HydroClim Minnesota for Early December 2021

A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the first Thursday of the month.

State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: December 9, 2021


What happened in November 2021:

  • November 2021 was a fairly dry month across the state, with some notable exceptions. The rain and snow event from November 10-13 brought a November months’ worth of precipitation and then some across northern Minnesota. Some places along the North Shore saw three inches of precipitation from this event. The highest November precipitation total found so far is 4.09 inches or 2.28 inches above normal at Grand Marias. The statewide preliminary precipitation total was 1.17 inches or .32 inches below normal. The direst locations were in southwest Minnesota with some monthly totals less than a half an inch.
    [see: November 2021 Preliminary Precipitation Total Map  | November 2021 Precipitation Departure Map  | November 2021 Climate Summary Table  |  November 2021 Percent of Normal Precipitation Map]
  • There was one significant precipitation event in November:
  • A developing area of low pressure moved east from South Dakota to the Twin Cities on November 10 and 11, bringing with it rain and snow. Strong winds blowing inland along the North Shore caused lake enhanced precipitation and street flooding in Grand Marias from large waves on Lake Superior. The entire state saw precipitation, but it was heaviest in the north where one to three inches of precipitation fell. The first significant snow of the season fell as well with one to four inches of snow across the north, with some higher totals south of International Falls. The precipitation was welcome in the areas seeing deficits from the ongoing drought. [see: Last week’s rain/snow event helped alleviate drought]
  • November temperatures continued the streak of above normal temperatures. The preliminary statewide average is 33.4 degrees, 2.5 degrees above normal. The coldest reading for November 2021 was -13F at Camp Norris on the 25th. The warmest high temperature reading was 74 degrees at Granite Falls in west central Minnesota on November 6. [see: November 2021 Climate Summary Table  |  2021 November Departure from Normal Temperature Map]

Where we stand now:

  • As of December 9, 2021 there is four to eight inches of snowpack over northern Minnesota, with a foot or more inland from Lake Superior. There is one to four inches across the central Minnnesota, and around an inch or less on the ground in the south.
    [see: NWS Snow Depth Estimation Map | Midwest Regional Climate Center Snow Depth Map| MNDNR Snow Depth Maps]
  • The U. S. Drought Monitor map released on December 7, depicts 72% of Minnesota with some level of drought designation. About 23% of the state was Abnormally Dry, 22% of the state was in Moderate Drought conditions. Severe Drought is over 35% of the state confined in north central and northeast Minnesota. Extreme Drought has been reduced to just over 1% of the state in northern Lake and Cook Counties. This is quite an improvement since three months ago, when Extreme Drought covered 31% of the state on September 7. The U.S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc.) are based on several indicators.
    [see: Drought Conditions Overview]
  • Ice is affecting many streams across Minnesota. Where there is some open water the U.S. Geological Survey reports that stream discharge values are much below in the northeast to much above normal in the west central.
    [see: USGS Stream Flow Conditions]
  • On December 9 the level of Mille Lacs was about a half foot below the median for the date and has been below the median since June 2021. Mille Lacs has fallen about a foot since December 2020. The approximate date of lake ice in for Mille Lacs was December 7. The level on Lake Minnetonka on December 9 was 927.97 feet, .54 feet lower than this time last year and the Grays Bay Dam closed on July 21. White Bear Lake was at 923.11 feet on December 9. The current level of White Bear Lake is 1.03 feet lower than in early December 2020. The approximate lake ice in for White Bear is December 7. The highest level White Bear Lake reached since the lake began rising in 2013 was 925.41 feet on July 5, 2019. Rainy Lake had quite a rebound over the last two months and is currently on the high end of the median range. Lake of the Woods has also improved over the past two months and in early December is just below the median range. Lake Superior continues to fall and had a forecasted level of 601.41 feet on December 3, four inches lower than the long term median and 1.21 feet lower than early December 2020.
    [see: Mille Lacs Lake Water Level  |  Lake Minnetonka Water Level  |  White Bear Lake Water Level  |  Lake of the Woods Control Board Basin Data  |  Corps of Engineers Great Lakes Water Levels]
  • The Agricultural Statistics Service on November 29 reported that topsoil moisture across Minnesota is 2 percent Very Short, 11 percent Short, 80 percent Adequate, and 7 percent Surplus. Corn for grain harvest was 97% completed by November 14. Five days ahead of 2020 and fifteen days ahead of the five year average. Soil moisture levels at Lamberton on November 15 had fully recovered from the drought and are showing about a two inch surplus.
    [see: Agricultural Statistics Service Crop Progress and Condition  |  U. of M. Southwest Research and Outreach Center (Lamberton)  |  U. of M. Southern Research and Outreach Center (Waseca)]
  • On December 9, the top few inches of the soil is frozen over central Minnesota, while there is still thin frost over the south. The Twin Cities Metro area has from 4-8 inches of frost and Duluth is around a foot. Soil temperatures at six inches under sod are in the low to mid 30’s.
    [see: National Weather Service Frost Depth Data | National Weather Service Soil Temperature Data
  • The potential for wildfires on December 9, 2021 is currently rated by DNR Forestry as Low across Minnesota. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
    [see: Fire Danger Rating Map]

Future prospects:

  • The December precipitation outlook that was released on November 30 has most of Minnesota with equal chances of above, below and normal precipitation. The exception is the far northeast that tilts into the above normal category.
    [see: Climate Prediction Center 30-day Outlook  |  December Precipitation Normal Map]
  • The December temperature trend (according to the Climate Prediction Center) has a tendency for above normal temperatures in the south, with equal chances across the rest of the state. Normal December high temperatures are in the upper 20's to low 30's to start the month, dropping to the low to mid 20's by month's end. Normal lows are in the teens early in the month, falling to single digits by late December.
    [see: Climate Prediction Center 30-day Outlook  | December Temperature Normal Map]
  • The 90-day temperature outlook for December through February shows equal chances for above, near normal and below normal temperatures across all the far northeast and south east, where there is a slight tilt for above normal temperatures. The 90-day precipitation outlook for December through February indicates a tendency for above normal precipitation in eastern Minnesota with equal chances for the rest of the state.
    [see: Climate Prediction Center 90-day Outlook]
  • The National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. These products address both high flow and low flow probabilities.
    [see: National Weather Service - North Central River Forecast Center]

From the author:

  • The Autumn of 2021 was very warm. The preliminary statewide average temperature from September-November was 48.3 degrees or 3.8 degrees above the 1990-2020 mean. This was enough for the autumn of 2021 to finish fifth warmest, and was the warmest autumn since 2016.
  • With arctic air sweeping across the state on December 7, many lakes in the state were in the process of freezing over. [see: Median Lake Ice in Dates]

Upcoming dates of note:

  • December 16: National Weather Service releases 30/90 day temperature and precipitation outlooks

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Pete Boulay, DNR Climatologist