NWS: Friday's Storm Could Be Most 'Extreme' Rain Event In 20 Years For Twin Cities

TWIN CITIES, MN — The National Weather Service is warning that Friday's rain event could rank among the most extreme rainfall events the Twin Cities region has seen in two decades, with the potential for localized flooding.

Forecasters at NWS Twin Cities/Chanhassen say a long-duration round of soaking rain will begin Friday morning and continue through much of the day into early Saturday.

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A broad swath of the region can expect 1 to 2 inches of rain, and NWS said in its Wednesday morning forecast discussion that "a stripe of at least 3 inches will fall somewhere and possibly greater than 5 or 6."

The system driving the rain is currently sitting far away in the Gulf of California, forecasters said.

It will track north through the Four Corners region and the western High Plains before reaching Minnesota on Friday, pulling in significant moisture along the way. Meteorologists say dewpoints will climb into the 60s as the system approaches.

What has forecasters especially concerned is the strength of the signal.

NWS cited the ECMWF Extreme Forecast Index at 0.8 to 0.9 for the region, meaning model data is pointing toward rainfall totals that are highly unusual for mid-September.

In its discussion, the agency put it bluntly: "This may be an extreme event."

Confidence is high that most of the metro will see at least an inch of rain.

Where confidence drops is in pinpointing the exact location of the heaviest band. As of Wednesday morning, guidance suggested the heaviest rain could fall somewhere between Willmar and Redwood Falls, stretching east through the southern Twin Cities metro and into the Eau Claire and La Crosse areas, though NWS cautioned that placement could still shift.

The agency also raised the possibility of formal warnings ahead of the storm. "Flood watches may eventually be needed," NWS said, adding that the risk is heightened if the heaviest rainfall lands over an urban area, where runoff moves quickly into storm systems and low lying roads.

Drier weather is expected to return Saturday as the front temporarily pushes south. Another system will move in from the Rockies by early next week, which forecasters say could bring another round of unsettled weather.

Residents are urged to monitor updated forecasts as Friday approaches, since the exact placement of the heaviest rainfall remains one of the biggest open questions in the forecast.