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HydroClim Minnesota - March 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 3/3/2009 (early distribution)

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What happened in February:

• February 2009 precipitation totals were near, to somewhat above, historical averages across Minnesota. February precipitation was light in the southern three-quarters of Minnesota until a significant winter storm raced through the state on the 26th. That event brought four to eleven inches of snow to much of Minnesota and lifted monthly precipitation values to close to average.
  [see: February 2009 Climate Summary Table  |  Heavy Snow - February 26]
• Seasonal snowfall totals through February were near, to somewhat above, historical averages in most Minnesota locales. In the northern tier of Minnesota counties, seasonal snowfall totals were well above average. Persistent snowfalls throughout the winter in International Falls totaled 93 inches through March 2, nearly 41 inches above normal.
• Monthly mean temperatures for February 2009 were close to historical averages across Minnesota. Extreme temperature values for February ranged from a high of 53 degrees in various southwestern Minnesota stations on the 24th, to a low of -36 degrees in Babbitt (St. Louis County) on the 4th.
  [see: February 2009 Climate Summary Table]
• Temperatures for the meteorological winter (December through February) were three to six degrees below the historical average. It was the coldest meteorological winter since 2000-2001.

Where we stand now:

• The snow depth map prepared on February 27 shows that most of the southern one-third of Minnesota has one to eight inches of snow on the ground. Snow depths in the northern two-thirds of the state exceed eight inches. Sections of west central, north central, and northeastern Minnesota report more than 15 inches of snow cover. When compared with historical snow depths for the date, February 27 snow depths in some southwest and west central Minnesota counties ranked above the 80th percentile. Nearly all Minnesota locations were near or above the median for the date.
  [see: Snow Depth Maps]
• The U. S. Drought Monitor, released on February 26, classified some Minnesota counties in the D0 - Abnormally Dry category. Portions of east central and southeastern Minnesota were placed in the D1 - Moderate Drought classification. Precipitation during the last half of 2008 was five to eight inches short of average for many southeastern Minnesota communities. The U. S. Drought Monitor index is a blend of science and subjectivity where intensity categories are based on several indicators.
  [see: U.S. Drought Monitor]
• The U.S. Geological Survey reports that stream discharge values are high in the Red River basin. Stream flow measurements (where winter monitoring is possible) in the watershed are above the 90th percentile when compared with the historical distribution for this time of year.
  [see: USGS Streamflow]
• The Lake Superior water level is up four inches from last year at this time but remains below the long-term average. Levels on inland lakes in Minnesota's drought areas are low. In some cases, east central Minnesota lake levels are similar to those observed during the droughts of 2006 and 2007.
  [see: Corps of Engineers Great Lakes Water Levels]
• In their final soil moisture summary of 2008, the Minnesota Agricultural Statistics Service reported that late-November topsoil moisture was 1% "Very Short", 6% "Short", 77% "Adequate", and 16% "Surplus". Surplus soil moisture conditions are found throughout the Red River basin. Subsoil moisture supplies were reported as 2% "Very Short", 16% "Short", 71% "Adequate", and 11% "Surplus". The focus of subsoil moisture deficits is on east central and southeast Minnesota. With soils frozen, substantial subsoil moisture recharge will not be possible until spring.
  [see: Ag. Statistics Service Crop Progress and Condition]
• Seasonal temperatures in February maintained or deepened the frost layer in Minnesota's soils. Variable snow depths and a variety of ground covers lead to large variations in soil frost depths. Generally speaking, frost depths under sod range from one and one-half feet to three and one-half feet in across the state.
  [see: National Weather Service Frost Depth Data  |  Corps of Engineers Snow, Ice, Frost Data  |  MnDOT Road Frost Depths]
• A cold winter means that Minnesota's lakes and many of its rivers are covered with thick ice. Deep ice on lakes creates the possibility that ice-out dates will be later than average. Thick ice on rivers may lead to ice jam problems during the late-winter/early-spring break-up. Some ice jams were already reported in southeastern Minnesota in mid-February.
  [see: Historical Lake Ice-Out Dates]

Future prospects:

• The March precipitation outlook favors above-normal conditions across Minnesota. 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 offers equal chances of below-normal, near-normal, or above-normal conditions. Normal March high temperatures climb from the upper 20's early in the month to the low to mid-40's 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 20's 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 climatological probabilities across Minnesota. The March through May temperature projection also offers equal chances of below, near, and above-normal conditions.
  [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). The risk for spring flooding is high in the Red River basin. Elsewhere in Minnesota, flood potential is of lesser concern. The highest probability for flooding in the Red River basin is on the Red River at Fargo/Moorhead. At that forecast point, the National Weather Service describes the probability of MAJOR FLOODING as a NEAR CERTAINTY. The threat of moderate to major flooding also exists elsewhere along the Red River and its tributaries. The next National Weather Service probabilistic river outlook is scheduled to be released on or before Friday, March 13.
  [see: National Weather Service River Forecast Center]

From the author:

• Precipitation totals for the meteorological autumn (September through November) were far above long-term averages in the Red River basin. Precipitation values exceeded historical averages by four or more inches across most of the watershed. Both Fargo and Grand Forks set all-time autumn precipitation records for the three-month period. The present combination of saturated soils, deep frost, high stream base flows, and substantial snow cover, creates the strong possibility of spring flooding in this watershed.

Notes from around the state:

• None

Upcoming dates of note:

• March 13: National Weather Service Probabilistic Spring Flood Outlooks issued on or before this date
• March 19: 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://www.nass.usda.gov - USDA, National Agricultural Statistics Service
• http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center
• http://www.mvp-wc.usace.army.mil - US Army Corps of Engineers, St. Paul District
• http://www.dot.state.mn.us/mnroad - Minnesota Department of Transportation, Cold Weather Road Research
• http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center

Acknowledgements

• None

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Last modified: March 4, 2009