HydroClim Minnesota - March 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: March 2, 2011 (early release)

What happened in February 2011:

February 2011 precipitation totals were above historical averages in the southern two-thirds of Minnesota, below average in the northern one-third of the state. The bulk of the monthly precipitation in the southern two-thirds of Minnesota was dropped by a major winter storm that roared through the Midwest on February 20-21.
[see: February 2011 Climate Summary Table]
A large and intense winter storm on February 20-21 blanketed much of the southern two-thirds of Minnesota with over ten inches of snow. In many locations, storm snowfall totals broke daily records for the month of February. Some of the heaviest amounts included 20 inches in Madison (Lac Qui Parle County), 16 inches in Montevideo, and 15 to 19 inches across southern portions of the Twin Cities metropolitan area. The storm's snowfall contained a high amount of water content, worsening the potential for spring flooding. Liquid precipitation totals of one to two inches were reported in many communities. This is two to three times MONTHLY February normal precipitation values.
[see: Record Snowfall - February 20-21]
Monthly mean temperatures for February 2011 were below average across Minnesota, falling short of the historical mean by one to five degrees. A mid-February thaw was more than offset by cold temperatures early and late in the month. Extreme temperature values for February ranged from a high of 62 degrees F at the Wolf Ridge Environmental Learning Center (Lake County) on the 16th, to a low of -39 degrees F at Embarrass (St. Louis County) on the 11th. The maximum temperature at Hibbing on February 16 was 60 degrees, the warmest February temperature ever recorded in that community.
[see: February 2011 Climate Summary Table]

Where we stand now:

Most Minnesota counties report more than 12 inches of snow cover as of this writing. Snow depths for large sections of western and northern Minnesota exceed 18 inches. In most Minnesota locales, present snow depths rank at or above the historical median for the date. For much of west central and southwest Minnesota, present snow depths rank historically above the 95th percentile (1-in-20 year occurrence) for early March.
[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 Minnesota locations report snow water equivalence values of three to five inches, with some six-inch values reported in western Minnesota.
[see: NWS Observed Snow Water Equivalence Map]
The U. S. Drought Monitor, released on February 24, 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 above the 90th percentile for the date.
[see: USGS Streamflow]
The Lake Superior water level is down nine inches from last year at this time and down 15 inches from the long-term seasonal average. Water levels on a few larger lakes in east central Minnesota lakes remain very low. White Bear Lake (Ramsey/Washington county border) water levels are up somewhat after reaching an all-time record low level mark in November 2010.
[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 none to thirty inches, however frost depth under sod in most locations is less than 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. Historically, ice leaves Minnesota/Iowa border lakes around April 1. The average ice-out date for Minnesota/Canada border lakes is in late April to early May.
[see: DNR Conservation Officer Reports]

Future prospects:

The March precipitation outlook shows no significant tendencies away from climatological probabilities, except in far-northwest Minnesota where the outlook leans towards above-normal conditions. Historically, average March precipitation totals range from near three quarters of an inch in northwestern Minnesota to around two inches in southern sections of the state. March is a transition month when cold, dry continental air masses are gradually replaced by warmer, moister air on a more frequent basis. This is demonstrated by the fact that March's normal precipitation is 50 percent higher than February's normal precipitation, the greatest percentage increase between any two successive months.
[see: Climate Prediction Center 30-day Outlook | March Precipitation Normal Map]
The March temperature outlook is weighted in favor of below-normal conditions across the state. Normal March high temperatures climb from the upper 20s early in the month to the low to mid-40s by month's end. Normal March lows begin the month in the single digits above zero in the far north and mid-teens in the south. By late March, normal lows are in the low 20s in the north, near 30 in the south.
[see: Climate Prediction Center 30-day Outlook | March Temperature Normal Map]
The 90-day precipitation outlook for March through May indicates no significant tendencies away from historical climatological probabilities across Minnesota. The March through May 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 from an extraordinarily wet autumn, 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, especially in the Red River basin and forecast points in the vicinity of the Twin Cities. 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). The next probabilistic spring flood outlooks will be released March 4.
[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:

March 4: National Weather Service releases next round of probabilistic spring flood outlooks
March 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 Eco/Water Resources and U of M Dept. of Soil, Water, and Climate
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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