HydroClim Minnesota - July 2012
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 Division of Ecological and Water Resources, St. Paul
prepared: July 3, 2012 (early distribution)
What happened in June 2012:
- June 2012 monthly precipitation totals created a hodgepodge of very wet and very dry conditions across Minnesota. Due to two exceptional rainfall events, extremely large monthly rainfall totals were reported in portions of northeastern and southeastern Minnesota. Monthly rainfall totals in these areas exceeded 10 inches, more than doubling the historical average. By contrast, rainfall totals across much of Minnesota, especially the southern two tiers of Minnesota counties and some sections of northwestern and north central Minnesota, were short of the historical average by one to four inches.
[see: June 2012 Climate Summary Table | June 2012 Monthly Precipitation Map | June 2012 Precipitation Departure from Normal Map]
- Two intense rainfall events led to destructive flooding in June. Heavy thunderstorms on June 14 dropped rainfall totals of six to eight inches on portions of Rice, Dakota, and Goodhue Counties. The axis of the heaviest rainfall totals aligned nearly perfectly with the axis of the Cannon River watershed, amplifying the river flooding. On June 19 and 20, a large area of northeastern Minnesota received six to ten inches of rain over a 24-hour period. The rains, falling upon a landscape already saturated from previous rains, triggered major floods in Aitkin, Carlton, and St. Louis counties. Preliminary damage estimates for public infrastructure alone top 100 million dollars. In terms of rainfall intensity and the geographic extent of the heaviest of the rains, the event ranks among the worst in Minnesota's post-settlement history.
[see: Flooding Rains in Southeast Minnesota - June 14 | Flooding Rains in Northeast Minnesota - June 19 and 20]
- Monthly mean temperatures for June 2012 were two to four degrees above average over most of Minnesota. It was Minnesota's ninth consecutive month of above-normal temperatures. Extreme temperature values for June ranged from a high of 99 degrees F at Amboy (Blue Earth County) and St. James (Watonwan County) on the 27th, to a low of 28 degrees F at Brimson (St. Louis County) on the 1st. The completion of the July 2011-June 2012 heating season marked the lowest number of seasonal heating degree days (a climatological measure of heating demand) in the 141 year Twin Cities climate record.
[see: June 2012 Climate Summary Table | Record Low Number of Heating Degree Days]
Where we stand now:
- The 2012 growing season has been extraordinarily wet across sections of central, east central, and
northeast Minnesota. Seasonal precipitation totals starting with April 1 exceed 16 inches in many of these areas, topping the historical
average by eight or more inches. By contrast, growing season rainfall for most of northwestern Minnesota has been short of average by two or more inches.
[see: Wet Growing Season]
- The U. S. Drought Monitor, released on June 28, places some northwest Minnesota counties in the Moderate Drought category. Roughly one-quarter of the state is rated in the Abnormally Dry category. This week's excessive heat and recent precipitation shortages will likely lead to an expansion of Abnormally Dry areas in the next release. Nonetheless, the most recent release shows substantial improvement in the drought situation when compared with early May when 60 percent of Minnesota was said to be in the Moderate Drought or Severe Drought categories. 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 | Minnesota Drought Condition Summary | Red River Basin Drought Decision Support System]
- The U.S. Geological Survey and Minnesota DNR report that stream discharge values are very low at some northwest Minnesota reporting locations. Stream flow values rank below the 10th percentile for this time of year in some of these watersheds. Stream flows are very high in many east central and northeastern Minnesota basins. Stream discharge values in these watersheds rank above the 90th percentile when compared with historical data for the date.
[see: USGS stream flow conditions | MNDNR Weekly Stream Flow Maps and Tables]
- Water levels on Minnesota lakes located within areas receiving the season's heaviest rainfalls continued to be very high. Lake Superior water level rose notably in June in response to heavy rains in the eastern portion of the basin.
[see: Lake Minnetonka Water Levels | White Bear Lake Water Levels | Lake of the Woods Control Board Basin Data | Corps of Engineers Great Lakes Water Levels]
- In their July 1 report, the Minnesota Agricultural Statistics Service reported that topsoil moisture is 3% Very Short, 19% Short, 69% Adequate, and 9% Surplus across Minnesota. This represents a degradation in conditions when compared with an early-June soil moisture survey reporting only 5% of the landscape Short or Very Short. However, 70 to 80 percent of Minnesota's corn and soybean crop is said to be in good or excellent condition. This is a significantly higher percentage of favorable conditions than those reported by other Corn Belt states.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research Center (Lamberton) Soil Moisture | U. of M. Southern Research Center (Waseca) Soil Moisture]
- The potential for wildfires is currently rated by DNR Forestry as Very High in far northwest Minnesota. For some counties in northern Minnesota, wildfire potential is considered High or Moderate. The wildfire potential is considered Low in most of northeastern Minnesota and all of southern Minnesota.
[see: Fire Danger Rating Map]
- The July precipitation outlook projects equal chances of above-normal, near-normal, and below-normal conditions throughout Minnesota. July precipitation normals range from just over three inches in far northwestern Minnesota to over four inches in eastern sections of the state.
[see: Climate Prediction Center 30-day Outlook | July Precipitation Normal Map]
- The July temperature outlook is weighted towards above-normal conditions across the state. Normal July high temperatures are in the low to mid-80s. Normal July lows are around 60 degrees. July is historically the warmest month of the year in Minnesota.
[see: Climate Prediction Center 30-day Outlook | July Temperature Normal Map]
- The 90-day precipitation outlook for July through September offers an equal likelihood of below-normal, near-normal, or above-normal conditions across the state. The July through September temperature projection tilts towards above-normal conditions in southern Minnesota, an equal likelihood of below-normal, near-normal, or above-normal conditions in northern Minnesota.
[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 address both high flow and low flow probabilities.
[see: National Weather Service - North Central River Forecast Center]
From the author:
Notes from around the state:
Upcoming dates of note:
- July 19: 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 Eco/Water Resources and U of M Dept. of Soil, Water, and Climate
- http://water.weather.gov/precip/ - National Weather Service, Advanced Hydrologic Prediction Service
- http://www.drought.unl.edu - National Drought Mitigation Center
- http://www.rrbdin.org/rddss - Red River Basin Drought Decision Support System, International Water Institute
- 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 Ecological and Water Resources
- http://www.minnehahacreek.org - Minnehaha Creek Watershed District
- http://lwcb.ca/ - Lake of the Woods Control Board
- 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://sroc.cfans.umn.edu - University of Minnesota, Southern Research and Outreach Center, Waseca
- http://mndnr.gov/forestry - Minnesota Department of Natural Resources, Division of Forestry
- http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center
- http://www.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center
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