HydroClim Minnesota - December 2009

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

State Climatology Office - DNR Waters
compiled 12/8/2009 (distributed one day early)

What happened in November:

November 2009 precipitation was quite light across most of Minnesota. Monthly precipitation totals fell short of historical averages by one-half inch to one and one-half inches in most locales. November snowfall totals were very small or nonexistent. For some communities, November 2009 ranked among the least snowiest November on record.
[see: November 2009 Climate Summary Table]
In contrast to a very cold October, monthly mean temperatures for November 2009 were quite mild. November mean temperatures across Minnesota ranged from nine to twelve degrees above historical averages, making November 2009 the third warmest November in history on a statewide basis. The statewide October 2009 mean monthly temperature was only 1.5 degrees warmer than the statewide November 2009 mean monthly temperature, whereas the long-term normals are separated by 15 degrees. Numerous warmest daily minimum temperature records were set during the month. Extreme temperature values for November ranged from a high of 72 degrees at Canby (Yellow Medicine County) on the 6th, to a low of 9 degrees in Embarrass (St. Louis County) on the 21st and 22nd.
[see: November 2009 Climate Summary Table | Warm November 2009]

Where we stand now:

If today's weather forecasts verify, the snow depth map to be prepared on Thursday, December 10 will depict four or more inches of snow on the ground in southern and eastern Minnesota. As of this writing, the northern tier of Minnesota counties report a snow cover of two to six inches.
[see: Snow Depth Maps]
The U. S. Drought Monitor, released on December 3, reflects long-term precipitation deficits in a few Minnesota counties. A small area of east central Minnesota remains in the Moderate drought category due to lingering precipitation shortfalls that extend back to early-summer 2008. Portions of north central and northeast Minnesota are categorized as Abnormally Dry, as that area rebounds from a very dry 2009 growing season. Most of Minnesota is without drought designation. 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: U.S. Drought Monitor]
The U.S. Geological Survey reports that stream discharge values (where winter monitoring is possible) for many Minnesota streams are near the middle of the historical distribution for this time of year. However, the Red River and many of its tributaries report above-median flows in response to heavy rains that fell during the autumn. Some monitoring locations along the Minnesota River also report high than median stream flow.
[see: USGS Streamflow]
The Lake Superior water level is up four inches from last year but remains somewhat below the long-term average. Water levels on many Minnesota lakes and wetlands rose markedly due to the heavy October precipitation. However, water levels on some larger lakes and wetlands complexes in east central Minnesota lakes remain very low. White Bear Lake, on the Ramsey/Washington county border, is near its all-time record low level.
[see: Corps of Engineers Great Lakes Water Levels | White Bear Lake Water Level]
The Minnesota Agricultural Statistics Service reports that as of December 6, topsoil moisture was 0% Very Short, 2% Short, 70% Adequate, and 28% Surplus. The heavy October rains amply recharged the soil moisture profile across Minnesota. This greatly improved forestry, horticultural, and agricultural prospects for the early 2010 growing season. However, the saturated topsoils also led to inconvenience and high costs for the agricultural community. Over 10% of Minnesota's corn crop was yet to be harvested as of December 6.
[see: Agricultural Statistics Service Crop Progress and Condition]
A very warm November delayed the onset of frozen soils. Cold temperatures during early December has led to some soil freezing. Frost depths under sod range from one to six inches across Minnesota.
[see: Corps of Engineers Snow, Ice, Frost Data | MnDOT Road Frost Depths | National Weather Service Frost Depth Data]
Many of Minnesota's lakes are now ice covered. Cold temperatures in early December, light winds, and little snow cover, created suitable ice-making conditions. However, the ice formation season was delayed due to the warm November temperatures and the ice is unseasonably thin. As always, please remember that ice conditions are highly variable and those venturing onto water bodies should utilize caution and common sense.
[see: DNR Conservation Officer Reports]

Future prospects:

The December precipitation outlook indicates no significant tendencies away from climatological probabilities across Minnesota. December precipitation normals range from around one-half inch in western Minnesota to over one and one-quarter inches in eastern sections of the state. The median snow cover at the end of December ranges from over 10 inches on the ground in northeastern Minnesota (20 inches in the Lake Superior highlands), to under 5 inches in southwestern counties.
[see: Climate Prediction Center 30-day Outlook | December Precipitation Normal Map]
The December temperature outlook shows no significant tendencies away from climatological probabilities. Normal December high temperatures are in the mid 20s to near 30 to start the month, dropping to the mid-teens to near 20 by month's end. Normal lows are around 10 degrees early in the month, falling to the mid-single digits above and below zero by late December.
[see: Climate Prediction Center 30-day Outlook | December Temperature Normal Map]
The 90-day precipitation outlook for December through February shows no significant tendencies away from climatological probabilities. The December through February temperature projection indicates a strong tendency towards above-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 are part of the National Weather Service's Advanced Hydrologic Prediction Service (AHPS).
[see: National Weather Service River Forecast Center]

From the author:

A note of concern from the author ... saturated soils in the upper reaches of the Red River basin along with high early-winter stream base flows create the possibility of spring flooding along the Red River and its tributaries in 2010. A recent tour of northern Wilken County showed thousands of acres of unharvested row crops, pooled water on the fields, and a substantial amount of water in the ditches.

Notes from around the state:

None

Upcoming dates of note:

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

Web sites featured in this edition:

http://climate.umn.edu - Minnesota Climatology Working Group, Minnesota DNR Waters and U of M Dept. of Soil, Water, and Climate
http://www.drought.unl.edu - National Drought Mitigation Center
http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey
http://www.lre.usace.army.mil - US Army Corps of Engineers, Detroit District
http://mndnr.gov/waters - Minnesota Department of Natural Resources, Division of Waters
http://www.nass.usda.gov - USDA, National Agricultural Statistics Service
http://www.mvp-wc.usace.army.mil - US Army Corps of Engineers, St. Paul District
http://www.dot.state.mn.us/materials - Minnesota Department of Transportation, Materials Engineering and Testing
http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center
http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center

Acknowledgements

None

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