Comparing NWS PoP Forecasts to Third-Party Providers

Abstract

n this paper, the authors verify probability of precipitation (PoP) forecasts provided by the National Weather Service (NWS), The Weather Channel (TWC), and CustomWeather (CW). The n-day-ahead forecasts, where n ranges from 1 to 3 for the NWS, from 1 to 9 for TWC, and from 1 to 14 for CW, are analyzed. The dataset includes almost 13 million PoP forecasts, or about 500 000 PoPs per provider per day of lead time. Data were collected over a 2-yr period (1 November 2008?31 October 2010) at 734 observation stations across the contiguous United States. In addition to verifying these PoP forecasts in an absolute sense, relative comparisons are made between the providers. It is found that, in most cases, TWC does not add skill to NWS forecasts. Perhaps most interestingly, it is also found that CW does have the ability to forecast PoPs at a resolution of 0.01.