HydroClim Minnesota - March 2010

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 3/3/2010

What happened in February:

February 2010 precipitation totals were above average in portions of west central and southwestern Minnesota, somewhat below average in north central and northeastern Minnesota. Elsewhere, monthly precipitation totals were close to the historical average. Much of the February's precipitation resulted from one major storm: a snowstorm on February 7-9. The weather for the second half of February was tranquil and produced little to no precipitation.
[see: February 2010 Climate Summary Table | February 7-9 Snow Storm]
Monthly mean temperatures for February 2010 were well below average in west central, southwestern, and south central Minnesota where snow cover is unusually deep. Elsewhere across Minnesota, February temperatures were nearer the historical average. Extreme temperature values for February ranged from a high of 45 degrees at Grand Marais on the 27th, to a low of -30 degrees at Roseau on the 24th.
[see: February 2010 Climate Summary Table]

Where we stand now:

The snow depth map prepared on February 25 shows that nearly all of Minnesota has more than eight inches of snow on the ground. The heaviest snow cover is along the Lake Superior highlands where snow depths exceed 24 inches. Many counties in west central and southwestern Minnesota report 18 or more inches of snow on the ground. When compared with historical snow depths for the date, current snow depths across much of southern and western Minnesota rank above the 95th percentile, a one-in-twenty year occurrence.
[see: Snow Depth Maps]
Snow water content estimates provided by NOAA's Hydrologic Remote Sensing Center range from four to six inches over large portions of the Red River and Minnesota River watersheds. The water content of the snow pack in the Lake Superior highlands and far north central Minnesota is modeled to be between four and five inches. Snow water equivalence values in the upper Mississippi watershed and the St. Croix basin range from two to four inches.
[see: Snow Water Equivalence Estimates]
The U. S. Drought Monitor, released on February 25, reflects long-term precipitation deficits in a few Minnesota counties. A small area of east central Minnesota remains in the Moderate drought category due to lingering precipitation shortfalls that extend back to early-summer 2008. Impacts from these shortfalls are mostly observed in large-basin water levels. Portions of north central Minnesota are categorized as Abnormally Dry, as that area rebounds from a very dry 2009 growing season. Most 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 are high in the Red River basin. Stream flow measurements (where winter monitoring is possible) in the watershed are above the 95th percentile when compared with the historical distribution for this time of year.
[see: USGS Streamflow]
The Lake Superior water level is up one inch from last year at this time but remains below the long-term average. Water levels on many Minnesota lakes and wetlands rose markedly due to the heavy October precipitation. However, water levels on some larger lakes and wetlands complexes in east central Minnesota lakes remain very low. White Bear Lake, on the Ramsey/Washington county border, is just above its all-time record low level.
[see: Corps of Engineers Great Lakes Water Levels | White Bear Lake Water Level]
In their final soil moisture summary of 2009, the Minnesota Agricultural Statistics Service reported early-December topsoil moisture was 0% Very Short, 2% Short, 70% Adequate, and 28% Surplus. Heavy October 2009 rains amply recharged the soil moisture profile across Minnesota. This greatly improved forestry, horticultural, and agricultural prospects for the early 2010 growing season. However, saturated topsoils exacerbate the spring flood potential.
[see: Agricultural Statistics Service Crop Progress and Condition]
Soil frost depths under sod range from three to twelve inches in the southern Minnesota, eighteen to thirty inches in northern Minnesota. A heavy blanket of snow cover in most locales impeded frost penetration in spite of winter temperatures that were at, or somewhat below, historical averages.
[see: Corps of Engineers Snow, Ice, Frost Data | National Weather Service Frost Depth Data | MnDOT Road Frost Depths]
Minnesota's lakes are ice covered. As always, please remember that ice conditions are highly variable and those venturing onto water bodies should utilize caution and common sense. Lake and river ice is never completely safe. Historically, ice leaves Minnesota/Iowa border lakes around April 1. The average ice-out date for Minnesota/Canada border lakes is in late April/early May.
[see: DNR Conservation Officer Reports | Historical Lake Ice-Out Dates]

Future prospects:

The March precipitation outlook leans towards below-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 indicates a tilt towards above-average conditions in the northeastern one-quarter of Minnesota. Elsewhere across the state there are no tendencies away from climatological probabilities. 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 shows no significant tendencies away from climatological probabilities except in far northeastern Minnesota where the outlook tilts towards below-normal conditions. The March through May temperature projection is also inconclusive for most of Minnesota with the exception of a tendency towards above-normal temperatures in northeastern counties.
[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 long-range probabilistic outlooks issued on February 19 indicates a strong likelihood of flooding along many of Minnesota's rivers. An updated outlook will be released Friday, March 5.
[see: National Weather Service North Central River Forecast Center | National Weather Service Probabilistic Flood Outlooks]

From the author:

Locations along the Red River and its tributaries, the Minnesota River and its tributaries, the Crow River, and the Mississippi River downstream of the Minnesota River confluence, are all at an elevated risk for spring flooding. The Fargo/Moorhead area is at the highest risk for major spring flooding. Minnesota homeowners are reminded to consider flood insurance before the snowmelt. Flood insurance becomes effective 30 days after it is purchased, therefore advanced planning is necessary. The next National Weather Service probabilistic flood outlooks will be issued on Friday, March 5.
[see: DNR Flood Information | National Weather Service Probabilistic Flood Outlooks]

Notes from around the state:

None

Upcoming dates of note:

March 5: National Weather Service releases newest rendition of probabilistic flood outlooks
March 18: 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.nohrsc.nws.gov - National Weather Service, National Operational Hydrologic Remote Sensing Center, Chanhassen
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 Waters
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 Engineering and Testing
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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