HydroClim Minnesota - February 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 2/4/2009

What happened in January:

January 2009 precipitation totals were below average across much of Minnesota. The water content of January's snowfalls fell short historical averages by one-quarter to one-half inch in many locales. Only a handful of Minnesota communities reported near-average monthly snowfall totals.
[see: January 2009 Climate Summary Table]
The most significant widespread precipitation event of January was associated with a winter storm that drifted through the Upper Midwest on January 3 and 4. Snowfall totals of four to twelve inches were reported across the northern one-half of Minnesota. Freezing rain and freezing drizzle fell on southeastern Minnesota, glazing surfaces and creating treacherous travel conditions.
[see: National Weather Service Summary | WeatherTalk]
Monthly mean temperatures for January 2009 were four to eight degrees below historical averages across most of Minnesota, making it the coldest January since 1994. It was the second consecutive cold month. Extreme temperature values for January ranged from a high of 49 degrees at Forest Lake on the 31st, to a low of -48 degrees in Babbitt (St. Louis County) on the 14th. For many locations, January brought no thawing temperatures until the 31st, a fairly rare occurrence for most Minnesota communities.
[see: January 2009 Climate Summary Table]

Where we stand now:

The snow depth map prepared on January 29 shows that the southern one-half of Minnesota has 4 to 12 inches of snow on the ground. Snow depths in the northern one-half of the state exceed 12 inches. Sections of west central, north central, and northeastern Minnesota report more than 18 inches of snow cover. When compared with historical snow depths for the date, current snow depths in some west central Minnesota counties rank above the 80th percentile.
[see: Snow Depth Maps]
The U. S. Drought Monitor, released on January 29, classified many 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 one inch 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 the soils now frozen, substantial subsoil moisture recharge will not be possible until spring.
[see: Ag. Statistics Service Crop Progress and Condition]
Cold temperatures in January 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 foot to one and one-half feet in southern Minnesota, one and one-half feet to three feet in western and northern Minnesota.
[see: National Weather Service Frost Depth Data | Corps of Engineers Snow, Ice, Frost Data | MnDOT Road Frost Depths]
Minnesota's lakes and rivers are frozen over with thick ice. Slush layers are found on some water bodies due to a substantial snow cover. As always, ice conditions can be highly variable and those venturing onto water bodies should utilize caution and common sense.
[see: DNR Conservation Officer Reports]

Future prospects:

The February precipitation outlook favors above-normal conditions in across Minnesota. Historically, February is Minnesota's driest month with precipitation normals ranging from near one-half inch in northwestern Minnesota to just over one inch in far eastern sections of the state. The median snow depth at the end of February ranges from under 5 inches in southwest Minnesota to over 18 inches on the ground in northeastern Minnesota (greater than 30 inches in the Lake Superior highlands).
[see: Climate Prediction Center 30-day Outlook | February Precipitation Normal Map]
The February temperature outlook offers equal chances of below-normal, near-normal, or above-normal conditions. Normal February high temperatures range from the low-teens in the north to near 20 in the south early in the month, climbing to the mid-20s to low 30s by month's end. Normal February low temperatures range from near minus 10 degrees in the far north to the single digits above zero in southern Minnesota early in the month; ascending to the low single digits in the north, mid-teens in the south by the end of February.
[see: Climate Prediction Center 30-day Outlook | February Temperature Normal Map]
The 90-day precipitation outlook for February through April indicates no significant tendencies away from climatological probabilities across Minnesota. The February through April 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, flood potential is not of immediate 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 places the probability of MAJOR FLOODING at GREATER THAN 90%. The threat of MINOR to MODERATE FLOODING exists elsewhere along the Red River and its tributaries.
[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, 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:

February 19: National Weather Service releases 30/90 day temperature and precipitation outlooks
February 27: National Weather Service Probabilistic Spring Flood Outlooks Issued on or before this date

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.crh.noaa.gov/dlh - National Weather Service, Duluth Forecast Office
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://mndnr.gov/enforcement - Minnesota Department of Natural Resources, Enforcement Division
http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center

Acknowledgements

None

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