HydroClim Minnesota for Early December 2020

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 8, 2020


What happened in November 2020:

  • November 2020 was a somewhat dry month. The exceptions were in the southeast and in a line from St. Cloud to Duluth. Overall, precipitation fell a bit short. The statewide preliminary precipitation total was 1.41 inches or .20 inches below normal. The direst locations were in northwest Minnesota with some monthly totals around a tenth of an inch. The wettest locations were in southeast Minnesota with Rochester finishing with 2.52 inches or .61 inches above normal.
    [see: November 2020 Preliminary Precipitation Total Map  | November 2020 Precipitation Departure Map  | November 2020 Climate Summary Table  |  November 2020 Percent of Normal Precipitation Map]
  • There was one significant precipitation event in November:
  • Within 36 hours of an amazing warm spell in early November, old man winter returned with a compact and fast-moving winter storm. Freezing rain struck southeast Minnesota, while a wide swath across southwest, central and northeast Minnesota saw four to eight inches of snow. [see: Winter Storm, November 10, 2020]
  • November temperatures were well above normal. The preliminary statewide average is 33.9 degrees, six degrees above normal and tied for the 12th warmest November on record. Last November the departure was 1.9 degrees below normal. The coldest reading for November 2020 was -2F at Camp Norris on the 13th. The warmest high temperature reading was 84 degrees at Granite Falls in west central Minnesota on November 4. This tied the all-time highest November temperature for Minnesota. [see: Record Warmth in November  |  November 2020 Climate Summary Table  |  2020 November Departure from Normal Temperature Map]

Where we stand now:

  • As of December 8, 2020 there is a scant snow cover across the state. What snow cover exists is confined to northeast Minnesota, with only two to six inches on the ground away from Lake Superior.
    [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 November 3, depicts three-quarters of Minnesota with some level of drought designation. Last year at this time the state was free of any drought. On December 3, 2020 about 66% of the state was Abnormally Dry, and 11% of the state in Moderate Drought conditions. A small area in Rock County in southwest Minnesota had Severe Droughtconditions. 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, especially across the central and north. Where there is some open water the U.S. Geological Survey reports that stream discharge values are above normal to much above normal across central and southern Minnesota.
    [see: USGS Stream Flow Conditions]
  • On December 8 the level of Mille Lacs was slightly above the median for the date and has been above the median since May 2018. Mille Lacs has fallen about a foot since December 2019. The approximate date of lake ice in for Mille Lacs was December 3. The level on Lake Minnetonka on December 3 was 928.51 feet and the Grays Bay Dam closed on October 19. White Bear Lake was at 924.14 feet on December 8. The current level of White Bear Lake is .93 foot lower than in early December 2019. The highest level White Bear Lake reached since the lake began rising in 2013 was 925.41ft on July 5, 2019. The level of Rainy Lake continues to be in the median range and Lake of the Woods continues to be below the median range for early December. Lake Superior was at 602.62 feet on December 4, eleven inches higher than the monthly average for early December and four inches lower than the same date in 2019.
    [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 30 reports that topsoil moisture across Minnesota is 2 percent Very Short, 11 percent Short, 83 percent Adequate, and 4 percent Surplus. Corn for grain harvest was 99% completed by November 22 compared in 2019 when the corn harvest was 93% complete on December 9. Soil moisture levels at Lamberton was near the historical median for the last report in early November.
    [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)]
  • Soils experienced some freeze-thaw cycles for the top few inches in November, especially for areas of bare ground. Most places have little or no frost in the ground under sod on December 8. Soil temperatures at four 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 8, 2020 is currently rated by DNR Forestry as Moderate across southeast Minnesota, and Low over the rest of the state. 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 all of Minnesota and the Upper Midwest pegged to have a fairly strong tendency for below normal precipitation.
    [see: Climate Prediction Center 30-day Outlook  |  December Precipitation Normal Map]
  • The December temperature trend (according to the Climate Prediction center has a fairly strong tendency for above normal temperatures statewide. 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 a tendency for below normal temperatures over the north and west central and equal chances for above, near normal and below normal temperatures . The 90-day precipitation outlook for December through February indicates a tendency for above normal precipitation. Because the December outlooks leans warm and dry, the cool and wet part of the winter is weighted for January and February.
    [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 2020 has seen some wild swings of temperatures, from record cold in October and record warmth in November. Some small lakes had ice form on them in late October, only to have the ice cover thaw in early November. With the return of cooler air in lake November, many small and medium lakes in the state froze over from November 30 to Dec 3.
    [see: Median Lake Ice in Dates]

Upcoming dates of note:

  • December 17: National Weather Service releases 30/90 day temperature and precipitation outlooks

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Pete Boulay, DNR Climatologist