CNRFC/HPC Quantitative Precipitation Forecasts (QPF)

QPF forecasts are issued several times daily by the Hydrometeorological Prediction Center. QPF represents the total amount of liquid precipitation (in inches) expected during specific periods, typically 6 or 24 hours, at any point or basin in the forecast area. The river forecast models at the CNRFC use 6-hour QPF/QPE. QPE, or Quantitative Precipitation Estimate, represents the total amount of liquid equivalent precipitation (in inches) that has been observed during the specified period at a point or basin. HPC QPF guidance is reviewed by HAS meteorologists at the CNRFC and modified when appropriate.

The CNRFC uses 5 days of forecast precipitation and temperature in our 5-day river guidance products.  The same information is reflected in the Significant Flood Outlook product.

CNRFC Text Hydrometeorological Products

A discussion of the latest meteorological and hydrological conditions across portions of southern Oregon, California, and Nevada issued by the hydrologist and HAS meteorologist on duty. This product is issued once per day during the winter operational season (October 15 through April 15) around 9:30 AM PST.

CNRFC Hydrometeorological Discussion - [Alternate Link]

The graphics below display 6-hour, 24-hour, 72-hour and 120-hour QPF for the next 5 days for the CNRFC area of responsibility and 6-hour and 24-hour QPF for the next 3 days for the Weather Service Forecast Office (WFO) Hydrologic Service Areas (HSA). In most cases, this QPF is converted to basin Mean Areal Precipitation (MAP) and serves as input to our hydrologic models.

QPF images are issued daily at 8:00 AM. During CNRFC winter operations (Oct 15 - Apr 15), images are updated again at 1:30 PM daily with additional issuances as needed during extended hours of operation.

CNRFC Daily QPF Gridded Verification images are available for the entire CNRFC area of responsibility.  The daily 24-hour verification period runs from 12:00 UTC to 12:00 UTC (4 AM to 4 AM during PST or 5 AM to 5 AM during PDT).  All images are identified by the ending date of the 24-hour period.  The verification image is a grid created from subtracting QPE from QPF valid for the same time period. Areas that appear in green indicate where the QPF was too wet (QPF-QPE ≥ 0.25 inches), and areas in red highlight areas where the QPF was too dry (QPE-QPF ≥ 0.25 inches).  Areas that are gray indicate where the QPF-QPE differences were less than 0.25 inches or areas where no precipitation occurred.  The grid type “Comparison” (requires Abobe® Flash®) allows a visual overlay of QPF and QPE images.   A slider bar located just above the image allows a manual fade between the two images.  Adobe Flash is required to use the Comparison option.  An option is now available to view previously-issued QPF images, Verification images, and QPF-QPE comparisons from QPFs issued from 1 to 5 days prior to a specific date.  This option can be used to view prevously-issued QPF, Verification, and QPF-QPE comparisons.  Please Note:  Images for day 1 are available dating back to June 20, 2007. Images for days 2 through 5 are only available since June 13, 2012.

National Precipitation Verification - the National Precipitation Verification Unit (NPVU) provides precipitation verification statistics for the conterminous United States. Graphical continuous and categorical verification statistics are provided for each River Forecast Center area of responsibility, and includes monthly and seasonal verification of 6-hourly QPF for day 1, and 24-hour verification for days 1, 2, and 3 at 4 km and 32 km grid resolution. The NPVU also provides an archive of observed precipitation for each RFC area in graphic image format (GIF). Please Note:  As of January 2012, the verification services of the NPVU were suspended and verification data are no longer available.  However, the web site remains operational and the archive of QPF and QPE data is still accessible and up-to-date.

The Hydrometeorological Prediction Center (HPC) provides basic hydrometeorological analysis and forecasts for National Weather Service Field Offices and the entire meteorological community at the national scale. HPC meteorologists serve as experts in quantitative precipitation forecasting and numerical model interpretation. Products provided by the HPC include surface analyses, outlooks for heavy rain and snow, as well as guidance weather forecasts through five days. Below are links to HPC's national QPF guidance.

HPC QPF Discussions

Quantitative Precipitation Forecast Discussion (QPFPFD)
Excessive Rainfall Discussion (QPFERD)
Heavy Snow Discussion (QPFHSD)