HydroClim Minnesota - March 2001

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 3/7/01


- February precipitation was above normal across Minnesota. February precipitation totals topped one inch in most locations, and exceeded two inches in some areas of southern, central, and northeastern Minnesota. February 2001 precipitation doubled or even tripled the historical average in this traditionally dry month. Much of the February precipitation fell during a procession of storms that dropped heavy snow, sleet, and rain throughout the weekend of February 23 - 25. Snowfall totals of over 12 inches were reported in west central and central Minnesota during these storms, and snowfall amounts approached 24 inches in portions of Minnesota's Arrowhead region.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )

- February temperatures were cold, finishing four to eight degrees below normal. It was the coldest February since 1994, and for some communities, the coldest February since 1989.
(see: http://climate.umn.edu/cawap/monsum/monsum.asp )



- most of Minnesota reported more than 18 inches of snow cover as of March 1st. Snow depths across a large swath of Minnesota, extending from west central Minnesota into northeastern Minnesota, were greater than 24 inches. Snow depths in the southern two thirds of Minnesota ranked above the 95th percentile for the date, and snow depths for the remainder of Minnesota were above the 60th percentile. For some areas of west central and southwestern Minnesota, snow depths were at or near all-time record values for the date.
(see: http://climate.umn.edu/doc/snowmap.htm )

- snow water equivalent data gathered by the National Weather Service and the Army Corps of Engineers show that the snow pack across Minnesota generally contained three to five inches of water as of March 6. Some areas within the Minnesota River basin reported five to six inches of snow water equivalent. Portions of the upper reaches of the Red River basin report snow water content of four to five inches, but the snow pack over the majority of the Red River watershed contains less than three inches of water. Snow densities vary across the state but are generally around 20% (approximately one inch of water for each five inches of snow cover).
(see: http://www.crh.noaa.gov/ncrfc/html_frames/snowindex.html )

- soil frost depths across the state range from near zero to 12 inches in areas receiving early and persistent snow cover, 24 to 40 inches in areas blown free of snow.
(see: http://www.mvp-wc.usace.army.mil/bulletins/Snow_Ice_Frost.html )

- stream discharge values are difficult to determine during the frozen water season. However, for gauging locations that provide winter data, the U.S. Geological Survey indicates that many points in the Red River basin are above the 90th percentile when compared to historical values for the date. Stream flows in other areas of the state are near average for the date.
(see: http://water.usgs.gov/cgi-bin/daily_flow?mn )

- as of their March 1 release, the National Drought Mitigation Center - "U.S. Drought Monitor" shows Minnesota to be free of any drought designations. 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 March 3 Palmer Drought Severity Index (PDSI) depicts much of Minnesota as experiencing an "Unusual Moist Spell". Many counties in southern, central, and northwestern Minnesota fall in this grouping. Counties in the rest of the state are categorized as "Near Normal". 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 30-day outlook from the Climate Prediction Center shows no significant tendencies (equal chances of below, near, and above normal) in March precipitation for Minnesota. March precipitation normals range from three quarters of an inch in northwestern Minnesota to near two inches in the southeast. The March temperature outlook tilts towards below normal values. Normal March high temperatures are just below freezing early in the month, rising to the low to mid 40's by month's end. Normal March lows average around ten degrees to start the month and climb to the mid 20's 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 March through May tilts towards above normal precipitation. The March through May temperature outlook calls 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, water equivalent of the snow cover, soil moisture, and soil temperature. 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 Services (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)



- the heavy late-season snow cover inflates the risk for spring snow-melt flooding this year. Those with interests in flood-prone areas should carefully monitor National Weather Service flood outlooks and flood forecasts (see the description of the AHPS system in "Future Prospects" above and the flood outlook schedule in "Upcoming Dates of Note" below). The National Weather Service offices with forecast responsibilities for Minnesota's rivers offer excellent Web sites which present the latest flood outlook and forecast information. Look for the "Rivers/Hydrology" section of the following Web sites:

> Red River basin - (NWS Grand Forks) http://www.crh.noaa.gov/fgf/
> Minnesota River basin - (NWS Chanhassen) http://www.crh.noaa.gov/mpx/
> Mississippi River basin headwaters to Fort Ripley - (NWS Duluth) http://www.crh.noaa.gov/dlh/
> Mississippi River basin Fort Ripley to Red Wing - (NWS Chanhassen) http://www.crh.noaa.gov/mpx/
> Mississippi River basin Lake City to Iowa border - (NWS La Crosse) http://www.crh.noaa.gov/arx/

> Regional perspective (NWS North Central River Forecast Center) http://www.crh.noaa.gov/ncrfc/html_graphics/
> National perspective (NWS Office of Hydrology) http://www.nws.noaa.gov/oh/hic/nho/



- none



- March 9, Flood Potential Numerical Outlook from the National Weather Service
(Mississippi River and Minnesota River Basins)
- March 15, Climate Prediction Center releases 30/90 day temperature and precipitation outlooks
- March 16-21 (dates may vary), Probabilistic Flood Outlook from the National Weather Service
(Red River and Minnesota River Basins)
- March 23, Flood Potential Numerical Outlook from the National Weather Service
(Mississippi River and Minnesota River Basins)



http://climate.umn.edu - Minnesota Climatology Working Group
http://www.crh.noaa.gov/ncrfc - National Weather Service - North Central River Forecast Center
http://enso.unl.edu/ndmc - National Drought Mitigation Center
http://www.cpc.ncep.noaa.gov - Climate Prediction Center
http://water.usgs.gov/cgi-bin/daily_flow?mn - U.S. Geological Survey, Minnesota
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
http://www.crh.noaa.gov/dlh - National Weather Service Forecast Office - Duluth
http://www.crh.noaa.gov/arx - National Weather Service Forecast Office - La Crosse
http://www.nws.noaa.gov/oh/hic/nho - National Weather Service Office of Hydrology
http://www.mvp-wc.usace.army.mil - U.S. Army Corps of Engineers, St. Paul District
http://water.usgs.gov/mn/nwis - U.S. Geological Survey - Water Resources for Minnesota test site


- none

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