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Nevada and Eastern Sierra Normals Dashboard

On October 1, 2021 the NRCS updated its 30-year normals period from 1981-2010 to 1991-2020. The NRCS uses normals in a variety of products to represent data as a percent of normal. Changing normals impacts percentages and requires users to re-calibrate themselves.

The following data types have normals:

  • Daily and Monthly SNOTEL Snow Water & Accumulated Precipitation
  • Peak SNOTEL Snow Water & Peak Date  (new)
  • SNOTEL dates for Snow Onset &Melt-out (new) - click here for explanation
  • Monthly Snow Course, Streamflow Volumes & Reservoir Storage

A Technical Summary about the new normals is available from the National Water and Climate Center.

Overview Presentation

The following video presentation highlights how the normals update impacts Nevada. For a pdf of the presentation slides click here.

Key Points about 1991-2020 Normals in Nevada:

  • The median is the new default normal used in all NRCS products.
  • Most 1991-2020 medians for snow, precipitation and streamflow in Nevada are less than 1981-2010 normals (exceptions exist).
  • The main impact of a smaller normal is it produces a larger percentage.
  • The reason 1991-2020 medians are less than the 1981-2010 normals is due to a combination of shifting the climate periods (1981-2010 to 1991-2020) and the statistical change from average to median.
  • Streamflow forecasts have been re-calibrated with 1991-2020 data.
  • New medians do NOT change SNOTEL data collection methods.

Tips for Adjusting to New 1991-2020 Medians

  • Pay attention to how percentages are reported – median vs. average. External sources may mis-label data.
  • Don’t expect as much water from a given percentage snowpack.
  • Think like a water manager. Concentrate on streamflow volumes not on percentages.
  • Investigate the new normals yourself using the tools lower on this page.
  • Use tools that compare current data with historic years without percentages. Examples include:

Investigate the 1991-2020 Normals

NWCC Normals Webpage

Normals Technical Summary

This Technical Summary of 1990-2020 Normals was produced by National Water and Climate Center and explains calculation methods and additional information.

Basin SWE Normals Compare

Basin Snow Water Normals Comparison


Basin charts combine data from multiple SNOTEL sites within and adjacent to a watershed. Drop downs use ALL CAPS for main basins, while Title Case is used for sub-basins.

Basin Prec Normals Compare

Basin Precipitation Normals Comparison


Basin charts combine data from multiple SNOTEL sites within and adjacent to a watershed. Drop downs use ALL CAPS for main basins, while Title Case is used for sub-basins.

SNOTEL SWE and Prec Normals Compare

SNOTEL Snow & Precipitation Normals Comparison


Apr-July Stream-normals-comparison

April-July Streamflow Normals Comparison


 

For help accessing historic time series and histogram plots click here.

Retrieve 1991-2020 Normals

Interactive Map:

Snow:  Today's Median / Average  |  April 1 Median / Average

Precipitation:  Today's Median / Average  |  Water Year Median / Average

Streamflow:  Seasonal (April - July)  Median / Average  |  Water Year (Oct-Sep)  Median / Average

 

Update Reports by Basin:

Snow and Precipitation:         Today's % of 1991-2020 Median  |  Today's % of 1991-2020 Average

Month to Date Precipitation:  Today's % of 1991-2020 Median  |  Today's % of 1991-2020 Average

Snowpack % of Peak:            Today's % of 1991-2020 Median  |  Today's % of 1991-2020 Average

 

Tabular Reports:

See "Retrieving 1991-2020 Normals" link here