A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the first Thursday of each month.
State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: January 4, 2013 (distribution delayed by one day)
What happened in December 2012:
- December precipitation totals were variable across Minnesota. Monthly precipitation totals exceeded the historical average by one-half inch to one inch in many southwest, west central, and central Minnesota communities. Conversely, December precipitation totals were short of average by one-half inch in some northwest and northeast Minnesota locales. Elsewhere, monthly precipitation totals were close to historical averages. Monthly snowfall totals topped 20 inches in southwest and west central Minnesota locations such as Marshall, Granite Falls, and Madison.
- One of the more significant weather events of the month was a winter storm that dropped heavy snowfall on many communities in the southern one-half of Minnesota on December 8 and 9. Snowfall totals in excess of 10 inches fell in a 100-mile wide band centered on a transect that extended from Canby to the Twin Cities. For some communities, the liquid content of the snowfall (0.75 - 1.25 inches) represented the largest single-day precipitation event since July.
- December average monthly temperatures in Minnesota generally ranged from one to four degrees above normal. Warm temperatures during the first half of the month were counterbalanced by more winter-like temperatures in the second half of December. Extremes for the month ranged from a low of -21 degrees at Warroad on the 10th, to a high of 64 degrees on the 3rd at Rushford and Winona. Daily maximum temperature records were set in some southeast Minnesota locations on December 3. Preliminary data indicate that the statewide average annual temperature in 2012 for Minnesota was the third warmest on record. In the Twin Cities, the 2012 average annual temperature tied the record for the all-time warmest year.
Where we stand now:
- The U. S. Drought Monitor, released on January 3, places portions of northwestern, west central, central, southwestern, and south central Minnesota in the Extreme Drought category. Most of the rest of Minnesota is deemed to be in Severe Drought. In total, 83% of Minnesota's landscape is in Extreme Drought or Severe Drought. The drought situation in northwest Minnesota is the result of an historically dry autumn in 2011, a snow-sparse 2011-2012 winter, and a dry 2012 growing season. The moisture deficits elsewhere in Minnesota developed rapidly due to very hot and very dry conditions that began in late-June and continued through the autumn. For large portions of Minnesota, July-through-November 2012 precipitation totals ranked at or below the lowest on record. The U. S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc) are based on several indicators.
- Snow depths across Minnesota generally range from four to eight inches. Some locations in west central Minnesota and in the Lake Superior highlands of northeast Minnesota report eight to 12 inches of snow cover. The present snow depth, when compared to other years on this date, is below the historical median in the northern one-third of Minnesota, near to somewhat above the historical median in the southern two-thirds of the state.
- The U.S. Geological Survey and Minnesota DNR report that stream discharge values are low at numerous Minnesota reporting locations. Many stream flow values rank below the 25th percentile when compared with historical data for this time of year.
- Water levels on most Minnesota lakes are low due to the dry summer and autumn. Lake Superior's water level is well below its historical average for this time of year.
- In their final report of the season (October 31), the Minnesota Agricultural Statistics Service reported that topsoil moisture was 27% Very Short, 42% Short, 29% Adequate, and 2% Surplus across Minnesota. Subsoil moisture is said to be 88% Very Short or Short. Soil moisture measurements made during November at University of Minnesota Research and Outreach Centers indicated extraordinarily dry conditions in the soil profile. Soil moisture content in the top five feet of soil at these locations is near all-time lows for this time of year. Ample early-spring rains are critically needed to replenish soil moisture reserves before the commencement of the 2013 growing season.
- Soil frost depth under sod ranges from six to eighteen inches across Minnesota.
- Minnesota lakes and rivers are ice covered. Lake and river ice is never completely safe. Caution is always advised when venturing onto the ice.
Future prospects:
- The January precipitation outlook leans towards above-normal conditions in the northern two-thirds of Minnesota, and presents an equal likelihood of below-normal, near-normal, or above-normal conditions elsewhere in the state. January precipitation normals range from near one-half inch of liquid equivalent in western Minnesota to just over one inch liquid in eastern sections of the state. The median snow cover at the end of January ranges from near five inches in southwest Minnesota, to over 15 inches on the ground in northeastern Minnesota (greater than 24 inches in the Lake Superior highlands).
- The January temperature outlook is weighted towards above-normal conditions in the southern two-thirds of Minnesota, equal chances of below-normal, near-normal, or above-normal conditions for the rest of the state. Historically, January is Minnesota's coldest month. Normal January high temperatures range the low-teens in the north, to near 20 in the south. Normal January lows range from near minus 10 degrees in the far north, to the single digits above zero in southern Minnesota.
- The 90-day precipitation outlook for January through March offers an equal likelihood of below-normal, near-normal, or above-normal conditions statewide. The January through March temperature projection tilts towards below-normal conditions in far northwest Minnesota, with equal chances of below-normal, near-normal, or above-normal conditions for the rest of the state.
- 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 address both high flow and low flow probabilities.
From the author:
- It is reasonable to assume that the present drought status will remain relatively unchanged for the remainder of the winter. The historical average precipitation over the next two months is less than two inches and the topsoil is sealed by frost. Therefore, Minnesota will be highly dependent on spring rains to ease the situation. Without abundant spring rains, a number of critical drought issues involving public water supply, agriculture, horticulture, tourism, and others will rapidly surface early in the growing season.