HydroClim Minnesota - February 2011

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
prepared: February 2, 2011 (early release)

What happened in January 2011:

January 2011 precipitation totals were near, to somewhat above, historical averages in nearly all Minnesota counties. While January 2011 was not newsworthy for major winter storms, it was notable for a very large number of snowfall events. An active weather pattern, moving storm systems rapidly from northwest to southeast through the state, produced many small to moderate snowstorms with relatively light water content. For example, the Twin Cities reported only four days during January without at least a trace of snowfall. Duluth, International Falls, Rochester, Fargo/Moorhead had only five snow-free days. Communities with above-average monthly snowfall totals during January included: Tower (32.1 inches), Pipestone (28.7 inches), Fairmont (24.0 inches), and Amboy (22.0 inches). Numerous locations received over 16 inches of snow for the month.
[see: January 2011 Climate Summary Table | January Precipitation Departure from Normal]
Monthly mean temperatures for January 2011 were below average across Minnesota, falling short of the historical average by two to five degrees. Extreme temperature values for January ranged from a high of 39 degrees F at Browns Valley on the 28th, to a low of -46 degrees F at International Falls and Babbitt on the 21st. The -46 degree F temperature at International Falls was a local record for the date and the coldest temperature recorded in that community in over 40 years. Statewide, the temperature stayed below freezing for nearly the entire month. For many communities, the temperature never reached 32 degrees F once during January. The enduring below-freezing temperatures led to very little melting of the snow pack. Persistently heavy snow loads on roofs led to some structural failures.
[see: January 2011 Climate Summary Table | Extreme Cold: January 20-21]

Where we stand now:

Many Minnesota counties report more than 16 inches of snow cover as of this writing. Snow depths for portions of west central Minnesota, and all of northeastern Minnesota, exceed 24 inches. The least amount of snow cover is found in east central Minnesota and the southern tier of Minnesota counties where snow depths range from 8 to 12 inches. In nearly all Minnesota locales, snow depths are at or above the median for the date. For numerous locations, snow depths rank in the top 20th percentile.
[see: NWS Snow Depth Estimation Map | Weekly Snow Depth Maps]
The liquid content of the snowpack is very high for this time of year. Most locations report snow water equivalence values of three to five inches, with a few reports approaching six inches.
[see: NWS Snow Water Equivalence Map]
The U. S. Drought Monitor, released on January 27, 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 winter has improved the situation significantly. 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 eight inches from last year at this time and down 14 inches from the long-term seasonal average. Other than some near-shore ice, Lake Superior is mostly open water at this time. 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 mid-November, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 0% Very Short, 1% Short, 78% Adequate, and 21% Surplus. Late-autumn reports are a good measure of the present soil moisture situation and an indicator of the soil moisture status entering the coming growing season.
[see: Agricultural Statistics Service Crop Progress and Condition]
The upper layer of the soil profile is frozen throughout Minnesota. Early and abundant snow cover has inhibited frost penetration despite cold winter temperatures. Frost depths under sod range from near-zero to thirty inches, however frost depth under sod in most locations is roughly 12 inches. This is shallower than average for this time of year and some observers report that the frost is unconsolidated.
[see: Corps of Engineers Snow, Ice, Frost Data | National Weather Service Frost Depth Data | MnDOT Road Frost Depths]
Minnesota's lakes and rivers are ice covered. Ice formation was hindered by early and abundant winter snow cover. Slushy conditions are found on some water bodies. Lake and river ice is never completely safe for walking or driving.
[see: DNR Conservation Officer Reports]

Future prospects:

The February precipitation outlook leans towards above-normal conditions in most Minnesota locations, however the monthly precipitation outlook for southwestern Minnesota shows no significant tendencies away from climatological probabilities. Historically, February is Minnesota's driest month with precipitation normals ranging from near one-half inch in northwestern Minnesota to just over one inch in far eastern sections of the state. The median snow depth at the end of February ranges from under 5 inches in southwest Minnesota to over 18 inches on the ground in northeastern Minnesota (greater than 30 inches in the Lake Superior highlands).
[see: Climate Prediction Center 30-day Outlook | February Precipitation Normal Map]
The February temperature outlook is weighted in favor of below-normal conditions across the state, especially in northern Minnesota. Normal February high temperatures range from the low-teens in the north to near 20 in the south early in the month, climbing to the mid-20s to low 30s by month's end. Normal February low temperatures range from near minus 10 degrees in the far north to the single digits above zero in southern Minnesota early in the month; ascending to the low single digits in the north, mid-teens in the south by the end of February.
[see: Climate Prediction Center 30-day Outlook | February Temperature Normal Map]
The 90-day precipitation outlook for February through April indicates no significant tendencies away from historical climatological probabilities across Minnesota. The February through April temperature projection tilts towards below-normal conditions throughout Minnesota.
[see: Climate Prediction Center 90-day Outlook]
There are several factors pointing towards major spring flooding for many of Minnesota's rivers and streams. Saturated soils, abundant snow cover, and high winter stream base flows combine to produce a high risk scenario. Projections for many Minnesota river communities indicate a greater than 60 percent probability of major flooding. The probability of major flooding exceeds 80 percent at some locations and the possibility of record flooding exists for some locales. The National Weather Service produces long-range probabilistic river stage and discharge outlooks. These products are part of the National Weather Service's Advanced Hydrologic Prediction Service (AHPS).
[see: Spring Flood Outlook | National Weather Service North Central River Forecast Center]

From the author:

None

Notes from around the state:

None

Upcoming dates of note:

February 17: National Weather Service releases 30/90 day temperature and precipitation outlooks
February 17: National Weather Service releases next round of probabilistic spring flood outlooks

Web sites featured in this edition:

http://climate.umn.edu - Minnesota Climatology Working Group, Minnesota DNR Eco/Water Resources 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.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center
http://www.dot.state.mn.us/materials - Minnesota Department of Transportation, Materials and Road Research
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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