|HydroClim Minnesota - August 2004
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 HAS HAPPENED
- rainfall totals across Minnesota were highly variable in July 2004. As is often the case during a Midwestern summer, thunderstorm-delivered rainfall occurred in striped patterns that often affected one locale, while leaving a neighboring community dry. The heaviest precipitation in July occurred in portions south central Minnesota where rainfall totals topped historical averages by two to four inches. Rainfall was short of average by one to two inches in some sections of northeastern Minnesota.
- flooding rains were reported in a few communities in July. Perhaps the most significant event of the month occurred in Freeborn county on July 5. Torrential rains of two to five inches fell in the Albert Lea area leading to street flooding and the temporary closure of some rural roads.
- following a trend established in May and June, July 2004 temperatures were cool. July monthly mean temperatures were one to four degrees below normal. Daily minimum temperature records were set throughout the month in many locations. The temperature extremes for July ranged from 99 degrees at Ortonville (Big Stone county) on the 21st, to 26 degrees at Tower (St. Louis county) on the 24th.
WHERE WE STAND NOW
- growing season precipitation totals to date (April 1 through early August) are quite variable across Minnesota. Seasonal precipitation totals are short of the historical average by three to five inches over significant sections of north central and northeastern Minnesota. When compared with other April through early August periods in the historical database, this season's rainfall ranks below the 25th percentile in these locations. Conversely, growing season rainfall totals in portions of northwestern, central, south central and southeastern counties, have been well above normal. Rainfall since April 1 has exceeded the historical average by more than six inches in most southeastern Minnesota communities. In northwestern Minnesota and much of the southern one half of the state, growing season rainfall totals rank above the 75th percentile when compared with past years. In far southeastern counties, the growing season rainfall-to-date ranks above the 98th percentile.
- as of July 27, the National Drought Mitigation Center (NDMC) - U. S. Drought Monitor indicated that most of the state of Minnesota is free of drought designations. However, an area of north central and northeastern Minnesota is judged to be in the "D0 - Abnormally Dry" category. The NDMC index is a blend of science and subjectivity where intensity categories are based on six key indicators and numerous supplementary indicators.
- the Minnesota Agricultural Statistics Service reports that as of July 30, the state's topsoil moisture was 3% very short, 16% short, 76% adequate, and 5% surplus.
- U.S. Geological Survey stream gauging indicates that stream discharge values for nearly three fourths of Minnesota's rivers rank near the middle of the historical distribution. However, stream levels in portions of north central and northeastern Minnesota rank below the 25th percentile for the date. By contrast, many streams in far southern Minnesota are discharging volumes that rank above the 75th percentile for the date.
- the potential for wildfires is rated by DNR Forestry as "moderate" in northeastern Minnesota and "low" elsewhere in Minnesota.
- the August precipitation outlook from the Climate Prediction Center indicates a tilt towards above normal conditions across nearly all of Minnesota. August precipitation normals range from under three inches in northwestern and west central Minnesota to over four and one half inches in southeastern counties.
- the August temperature outlook shows no significant tendencies away from climatological probabilities. 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 a tilt towards above normal conditions for the southern one half of Minnesota, and no significant tendencies away from climatological probabilities in northern Minnesota. The August through October temperature outlook indicates a tilt towards below normal conditions throughout Minnesota.
- the National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. A hydrologic model is initialized using current conditions of stream flow and soil moisture across a basin. The model is allowed to run into the future with multiple scenarios using many years of historical climatological data. The climatological data are weighted by 90-day climate outlooks for temperature and precipitation trends. Model output offers a complete range of probabilistic values of stream stage and discharge for numerous forecast points. The product provides a risk assessment tool which can be used in long-range planning decisions involving flooding or low flow concerns. These products are part of the National Weather Service's Advanced Hydrologic Prediction Service (AHPS) and are produced near the middle of each month.
FROM THE AUTHOR
NOTES FROM AROUND THE STATE
UPCOMING DATES OF NOTE
- August 19, Climate Prediction Center releases 30/90 day temperature and precipitation outlooksWEB SITES FEATURED IN THIS EDITION
http://climate.umn.edu - Minnesota Climatology Working Group
http://www.drought.unl.edu/ - National Drought Mitigation Center
http://www.nass.usda.gov/mn/ - Minnesota Agricultural Statistics Service
- Midwestern Regional Climate Center
http://swroc.coafes.umn.edu/ - University of Minnesota Southwest Research and Outreach Center, Lamberton
- U.S. Geological Survey, Minnesota
- Minnesota Department of Natural Resources - Division of Waters
- Minnesota Department of Natural Resources - Division of Forestry
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://www.crh.noaa.gov/ahps - National Weather Service, Central Region Headquarters
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