HydroClim Minnesota - August 2007
A monthly electronic newsletter summarizing Minnesota climate conditions and the resulting impact on water resources.
Distributed on the Wednesday following the first Monday of each month.
State Climatology Office - DNR Waters
WHAT HAPPENED IN
- July 2007 rainfall totals were
well below historical averages in most Minnesota communities. Many locations
reported less than two inches of rain for the month. Most locations in west
central, central, and southwestern Minnesota received less than one inch of
rain in July. Hutchinson reported their 2nd driest July in history with 0.50
inch of rainfall for the month. A 0.30 inch July rainfall total in Pipestone
was also the second driest on record. The monthly rainfall total for Redwood
Falls was 0.16 inch, the driest July in their historical record.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp , http://climate.umn.edu/doc/journal/warm0707.htm , http://climate.umn.edu/weathertalk/070803.txt , http://www.crh.noaa.gov/crnews/display_story.php?wfo=fsd&storyid=9444&source=0
- rainfall for the eight-week period from June 5 through July 30
totaled less than three inches over much of the southern two thirds of
Minnesota. In most of these areas, rainfall totals for the period were four
or more inches short of the historical average. When compared with
historical rainfall totals for the same eight-week time frame, 2007 values
ranked at or below the 5th percentile for many central and southern
Minnesota counties. In a few areas, the June 5 - July 30 rainfall totals
were near all-time record low values.
- monthly mean temperatures for July 2007 were near, to somewhat above,
historical averages across Minnesota. A spell of seasonally cool weather
during the middle of the month was counterbalanced by a warm finish to the
month. Extreme values for July ranged from a high of 101 degrees at Browns
Valley (Traverse County) and Canby (Yellow Medicine County) on the 7th, to a
low of 32 degrees at Embarrass (St. Louis County) on July 13.
WHERE WE STAND NOW
- growing season rainfall totals
(April 1 to present) are less than nine inches across much of central
Minnesota. Seasonal rainfall totals have deviated negatively from historical
averages by more than four inches across many central, east central,
southwestern, and south central Minnesota counties. This is roughly the
equivalent of missing all of June's rainfall. Seasonal rainfall deficits
exceeding six inches are reported in a band that extends from Litchfield in
central Minnesota eastward into portions of the Twin Cities metropolitan
area. Six-inch shortfalls are also in place in some south central Minnesota
counties. When compared with other seasonal rainfall totals-to-date in the
historical database, this year's rainfall for the season ranks just above
the 10th percentile (one year in ten occurrence) in many Minnesota counties.
, http://climate.umn.edu/doc/weekmap.asp )
- the U. S.
Drought Monitor released on July 31 places portions of northeastern
Minnesota, and most of the southern one half of Minnesota, in the Severe
Drought category. With the exception of northwestern counties, the remainder
of Minnesota is classified as experiencing a Moderate Drought or 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, a
snow-sparse 2006-2007 winter, and dry 2007 mid-summer weather. The drought
situation in the southern two thirds of Minnesota is due to an extremely dry
2007 growing season. The U. S. Drought Monitor index is a blend of science
and subjectivity where intensity categories are based on several
(see: http://www.drought.unl.edu/dm/monitor.html , http://climate.umn.edu/img/journal/drought_2007/dm_animation_070731.gif
- the U.S. Geological Survey reports that stream discharge values in
roughly 45% of Minnesota's rivers and streams are below the 25th percentile
when compared with historical data for this time of year. Flow conditions in
many northeastern, central, and east central Minnesota watersheds fall below
the 10th percentile for the date, leading the Department of Natural
Resources to suspend surface water appropriation permits in some areas.
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 heart of some of Minnesota's more famous
droughts (1976, 1988, 2006).
- lake levels continue to drop throughout Minnesota, exposing
shoreline, and in some cases, making water access difficult. Anecdotal
reports indicate that many lakes, especially in 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 could fall
below the all-time seasonal low by early autumn.
, http://www.dnr.state.mn.us/lakefind/ )
Minnesota Agricultural Statistics Service reports that as of August 3,
topsoil moisture across nearly 85% of Minnesota's landscape was "Short" or
"Very Short". Corn and soybean conditions in many areas continue to decline
in response to the diminishing soil moisture reserves. Only 25% of
Minnesota's corn acreage is considered to be in "Good" or "Excellent"
condition. A federal agricultural disaster has been declared for 24
Minnesota counties suffering from drought. Farmers and ranchers in an
additional 32 adjacent counties will also be eligible for drought recovery
- the DNR Division of Forestry classifies current wildfire danger as
"High" or "Very High" across much of central, east central, and northeastern
Minnesota. Most of the remainder of the state is depicted in the "Moderate"
(see: http://www.dnr.state.mn.us/forestry/fire/ )
- the August precipitation
outlook from the Climate Prediction Center indicates no significant
tendencies away from climatological probabilities across Minnesota. August
precipitation normals range from under three inches in northwestern and west
central Minnesota to over four and one half inches in southeastern
- the August temperature outlook indicates no significant tendencies
away from climatological probabilities across Minnesota. Normal August high
temperatures are around 80 degrees to start the month, dropping to the
mid-70's by month's end. Normal lows are around 60 degrees early in the
month, falling to the mid-50's by late August.
- the 90-day precipitation outlook for August through October indicates
no significant tendencies away from climatological probabilities across
Minnesota. The August through October temperature projection tilts towards
above-normal conditions across northeastern Minnesota, with no significant
tendencies away from climatological probabilities elsewhere.
- the National Weather Service produces long-range probabilistic river
stage and discharge outlooks for the Red River, Minnesota River, and
Mississippi River basins. These products are part of the National Weather
Service's Advanced Hydrologic Prediction Service (AHPS).
(see: http://www.crh.noaa.gov/ncrfc/ )
- until drought
conditions improve in the Upper Mississippi River basin, the National
Weather Service will routinely produce low flow projections for the
Mississippi River near Anoka.
NOTES FROM THE AUTHOR
NOTES FROM AROUND THE STATE
UPCOMING DATES OF NOTE
- August 16: National Weather Service releases 30/90 day temperature and precipitation outlooks
WEB SITES FEATURED IN THIS EDITION
http://climate.umn.edu - Minnesota
Climatology Working Group, Minnesota DNR Waters and University of Minnesota
Department of Soil, Water, and Climate
http://www.drought.unl.edu - National
Drought Mitigation Center
- U.S. Geological Survey
- Minnesota DNR Waters
Detroit District, US Army Corps of Engineers
http://www.nass.usda.gov - USDA,
National Agricultural Statistics Service
- Minnesota DNR Forestry
Climate Prediction Center, National Weather Service
North Central River Forecast Center - Chanhassen, National Weather Service
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