HydroClim Minnesota - August 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: August 3, 2012 (early distribution)

What happened in July 2012:

July 2012 monthly precipitation totals were very low across much of Minnesota, especially in southwestern counties. July rainfall totals were well under one inch in the driest areas. In many Minnesota communities, monthly rainfall amounts fell short of the historical average by one and one-half to three inches. The overall dry pattern was dissected by narrow stripes of heavier precipitation. Confined areas from Warroad to Grand Portage, and from Moorhead to Aitkin, received above-average July rainfall.
[see: July 2012 Climate Summary Table | July 2012 Monthly Precipitation Map | July 2012 Precipitation Departure from Normal Map]
Monthly mean temperatures for July 2012 were four to seven degrees above average over most of Minnesota. Preliminary data indicate that July 2012 was the second warmest month (any month) in the modern climate record. It was Minnesota's tenth consecutive month of above-normal temperatures. Extreme temperature values for July ranged from a high of 103 degrees F at Gaylord (Sibley County) and Minnesota City (Winona County) on the 6th, to a low of 42 degrees F at Agassiz National Wildlife Refuge (Marshall County) on the 27th.
[see: July 2012 Climate Summary Table | Hot July in Twin Cities]

Where we stand now:

The U. S. Drought Monitor, released on July 31 places many northwestern and southwestern Minnesota counties, and portions of some southeastern Minnesota counties, in the Severe Drought category. Other northwest and southern Minnesota counties are described as undergoing Moderate Drought. In total, approximately 50 percent of Minnesota is considered to be in the Abnormally Dry category or worse. The drought situation in northwest Minnesota is the result of a dry autumn, a snow-sparse winter, and a dry growing season. The moisture deficits in southern Minnesota developed rapidly due to very hot and very dry conditions in late June and throughout July. 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 discharge values are also quite low at many locations in southern Minnesota counties. Stream flows are high in some east central and northeastern Minnesota basins. Stream discharge values in these watersheds rank above the 75th percentile when compared with historical data for the date.
[see: USGS stream flow conditions | MNDNR Weekly Stream Flow Maps and Tables]
Water levels on many Minnesota lakes are falling in response to the dry, hot weather. Lake Superior water level is similar to the 2011 level at this time of year and somewhat below the long-term average for the date.
[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 29 report, the Minnesota Agricultural Statistics Service reported that topsoil moisture was 18% Very Short, 32% Short, 47% Adequate, and 3% Surplus across Minnesota. This represents a significant degradation in conditions when compared with an early-June soil moisture survey reporting only 5% of the landscape Short or Very Short. However, 55 to 60 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 Moderate in northwest Minnesota and in the southern one-third of the state. The wildfire potential is considered Low elsewhere in Minnesota.
[see: Fire Danger Rating Map]

Future prospects:

The August precipitation outlook projects equal chances of above-normal, near-normal, and below-normal conditions throughout 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.
[see: Climate Prediction Center 30-day Outlook | August Precipitation Normal Map]
The August temperature outlook is weighted heavily towards above-normal conditions across the state. Normal August high temperatures are around 80 degrees to start the month, dropping to the mid-70s by month's end. Normal lows are around 60 degrees early in the month, falling to the mid-50s by late August.
[see: Climate Prediction Center 30-day Outlook | August Temperature Normal Map]
The 90-day precipitation outlook for August through October offers an equal likelihood of below-normal, near-normal, or above-normal conditions across most of Minnesota. However, the outlook leans towards below-normal precipitation in southeast Minnesota. The August through October temperature projection tilts towards above-normal conditions statewide.
[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:

None

Notes from around the state:

None

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 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.cpc.ncep.noaa.gov - National Weather Service, Climate Prediction Center
http://www.crh.noaa.gov/ncrfc - National Weather Service, North Central River Forecast Center

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