Through the Eyes of the Experts: The Perception of the Probability of Precipitation

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Sunday, 4 January 2015
Castle Adam Williams, University of Georgia, Athens, GA; and M. D. Phan, A. E. Stewart, and A. Horst

Prior surveys of the general public indicated that a variety of meanings and interpretations exist regarding the probability of precipitation (PoP). Do the same variety of meanings for the PoP exist among members of the professional atmospheric science community? What do members of the professional community think that the public should know about PoP? To address these questions we surveyed over 155 meteorologists and broadcasters via an online survey and over 10 meteorologists and broadcasters in unstructured telephone interviews to assess their meanings, perceptions, and recommendations regarding the PoP. We observed that among the professional meteorological community, varied meanings existed regarding the definition of PoP despite the survey respondents' indicating a high degree of confidence in their definitions. Differences in the definitions stemmed from the way PoP was derived from model output statistics, parsing of a 12-hour PoP over smaller time frames, and generalizing from a point PoP to a wider covered warning area. In this regard 43% of the online survey respondents believed that a there was no or very little consistency in the definition of PoP; only 8% believed that the PoP definition has been used in a consistent manner. The respondents believed that PoP was limited in its value to the general public and that, on average, only 22% of the general population had an accurate conception of the PoP. These results imply that the professional weather community should work to achieve a wider consensus about the meaning of the PoP. Further, until meteorologists develop a consistent conception of the PoP and disseminate it, the public's understanding of PoP-based forecasts will remain limited.