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 /06Z TAFS THROUGH 12Z SATURDAY/

Issued at 1237 AM CDT Fri Sep 18 2026

Rain is working its way into southwestern Minnesota early this morning with MVFR cigs encroaching on KMKT and KRWF. Rain should begin at our western/southern sites before 12z with KSTC/KMSP following by 14z and finally our Wisconsin terminals by mid/late morning. Maintained the -TSRA mention for KMKT and added KRWF for a few hours later this morning. Prevailing low end MVFR/IFR seems pretty likely through much of the TAF period. East winds may gust to around 20-25kts during the afternoon before diminishing after 00z. Once the bulk of the rain comes to an end, IFR cigs/vis will persist with fog/drizzle through the end of the forecast period.

KMSP...No big changes from the previous forecast. Left thunder out as the better environment remains to the south and west.

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

MPX WATCHES/WARNINGS/ADVISORIES

MN...Flood Watch from this evening through Saturday morning for Freeborn. WI...None.