Dry Mid-Summer 2008 (updated July 31, 2008)
Abrupt changes in precipitation patterns over time are common in Minnesota. This was the case during the 2008 growing season. A stretch of very dry weather arrived immediately on the heels of an extremely wet first half of June.
For a six-week period during the last two weeks of June and into late July, many Minnesota communities received less than two inches of rainfall. This came at a time of year when rainfall rates average roughly one inch per week. Thus, rainfall deficits over the six-week dry spell topped three inches in many areas. Described another way, six-week rainfall totals were less than 50 percent of normal for the period (see maps below).
Temperatures over the six-week period were at, to slightly below, historical averages. This kept evaporative demand near seasonal norms and mitigated the situation somewhat. In 2007, late-June and early-July temperatures were well above average, amplifying evaporation and transpiration rates.
As of July 29, the U.S. Drought Monitor rated a large portion of central and southern Minnesota and some counties in northern Minnesota as D0 - Abnormally Dry (see map at right). A portion of Traverse county was placed in the D1 - Moderate Drought category.
- Agriculture - The Agricultural Statistics Service reported that as of July 25, topsoil moisture across 28 percent of Minnesota's landscape was "Short" or "Very Short". Some of the driest topsoil conditions were found in central and southwestern Minnesota, and a small section of north central Minnesota. Fortunately, stored moisture lower in the soil profile supported crop conditions into late July. In the July 28 Crop Progress and Condition Report, 73 percent of corn and 74 percent of soybeans were rated in good or excellent condition.
- Stream flow - Stream discharge in most Minnesota rivers and streams was near the middle of the historical distribution for late July. However, stream flows were trending downward, and in a few watersheds, flow conditions were below the 25th percentile for the date.
- Lake Superior water level - The Lake Superior water level remained below its historical average in late July 2008, but was well above the very low readings of 2007.
- Wildfire Danger - The Department of Natural Resources - Division of Forestry classified late-July wildfire danger as Low, across Minnesota.