HydroClim Minnesota - March 2008

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 3/5/2008

What happened in February:

February 2008 precipitation totals were below the historical average in most Minnesota locations. Many communities reported less than one half of an inch of liquid precipitation. The exception to this snow-sparse pattern was the far southeastern corner of Minnesota where precipitation totals were at, to somewhat above, historical averages.
[see: February 2008 Climate Summary Table]
Monthly mean temperatures for February 2008 were well below historical averages. February temperatures ranged from five to seven degrees below normal across Minnesota. Extreme values for February ranged from a high of 52 degrees on the 24th in Canby (Yellow Medicine County), to a low of minus 40 degrees at International Falls and at Embarrass (St. Louis County) on the 11th. The minus 40-degree temperature at International Falls on the 11th was a new all-time record low temperature for the date at that location. Numerous low temperature records were set on February 20 when temperatures dropped into the minus 20's and minus 30's in northern and western Minnesota.
[see: February 2008 Climate Summary Table]
Due to colder than average temperatures in December and February, the 2007-2008 winter season (December through February) was the coldest since the winter of 2000-2001.

Where we stand now:

The snow depth map prepared on February 28 shows that the northern one-third of Minnesota has at least eight inches of snow on the ground. Much of Minnesota's Arrowhead region is covered by more than 18 inches of snow. In the southern two-thirds of Minnesota, snow depths range from a trace to eight inches. Portions of west central, central, and southwest Minnesota have very little snow cover, whereas some counties in far southeastern Minnesota report around eight inches on the ground. Snow depth values are near the historical median for the date across much of Minnesota.
[see: February 28 Snow Depth Map]
The U. S. Drought Monitor, released on February 28, continues to place a small area of west central and central Minnesota in the "Moderate Drought" category. Portions of northwestern and north central Minnesota remain designated as "Abnormally Dry". This is an acknowledgement of some lingering precipitation deficits. All other Minnesota locales are deemed to be free of drought conditions. 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, for observation points where winter measurements are possible, are near the historical median for the date in most locations.
[see: USGS Streamflow]
The Lake Superior water level is up eight inches from last year at this time. While the Lake Superior water level is no longer near the all-time seasonal low, it remains below the long-term average.
[see: Corps of Engineers Great Lakes Water Levels]
In their final report of 2007, the Minnesota Agricultural Statistics Service reported that despite the dry November weather, mid-November topsoil moisture was "Adequate" across 83% of Minnesota's landscape. Topsoil moisture deficits should not be a concern in most areas at the start of the 2008 growing season.
[see: Ag. Statistics Service Crop Progress and Condition]
Soil frost was driven to even lower depths during the month of February by cold weather. Frost depths generally range from 24 to 36 inches. In those locations with deeper and less compacted snow cover, especially far southeastern Minnesota, frost depths are shallower. In snow-sparse areas of west central and southwestern Minnesota, frost depths of 36 to 48 inches are reported. Frost depths have reached their maximum extent for the season. On average, the soil profile will thaw by late March to early April in the south, early April to mid-April in the north. The soil thaws from both the top and the bottom, leaving a mid-layer lens of frozen soil to be the last to climb above freezing.
[see: National Weather Service River Forecast Center | U of M Climate Observatory | Ag. Statistics Service Ag News | MnDOT Road Frost Depths]

Future prospects:

The March precipitation outlook is for equal chances of below, near, or above normal conditions. Normal March precipitation ranges 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 no strong indications of either above or below normal temperatures in Minnesota. 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 offers equal chances of above, near, or below average conditions.
[see: Climate Prediction Center 90-day Outlook]
At this time, there is no reason to anticipate significant flooding along Minnesota's rivers this spring. However, due to cold winter temperatures, thick ice has formed on many rivers and streams. Ice jams are always a possibility given these conditions. 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 River Forecast Center]

From the author:

The Minnesota Department of Natural Resources - Division of Waters has released its 2005-2006 Water Year Data Summary. The publication provides a review and summary of basic hydrologic data gathered through DNR Waters programs during the 2005 and 2006 Water Years.
[see: Water Year Data Summary: 2005 and 2006]

Notes from around the state:

None

Upcoming dates of note:

March 20: National Weather Service releases 30/90 day temperature and precipitation outlooks
March 6 and March 27: National Weather Service releases probabilistic flood 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 - Detroit District, US Army Corps of Engineers
http://www.nass.usda.gov - USDA, National Agricultural Statistics Service
http://www.crh.noaa.gov/ncrfc - North Central River Forecast Center, National Weather Service
http://www2.mvr.usace.army.mil/WaterControl/new/layout.cfm - St. Paul District, US Army Corps of Engineers
http://www.mrr.dot.state.mn.us - Minnesota Department of Transportation, Office of Materials
http://www.cpc.ncep.noaa.gov - Climate Prediction Center, National Weather Service
http://mndnr.gov/waters - Minnesota Department of Natural Resources, Division of Waters

Acknowledgements

None

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