Seasonal to sub-seasonal forecasting

Western States experience great variability in sub-seasonal to seasonal (S2S) precipitation, with serious impacts and consequences for water supply planning and management. NOAA’s Climate Prediction Center has been issuing S2S precipitation outlooks since the mid-1990s. Their skill for the western U.S. has been minimal, just slightly better than predicting average weather conditions, and has shown little improvement over time. Forecasting precipitation at S2S timescales is scientifically challenging and has historically received little federal research support.


For several years, the WSWC and the California Department of Water Resources (CDWR) have co-sponsored annual workshops to foster a continuing dialogue between western states, the National Oceanic and Atmospheric Administration (NOAA), and the research community on improving sub-seasonal to seasonal (S2S) precipitation forecasting to support water management decisionmaking. The following links include meeting materials, powerpoint presentations, and (for the 2022 workshop) videos.

S2S Workshop May 2023

S2S Workshop May 2022

S2S Workshop May 2019

S2S Workshop May 2018

S2S Workshop May 2017

S2S Workshop May 2016

S2S Workshop May 2015


In 2020, NOAA submitted a report to Congress pursuant to Section 201 of the Weather
Research and Forecasting Innovation Act of 2017 (P.L. 115-25) recommending pilot projects to improve S2S forecasts for water management in the western U.S. The WSWC has written several letters of support for Congressional authorization and appropriations for these pilot projects.


Policy Positions

Position #491

Position #500

Position #483