HydroClim Minnesota - September 2010

A monthly electronic newsletter summarizing Minnesota's 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
compiled: September 9, 2010

What happened in August:

August 2010 rainfall totals varied widely across Minnesota. Monthly rainfall totals topped six inches in many locales, exceeding the historical average by two or more inches. In some central Minnesota communities, August rainfall totaled over eight inches, double the long-term mean. Conversely, August rainfall was short of average by roughly one inch in northwest, northeast, and south central Minnesota.
[see: August 2010 Climate Summary Table | August Rainfall - Departure from Normal]
As was the case during June and July, outbreaks of severe weather and/or heavy rain occurred frequently in the month of August. Tornadoes, hail, damaging winds, and flooding rains were reported somewhere in Minnesota on 14 different August dates.
[see: Heavy Rains: August 10-11 | Heavy Rains: August 12-13 | Storm Report Data]
Monthly mean temperatures for August 2010 were quite warm across Minnesota, exceeding the historical average by two to six degrees. Extreme temperature values for August ranged from a high of 96 degrees at the Twin Cities International Airport on the 8th, to a low of 33 degrees at Brimson (St. Louis County) on the 26th. High dew point temperatures were common in August, often topping 70 degrees in many locations. A new record was set in Rochester for the highest June-August average dew point temperature. Elsewhere, average summer dew point temperatures were near the top of the historical rankings.
[see: August 2010 Climate Summary Table | Warm Summer and August | Summer Dew Point Statistics]

Where we stand now:

Growing season precipitation totals through early September are well above historical averages in most Minnesota communities. Large sections of the state report growing season rainfall totals that rank above the 75th percentile when compared with the historical record for the same April 1-to-present time interval. In some locales, seasonal precipitation totals rank close to the wettest on record. Total seasonal rainfall in these areas has topped the historical average by four or more inches, the statistical equivalent of receiving an extra June's worth of precipitation. There have been geographically-isolated exceptions to this generally wet pattern. Seasonal precipitation totals have fallen short of average in portions of Minnesota's Arrowhead region. In these areas, less than 14 inches of precipitation was reported from mid-March through early September, a two to four inch negative departure from average.
[see: Weekly and Seasonal Precipitation Maps | Wet Summer | Wet Summer in SE MN | Dry Weather, Northeast MN]
The U. S. Drought Monitor, released on September 9, depicts all of Cook County and portions of Lake County as undergoing Severe drought. Other northeastern Minnesota counties are considered to be under the influence of Moderate drought or are Abnormally Dry. Although the U.S. Drought Monitor no longer depicts drought in east central Minnesota, some hydrologic systems in this area remain impacted by long-term dryness that began in June of 2008. This long-term precipitation anomaly is responsible for low water levels in larger lakes and wetland complexes across Anoka, Ramsey, Chisago, and Washington counties. The rest of Minnesota is without drought designation. The U. S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc) are based on several indicators.
[see: U.S. Drought Monitor]
The U.S. Geological Survey reports that stream discharge values in some northeastern Minnesota watersheds are below the 10th percentile when compared with historical data for the date. Stream levels are high to very high in many other Minnesota basins.
[see: USGS Streamflow | DNR Streamflow]
The Lake Superior water level is down eight inches from last year at this time and remains below the long-term average. Water levels on some northern, central, and east central lakes are below average. Water levels on a few larger lakes in east central Minnesota lakes remain exceptionally low. White Bear Lake, on the Ramsey/Washington county border is at its all-time record low level.
[see: Corps of Engineers Great Lakes Water Levels | White Bear Lake Water Level]
As of September 5, the Minnesota Agricultural Statistics Service reports that topsoil moisture was 0% Very Short, 3% Short, 74% Adequate, and 23% Surplus. 91 percent of Minnesota's corn crop is considered to be in Good or Excellent condition. 89 percent of soybeans were rated Good or Excellent.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research Center (Lamberton) Soil Moisture]
The potential for wildfires is currently rated by DNR Forestry as Moderate in Cook and Lake counties, Low elsewhere in the state.
[see: Fire Danger Rating Map]

Future prospects:

The September precipitation outlook leans towards above-normal rainfall in most Minnesota counties. September precipitation normals range from near two inches in far western Minnesota to around three and one-half inches in eastern sections of the state.
[see: Climate Prediction Center 30-day Outlook | September Precipitation Normal Map]
The September temperature outlook shows no significant tendencies away from historical climatological probabilities across Minnesota. Normal September high temperatures are in the mid-70s to start the month, dropping to the low to mid-60s by month's end. Normal lows are in the mid-50s early in the month, falling to around 40 by late September.
[see: Climate Prediction Center 30-day Outlook | September Temperature Normal Map]
The 90-day precipitation outlook for September through November shows no significant tendencies away from historical climatological probabilities across Minnesota. The September through November temperature projection tilts towards above-normal temperatures in all Minnesota counties.
[see: Climate Prediction Center 90-day Outlook]
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: National Weather Service North Central River Forecast Center]

From the author:

Two of Minnesota's important agricultural commodities, corn and soybeans, are enjoying an excellent growing season. An early plant, ample rain, and adequate heat unit accumulations have created a situation where yield potential is very high.

Notes from around the state:

None

Upcoming dates of note:

September 16: National Weather Service releases 30/90 day temperature and precipitation outlooks
September 16: Kuehnast Lecture

Web sites featured in this edition:

http://climate.umn.edu - Minnesota Climatology Working Group, Minnesota DNR Waters and U of M Dept. of Soil, Water, and Climate
http://www.spc.noaa.gov - National Weather Service, Storm Prediction Center
http://www.crh.noaa.gov/mpx/ - National Weather Service, Weather Forecast Office - Chanhassen
http://www.crh.noaa.gov/arx/ - National Weather Service, Weather Forecast Office - La Crosse
http://www.drought.unl.edu - National Drought Mitigation Center
http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey
http://mndnr.gov/waters - Minnesota Department of Natural Resources, Division of Waters
http://www.lre.usace.army.mil - US Army Corps of Engineers, Detroit District
http://www.nass.usda.gov - USDA, National Agricultural Statistics Service
http://swroc.cfans.umn.edu - University of Minnesota Southwest Research and Outreach Center, Lamberton
http://mndnr.gov/forestry - Minnesota Department of Natural Resources, Division of Forestry
http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center
http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center

To subscribe or unsubscribe to HydroClim Minnesota please notify .

Contributions of information and suggestions are welcome!