Winter Storm — Watonwan, Minnesota

2021-12-10 to 2021-12-11 · Watonwan, Minnesota

Event narrative

Light snow developed Friday morning and continued for most of the day before tapering off early Saturday morning. Total snowfall amounts across the county averaged between 8 to 9 inches. Some moderate snowfall occurred in the morning and afternoon allowing for totals to exceed 5-6 inches by late afternoon.

Wider weather episode

The Winter Storm that brought over a foot of snow across portions of the southern, and eastern Twin Cities metro area, and into adjacent west-central Wisconsin, was a classic Colorado Low storm track. Winter Storm watches were posted nearly 60 hours in advance of the first snow flakes that fell across southern Minnesota. Warnings were issued Thursday morning and had nearly 24 hours of lead time before the heaviest snowfall began across the state.

During the morning of Friday, December 10, an area of low pressure had developed across eastern Colorado. By the afternoon, and early evening, the storm moved across Kansas, and into northern Missouri. By Saturday morning, this storm system moved over the Great Lakes region. Light snow started to develop as early as Friday morning across far southern Minnesota. Regional radar noted a very elongated band of higher reflectivity over southern Minnesota that steadily moved northward Friday morning. This band was associated with strong upward mid-level forcing that remained nearly stationary across the southern part of the Twin Cities metro area, and into west central Wisconsin for several hours. As moisture from the main storm system moved northward into southern Minnesota Friday evening, snowfall rates intensified. Locally, snowfall rates were 1 to 2 inches per hour, with isolated higher rates. Snowfall totals by the time it tapered off were approaching 20 inches.

Outside of this intense band of snowfall, this storm system brought widespread light snow to the area with accumulations ranging from a few inches up to a foot and a half of fresh snow. The heaviest snowfall was observed from the southwest to eastern Twin Cities metro, with amounts drastically decreasing as you moved into the northern Twin Cities.

Schools closed early due to anticipated snowfall with several businesses closing early over the south metro. The timing of the event led to numerous travel impacts, as some of the most intense snow fell during the Friday evening commute. Roadways quickly became snow covered, with reduced visibility due to intense snowfall rates also briefly shutting down flights at MSP airport. In addition, to the airport shutting down, there were cancellations as early as Friday morning due to the anticipated snowfall rates during the afternoon and evening. MnDOT reported over 600 accidents across Minnesota during the height of the storm.

Some of the higher snowfall totals that occurred during this event included;

21.0 inches near St. Paul Airport.

20.0 inches near Lake Elmo.

19.0 inches near Inver Grove Heights.

and several reports of 18.0 inches around Eagan, Prior Lake and Woodbury.

Source: NOAA Storm Events Database, event_id 989935. Narrative written by the NWS forecast office that issued the report.