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Flattop Mountain SNOTEL Snowpack: Water Year 2001

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These materials prepared by the Global Change Research Program -- U.S. Geological Survey, Northern Rocky Mountains, Glacier Field Station.  Dan Fagre, Program Coordinator, email: dan_fagre@usgs.gov.  For more information, visit the Glacier Field Station - Climate Change in Mountain Ecosystems program (CCME) web site. 



Snow PillowSNOTEL (SNOw TELemetry) sites are operated by the US Department of Agriculture, Natural Resources Conservation Service (NRCS) and used for forecasting water availability.  SnowTel siteThese stations measure Snow Water Equivalent (SWE), the weight of snow equivalent to inches of water, along with temperature and precipitation.  SWE is recorded daily at Flattop Mountain, located at approximately 6300 feet in elevation along the upper edge of the McDonald drainage in Glacier National Park, Montana (a second SNOTEL station is located in the Many Glacier valley).  The Flattop Mountain SNOTEL station has been in operation since October 1st, 1969.  To assist in calculation of water storage and availability during agricultural growing seasons, the data are compiled by water year (a water year runs from 1 October - 30 September).

The data plotted above includes:

  • 30-year long-term average SWE, from 1970-1999
  • The water year of maximum SWE - 1972
  • The water year of minimum SWE - 1992
  • The previous water year SWE - 2000
  • The current water year SWE - 2001
  • The current snow depth

On June 20, 2001 the SNOTEL site melted out to zero inches of snow water equivalent. The winter’s snowpack is gone, just before the first day of summer. On average, there are 20 inches of SWE at Flattop on June 20.

SWE at the Flattop SNOTEL has stayed below the 30-year minimum all season, making 2001 the new water year of minimum SWE.  For most of the season, SWE at Flattop remained significantly below the SWE for the previous minimum in 1992.  It wasn’t until a series of storms in April that the 2001 SWE approached that of 1992.  The year’s maximum SWE value of 30.8 inches occurred on April 23/24. 
Despite the dramatic difference in SWE, that date is only several days earlier than the average peak SWE of April 27 and a week later than last
year’s peak on April 17.  Visit this site again next year to view weekly updates of the SNOTEL data.