Arctic air was entrenched across northern Wisconsin with morning low temperatures from -15 F to -30 F on February 7th. The combination of the bitter cold and light winds created wind chills of -35 F to -45 F.
Every event with a place to put it; 10 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS GRB wrote it up.
Arctic air was entrenched across northern Wisconsin with morning low temperatures from -15 F to -30 F on February 7th. The combination of the bitter cold and light winds created wind chills of -35 F to -45 F.
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 Green Bay, WI wrote its last area forecast discussion before the first event at Feb 6, 8:43 PM CST, 3 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Green Bay WI 843 PM CST Sat Feb 6 2021 Updated aviation portion for 06Z TAF issuance and new information added to update section .UPDATE... Issued at 831 PM CST Sat Feb 6 2021 No changes planned to wind chill headlines this evening. Hourly temperatures have been tracking pretty well with those from the afternoon forecast, and don't see any reason for that to change much overnight. So anticipate the apparent temperature (wind chill) grids in the going forecast will work out fairly well. (These wind chill headline events are never "clean". There are always sites that hit while nearby sites don't, and it changes from hour to hour depending on the exact temperature and wind. I suppose the only way to get something more consistent would be to be buried way down in warning criteria, but most people would rather not have that!) Some refreezing on water on roads likely resulted in icy conditions that were being reported in central Wisconsin. That probably occurred in other places as well--especially urban areas where the roads were treated during the day. Issued an SPS for that a little earlier this evening. && .SHORT TERM...Tonight and Sunday Issued at 353 PM CST Sat Feb 6 2021 The main focus for this forecast period is the continuation of the Arctic air mass spilling very cold air across the region. Tonight...Some of the coldest air from the Arctic air mass is expected to spread across the Upper Mississippi Valley tonight due to the support from an upper-level trough overhead. As the trough tracks further east overnight, the mean northwest flow will allow the dry and cold air to spread across Minnesota, Wisconsin, and Upper Michigan. The coldest air is expected across northern Minnesota, far northern Wisconsin, and western Upper Michigan. Low temperatures will be about 20 to 30 degrees below normal ranging from -15 to -25 degrees in central and north-central Wisconsin to -8 to -15 degrees in east-central and far northeast Wisconsin. Although surface winds will be generally light, it won't take much for very cold and dangerous wind chills to occur overnight. Wind Chill Warnings and Advisories have been issued for tonight through Sunday morning. The coldest wind chills will be in north-central Wisconsin with values between -35 and -40. Elsewhere can expect wind chill values between -25 and -35, however central Wisconsin may see some of the colder wind chills at times. In addition to the cold, skies are expected to clear overnight, which may allow temperatures to drop in some spots if winds become calm. Sunday...The dry and cold conditions are expected to continue through Sunday as the Arctic air mass continues to funnel the cold air across the Upper Mississippi Valley. The upper-level northwest flow will transition to a more zonal flow, which will allow the main jetstreak to lift north over the Middle Mississippi Valley. Although, a weak system in the left exit region of the jet will pass to the south of the state, the nearby clouds will spread over portions of central and east-central Wisconsin throughout the afternoon and evening. High temperatures will be about 25 to 30 degrees below normal ranging from the single digits below zero in central and north-central Wisconsin to the single digits above zero in east-central and far northeast Wisconsin. Afternoon wind chill values will range from -15 to -20, with colder wind chills at times. .LONG TERM...Sunday Night Through Saturday Issued at 353 PM CST Sat Feb 6 2021 Three words sum up the long term forecast...cold...cold...and cold. Winter 2021 has officially arrived. Upper level low pressure will sit and meander across Canada through the period. This will keep west/northwest flow over the western Great Lakes and keep the Arctic airmass (temps 15-30 degrees below normal) situated over the region. Wind chills will be well below zero, approaching -30 at times. Within this flow, a few weak shortwaves will track across the Great Lakes, bringing chances for light snow or flurries. Sunday night and Monday...first of the weak shortwaves will pass south of the area, possibly clipping our southern tier with some flurries (highest chance over Manitowoc Co.). Atmosphere just too dry to really produce much in the way of accumulation in our area. It will be another cold night, but just how cold is the question. Clouds will limit a full out free fall in temps for most of the area. Clouds or no clouds, looking like we will be near/below wind chill criteria over parts of central and northern WI, with east central WI more of a question. Rest of the extended...mainly dry conditions are expected as it will be tough to get any precip in the dry airmass. Another weak shortwave is forecast to pass south of the area mid-week, then a possibly stronger system toward the end of the week could be our next chance for any notable snow. Highs look to generally remain between 0 and 15 above, with lows between 0 and -20. Several nights/mornings look to require a wind chill headline, especially across central and northern WI. Bottom line...the frigid temps are here to stay through the week. Looking like it will be pretty hard to break any record low temp or low max's but we could flirt with a few on the coldest days. Latest indications are that the polar vortex (or at least a piece of it) could make a visit to the area next weekend, with an even colder shot of air, along with the chance for some accumulating to boot. Winter is definitely here to stay for the foreseeable future!. && .AVIATION...for 06Z TAF Issuance Issued at 831 PM CST Sat Feb 6 2021 Generally good flying conditions are anticipated through tomorrow evening. Some patchy Sc may redevelop tomorrow, but coverage will be very limited and not worthy of a tempo group for MVFR cigs. High and then middle clouds will begin to spread back across the area tomorrow afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory until noon CST Sunday for WIZ013-020>022-030- 031-035>040-045-048>050-073-074. Wind Chill Warning until noon CST Sunday for WIZ005-010>012-018- 019. && UPDATE.........Skowronski SHORT TERM.....Hykin LONG TERM......Bersch AVIATION.......Skowronski
Hazardous Weather Outlook National Weather Service Green Bay WI 903 PM CST Sat Feb 6 2021 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-071200- Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln- Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano- Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago- Calumet-Manitowoc-Southern Marinette County- Southern Oconto County- 903 PM CST Sat Feb 6 2021 This Hazardous Weather Outlook is for north-central and northeast Wisconsin. .DAY ONE...Tonight Dangerously cold conditions are expected tonight. If you will be outdoors, even for a short period of time, be sure to wear several layers of clothing, and cover all exposed skin to prevent frostbite. Refreezing of water will result in patches of glare ice and very hazardous conditions on roads, sidewalks, and parking lots. .DAYS TWO THROUGH SEVEN...Sunday through Saturday A dangerous combination of wind and cold is expected at times throughout the upcoming week. Wind chills will drop to 15 below to 25 below zero or lower each night, possibly reaching 35 below zero or lower on a few nights. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed tonight. LMZ521-522-541>543-071200- The Bay of Green Bay south of a line from Cedar River MI to Rock Island Passage-Lake Michigan from Washington Island to Sheboygan- 903 PM CST Sat Feb 6 2021 This Hazardous Weather Outlook is for portions of northwest Lake Michigan and the waters of Green Bay. .DAY ONE...Tonight The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Saturday The probability for widespread hazardous weather is low. Skowronski
Special Weather Statement National Weather Service Green Bay WI 719 PM CST Sat Feb 6 2021 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-070500- Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln- Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano- Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago- Calumet-Manitowoc-Southern Marinette County- Southern Oconto County- 719 PM CST Sat Feb 6 2021 ...ICY SPOTS REDEVELOPING ON ROADS AND SIDEWALKS THIS EVENING... During the day Saturday, sunshine and ice melting agents resulted in partial melting of some of the snow and ice that was lingering on area roadways and sidewalks. However, the onset of night combined with falling temperatures was causing the water to refreeze into glare ice. This was resulting in very hazardous conditions since the patches of ice were difficult to detect. Use extreme caution if you are traveling this evening. Be prepared for the possibility of encountering icy pavement. Drive at a safe speed, and be sure to maintain adequate distance between your vehicle and others on the road. Skowronski
Special Weather Statement National Weather Service Green Bay WI 1047 PM CST Sat Feb 6 2021 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-071000- Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln- Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano- Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago- Calumet-Manitowoc-Southern Marinette County- Southern Oconto County- 1047 PM CST Sat Feb 6 2021 ...ICY SPOTS LIKELY ON ROADS, SIDEWALKS, AND PARKING LOTS OVERNIGHT... During the day Saturday, sunshine and ice melting agents resulted in partial melting of some of the snow and ice that was lingering on area roadways, parking lots, and sidewalks. That water refroze during the evening, resulting in patches of glare ice and very hazardous conditions since the ice was difficult to distinguish from clear pavement. Use extreme caution if you are traveling overnight. Be prepared for the possibility of encountering icy pavement, especially in urban areas where ice melting agents were used to try and clear the roads. Drive at a safe speed, and be sure to maintain adequate distance between your vehicle and others on the road. Skowronski
The national radar mosaic for the moment the first event began.
10 cold/wind chill. Local standard time, as filed.
Low temperatures fell to -15 to -30 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -46 degrees.
Low temperatures fell to -15 to -30 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -41 degrees.
Low temperatures fell to -15 to -30 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -43 degrees.
Low temperatures fell to -15 to -30 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -45 degrees.
Low temperatures fell to -15 to -30 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -43 degrees.
Low temperatures fell to -15 to -30 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -44 degrees.
Low temperatures fell to -10 to -20 degrees during the morning of February 7th. The combination of the bitter cold and winds of 5 to 10 mph created wind chills of -35 to -41 degrees.
Low temperatures fell to -10 to -20 degrees during the morning of February 7th. The combination of the bitter cold and light winds created wind chills of -35 to -38 degrees.
Low temperatures fell to -10 to -20 degrees during the morning of February 7th. The combination of the bitter cold and winds around 10 mph created wind chills of -35 to -38 degrees.
Low temperatures fell to -10 to -20 degrees during the morning of February 7th. The combination of the bitter cold and winds of 5 to 10 mph created wind chills of -35 to -38 degrees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2021Every state in 2021This day in weather historyWarnings in Wisconsin, February 2021
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 2026-09-24. Each event’s entry at NCEI: 935906, 935925, 935905, 935907, 935917, 935922, 935927, 935939, 935938, 935930.