HydroClim Minnesota - December 2010

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: December 7, 2010 (released one day early)

What happened in November:

November 2010 precipitation totals were varied across Minnesota. Precipitation in southwestern and west central Minnesota was roughly one inch below average for the month; whereas monthly precipitation totals in south central, southeastern, north central, and northeastern Minnesota topped the average by approximately one-half inch. Monthly snowfall totals topped 24 inches in communities such as International Falls and Duluth, placing the month as one of the snowiest Novembers on record in those locations.
[see: November 2010 Climate Summary Table | November Precipitation Departure from Normal]
Much of November's precipitation came in the form of snow. An early-winter storm dropped six to ten inches of wet snow on November 13-14 along a narrow band that extended from south central Minnesota, through the Twin Cities, through Duluth, and along the North Shore. It was the largest pre-Thanksgiving snowfall for the Twin Cities in 19 years. The month concluded with another major winter storm. Six to twelve inches of snow fell over large sections of Minnesota from November 29 through December 1.
[see: November Weather Recap | Heavy Snow: November 13-14 | Winter Storm: November 29-30]
Monthly mean temperatures for November 2010 were somewhat above average across Minnesota, topping the historical mean by one to three degrees. Very warm early-November temperatures were somewhat offset by colder-than-average temperatures later in the month. Extreme temperature values for November ranged from a high of 76 degrees at Blue Earth (Faribault County) on the 9th, to a low of -13 degrees at Sabin (Clay County) on the 23rd. Many records were set on November 9 and 10 when temperatures climbed into the 60s in numerous locations.
[see: November 2010 Climate Summary Table]

Where we stand now:

Most Minnesota communities report four or more inches of snow cover at this time. Snow depths across northern Minnesota are greater than eight inches. In a few north central and northeastern Minnesota locales, snow depth exceeds 16 inches. For much of Minnesota, snow depths are greater than the median for the date.
[see: NWS Snow Depth Estimation Map | Snow Depth Maps]
The U. S. Drought Monitor, released on December 2, depicts most of Cook County and portions of Lake County as undergoing Moderate drought. Other northeastern Minnesota areas are considered to be Abnormally Dry. Heavy rain and snow in this area during the autumn and early winter improved the situation significantly, but did not completely erase the impacts of long-term precipitation deficits. Although the U.S. Drought Monitor no longer depicts drought in east central Minnesota, some hydrologic systems in this area remain impacted by long-term dryness that began in June of 2008. This long-term precipitation anomaly is responsible for low water levels in larger lakes and wetland complexes across Anoka, Ramsey, Chisago, and Washington counties. The remainder 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) at many river monitoring locations across Minnesota are near all-time highs for the date. Conversely, stream discharge values in northern Lake County rivers remain low due to long-term precipitation deficits.
[see: USGS Streamflow]
The Lake Superior water level is down nine inches from last year at this time and down 11 inches from the long-term December average. Water levels on a few larger lakes in east central Minnesota lakes remain very low. White Bear Lake, on the Ramsey/Washington county border is at an all-time record low level mark.
[see: Corps of Engineers Great Lakes Water Levels | White Bear Lake Water Level]
As of November 14, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 0% Very Short, 1% Short, 78% Adequate, and 21% Surplus. With most soils now frozen, late-autumn conditions will act as a predictor of the soil moisture situation entering the 2011 growing season.
[see: Agricultural Statistics Service Crop Progress and Condition]
The upper layer of the soil profile is frozen in most Minnesota locales. However, snow cover has inhibited frost penetration despite the cold early-December temperatures. Frost depths under sod range from one to ten inches across Minnesota.
[see: Corps of Engineers Snow, Ice, Frost Data | MnDOT Road Frost Depths | National Weather Service Frost Depth Data]
Most of Minnesota's lakes and rivers are ice covered. Cold temperatures in early December accelerated ice development. However, ice formation is hindered in many locations by snow cover. Ice conditions are highly variable. Lake and river ice is never completely safe for walking or driving.
[see: DNR Conservation Officer Reports]

Future prospects:

The December precipitation outlook depicts no significant tendencies away from historical 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 under 5 inches in southwestern counties, to over 10 inches on the ground in northeastern Minnesota (20 inches in the Lake Superior highlands).
[see: Climate Prediction Center 30-day Outlook | December Precipitation Normal Map]
The December temperature outlook indicates no significant tendencies away from historical climatological probabilities across Minnesota. 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 historical climatological probabilities across Minnesota. The December through February temperature projection tilts towards below-normal conditions in the northern one-half of Minnesota and equal chances of below, near, or above-normal conditions in southern Minnesota.
[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 North Central River Forecast Center]

From the author:

A note of concern from the author ... saturated soils in the Red River basin along with high winter stream base flows enhance the possibility of spring flooding along the Red River and its tributaries in 2011.

Notes from around the state:

None

Upcoming dates of note:

December 16: 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://water.weather.gov/ahps - National Weather Service, Advanced Hydrologic Prediction Service
http://www.nohrsc.noaa.gov - National Weather Service, National Operational Hydrologic Remote Sensing Center
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 Ecological and Water Resources
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 and Road Research
http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center
http://mndnr.gov/enforcement - Minnesota Department of Natural Resources, Division of Enforcement
http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center

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