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HydroClim Minnesota - May 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: May 4, 2011

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What happened in April 2011:

• Significant flooding was reported across Minnesota during much of the month of April. River levels reached major flood stage along the Mississippi River, the Minnesota River, the St. Croix River, and the Red River, along with their tributaries. In some locations, peak river crests were among the highest ever recorded. Advanced warning, effective flood fighting measures, and somewhat favorable March and April weather helped to minimize damage. The total volume of water that left the landscape and entered the river systems was enormous. Thankfully, the nature of the spring weather kept peak crests from reaching even higher levels. Had temperatures spiked during the heart of the melt, or the spring storms dropped ill-timed rains, the flooding could have been far worse.
• April 2011 precipitation totals were variable across Minnesota. April precipitation was below average in west central Minnesota. However, April precipitation totals were near to well above average in all other locations. Monthly precipitation totals (rain plus the liquid equivalent of the snow) exceeded average by an inch or more in southeastern Minnesota as well as many counties in the northern one third of the state. Some northeastern Minnesota communities reported over a foot of April snow.
  [see: April Precipitation Percent of Normal and Ranking  |  April 2011 Climate Summary Table]
• Spring storms dropped substantial amounts of rain and/or snow over large areas of Minnesota during April. Thunderstorms on April 10 produced rainfall totals in excess of one inch in some southeast, northwest, and north central Minnesota locations. The April 10 rainfall total for Grand Meadow (Mower County) was 2.40 inches, a state-wide record for the date. On April 15 and 16, an intense winter-like storm left a swath of three to eight inches of snow across much of the northern one-half of the state. On April 26 and 27, the same storm that spawned the devastating tornadoes in the Gulf states generated large amounts of rain (and some snow) in the eastern one-half of Minnesota. Rainfall totals in excess of one inch were common in southeastern and east central Minnesota. The Twin Cities International Airport reported 1.46 inches of rain on April 26, an all-time local record for the date.
  [see: Spring Snow Storm - April 15-16  |  Spring Storm - April 26-27]
• Monthly mean temperatures for April 2011 were somewhat below average across Minnesota. This was the fifth consecutive month of below-average temperatures. April temperatures generally fell short of the historical mean by one to three degrees. It was a month with a dual personality, with mild temperatures early in the month being offset by very cold temperatures at month's end. The cold late-April temperatures and wet weather slowed the onset of spring. Extreme temperature values for April ranged from a high of 85 degrees F at Blue Earth (Faribault County) on the 10th, to a low of 9 degrees F at Embarrass (St. Louis County) on the 19th and 20th.
  [see: April 2011 Climate Summary Table]

Where we stand now:

• The U.S. Geological Survey reports that stream discharge values remain high in nearly every major Minnesota watershed. River levels remain above flood stage at most locations along the Red River, and a few locales along the Mississippi and Minnesota rivers.
  [see: USGS Streamflow  |  DNR Streamflow]
• Other than some wooded areas in the Lake Superior highlands, Minnesota is free of snow cover.
  [see: NWS Snow Depth Estimation Map]
• The U. S. Drought Monitor, released on April 28, depicts most of Cook County and portions of Lake County as Abnormally Dry. Substantial rain and snow in this area during the autumn and winter improved the drought situation significantly. The hydrologic situation will become more clear when the ice leaves the lakes and rivers. 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 Lake Superior water level is down four inches from last year at this time and down 12 inches from the long-term seasonal average. Water levels on a few larger lakes in east central Minnesota lakes remain 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 May 1, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 0% Very Short, 0% Short, 56% Adequate, and 44% Surplus. Because of wet soils and flood inundation, there was minimal planting progress in Minnesota's agricultural regions during April. Corn planting is one percent complete versus a five-year average of 46 percent for this time of year.
  [see: Agricultural Statistics Service Crop Progress and Condition  |  U. of M. Southwest Research Center (Lamberton) Soil Moisture]
• Larger lakes in north central and northeast Minnesota remain ice covered. For Minnesota lakes that have lost their ice, ice-out was three to eight days later than average this season.
  [see: Lake Ice Status  |  DNR Conservation Officer Reports]
• The potential for wildfires is currently rated by DNR Forestry as "Moderate" across Minnesota. These conditions can change rapidly in response to warm, sunny, and windy weather. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
  [see: Fire Danger Rating Map]

Future prospects:

• The May precipitation outlook shows a bias towards above-normal conditions. May precipitation normals range from just over two inches in northwestern Minnesota to just less than four inches in southeastern counties. The historical probability of measurable precipitation for any given day in May ranges from 25 percent in the northwest to near 40 percent in the southeast.
  [see: Climate Prediction Center 30-day Outlook  |  May Precipitation Normal Map]
• The May temperature outlook is weighted in favor of below-normal conditions across the state. Normal May high temperatures are in the low to mid-60s early in the month, rising to the low to mid-70s at month's end. Normal May low temperatures are in the mid-30s to near 40 to start the month and climb to the mid-40s to low 50s as the month ends.
  [see: Climate Prediction Center 30-day Outlook  |  May Temperature Normal Map]
• The 90-day precipitation outlook for May through July indicates no significant tendencies away from historical climatological probabilities across Minnesota except in the far northwestern corner of the state where the outlook favors above-normal precipitation. The May through July temperature projection tilts strongly towards below-normal conditions throughout 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:

• None

Notes from around the state:

• None

Upcoming dates of note:

• May 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 Eco/Water Resources and U of M Dept. of Soil, Water, and Climate
• http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey
• http://mndnr.gov/waters - Minnesota Department of Natural Resources, Division of Ecological and Water Resources
• http://www.nohrsc.noaa.gov - National Weather Service, National Operational Hydrologic Remote Sensing Center
• http://www.drought.unl.edu - National Drought Mitigation Center
• http://www.lre.usace.army.mil - US Army Corps of Engineers, Detroit District
• http://www.nass.usda.gov - USDA, National Agricultural Statistics Service
• http://swroc.cfans.umn.edu - University of Minnesota, Southwest Research and Outreach Center
• http://mndnr.gov/enforcement - Minnesota Department of Natural Resources, Division of Enforcement
• http://mndnr.gov/forestry - Minnesota Department of Natural Resources, Division of Forestry
• http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center
• http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center

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Last modified: May 4, 2011