Local Aviation Performance Statistics: Scale Normalization for IFR-Frequency Effects in Central Pennsylvania Using the Total Performance Index

The National Weather Service (NWS) uses probability of detection (POD) and false alarm ratio (FAR) to assess aviation forecast performance. Statistical evidence indicates that a quantitative relationship exists between these forecast performance metrics and the frequency with which a forecasted condition occurs. Current aviation forecast metrics do not account for IFR frequency, which reduces their utility to assess performance. This weakness in the verification methodology can be especially evident and detrimental at NWS Forecast Offices with high seasonal IFR variability.

Since the Northeastern United States in general, and Central Pennsylvania specifically, can display high seasonal IFR variability, the hypothesis is that aviation verification scores could improve through incorporation of a technique, such as the Total Performance Index (TPIX), which can mitigate the influences of IFR frequency through scale normalization. This hypothesis will be tested through an analysis of regional aviation verification statistics, so that potential ramifications and benefits of utilizing TPIX can be investigated. As such, this paper will build upon recent studies conducted in other sections of the United States.