| 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 WHAT HAS HAPPENED - 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. - 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. 
 WHERE WE STAND NOW - 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. - 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). - 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. - 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. - 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. - 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. 
 FUTURE PROSPECTS - 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. - 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. - 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. 
 FROM THE AUTHOR - 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/ 
 NOTES FROM AROUND THE STATE - none 
 UPCOMING DATES OF NOTE - March 9, Flood Potential Numerical Outlook from
      the National Weather Service 
 WEB SITES FEATURED IN THIS EDITION http://climate.umn.edu
      - Minnesota Climatology Working Group ACKNOWLEDGEMENTS - none To subscribe or unsubscribe to "HydroClim" please notify:  Contributions of information and suggestions are welcome! |