A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the first Monday of each month.
State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: June 6, 2012
What happened in May 2012:
- May 2012 precipitation totals were extraordinarily high along a broad arc that extended from southwest Minnesota into Minnesota's Arrowhead region. Along this swath, monthly precipitation totals in excess of eight inches were common. May rainfall totals topping 10 inches were reported in many southwest and east central Minnesota counties. The long-term average for May rainfall ranges from two to four inches across Minnesota. Therefore, May rainfall totals in many communities tripled the long-term average. Some locales reported their wettest May ever. As is often the case in a state the size of Minnesota, broad generalizations do not tell the whole story. While much of the southeastern two-thirds of Minnesota received abundant to excessive rainfall, the northwest corner of the state was missed by most of May's heavy rainfall events. Monthly precipitation totals in northwestern counties were short of average by one to two inches.
- Two very heavy rainfall events were responsible for much of the May rainfall. Large sections southern Minnesota received three or more inches of rain from May 4 through May 6. Later in the month, a very slow-moving cold front dropped two or more inches of rain on much of the state on May 23 and 24. Over four inches of rain fell during these two days in some southern and eastern Minnesota communities.
- Monthly mean temperatures for May 2012 were above average in the northern one-half of Minnesota, and well above average in the south. In southern Minnesota, May's mean monthly temperature topped the historical average by four or more degrees in most locales. It was Minnesota's eighth consecutive month of above-normal temperatures. For many Minnesota communities, it was the warmest meteorological spring (March - May) of the modern record. Extreme temperature values for May ranged from a high of 97 degrees F at Madison (Lac Qui Parle County) on the 18th, to a low of 24 degrees F at Embarrass (St. Louis County) and Brimson (St. Louis County) on the 16th. Maximum temperature records were set at some Minnesota communities on May 17, 18, 19, and 23 when the thermometer climbed into the upper 80s and low 90s. A few minimum temperature records were set in far northern Minnesota on May 31 when the temperature dropped to the upper 20s.
Where we stand now:
- Abundant spring rainfall dramatically improved Minnesota's drought situation in many counties. April-plus-May rainfall totals in excess of ten inches were common over large sections of southwest, central, east central, and northeast Minnesota. In many of these areas, it was the wettest April-plus-May of the modern record.
- The U. S. Drought Monitor, released on May 29, places some northwest Minnesota counties in the Moderate Drought category. Roughly one-third of the state is rated in the Abnormally Dry category. In this case, the Abnormally Dry designation is used by the U.S. Drought Monitor authors to indicate that the landscape is "coming out of drought", with perhaps some minor lingering drought impacts. Over one-half of Minnesota is free of any drought designation. This week's map shows substantial improvement in the drought situation when compared with early May when 60 percent of Minnesota was said to be in the Moderate Drought or Severe Drought categories. 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 very low at some northwest Minnesota reporting locations. Stream flow values rank below the 10th percentile for this time of year in these areas. Stream flows are very high in southwest, central, east central, and northeast Minnesota. Stream discharge values in these watersheds rank above the 90th percentile when compared with historical data for the season.
- Water levels on most Minnesota lakes located within areas receiving spring's heaviest rainfalls rose notably this past month.
- In their June 3 report, the Minnesota Agricultural Statistics Service reported that topsoil moisture is 0% Very Short, 5% Short, 77% Adequate, and 18% Surplus across Minnesota. This represents a significant improvement over the early-April soil moisture survey when topsoil conditions were said to be 54% Very Short or Short.
- The potential for wildfires is currently rated by DNR Forestry as High in far northwest Minnesota. Elsewhere in Minnesota, wildfire potential is considered Low.
Contributions of information and suggestions are welcome!