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* HydroClim Minnesota - February, 2000 *
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* A monthly electronic newsletter summarizing Minnesota climate *
* conditions and the resulting impact on water resources. *
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* Distributed on the Wednesday following the first Sunday of *
* each month. *
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* State Climatology Office - DNR Waters *
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* compiled 2/9/99 *
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WHAT HAS HAPPENED:
- to reiterate from the January HydroClim newsletter ... the last quarter of 1999 (October 1 - December 31) was extraordinarily dry across most of Minnesota. Many western Minnesota communities were at or near all-time record low precipitation totals for the period. The lack of precipitation created deficits in surface hydrology normally benefitting from autumn recharge.
(see http://climate.umn.edu/doc/journal/dry_finish1999.htm)
- three significant snow events occurred during the month of January, affecting portions of Minnesota. A snowfall event on January 12 brought up to eight inches of snow to central and southeastern Minnesota. Far northeastern Minnesota received 10 or more inches of snow on January 17. Most of the southern one half of the state reported five or more inches of snow on January 19. Much of northern Minnesota received very little January snowfall. Precipitation totals (the liquid equivalent of the snow) for the month of January were below average in the north, above average in south central and southeastern Minnesota.
(see http://climate.umn.edu/cawap/monsum/monsum.htm)
- January temperatures were seasonably warm throughout Minnesota, ranging from three to five degrees above the normal. This marked the third consecutive month of above average temperatures.
(see http://climate.umn.edu/cawap/monsum/monsum.htm)
WHERE WE STAND NOW:
- the National Drought Mitigation Center continues to classify southwestern Minnesota in their "D2" category ("Severe Drought - crop or pasture losses likely; fire risk very high; water shortages common; water restrictions imposed"). Much of the remainder of Minnesota has edged into the "D1" category ("First Stage Drought"). The NDMC index is a blend of science and subjectivity where intensity categories are based on six key indicators and numerous supplementary indicators.
(see http://enso.unl.edu/monitor/monitor.html)
- the Palmer Drought Index places southwestern Minnesota in the moderate drought category, near normal elsewhere. The Palmer Drought Index is used for assessing long-term meteorological conditions.
(see http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif)
- soil moisture conditions seldom change substantially during the frozen soil season. As of late autumn, topsoil moisture was deficient in nearly all locations. Dry conditions extended throughout the rooting zone in the southwest, with near average to moist middle and lower soil layers elsewhere.
(see http://www.nass.usda.gov/mn/cropwthr.htm , http://climate.umn.edu/img/soil_moisture/lambsm11.gif , http://climate.umn.edu/img/soil_moisture/wassm12.gif)
- according to the USGS, current stream flows are a mosaic of high and low levels across Minnesota. Stream flows in southwestern Minnesota are very low. Red River flows are high relative to historical values for the date, however mid-winter Red River flows are typically insignificant at this time of year.
(during the open water season, see http://water.usgs.gov/realtime.html)
- according to the Corps of Engineers, Mississippi River headwater reservoirs are at or near target winter drawdowns. Red River basin reservoirs have dropped from their unusually high levels in response to the dry autumn weather. The Corps of Engineers will maintain a flexible position in the drawdown of Minnesota River basin reservoirs, monitoring the ongoing dry spell.
(see http://www.mvp-wc.usace.army.mil)
- snow depths are generally less than 8 inches across the state. The northern half of the state (with the exception of the far northeast) is far below the median for the date. Many north central and northeastern areas are at or near all-time record low snow depths for this point in the winter. For some, three consecutive snow-deficient winters has led to economic hardship. These parties are exploring a request for public assistance.
(see http://climate.umn.edu/doc/snowmap.htm)
- the water equivalent of the snow pack is generally an inch or less in most locations.
- frost depths are around 18 inches in most locations, shallower than last year and somewhat shallower than historical averages. Exceptions to this exist in some north central and northeastern Minnesota communities where below average snow depths allowed deeper frost penetration.
(see ftp://ftp.mvp-wc.usace.army.mil/pub/bulletins/Snow_Ice_Frost)
FUTURE PROSPECTS:
- the outlook from the Climate Prediction Center calls for near normal precipitation for the month of February, and for the February through April period. The temperature outlook tilts towards below normal conditions in February, and a colder than average February through April in the north.
(see http://www.cpc.ncep.noaa.gov)
- (REPEATED FROM LAST MONTH) from agricultural climatologist Mark Seeley ... "Drought which begins in the fall season is typically less consequential than drought which begins in the winter, spring or summer. Winter drought can cause desiccation of plants, and winter injury to pasture grasses, winter wheat and alfalfa. Spring drought can cause delayed crop planting and emergence and/or significant soil loss from wind erosion, while summer drought can stunt plants, cause drastically reduced crop yields, and very low river flows that present navigation problems. The current dry conditions can yet be mitigated in two ways: (1) by heavy overwinter snow cover which will infiltrate into the dry soil layers with each thaw cycle of the late winter; or (2) by early spring precipitation which will recharge the depleted surface layers of the seedbed and perhaps bridge the dry layers of the root zone with the more saturated layers of soil below. Thus, though the current lack of soil moisture in parts of Minnesota is of concern, there are still a number of ways that the soil could be recharged sufficiently for the year 2000 crop season."
- (REPEATED FROM LAST MONTH) foresters are concerned about the potential for a major burn in the BWCA. Many trees blown down by the July superstorm rest on their larger branches, keeping most of the heavier fuel off the ground. This architecture, plus a lack of shade, creates an excellent drying condition. A modest dry spell in future growing seasons will lead to high forest fire danger in that area.
A THOUGHT FROM THE AUTHOR:
- for many locales, the decade of the 1990's was the wettest of the 20th century. An entire generation of water resource professionals have experienced only water abundance or water surplus. We must remind ourselves that water DEFICITS are part of Minnesota's climate and will inevitably occur in the future. All water resource planning efforts must acknowledge this fact.
(see http://www.dnr.state.mn.us/waters/climate/hiwater/high_water.html)
NOTES FROM THE FIELD:
- Hubbard County: Lake Belle Taine in Hubbard County, which is landlocked, reached an all-time high on Sept. 9 and had dropped 0.36 feet as of Dec. 10, but was still 2.15 feet above its ordinary high water level.
- Ottertail County: smaller wetlands are dry because of the dry fall. Perhaps one of the most interesting observations is that in the Ottertail River watershed, the tailwater on three major lake dams in the system has finally dropped below the elevation of the dam for the first time since the spring of 1997. The big sponge has finally released the majority of what it stored for over two years, and it was helped by the dry fall. Most landlocked lakes are down somewhere in the neighborhood of 6"-12".
- Brainerd: Mississippi River flows remain high. May be the result of pre-August excess precipitation and reservoir drawdowns. The flow conditions at this time do not match the lack of precipitation.
UPCOMING DATES OF NOTE:
- February 11, optional spring flood outlook narrative from NWS River Forecast Center
- February 17, Climate Prediction Center releases 30/90 day outlooks
- February 23, Interagency Flood Planning Meeting, National Weather Service - Chanhassen
- February 25, required spring flood outlook narrative from NWS River Forecast Center
(see http://www.crh.noaa.gov/ncrfc/html_graphics/index.html)
WEB SITES FEATURED IN THIS EDITION:
http://climate.umn.edu - Minnesota Climatology Working Group
http://enso.unl.edu - National Drought Mitigation Center
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://www.nass.usda.gov/mn - Minnesota Agricultural Statistics Service
http://mn.water.usgs.gov - U.S. Geological Survey in Minnesota
http://www.mvp-wc.usace.army.mil - U.S. Army Corps of Engineers - St. Paul District
http://www.crh.noaa.gov/ncrfc/html_graphics/index.html - NWS River Forecast Center
http://www.dnr.state.mn.us/waters - DNR Waters
ACKNOWLEDGEMENTS:
Kirk English, DNR Waters Area Hydrologist - Bemidji
Terry Lejcher, DNR Waters Area Hydrologist - Fergus Falls
Lonnie Thomas, DNR Waters Area Hydrologist - Brainerd
Greg Mitton, USGS - Mounds View
Ferris Chamberlin, Corps of Engineers - St. Paul
Mark Seeley, University of Minnesota Extension Meteorologist/Climatologist
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