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 4, 2018
What happened in December 2017:
- December appeared to be another month where the average monthly temperature would wind up above normal. The last week of the month saw the mercury plunge and the end result was a month that wound up below normal for most locations in Minnesota. It was another dry month overall with the average statewide precipitation only .61 inches for the month or a .39 departure from normal. The exceptions to the dryness was in the north, where there were enough snowfall events to boost the monthly total to .35 inches above normal at International Falls. Despite both November and December finishing below normal, the 2017 Minnesota annual preliminary precipitation total was 2.06 inches above normal or 31.93 inches. 2016 was much wetter with 33.54 inches.
[see: December 2017 Preliminary Precipitation Total Map | December 2017 Precipitation Departure Map | December 2017 Climate Summary Table | December 2017 Percent of Normal Precipitation Map] - Minnesota teetered on the edge of winter in December 2017 with the farther north and east one traveled in the state, the more winter there was to find. The first significant weather event of December 2017 was an intensifying low pressure area on December 4 that had temperatures in the 50's ahead of the system and 20's behind it. In the wake of this storm was the start of the continuous snow-cover season for the state. Mild air then returned for the central and south, with a series of light snowfalls and closer to normal temperatures in the north.
[see: Winter Returns: Dec 4-5, 2017 - The average monthly temperature for December finished below normal, but the month didn't start out that way. For the first 24 days of December, the average temperature was 22.1 degrees F or 4.8 degrees F above normal. The final seven days had an average of -7.2 degrees F or 20 degrees below normal. This was enough to offset the previous three weeks and December 2017 wound up being 15.5 degrees or .9 degrees F short of normal. Extremes for December ranged from 64 degrees F at Rochester on December 4 to -45 degrees F at Embarrass on December 31. This is a monthly temperature spread of 109 degrees, a relatively uncommon occurrence.
[see: December 2017 Climate Summary Table | 2017 December Departure from Normal Temperature Map | Arctic Air: December 25-31, 2017]
Where we stand now:
- Snow depths across Minnesota range from as little as an inch in the counties along and north of the Minnesota River, to nearly a foot in north central and northeast Minnesota. The Lake Superior Highlands has the most snow on the ground, with over a foot in parts of Lake and Cook Counties. Snow depths are near or slightly below historical medians for the date in the northern one-third of Minnesota. Snow cover is below the historical median for the date in many southern and central Minnesota counties. Season snowfall to date lags far behind normal for cities such as St. Cloud, Rochester and the Twin Cities.
[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 4 depicts parts of north central, northwest and southwest Minnesota in Abnormally Dry conditions. There is a small area confined to Koochiching County that has Moderate Drought. 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 at to 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] - In their final report of the 2017 growing season (November 27), the Agricultural Statistics Service reported that topsoil moisture across Minnesota was 0 percent Very Short, 3 percent Short, 85 percent Adequate, and 12 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)] - Soil frost depths under sod are near average for early January, ranging from a about a foot to nearly two feet at most Minnesota observing locations.
[see: National Weather Service Frost Depth Data | MnDOT Road Frost Depths | University of Minnesota - St. Paul Campus Soil Temperatures Under Sod] - The progress for ice in this season was a real challenge, with a number of lakes freezing up in November and then thawing out and then refreezing again. Some of the northern lakes that froze in November stayed frozen through the warm spell. Most lakes that were still open became ice covered by the middle of December. There were some earlier than the median ice in dates in the north but for the central and south ice in about a week later than the median. The arctic temperatures came in time at the end of 2017 and the beginning of 2018 for the ice blocks to be harvested out of Green Lake in Kandiyohi County for the St. Paul Winter Carnival Ice Palace. The blocks that were harvested were 16 inches thick on January 3. Lake and river ice is never completely safe.
[see: DNR Conservation Officer Reports | 2017 Ice-In Dates] | Median Lake Ice-In Dates]
Future prospects:
- The January precipitation outlook notes a tendency for below-normal conditions in Minnesota. 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 leans towards below normal conditions across Minnesota. 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 | January Temperature Normal Map] - The 90-day precipitation outlook for January through March indicates a slight tendency for above normal conditions across all be the southwest part of the state. The January through March temperature projection indicates a tilt towards below-normal temperatures.
[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:
- none
Upcoming dates of note:
- January 18: National Weather Service releases 30/90 day temperature and precipitation outlooks
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Pete Boulay, DNR Climatologist