Minnesota Drought Situation Report - September 6, 2007

Drought Monitor - September 4, 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. This week's Drought Monitor map includes no significant changes from the previous week.

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 Tuesday morning, September 4 was highly variable across the state. Welcome rainfall totals of one to two inches were reported in Lake and Cook counties (see map at left). One to two inch rainfall amounts were also reported along a narrow band from Detroit Lakes to Duluth. Western counties were the driest, with most of the western one third of Minnesota reporting less than one-quarter inch of rain for the August 28 through September 4 time frame. Temperatures last week were warm, averaging three to four degrees above normal. Many locations reported at least one temperature of over 90 degrees.

Summer Dryness (June 5 - September 4):
Dryness has been entrenched across north central, northeastern, and central Minnesota for much of the summer. Rainfall for the thirteen-week period from June 5 through September 4 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 thirteen-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 - September 4 rainfall totals were near all-time record low values. 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 September 4 2007 Precipitation June 5 to September 4 2007 Precipitation Departure Map June 5 to September 4 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_070906.htm
Last modified: September 6, 2007