California precip forecasts have been suspended during the dry season. We will resume these forecasts on Oct 1, 2017.
California Medium-Range Precipitation Forecasts, Based on NCEP GEFS Reforecasts and CCPA
Censored, Shifted Gamma Distribution (CSGD) Parametric Method
This page presents high resolution (1/8 degree) experimental precipitation forecasts, based on GEFS (Version 10) Reforecasts and Climatology-Calibrated Precipitation Analysis (CCPA, 2002-2013) datasets. A nonhomogeneous regression model that employs censored, shifted gamma distributions (CSGD) is fitted to these data, and then applied to the real-time ensemble forecasts to turn them into probabilistic forecasts. A detailed description of this technique, including an evaluation of its forecast skill, is given in Scheuerer and Hamill (2015).
These forecasts will usually (but not always) be updated by 16 UTC each day. They likely will not be available as consistently as operational products from the National Weather Service. Also please note that this is an experimental forecast product, and is not an official forecast of NOAA or its National Weather Service. Precipitation units are mm (25.4 mm = 1 inch).
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