Minnesota Drought Situation Report - July 24, 2007

Drought Monitor - July 17, 2007
Drought Monitor Map
Drought Monitor Legend

Drought Status
The latest U. S. Drought Monitor (see map at right) 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 Minnesota (see map below). Most locations in the state received less than a quarter inch of rain for the seven-day period ending Monday morning, July 23. Significant rainfall was reported in just a few areas. Many locations along the southern tier of Minnesota counties received one to two inches of rain for the week. Heavier rainfall totals were also reported to the south and east of Bemidji, in portions of southern St. Louis County, and along a narrow band through the heart of the Twin Cities metropolitan area. Weekly temperatures were near the long-term mean last week. Historically, the last two weeks of July and the first week of August are the warmest of the summer. 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 July. 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 during a warm June, has led to deteriorating crop conditions, lower stream flows and lake levels, and increased wildfire danger.

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 (see map below). Growing season rainfall totals have deviated negatively from historical averages by more than four inches across many central, east central, southwestern, and south central Minnesota counties (see map below). This is roughly the equivalent of missing all of June's rainfall. Seasonal rainfall deficits exceeding five inches are reported along a band extending from the metropolitan area through Mankato and southwestward into Fairmont. Five-inch deficits are also reported in central Minnesota, and in portions of southwestern Minnesota. When compared with other seasonal rainfall totals-to-date in the historical database, this year's rainfall totals for the season rank below the 20th percentile (one year in five) across much of southern Minnesota (see map below).

April 1 to July 23 2007 Precipitation Map April 1 to July 23 2007 Precipitation Departure Map April 1 to July 23 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_070724.htm
Last modified: July 24, 2007