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 /06Z TAFS THROUGH 12Z FRIDAY/

Issued at 1236 AM CDT Thu Sep 17 2026

Shield of rain & thunderstorms is departing east into central WI for the start of the 6z period. We'll have a few hours of lingering showers at the eastern MN/western WI terminals before dry weather returns. MVFR/IFR conditions across southern MN will expand northward in the coming hours and have included TEMPOs for IFR (or lower) cigs and visibility that will prevail through daybreak before improvements are observed mid-morning. RWF/MKT will be stuck in the very lower cigs/fog the longest, but eventually all terminals observe improvements to VFR by early afternoon. Light winds between 5-7kts out of the ENE today.

KMSP...Heaviest rain has moved east of the terminal, though we'll keep the chance for additional showers in the TAF until 8z. Bank of MVFR (and lower) ceilings and visibility is creeping north into southern MN. Anticipate MVFR ceilings will reach the terminal around 8z and we've also included a TEMPO for IFR cigs with visibility reductions through 12z. MVFR cigs will be slow to clear after daybreak, but VFR conditions with light easterly flow should return by 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.