Figure shows the biases [the radar-to-gauge ratio (R/G)] for four conditions of rain rate for each RFC for each season: winter (DJF), spring (MAM), summer (JJA), and fall (SON). The conditions of the rain rate correspond to light rainfall, where 0 < Go < 50th percentile; light-to-moderate rainfall, where 50th percentile < Go < 70th percentile; moderate-to-heavy rainfall, where 70th percentile < Go < 90th percentile; and heavy rainfall, where 90th percentile < Go.

Olivier Prat of CICS-NC is a contributing author on a paper in Weather and Forecasting that explores and assesses the stage IV quantitative precipitation estimates (QPE) provided by NOAA’s National Centers for Environmental Prediction. The stage IV product provides near-real-time estimates of precipitation based on NEXRAD radar data. Lead author Brian Nelson of NOAA’s National Centers for Environmental Information and his coauthors provide details on how the stage IV product is produced and assess its performance for 2002–2012.

The authors describe several challenges that affect the quality of the stage IV data. For example, variations in the techniques and quality control processes used by the 12 individual River Forecast Centers (RFC) in the continental United States can result in discontinuities in the data constructed as a mosaic of the information from each RFC area.

To provide a quantitative assessment of the stage IV QPE, the authors examine daily rainfall estimates for various intensities on a seasonal basis. They also present results of an effort to verify the QPE using in situ data from NOAA’s U.S. Climate Reference Network (USCRN) stations. Biases, fractional standard errors, and correlations are presented for each RFC for each season.

The team concludes with several recommendations based on their results, including separating out western RFCs from the others, improvements in how data from adjacent radars and RFCs are merged, and improving estimates of both light and heavy precipitation.

Nelson, B. R., O. P. Prat, D. J. Seo, and E. Habib, 2015: Assessment and implications of NCEP Stage IV quantitative precipitation estimates for product intercomparisons. Weather and Forecasting, 31, 371-394.