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

compiled 5/9/01

WHAT HAS HAPPENED

- April 2001 brought major flooding to many of Minnesota's rivers. For some locations, river levels approached the flood of record. The spring flooding was the result of four contributing climatic factors:
1) significant autumn precipitation (heavy early November rains before soil freeze-up)
2) heavy winter snowfall (18 to 24 inches above average in many southern Minnesota locations)
3) less than ideal snowmelt scenario (below normal March temperatures)
4) record-breaking April precipitation (see below)
(see: http://climate.umn.edu/doc/journal/flood_2001/flood_2001.htm )
- April precipitation totals were extraordinarily high across most of Minnesota. A broad swath of southwestern, central, east central, and northeastern Minnesota received over six inches of precipitation from April 1 to April 23, 2001. Precipitation totals surpassed the historical average by more than four inches in these areas. For many communities, all-time April monthly precipitation records were set before the month came to a close. Three powerful storm sequences (April 6-7, April 10-11, and April 21-23) accounted for most of the precipitation. During the later stages of the April 21-23 event, heavy snow fell in a 100 mile wide band from Browns Valley to Minnesota's arrowhead region. Some locations received up to a foot of snow. Ice buildup on power lines and trees in northeastern Minnesota led to power outages and caused significant damage. 
(see: http://climate.umn.edu/cawap/monsum/monsum.asp , http://climate.umn.edu/doc/journal/april2001.htm , http://climate.umn.edu/doc/journal/20010423.htm )
- April temperatures were near normal across most of Minnesota, but finished roughly three degrees above normal in south central and southeastern Minnesota.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )


WHERE WE STAND NOW

- as of May 7, growing season precipitation (beginning April 1) was 200 to 300 percent of normal across much of the state. Growing season precipitation in some far northwestern Minnesota counties was somewhat closer to average for the period, but exceeded the normal nonetheless.
(see: http://climate.umn.edu/doc/weekmap.asp )
- the May 5 Palmer Drought Severity Index (PDSI) depicts southern Minnesota and sections of central Minnesota as "Extremely Moist", the wettest designation. East central and northeastern Minnesota counties are categorized as experiencing a "Very Moist Spell". West central and northwestern Minnesota communities are undergoing an "Unusual Moist Spell". The Palmer Drought Severity Index is used for assessing long-term meteorological conditions.
(see: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif )
- the Minnesota Agricultural Statistics Service reports that topsoil moisture statewide as of Sunday, May 6 was rated 57% surplus, 43% adequate, 0% short, and 0% very short. Quantitative soil moisture measurements are rare. However, recent soil moisture measurements from University of Minnesota research locations show exceedingly high values. Plant available soil moisture measured at the U. of M. facility in Waseca (Waseca county) exceeds ten inches in a five foot profile. Plant available moisture measured at Lamberton (Redwood county) is in excess of nine inches. For Lamberton, present soil moisture values are nearly 50 percent greater than the historical average for early May. Measurements at both research locations are made in plots planted in corn, soybeans, or a corn/soybean rotation. Across Minnesota, ground preparation and spring planting are far behind historical averages due to the wet soils.
(see: http://www.nass.usda.gov/mn/cwmn.htm , http://swroc.coafes.umn.edu/Weather/Charts/Soil/2001/01_soil_water.html )
- streams flows, while receding, remain high along all of Minnesota's rivers. The U.S. Geological Survey indicates that stream flows at many locations along the Red, Minnesota, and Mississippi rivers are at record highs for the date. For all other locations within these basins, stream flows are above the 75th percentile when compared to historical values for the date.
(see: http://water.usgs.gov/cgi-bin/daily_flow?mn )
- all of Minnesota's lakes are now free of ice. Lakes in the southern three quarters of Minnesota lost their ice one to two weeks later than historical averages. Later than average ice-outs are notable coming on the heels of record-breaking or near record-breaking early lake ice-outs in 2000. Ice-out dates for lakes in far northern Minnesota were close to historical averages.
(see: http://climate.umn.edu/doc/ice_out/ice_out_status_01.htm )
- the potential for wildfires is low for most Minnesota counties. Burning restrictions are being lifted as vegetative green-up occurs.
(see: http://www.dnr.state.mn.us/forestry/fire/ )


FUTURE PROSPECTS

- the 30-day outlook from the Climate Prediction Center shows no significant tendencies (equal chances of below, near, and above normal) in May precipitation for Minnesota. May precipitation normals range from two and a half inches in northwestern Minnesota to near four inches in the southeast. The May temperature outlook shows no significant tendencies away from climatological probabilities. Normal May high temperatures are in the low to mid 60's early in the month, rising to the low to mid 70's by month's end. Normal May lows are near 40 to start the month and climb to around 50 as the month ends. 
(see: http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/seasonal_forecast.html )
- the 90-day precipitation outlook for May through July shows no significant tendencies away from climatological probabilities. The May through July temperature outlook shows no significant tendencies away from climatological probabilities.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/seasonal_forecast.html )
- the National Weather Service now produces long-range probabilistic river stage and discharge outlooks for the Red River and Minnesota River basins. A hydrologic model is initialized using the current conditions of the river and soil moisture across the basin. The model is then allowed to run into the future with multiple scenarios using more than 30 years of climatological data. The climatological data are weighted by the 90 day outlooks for temperature and precipitation trends. The model output offers a complete range of probabilistic values of stream stage and discharge for numerous forecast points. The product offers 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 will be produced near the middle of each month. The AHPS service will be available for the Mississippi River Basin in the autumn of 2002.
(see: http://www.crh.noaa.gov/fgf/ahps/ahpsmain.htm for the Red River basin, http://www.crh.noaa.gov/mpx/ahps/index.html for the Minnesota River basin)


FROM THE AUTHOR

NOTES FROM AROUND THE STATE

- from John Linc Stine, DNR Waters Water Management Section Administrator - St. Paul

Preliminary Summary of Impacts of 2001 Spring Flooding:

•  67 out of 87 MN counties affected
•  estimated public damages in excess of $25 Million as of 5/1/01
•  estimated damage to over 300 homes and businesses, mostly in 5 counties
•  1 death
•  3rd highest flood of record at St. Paul and Breckenridge
•  2nd highest flood of record at Stillwater and Granite Falls
•  the cost to fight this flood at Granite Falls, for example, was $1 Million.
•  despite the magnitude and duration of this year’s flood events, it is remarkable that so many damages 
  have been averted. This is attributable to: 
  1) effective planning and flood preparedness by MN communities and the MN Dept. 
  of Public Safety, Division of Emergency Management.
  2) significant investments in protecting MN communities from flooding such as Mankato, St. Paul, 
  Moorhead, East Grand Forks, Chaska, Winona, Rochester and others.
  3) removal of over 2500 buildings from MN flood plains since the ‘97 flood.
  

UPCOMING DATES OF NOTE

WEB SITES FEATURED IN THIS EDITION

http://climate.umn.edu - Minnesota Climatology Working Group
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://www.nass.usda.gov/mn/ - Minnesota Agricultural Statistics Service
http://swroc.coafes.umn.edu - Univ. of MN. Southwest Research and Outreach Center
http://water.usgs.gov/cgi-bin/daily_flow?mn - U.S. Geological Survey, Minnesota
http://www.dnr.state.mn.us/forestry/fire/ - Minnesota Department of Natural Resources - Division of Forestry http://www.crh.noaa.gov/fgf - National Weather Service Forecast Office - Grand Forks
http://www.crh.noaa.gov/mpx - National Weather Service Forecast Office - Chanhassen


ACKNOWLEDGEMENTS

Contributions of information and suggestions are welcome!