Scaled version in which points are weighted by expected (normal) SWE amount on this date

The plot at left shows current observed snow water equivalent (SWE) percent of average for nearly all NRCS SNOTEL stations, California DWR snow pillow stations, and a selection of Environment Canada snow pillow stations that fall into the upper Columbia River basin. The anomalies are taken with respect to a common base period 1990-2004 (15 years) for all stations, even though longer records exist at some. Standardizing the base period means that using a longer period would exclude stations from the analysis, but having a standard period (which not the case for some other sources of the same types of plots) is required for the use of this data in assimilation activities used in the forecast system, and provides a consistent assessment of conditions relative to normal across the West.

The following links lead to additional plots related to the observed SWE data:

• SWE Percentiles
• SWE Changes

Related External Links:
    NOAA NOHRSC Interactive Maps (different displays of snow-related variables over a user-specified domain).
    West. Reg. Clim. Ctr. summary of NRCS snotel anomalies (for western US).

Scaled version in which points are weighted by expected (normal) SWE amount on this date

Current observed SWE conditions are shown at left as percentiles with respect to the 1990-2004 distribution for SWE on the current day of year. Percentiles is in some ways a more consistent metric than anomalies for comparing SWE conditions because they they are not directly influenced by SWE variability.

CHANGE in SWE percentile during previous WEEK

CHANGE in SWE percentile during previous 2 WEEKS