 kts. SUN...VFR. Wind NE 10-20 kts. MON...VFR. Wind E 5-10G15 kts.

MPX WATCHES/WARNINGS/ADVISORIES

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