HydroClim Minnesota - December 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 12/6/06

WHAT HAS HAPPENED

- November 2006 precipitation totals were below average in most Minnesota locations. November precipitation fell short of the historical normal by one half inch to one inch across the state. Many west central Minnesota communities reported less than one quarter inch of precipitation for the month. The dry weather perpetuated the drought conditions that have been in place in the northern one half of Minnesota for the past seven months. The unusually dry late-autumn weather has also increased concerns about topsoil moisture in the southern one half of the state.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )
- despite the general dryness, November precipitation totals approached or exceeded average for a few southeastern Minnesota counties. This was due to two significant precipitation events during the month. On November 10, a late autumn storm dropped a heavy band of snow across south central and southeastern Minnesota. Snowfall totals in excess of eight inches were reported in Mankato, Albert Lea, and Rochester. On November 28, significant rain, sometimes accompanied by thunder and lightning, fell upon much of Minnesota, especially the eastern one half of the state. Rainfall amounts for this event topped one inch in portions of southeastern Minnesota.
(see: http://climate.umn.edu/doc/journal/snow061110.htm ) - monthly mean temperatures for November 2006 were warmer than average throughout Minnesota. Average temperatures for the month generally ranged from three to five degrees above normal. Very warm late-November temperatures offset a cold start to the month. Maximum temperatures on November 8, and over the Thanksgiving weekend, approached or exceeded all-time high records for many communities. Extreme values for the month ranged from 83 degrees at Mankato on the 8th, to -6 degrees at Hallock (Kittson county) on the 30th.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )

WHERE WE STAND NOW

- the snow depth map to be prepared on December 7 will show that much of the northern tier of Minnesota counties have three to five inches of snow on the ground. The remainder of the northern half of Minnesota has one to three inches of snow on the ground. Elsewhere in Minnesota, snow cover is sparse to nonexistent.
(see: http://climate.umn.edu/doc/snowmap.htm )
- dryness has been entrenched across much of northern and central Minnesota for nearly seven months. Precipitation totals over the past seven months were less than nine inches in some areas of northwestern and north central Minnesota. Seven-month rainfall totals have deviated negatively from historical averages by more than five inches across most of the northern one half of Minnesota. (see: http://climate.umn.edu/doc/journal/drought_situation_report_2006.htm )
- the mid-summer dryness was ameliorated by substantial August and September rainfalls in across much of the southern one half Minnesota. However, October plus November precipitation totals fell short of average by one to three inches in most Minnesota counties. Fall recharge is important in establishing an adequate soil moisture reservoir for the upcoming growing season. In the absence of significant fall recharge, the soils will rely heavily upon early spring rains to bring moisture levels up to sufficient levels.
(see: http://mcc.sws.uiuc.edu/cliwatch/drought/moisture.htm ) - the National Drought Mitigation Center (NDMC) - U. S. Drought Monitor to be released on December 7 will continue to indicate that many northern Minnesota counties remain 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. The "Abnormally Dry" polygon covers much of central and southern Minnesota. The NDMC index is a blend of science and subjectivity where intensity categories are based on several indicators.
(see: http://www.drought.unl.edu/dm/monitor.html )
- the U.S. Geological Survey reports that stream discharge values, for locations where winter measurement are possible, are near or above the median for the date in far southeastern Minnesota. Stream discharge in northern and central Minnesota watersheds remains below the 10th percentile for the date. Mississippi River flow conditions are very low due to long-term precipitation deficits in the headwaters area.
(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 )
- lake levels are very low in northern and central Minnesota. Some northern Minnesota lakes are at their lowest levels in many years. Lake Superior is approaching its lowest December water level in 80 years.
(see: http://www.dnr.state.mn.us/lakefind/index.html , http://www.lre.usace.army.mil/_kd/Items/actions.cfm?action=Show&item_id=3886&destination=ShowItem )
- the combination of recent cold temperatures and little snow cover led to plummeting soil temperatures this past week. Frost depths under sod range from three to nine inches across Minnesota.
(see: http://climate.umn.edu/doc/observatory.htm , http://www.mvp-wc.usace.army.mil/projects/reservoirs.shtml )
- after a few false starts, Minnesota's lakes are now ice covered. Ice thickness is highly variable and ice safety is marginal in places. Those venturing onto the state's water bodies should utilize caution and common sense.
(see: http://www.dnr.state.mn.us/enforcement/co_report/index.html )

FUTURE PROSPECTS

- the December precipitation outlook from the Climate Prediction Center indicates a tilt towards below-normal conditions across Minnesota. December precipitation normals range from around one half inch in western Minnesota to over one and one quarter inches in eastern sections of the state. The median snow cover at the end of December ranges from over 10 inches on the ground in northeastern Minnesota (20 inches in the Lake Superior highlands), to under 5 inches in southwestern counties.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/30day , http://climate.umn.edu/img/normals/precip/precip_norm_12.htm )
- the December temperature outlook leans heavily towards above-normal conditions throughout Minnesota. Normal December high temperatures are in the mid-20's to near 30 to start the month, dropping to the mid-teens to near 20 by month's end. Normal lows are around 10 degrees early in the month, falling to the mid-single digits above and below zero by late December.
(see: http://www.cpc.ncep.noaa.gov/products/predictions/30day , http://climate.umn.edu/img/normals/temp_norm_adj/temp_norm_adj_12.htm )
- the 90-day precipitation outlook for December through February indicates no significant tendencies away from climatological probabilities across Minnesota. The December through February temperature outlook indicates a tilt towards above-normal conditions throughout the state.
(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/ )

FROM THE AUTHOR

- none

NOTES FROM AROUND THE STATE

- none

UPCOMING DATES OF NOTE

- December 21, 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://mcc.sws.uiuc.edu - Midwestern Regional Climate Center
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://www.dnr.state.mn.us/waters - Minnesota Department of Natural Resources, Division of Waters
http://www.mvp-wc.usace.army.mil - US Army Corps of Engineers, St. Paul District
http://www.dnr.state.mn.us/enforcement - Minnesota Department of Natural Resources, Enforcement Division
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

- none

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