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HydroClim Minnesota - December 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 12/3/2008

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What happened in November:

• November 2008 precipitation totals were variable across Minnesota. Many locales reported near-normal monthly precipitation, however monthly precipitation was above average in northwestern and north central Minnesota counties, and below average in east central Minnesota.
  [see: November 2008 Climate Summary Table | Radar-based November Precipitation Estimate]
• The largest precipitation event of the month came on November 5 and 6. Showers and thunderstorms, fed by an unusually warm and muggy air mass, dropped over three-quarters of an inch of rain on geographically-disbursed locations such as Grand Forks, International Falls, Mankato, and Albert Lea. Daily precipitation records were set in some of these locations.
• Monthly mean temperatures for November 2008 were two to four degrees above historical averages. Very warm early-November temperatures were offset by near-average to below-average temperatures for the final three weeks of the month. Extreme temperature values for November ranged from a high of 78 degrees at Redwood Falls on the 2nd, to a low of -8 degrees at Embarrass (St. Louis County) on the 21st. Maximum temperature records were set throughout Minnesota on November 2, 3, 4, and 5.
  [see: November 2008 Climate Summary Table | Warm November 2-3]

Where we stand now:

• The snow depth map to be prepared on Thursday, December 4 will show that the southern one-third of Minnesota has one to three inches of snow on the ground, with somewhat greater amounts in far southeastern Minnesota. North central and northeastern Minnesota counties also report a snow cover of one to three inches with greater amounts reported in the vicinity of Voyageurs National Park and the Boundary Waters Wilderness Canoe Area.
  [see: Snow Depth Maps (after 2:00 PM December 4)]
• 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 two or more inches across most of the watershed. Both Fargo and Grand Forks set all-time autumn precipitation records for the three-month period. Saturated soils and high stream base flows in the early winter increase the possibility of spring flooding in 2009.
  [see: Radar-based estimate of Autumn 2008 Precipitation Departure from Normal]
• The U. S. Drought Monitor, released on November 26, classified many Minnesota counties in the D0 - Abnormally Dry category or worse. Portions of east central and southeastern Minnesota were placed in the D1 - Moderate Drought classification. For the five and one-half month period beginning in mid-June and extending into early December, many southeastern Minnesota communities received less than ten inches of precipitation. This represents a negative departure from normal of five to eight inches in these areas. 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 variable across the state. Stream flow measurements (where winter monitoring is possible) for many Minnesota streams are near the middle of the historical distribution for this time of year. However, the Red River and many of its tributaries report above-median flows in response to heavy rains that fell during the late summer and autumn.
  [see: USGS Streamflow]
• The Lake Superior water level is up 3 inches 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, lake levels are similar to those observed during the droughts of 2006 and 2007.
  [see: Corps of Engineers Great Lakes Water Levels]
• The Minnesota Agricultural Statistics Service reports that as of November 28, 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, subsoil moisture recharge will not be possible until spring.
  [see: Ag. Statistics Service Crop Progress and Condition]
• Seasonal temperatures in late November and early December froze Minnesota's soils. Frost depths under sod range from one to ten inches across Minnesota.
  [see: Corps of Engineers Snow, Ice, Frost Data  |  MnDOT Road Frost Depths  |  National Weather Service Frost Depth Data]
• Minnesota's lakes are now ice covered. Sub-freezing temperatures in late November and early December, along with relatively little snow cover, created suitable ice-making conditions. However, as always, ice conditions are highly variable and those venturing onto water bodies should utilize caution and common sense.
  [see: DNR Conservation Officer Reports]

Future prospects:

• The December precipitation outlook offers equal chances of below-normal, near-normal, or above-normal conditions. December precipitation normals range from around one-half inch in western Minnesota to over one and one-quarter inches in eastern sections of the state. The median snow cover at the end of December ranges from over 10 inches on the ground in northeastern Minnesota (20 inches in the Lake Superior highlands), to under 5 inches in southwestern counties.
  [see: Climate Prediction Center 30-day Outlook  |  December Precipitation Normal Map]
• The December temperature outlook tilts towards below-normal conditions. Normal December high temperatures are in the mid 20's to near 30 to start the month, dropping to the mid-teens to near 20 by month's end. Normal lows are around 10 degrees early in the month, falling to the mid-single digits above and below zero by late December.
  [see: Climate Prediction Center 30-day Outlook  |  December Temperature Normal Map]
• The 90-day precipitation outlook for December through February indicates no significant tendencies away from climatological probabilities across Minnesota. The December through February temperature projection tilts towards above-normal conditions in southern Minnesota, and no significant tendencies away from climatological probabilities in northern 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 River Forecast Center]

From the author:

• None

Notes from around the state:

• None

Upcoming dates of note:

• December 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://water.weather.gov - National Weather Service, Advanced Hydrologic Prediction Service
• 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.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://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center
• 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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Last modified: December 3, 2008