textproduct: Twin Cities

KEY MESSAGES

- Widespread heavy rain is expected Friday into early Saturday, with amounts in excess of 2-4" likely from the southern Twin Cities metro south towards the Minnesota/Iowa border.

- Flooding is possible where repeated rounds of heavy rain occur, with the greatest concern Friday night into early Saturday morning.

DISCUSSION

Issued at 243 AM CDT Thu Sep 17 2026

An area of showers remains ongoing across east central MN into all of west central WI, driven by southwesterly 850 mb moisture transport across southern MN. Rain totals have been pretty impressive with MRMS suggesting three streaks of 3/4"+ amounts - St. Cloud and east, Willmar and east, and from Le Sueur Co and east. Estimates are even higher across central Meeker and southern Wright Counties where near an inch and half has likely fallen. The moisture transport will veer with time and should allow the showers to focus more in Wisconsin before things dry out for the rest of the day. Low clouds and light fog have developed across southern and western MN. It should take several hours to begin clearing out today, possibly not until late afternoon with a healthy inversion above 5 kft, but forecast soundings do show it occurring eventually.

Attention then turns to the heavy rain threat Friday. The system is currently over the Four Corners/southern Rockies and is being driven north by an upper low over the West Coast and the very large and intense ridge across the south. It will begin to crest the ridge and reach the Upper Midwest late tonight and Friday. Not much has changed with respect to the overall idea of this system's evolution, but now that CAMs are beginning to capture the event, some smaller scale details are becoming clearer. By early Friday morning, a large shield of showers will be advancing into central and southern MN, with the heaviest rates over eastern SD. As the day progresses, this shield will push east across the area and then weaken late in the day. Heavy rainfall totals (1-2+ inches) are likely where the elongated shield persists the longest. Most models highlight an area from west central MN towards the metro as the highest likelihood. That round will be driven primarily by mid level forcing. A second round tied to the surface warm front should develop later in the day farther south across south central and southeast MN into northeast IA. There will be potential for very heavy totals in this area given that training thunderstorms is a possibility with storm motions parallel to the surface front. How far north this develops and whether it will intersect any hard hit areas from the first round is the main question. Given large spread in the guidance with members continually shifting around, a blended approach for QPF remains appropriate. NBM may be too high in some places and not high enough in others, but it does sufficiently highlight the areas of most concern - the southern portion of the metro and south/east from there into northeast IA and southwest WI.

The front will settle south behind the Friday system, bringing drier weather Saturday. The upper low out west will make slow progress east and bring another chance of showers late Sunday into Monday.

AVIATION /12Z TAFS THROUGH 18Z FRIDAY/

Issued at 555 AM CDT Thu Sep 17 2026

Messy aviation scenario to open the 12z period following the departure of early morning showers. Satellite and observations show MVFR/IFR stratus across southern MN and into western WI. The worst of the conditions are near RWF, where LIFR cigs are in place at initiation. Satellite has captured some clearing across central MN, but that has allowed for the development of fog at STC and surrounding obs. General thinking is that fog erodes after daybreak, but the low stratus likely sticks around for much of the morning and into the afternoon given a strong inversion displayed on forecast soundings. Have delayed improvements to VFR at most terminals as a result. AXN, STC, MSP, RNH & EAU will likely improve to VFR before RWF & MKT. Cigs lower late tonight ahead of heavy rain that is forecast to move into southwestern MN towards the end of the 12z period.

KMSP...Low MVFR ceiling at initiation, with a brief dip to IFR possible through 14z. Latest trends are slower with delaying cig improvements, so the 12z TAF keeps MVFR cigs in place until 20z. Shower arrive around 12z Friday and will be followed by heavier rain and visibility reductions into the late morning.

/OUTLOOK FOR KMSP/ FRI...MVFR/RA. Chc IFR w/-TSRA. Wind SE 10-15G30kts. SAT...VFR. Wind NE 5-10G20kts. SUN...VFR. Wind NE 5-10G20kts.

MPX WATCHES/WARNINGS/ADVISORIES

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