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 Division of Ecological and Water Resources, St. Paul
distributed: May 2, 2012
What happened in April 2012:
- April 2012 precipitation totals were above normal in portions of west central, north central, and northeast Minnesota. Elsewhere, monthly precipitation totals were near the historical average. It was only the second month since July 2011 where monthly precipitation totals were near to above average.
- An unusually strong mid-April low pressure system brought a combination of severe weather, heavy rain, and heavy snow to Minnesota on April 15-16. The storm dropped between one and two inches of welcome precipitation over a large portion of Minnesota. Numerous daily precipitation records were broken and daily snowfall totals of five to eleven inches broke daily snowfall records in some north central and northeast Minnesota communities.
- Monthly mean temperatures for April 2012 were somewhat above average, topping the historical average by one to four degrees across Minnesota. Mean monthly April temperatures were only slightly warmer than March, an indication of March's historic warmth. Rochester's mean monthly April temperature and mean monthly March temperatures were identical. Extreme temperature values for April ranged from a high of 88 degrees F at Pipestone (Pipestone County) on the 1st and 24th, to a low of 7 degrees F at Embarrass (St. Louis County) on the 17th. Maximum temperature records were set at a few western Minnesota communities on April 1 when the thermometer climbed into the 70s and 80s. Very cold temperatures on April 10, 11, and 17 threatened perennial plants that were well advanced due to extraordinary March temperatures. A hard freeze in mid-April is not uncommon, but under these circumstance, the cold temperatures were notable.
Where we stand now:
- Adequate to abundant precipitation totals thus far in Spring 2012 have somewhat improved Minnesota's drought situation. The topsoil has laid first claim on the moisture and spring prospects for agricultural and horticultural interests have improved significantly. Nonetheless, subsoil moisture content in some areas is deficient due to multi-month precipitation deficits. Water levels on many lakes, rivers, and wetlands, as well as some aquifers, remain below average for this point in the season.
- The U. S. Drought Monitor, released on April 26, depicts nearly every Minnesota county as experiencing some level of drought. A section of northeast Minnesota is placed in the Severe Drought category. The Drought Monitor also places much of southern Minnesota in the Severe Drought category. Other Minnesota locales are determined to be in Moderate Drought or Abnormally Dry. As a state, the autumn of 2011 was the driest in Minnesota's modern climate record, and winter snowfall totals were quite meager. Over the last nine months, precipitation totals are short of normal by more than six inches in many Minnesota communities, especially in southern Minnesota. The U. S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc) are based on several indicators.
- The U.S. Geological Survey and Minnesota DNR report that stream discharge values are low at some northwest, northeast, and southern Minnesota reporting locations. Stream flow values rank below the 25th percentile for this time of year in these areas. Elsewhere in Minnesota, river flows rank near the middle of the historical data distribution for the season.
- Water levels on many Minnesota lakes are low when compared with historical averages for this time of year. However, water levels on some far northern Minnesota lakes appear to be responding to the spring rains. The Lake Superior water level is up two inches from its elevation of a year ago, but down nine inches from the long-term seasonal average.
- In their April 29 report, the Minnesota Agricultural Statistics Service reported that topsoil moisture is 3% Very Short, 17% Short, 77% Adequate, and 3% Surplus across Minnesota. This represents a significant improvement over the early-April soil moisture survey.
- The potential for wildfires is currently rated by DNR Forestry as Moderate to High in some northern Minnesota counties. Elsewhere in Minnesota, wildfire potential is considered Low. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
Contributions of information and suggestions are welcome!