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.
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.
Agriculture - The
Agricultural Statistics Service reports that as of August 24, topsoil moisture across 38% of Minnesota's landscape was "Short" or "Very Short". This is
a 30% improvement from the previous week's report. 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 40% of Minnesota's corn acreage is considered to be in "Good" or "Excellent" condition. 54% of Minnesota's soybean acreage is considered
to be in "Good" or "Excellent" condition. These percentages reflect a 10% improvement in the condition of Minnesota's major row crops from the previous week.
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.
Lake levels -
Water levels are very low on many Minnesota lakes, exposing shoreline, and in some cases, making water access difficult.
Quantitative lake level data are difficult to obtain in real time. However, 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 monthly value 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 or High across
much of northern Minnesota. The remainder of the state is depicted in the Low Danger category. The DNR has slightly eased burning restrictions in northeastern Minnesota counties, however
the threat of wildfire remains.
Public water supply - Many Minnesota communities
have imposed watering restrictions due to increased lawn watering demands.