HydroClim Minnesota - April 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: April 6, 2011

What happened in March 2011:

March 2011 precipitation totals were highly variable across Minnesota. March precipitation was below normal in north central and northeast Minnesota, whereas portions of central and southeast Minnesota reported above-average precipitation for the month.
[see: March 2011 Climate Summary Table]
A large and intense early-spring storm on March 22-23 brought rain, sleet, and snow to a good portion of Minnesota. Snowfall totals topped six inches in numerous northwest, southwest, and central Minnesota communities. Liquid precipitation totals of one to two inches were common and added to the flood threat. In most communities, this event accounted for the majority of the monthly precipitation for March.
[see: Early Spring Storm - March 22-23]
Monthly mean temperatures for March 2011 were below average across Minnesota. This was the fourth consecutive month of below-average temperatures. March temperatures fell short of the historical mean by one to eight degrees, with the largest negative departures occurring in west central Minnesota. Extreme temperature values for March ranged from a high of 59 degrees F at Wells (Faribault County) on the 16th, to a low of -24 degrees F at Embarrass (St. Louis County) and Babbitt (St. Louis County) on the 2nd.
[see: March 2011 Climate Summary Table]

Where we stand now:

The U.S. Geological Survey reports that stream discharge values at many river monitoring locations across Minnesota are above the 90th percentile at most locations for the date, and near all-time high discharge values for the date at some locales. River levels at many river communities are at moderate or major flood stage.
[see: Spring Flooding 2011 | USGS Streamflow]
The southern one-half of Minnesota has little or no snow cover. Portions of west central, north central, and northeast Minnesota report six or more inches of snow on the ground. Along the Lake Superior highlands, snow depth ranges from 12 to 18 inches.
[see: NWS Snow Depth Estimation Map]
The U. S. Drought Monitor, released on March 31, 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 drought 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 Lake Superior water level is down nine inches from last year at this time and down 16 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 April 4, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 0% Very Short, 0% Short, 35% Adequate, and 65% Surplus.
[see: Agricultural Statistics Service Crop Progress and Condition]
The upper layer of the soil profile is thawed in many locations. Frost depth is shallow elsewhere. Early and abundant snow cover inhibited frost penetration despite cold winter temperatures.
[see: Corps of Engineers Snow, Ice, Frost Data | National Weather Service Frost Depth Data | MnDOT Road Frost Depths]
With a few exceptions, Minnesota's lakes remain ice covered. A handful of south-central Minnesota lakes are partially ice free. 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: Lake Ice Status | DNR Conservation Officer Reports]
The potential for wildfires is currently rated by DNR Forestry as "Low" 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 April precipitation outlook shows a significant bias towards above-normal conditions. April precipitation normals range from one and one half inches in northwestern Minnesota to around three inches in southeastern counties. The historical probability of measurable precipitation for any given day in April ranges from 20 percent in the far northwest to 35 percent in the southeast.
[see: Climate Prediction Center 30-day Outlook | April Precipitation Normal Map]
The April temperature outlook is heavily weighted in favor of below-normal conditions across the state. Normal April high temperatures are in the mid to upper 40s early in the month, rising to the low 60s by month's end. Early April normal low temperatures are near 20 in the north, near 30 in the south. By month's end, low temperatures average in the mid 30s in the north, near 40 in the south.
[see: Climate Prediction Center 30-day Outlook | April Temperature Normal Map]
The 90-day precipitation outlook for April through June 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 April through June temperature projection tilts towards below-normal conditions throughout Minnesota.
[see: Climate Prediction Center 90-day Outlook]
Moderate to Major spring flooding is underway along many of Minnesota's rivers. Saturated soils from a wet autumn, abundant snow cover, and high winter stream base flows combined to produce the flooding. The Red River and its tributaries have yet to crest. Major flooding is underway along the upper reaches of the Red River. Major flooding will occur by this weekend in Red River communities such as Moorhead/Fargo and Halstad. Major flooding will begin early next week at locations such as East Grand Forks/Grand Forks, and later this month along the Red River at the Canadian border. An initial flood crest has already occurred along portions of the Minnesota and Mississippi rivers and their tributaries. A secondary, and potentially higher, crest is expected along portions of the Mississippi, Minnesota, and Crow rivers. Initial rises are still forthcoming for the Sauk, Long Prairie, and upper Mississippi rivers. River forecasting is the responsibility of the National Weather Service - North Central River Forecast Center (NCRFC). The NCFRC provides information to the six National Weather Service Forecast Offices that serve Minnesota. These offices in turn relay this information to the public.
[see: Spring Flooding | National Weather Service North Central River Forecast Center]

From the author:

None

Notes from around the state:

None

Upcoming dates of note:

April 21: 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://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://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://mndnr.gov/forestry - Minnesota Department of Natural Resources, Division of Forestry
http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center

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