Minnesota Drought Situation Report - July 17, 2007

Drought Monitor - July 10, 2007
Drought Monitor Map
Drought Monitor Legend

Drought Status
The latest U. S. Drought Monitor places portions of north central, northeastern, east central, central, south central, and southwestern Minnesota in the Moderate Drought category. Most of the Lake Superior watershed, including an area of northeastern Minnesota, is classified as experiencing a Severe Drought. Much of the remainder of the eastern three quarters of Minnesota is depicted as being Abnormally Dry. The drought situation in the northern one third of Minnesota is the result of the lingering impacts of a very dry 2006, and a snow-sparse 2006-2007 winter. The drought situation in the southern two thirds of Minnesota is due to a dry 2007 growing season. The U. S. Drought Monitor index is a blend of science and subjectivity where intensity categories are based on several indicators.

Last week's weather:
Precipitation last week was generally light across the southern one half of Minnesota. Most locations in this area received less than a quarter inch of rain for the seven-day period ending Monday morning, July 16. Rainfall amounts topped one inch for the week in northwestern and north central Minnesota. Monday rain occurring after the Monday morning map deadline ranged from one half inch to one inch in portions of southern Minnesota. It was a seasonally cool week with temperatures averaging three to five degrees below average. Cooler temperatures reduce evaporation rates and ease drought stress somewhat. Weekly Precipitation Map

Seasonal weather overview:
Dryness has been entrenched across much of the southern two thirds of Minnesota for much of May, June, and into mid-July. The timing of the dry weather has been 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 in June, has led to deteriorating crop conditions, low stream flows and lake levels, and increased the danger of wildfire.

Seasonal precipitation totals, departure, and ranking:
Rainfall totals since April 1 are less than eight inches across much of the southern one half of Minnesota. Growing season rainfall totals have deviated negatively from historical averages by more than four inches across many east central, central, southwestern, and south central Minnesota counties. Seasonal rainfall deficits exceeding five inches are reported along a band extending from the metropolitan area through Mankato and southwestward into Fairmont. Spotty four-inch deficits are also reported in central Minnesota, and in southwestern Minnesota. When compared with other seasonal rainfall totals to date in the historical database, this year's rainfall totals for the period rank below the 20th percentile (one year in five) in the driest areas.

April 1 to July 16 2007 Precipitation Map April 1 to July 16 2007 Precipitation Departure Map April 1 to July 16 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_070717.htm
Last modified: July 17, 2007