Minnesota Drought Situation Report - September 6, 2007
Drought Monitor - September 4, 2007
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
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.
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.
Agriculture - The
Agricultural Statistics Service reports that as of August 31, topsoil moisture across 40% of Minnesota's landscape was "Short" or "Very Short". This is a substantial improvement from
the conditions reported in early August when nearly 85% of the state reported less than adequate soil moisture conditions. Corn and soybean conditions in many areas continue to be
sub-par due to inadequate soil moisture supply during the core of the growing season. Only 45% of Minnesota's corn acreage is considered to be in "Good" or "Excellent" condition.
52% of Minnesota's soybean acreage is considered to be in "Good" or "Excellent" condition. On August 7, a
federal agricultural disaster was declared for 24 Minnesota counties suffering from drought.
Farmers and ranchers in an additional 32 adjacent counties are also eligible for drought recovery assistance.
Stream flow - Stream discharge in
27% of Minnesota's rivers and streams remains below the 25th percentile when compared with historical data for this time of year.
Flow conditions in many north central, northeastern, central, and east central
Minnesota watersheds rank below the 10th percentile for the date. Mississippi River flow conditions remain very low along the upper reaches of the river.
Mississippi River discharge near Anoka is at roughly the same flow rate as it was during the 2006 drought, but significantly above the all-time record
low for the date set in 1934.
Lake levels -
Water levels are very low on many Minnesota lakes, exposing shoreline, and in some cases, making water access difficult. Anecdotal reports indicate that many lakes in northern,
central, and east central Minnesota are a foot or more below average levels for the date. The
Lake Superior water level is near an all-time low
for the date, and the mean daily August level will likely be declared as the all-time August low when statistics are finalized.
Wildfire Danger - The Department of Natural Resources - Division of Forestry classifies current
wildfire danger as Moderate across much of Minnesota. Northwestern Minnesota
and the southern one quarter of Minnesota are in the Low Danger category. The DNR has slightly
eased burning restrictions in northeastern Minnesota counties, however the threat of wildfire is still in place.
Public water supply - Many Minnesota communities
have imposed watering restrictions due to increased lawn watering demands.
More drought information resources are found at http://climate.umn.edu/doc/journal/drought_information_resources.htm.
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Last modified: September 6, 2007