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: January 6, 2020
What happened in December 2019:
- December 2019 appeared to be on track to be a fairly dry month but a potent storm after Christmas tipped the scales. The preliminary average statewide precipitation total was 1.87 inches or .83 inches above normal. The wettest locations were in east central and northeast Minnesota with Wolf Ridge finishing with 4.91 inches or 3.34 inches above normal. Almost half of that total came at the end of the month. Rochester finished December 2019 with 1.19 inches or .04 inches below normal. However, the annual total for Rochester was 55.16 inches, a new annual record for Rochester and 22.14 inches above normal. The Twin Cities also saw a new record for annual precipitation with 43.17 inches, breaking the old record of 40.32 inches in 2016.
[see: December 2019 Preliminary Precipitation Total Map | December 2019 Precipitation Departure Map | December 2019 Climate Summary Table | December 2019 Percent of Normal Precipitation Map]
- December 2019 had two winter storm episodes of note for the month, one at the start of the month, the other at the end.
- December 1st saw the tail end of the Thanksgiving weekend storm. By Sunday December 1st snowfall accumulations of 8-16 inches were common across the northern half of Minnesota, with pockets of higher totals around Cloquet, Duluth, and just off the north shore of Lake Superior. This was Minnesota's first major Thanksgiving weekend winter storm since 1994.
[see: The 2019 Thanksgiving Weekend Winter Storm]
- A large winter storm over the weekend of December 28-29, brought icy conditions to much of Minnesota, followed by rain in the south and east, and heavy snow with strong winds in the north and west. The storm produced an inch of precipitation or so over almost all of Minnesota, but closer to two inches in isolated areas. The highest precipitation totals included 2.22 inches at the Wolf Ridge Environmental Learning Center, 2.17 inches near Breckenridge, and two inches at Melrose. Rain from the start of the storm on the 28th formed a glaze over roads and caused nearly 500 vehicle crashes on Minnesota with 43 injuries and two fatalities. The highest snowfall totals by the end of the storm included 13.5 inches at Climax and 13 inches at Bemidji.
[see: Ice Storm, Rain, and Blizzard: December 28-29, 2019]
- Just like December 2018, after two months of below normal temperatures, December 2019 was above normal with a preliminary 2.4 degree temperature departure. There was quite a seesaw in temperatures during the month, with below-zero low temperatures from the 10th to the 18th and then very mild conditions for the week before Christmas. The coldest temperature found in the state was -42 degrees F at Isabella in northeast Minnesota on December 18th and the warmest temperatures found was 50 degrees F at Caledonia on December 30 and also at Pokegama on the 23rd.
[see: December 2019 Climate Summary Table | 2019 December Departure from Normal Temperature Map]
Where we stand now:
- Snow depths vary greatly across the state. On January 5, snow cover is fairly thin across far southern Minnesota with just and inch or two. There is about 4-6 inches on the ground in the Twin Cities metro area. The snowpack deepens to a foot or more from Fargo to Duluth. This is some of the deeper snow depths found for early in January. Duluth had between 17 and 23 inches of snow on the ground for the whole month of December.
[see: Weekly Snow Depth and Ranking Maps | NWS Snow Depth Estimation Map | Midwest Regional Climate Center Snow Depth Map]
- The U. S. Drought Monitor map released on January 2 shows that the entire state is free of any drought designation. This has been the case since mid-September. 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]
- The U.S. Geological Survey reports that stream discharge values(where winter measurements are possible) are much above historical medians for the date on most Minnesota rivers. Most rivers and streams are now impacted by ice.
[see: USGS Stream Flow Conditions]
- On November 25, the Agricultural Statistics Service reported that topsoil moisture across Minnesota was 0 percent Very Short, 1 percent Short, 66 percent Adequate, and 33 percent Surplus.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research & Outreach Center (Lamberton) | U. of M. Southern Research & Outreach Center (Waseca)]
- The potential for wildfires is currently rated by DNR Forestry as Low across Minnesota.
[see: Fire Danger Rating Map]
- Soil frost depths under sod are shallow for early January, ranging from a about six inches or less at Minnesota observing locations in the south and central to twenty inches at Grand Forks.
[see: National Weather Service Frost Depth Data | MnDOT Road Frost Depths | University of Minnesota - St. Paul Campus Soil Temperatures Under Sod]
- Lake ice in started early due to the cold conditions in November, but mild conditions that followed caused some lakes to thaw and to refreeze again. Some lakes stayed frozen, others had multiple freeze-thaw dates. In general lakes first froze over for good during the first few days of December, close to historical averages. Mille Lacs froze over around December 2, which matches its median date. Lake and river ice is never completely safe.
[see: DNR Conservation Officer Reports | 2019 Ice-In Dates] | Median Lake Ice-In Dates]
- The January precipitation outlook has equal chances for above, below and normal precpitation. January precipitation normals range from near one-half inch of liquid equivalent in western Minnesota to just over one inch liquid in eastern sections of the state. The median snow cover at the end of January ranges from near five inches in southwest Minnesota, to over 15 inches on the ground in northeastern Minnesota (greater than 24 inches along the Lake Superior highlands).
[see: Climate Prediction Center 30-day Outlook | January Precipitation Normal Map]
- The January temperature outlook has equal chances for above, below and normal temperatures. Historically, January is Minnesota's coldest month. Normal January high temperatures range the low-teens in the north, to near 20 in the south. Normal January lows range from near minus 10 degrees in the far north, to the single digits above zero in southern Minnesota.
[see: Climate Prediction Center 30-day Outlook | Temperature Normals]
- The 90-day precipitation outlook for January through March indicates a fairly strong tendency for below normal temperatures and a tilt for above normal precipitation.
[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:
- Season snowfall for the 2019-20 winter through January 5 across much of the state is within six inches of historical averages. One of the snowier locations is Duluth with 56.8 inches or twenty inches above normal. International Falls is 3.4 inches short of normal. Season snowfall is about a foot above normal at Fargo. Many central and southern locations are near historical averages.
Upcoming dates of note:
- January 16: National Weather Service releases 30/90 day temperature and precipitation outlooks
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Pete Boulay, DNR Climatologist