HydroClim Minnesota - October 2006

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 10/4/06


WHAT HAS HAPPENED

- September 2006 precipitation totals were near to above average across much of Minnesota. In some west central and central Minnesota counties, September rainfall topped average by two or more inches. The heavier rain brought welcome relief to central Minnesota communities that had experienced precipitation shortfalls earlier in the season. Unfortunately, many of the drought-stricken areas of north central and northeastern Minnesota received below average rainfall for the month. In these northern Minnesota areas, the dry September marks the fifth consecutive month of precipitation deficits.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )
- monthly mean temperatures for September 2006 were generally cooler than normal in most areas of the state, except in northern counties. The average temperature for the month ranged from one to three degrees cooler than normal in the southern two thirds of the state, but near to slightly above normal in the far north. Extreme values ranged from 89 degrees at Moorhead on the 14th to just 19 degrees at Embarrass on the 9th. There were multiple frosts in the north and single frosts in some central and southern counties during the month. However, nearly all crops reached maturity without frost damage.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )

WHERE WE STAND NOW

- dryness has been entrenched across much of northern and central Minnesota for twenty weeks. The timing of the dry weather was unfortunate. The period from mid-May through early-September is historically the wettest time of the year in Minnesota. Long-term average rainfall rates during this time interval are around one inch per week. Very dry weather, occurring during a time of year when ample rain is typical, led to the rapid intensification of drought. The lack of precipitation, along with one of the hottest Julys on record, produced deteriorating crop conditions, low stream flows and lake levels, and increased the danger of wildfire. Rainfall totals over the past twenty weeks (May 16 - October 2) were less than eight inches in some areas of northwestern and north central Minnesota. Twenty-week rainfall totals deviated negatively from historical averages by more than four inches across most of the northern one half of Minnesota. Rainfall deficits exceeded six inches in many northern and central Minnesota communities. When compared with other May 16 to October 2 rainfall totals in the historical database, this year's rainfall totals for the period rank below the 5th percentile (one year in twenty) in many northern and central Minnesota counties. For isolated areas of northern Minnesota, rainfall totals are among the lowest on record for the twenty-week period.
(see: http://climate.umn.edu/doc/journal/drought_situation_report_2006.htm , http://climate.umn.edu/doc/weekmap.asp )
- the National Drought Mitigation Center (NDMC) - U. S. Drought Monitor indicates that as of October 3, many northern Minnesota counties fall in the "Extreme Drought" or "Severe Drought" categories. The northern reaches of the Red River Valley are depicted in the "Moderate Drought" or "Abnormally Dry" classification. Most of the southern one half of Minnesota does not warrant a drought classification. The NDMC index is a blend of science and subjectivity where intensity categories are based on five key indicators and numerous supplementary indicators.
(see: http://www.drought.unl.edu/dm/monitor.html )
- the Minnesota Agricultural Statistics Service reports that as of September 29, topsoil moisture for 20% of Minnesota's landscape was "Short" or "Very Short", a 5% improvement from the previous week. Topsoil moisture is rated as "Adequate" or "Surplus" across 80% of the state, up from a season low of 15% in late July.
(see: http://www.nass.usda.gov/Statistics_by_State/Minnesota/Publications/Crop_Progress_&_Condition/index.asp )
- the U.S. Geological Survey indicates that stream discharge in roughly one quarter of Minnesota's rivers and streams falls below the 25th percentile when compared with historical data for this time of year. Flow conditions in many northern and central Minnesota watersheds remain below the protected flow threshold (lowest 10th percentile), leading the Department of Natural Resources to maintain surface water appropriation permit suspensions in these areas. Mississippi River flow conditions remain very low due to season-long rainfall deficits in the headwaters area. Lake levels continue to drop in northern and central Minnesota, exposing shoreline, and in some cases, making water access difficult.
(see: http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd, http://climate.umn.edu/dow/weekly_stream_flow/stream_flow_weekly.asp )
- the potential for wildfires is rated by DNR Forestry as "moderate" in portions of northwestern and eastern Minnesota. The fire danger potential is rated as "low" elsewhere in the state.
(see: http://www.dnr.state.mn.us/forestry/fire/ )

FUTURE PROSPECTS

- the October precipitation outlook from the Climate Prediction Center tilts towards above normal precipitation in the southern one half of Minnesota, and indicates no significant tendencies away from climatological probabilities across northern Minnesota. Normal October precipitation ranges from one and one half inches in northwestern Minnesota, to over two and one half inches in portions of north central and northeastern Minnesota.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/30day , http://climate.umn.edu/img/normals/precip/precip_norm_10.htm )
- the October temperature outlook from the Climate Prediction Center indicates no significant tendencies away from climatological probabilities across Minnesota. Normal October high temperatures fall from the low to mid 60's early in the month to the upper 40's by month's end. Normal October low temperatures drop from the low 40's early in the month to near 30 by late October.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/30day , http://climate.umn.edu/img/normals/temp_norm_adj/temp_norm_adj_10.htm )
- the 90-day precipitation outlook for October through December indicates no significant tendencies away from climatological probabilities across most of Minnesota. However, the forecast leans towards below normal precipitation in far southeastern Minnesota. The October through December temperature outlook indicates a tilt towards above normal conditions over most of Minnesota.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/90day/lead01/index.html )
- 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: http://www.crh.noaa.gov/ncrfc/ahps/ESPMAPS )

FROM THE AUTHOR

- a wet October would greatly improve drought conditions in northern Minnesota. Fall rainfall is very efficient in replenishing soil moisture reserves and surface water systems. Autumn rains are often gentle and widespread. Additionally, native and agronomic plants have reached the end of their growing season and are no longer consuming water.
- drought situation reports are prepared frequently by this office. These reports, along with other drought information resources, are available at http://climate.umn.edu/doc/journal/dry_summer_2006.htm .
- we are pleased to announce that the 14th annual presentation in the Kuehnast Lecture Series in Meteorology and Climatology will be held Wednesday, October 4, 2005 at 3:30 PM. The lecture location is Room 335 of Borlaug Hall on the University of Minnesota St Paul Campus. The title of this year's lecture is "The Pileus Project: Climate Science in Support of Decision Making for an Intensively-Managed Agricultural Crop", presented by Dr. Julie Winkler of Michigan State University. The Kuehnast family established an endowment directed toward teaching and learning in atmospheric science. The lecture series is co-sponsored by the University of Minnesota Department of Soil, Water, and Climate - Kuehnast Endowment Fund and the local chapter of Sigma XI (The Scientific Research Society).

NOTES FROM AROUND THE STATE

- from Dave Dickey, DNR Area Wildlife Manager Aitkin

I've worked in Aitkin County going on some 35+ years. In that time, I've seen the Mississippi recede to very low levels, exposing mud banks. But, this is the first that these exposed mud banks have become vegetated! I also believe the Rice River is no longer flowing or very little.

UPCOMING DATES OF NOTE

- October 4, Kuehnast Lecture Series (see above)
- October 19, Climate Prediction Center releases 30/90 day temperature and precipitation outlooks

WEB SITES FEATURED IN THIS EDITION

http://climate.umn.edu - Minnesota Climatology Working Group
http://www.crh.noaa.gov/mpx - National Weather Service Forecast Office - Chanhassen
http://www.drought.unl.edu - National Drought Mitigation Center
http://www.nass.usda.gov/Statistics_by_State/Minnesota/Publications/Crop_Progress_&_Condition/index.asp - USDA, National Agricultural Statistics Service
http://water.usgs.gov/cgi-bin/dailyMainW?state=mn&map_type=weekd - U.S. Geological Survey
http://www.dnr.state.mn.us/waters - Minnesota Department of Natural Resources, Division of Waters
http://www.dnr.state.mn.us/forestry - Minnesota Department of Natural Resources, Division of Forestry
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://www.crh.noaa.gov/ncrfc - National Weather Service North Central River Forecast Center - Chanhassen

ACKNOWLEDGEMENTS

- Dr. Mark Seeley, Extension Climatologist and Meteorologist, University of Minnesota


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