Heavy Snow in Wisconsin, December 23 to 25, 2020

Name: Heavy Snow in Wisconsin, December 23 to 25, 2020
Start: 2020-12-23T11:00
End: 2020-12-25T12:00
Location: Wisconsin

December 23 to 25, 2020 · NWS DLH · 7 events in 7 counties and zones

Where it happened

Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $10,000
Crop damage: None recorded
Events: 7

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS DLH wrote it up.

A strong area of low pressure brought heavy snowfall and very strong winds to much of the Northland starting on Wednesday the 23rd and lingering into Thursday the 24th. Very strong frontogenesis occurred along a trowal axis that extended across much of northern Wisconsin west into Minnesota. Warm air advection caused temperatures across most of northwest Wisconsin to rise above freezing and produce mixed precipitation for several hours during the day. As the cold front gradually moved east, temperatures very quickly dropped and caused treacherous road conditions as mixed precipitation changed over to snow. Narrow bands of heavy snow set up over the Brainerd Lakes northeast towards the Iron Range during the early morning and early afternoon, and then translated east towards the Twin Ports, North Shore, and Interstate 35 corridor. The heavy snow bands coincided with the strong mid-level frontogenesis, which also produced very strong northwest winds that caused the widespread blizzard conditions. A few power outages were reported and widespread whiteout conditions made travel difficult if not impossible.

As the cold front swept rapidly eastward, bitterly cold air moved into the region and led to the development of a topographically-forced gravity wave during the night of the 23rd that dropped several more inches of snow from Two Harbors to Superior to Holyoke. The highest snowfall report was 13 inches of snow near Foxboro under this band. Further east, lake-effect snow continued into Thursday along the South Shore. Gile, Wisconsin, saw 18.5 inches of snow before lake-effect snow tapered off Thursday evening.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Duluth, MN wrote its last area forecast discussion before the first event at Dec 23, 10:43 AM CST, 17 minutes earlier.

Area forecast discussion, Dec 23, 10:43 AM CST, 17 minutes before

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Hazardous weather outlook, Dec 23, 5:22 AM CST, 5 hours 38 minutes before

Hazardous Weather Outlook
National Weather Service Duluth MN
522 AM CST Wed Dec 23 2020

MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-241130-
Koochiching-North St. Louis-Northern Cook/Northern Lake-
North Itasca-Central St. Louis-Southern Lake/North Shore-
Southern Cook/North Shore-North Cass-South Itasca-South Cass-
Crow Wing-Northern Aitkin-South Aitkin-Carlton/South St. Louis-
Pine-Douglas-Bayfield-Ashland-Iron-Burnett-Washburn-Sawyer-Price-
522 AM CST Wed Dec 23 2020

This Hazardous Weather Outlook is for portions of northeast
Minnesota and northwest Wisconsin.

.DAY ONE...Today and Tonight

A wintry mix of snow and freezing rain will spread into the area
this morning and early afternoon. The wintry mix will quickly
switch over to all snow and become heavy at times during the day
today. Snow should end Wednesday night for most areas with
lake effect snow continuing for the South Shore overnight. The
heaviest snowfall rates will be found today, producing snowfall
amounts of more than 6 inches over a large portion of the
Northland. Strong northwest winds developing this morning will
remain strong over much of northern Minnesota into this evening
before diminishing overnight. These winds will lead to blowing and
drifting snow this afternoon and tonight. Bitterly cold wind chill
values are expected overnight tonight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Snow will come to an end for most of the area Thursday morning,
but lake effect snow is expected to continuing for the South
Shore Thursday and Thursday night. Additional snowfall amounts of
up to 6 inches are possible by Friday morning for the Penokee
Range of northern Iron County. Dangerous wind chills are also
expected Thursday morning, and again Thursday night and Friday
morning.

Lake Effect snow may affect the South Shore of Lake Superior
Friday night and Saturday night.

.SPOTTER INFORMATION STATEMENT...

Snow spotters are requested to report their snowfall measurements
to the National Weather Service.

LSZ121-140>148-241130-
Bayfield to Oak Point WI-Grand Portage to Grand Marais MN-
Grand Marais to Taconite Harbor MN-
Taconite Harbor to Silver Bay Harbor MN-
Silver Bay Harbor to Two Harbors MN-Two Harbors to Duluth MN-
Duluth MN to Port Wing WI-Port Wing to Sand Island WI-
Sand Island to Bayfield WI-Oak Point to Saxon Harbor WI-
522 AM CST Wed Dec 23 2020

This Hazardous Weather Outlook is for portions of the Nearshore
waters of western Lake Superior.

.DAY ONE...Today and Tonight

Strong southeast to east winds over the lake this morning has
caused waves of 3 to 5 feet along parts of the North Shore. These
winds and waves are expected to diminish by mid morning. A Small
Craft Advisory remains in effect for parts of the North Shore
this morning.

Winds will increase once again out of the northwest this
afternoon. Gale-force winds are expected this afternoon into early
Thursday morning with a few storm-force gusts possible as well.
These winds and building waves are likely to cause hazardous
conditions over the nearshore waters. A Gale Warning and Freezing
Spray warning has been issued for this threat. Please see the
latest Marine Weather Message for additional information.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

The probability for widespread hazardous weather is low.

LE

More information may be obtained at the following web address:
http://www.weather.gov/duluth (all lower case)

In the hours before

Local storm report, Dec 23, 10:59 AM CST, 1 minute before

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The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

7 heavy snow. Local standard time, as filed.

Heavy Snow, Douglas

When: December 23, 11:00 AM CST to December 24, 6:00 AM CST
Where: Douglas forecast zone
Property damage: $10,000
Reported by: Trained Spotter
Coordinates: 46.464, -91.899 (the zone’s center; the record gives no point)

Heavy Snow, Bayfield

When: December 23, 11:00 AM CST to December 24, 3:00 PM CST
Where: Bayfield forecast zone
Reported by: Trained Spotter
Coordinates: 46.635, -91.181 (the zone’s center; the record gives no point)

Heavy Snow, Ashland

When: December 23, 12:00 PM CST to December 24, 3:00 PM CST
Where: Ashland forecast zone
Reported by: CoCoRaHS
Coordinates: 46.510, -90.720 (the zone’s center; the record gives no point)

Heavy Snow, Burnett

When: December 23, 1:00 PM CST to December 24, 5:00 AM CST
Where: Burnett forecast zone
Reported by: CoCoRaHS
Coordinates: 45.863, -92.368 (the zone’s center; the record gives no point)

Heavy Snow, Washburn

When: December 23, 2:00 PM CST to December 24, 6:00 AM CST
Where: Washburn forecast zone
Reported by: Public
Coordinates: 45.899, -91.791 (the zone’s center; the record gives no point)

Heavy Snow, Sawyer

When: December 23, 2:00 PM CST to December 24, 7:00 AM CST
Where: Sawyer forecast zone
Reported by: CoCoRaHS
Coordinates: 45.880, -91.145 (the zone’s center; the record gives no point)

Heavy Snow, Iron

When: December 23, 3:00 PM CST to December 25, 12:00 PM CST
Where: Iron forecast zone
Reported by: COOP Observer
Coordinates: 46.317, -90.264 (the zone’s center; the record gives no point)

What these are

Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Wisconsin in 2020 Every state in 2020 This day in weather history Warnings in Wisconsin, December 2020

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-30. Each event’s entry at NCEI: 933671, 933673, 933685, 933679, 933680, 933681, 933684.