Minnesota Drought Situation Report - August 30, 2007

Drought Monitor - August 28, 2007
Drought Monitor Map
Drought Monitor Legend

Drought Status
The latest U. S. Drought Monitor (see map at right) places Minnesota's Arrowhead region and portions of central Minnesota in the Extreme Drought category. Much of the rest of the northern two-thirds of Minnesota falls in the Severe Drought or Moderate Drought designation. Most of northwestern Minnesota is described as being Abnormally Dry.

The week's Drought Monitor map includes some notable changes from the previous week. Substantial August rains led to the elimination of drought designations in the southern three tiers of Minnesota counties. Heavy, but isolated, rain on August 20 somewhat diminished the area of extreme drought in west central Minnesota. Persistent dryness has expanded the Extreme Drought area in northeastern Minnesota to include much of northern St. Louis County.

The drought situation in the northern one third of Minnesota is the result of the lingering impacts of a very dry 2006, a snow-sparse 2006-2007 winter, and dry 2007 mid-summer weather. The drought situation in the central third of Minnesota is due to an extremely dry 2007 growing season (see: 12-week U.S. Drought Monitor animation). The U. S. Drought Monitor index is a blend of science and subjectivity where intensity categories are based on several indicators.

Weekly Precipitation Map Last week's weather:
Rainfall for the week ending Monday morning, August 27 was highly variable across the state. Significant portions of southern and central Minnesota received over one inch of rain, whereas most of northern Minnesota reported rainfall totals of one half inch or less (see map at left). Once again, very heavy rain fell upon portions of southeastern Minnesota, an area already burdened by excessive rainfall earlier in the month. In an event occurring after the Monday morning map deadline, a welcome one to two inches of rain fell across portions of central and northern Minnesota on Monday evening and early Tuesday morning. Isolated heavy rain reports came from drought-stricken counties such as Hubbard, Wadena, Todd, Cass, Crow Wing, Itasca, Aitkin, and St. Louis. As has been the case so often this growing season, the rain streaks were geographically isolated. The rain was welcome, but did not significantly change the drought status in these locales. For the second consecutive week, temperatures were near, or below, the long-term mean.

Summer Dryness (June 5 - August 28):
Dryness has been entrenched across central, north central, and northeastern Minnesota for much of the summer. Rainfall for the twelve-week period from June 5 through August 28 totaled less than six inches in many locations in central and northern Minnesota (see map below). In these areas, rainfall totals for the period were five or more inches short of the historical average (see map below). When compared with historical rainfall totals for the same twelve-week time frame, 2007 values ranked at or below the 5th percentile (one year in twenty occurrence) for many counties (see map below). In a few areas, the June 5 - August 28 rainfall totals were near all-time record low values. The timing of the dry weather is unfortunate. The period from May through September is historically the wettest time of the year in Minnesota. Long-term average rainfall rates during this time interval are around one inch per week. Very dry weather, occurring during a time of year when ample rain is typical, leads to the rapid intensification of drought. The lack of precipitation, along with very high evaporation rates, led to deteriorating crop conditions, lower stream flows and lake levels, and increased wildfire danger.

June 5 to August 28 2007 Precipitation June 5 to August 28 2007 Precipitation Departure Map June 5 to August 28 2007 Precipitation Ranking Map

Sector briefs:

More drought information resources are found at http://climate.umn.edu/doc/journal/drought_information_resources.htm.

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URL: http://climate.umn.edu/doc/journal/drought_situation_report_2007_070830.htm
Last modified: August 30, 2007