Equations were developed to forecast conditional probabilities of freezing precipitation, frozen precipitation, and liquid precipitation. These probabilities are conditional upon precipitation occurring.
A verification of these forecasts was conducted on an independent sample of approximately 90 days (the last half of the months of October 1998 through March 1999). Forecasts for 335 sites in the contiguous US and Alaska were included in the verification sample. The P-scores of the AVN MOS primary equations, AVN MOS secondary equations, and the operational NGM MOS precipitation type forecasts are presented for projections of 6 to 72 hours after the 0000 UTC and 1200 UTC model runs. Since the P-score is analagous to a mean squared error, smaller values represent more accurate forecasts.
For more details on the development of the AVN MOS precipitation type forecasts, please see the draft Technical Procedures Bulletin: AVN-Based MOS Precipitation Type Guidance for the United States.
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Developer: Rebecca Allen
Last Updated: January 24, 2000