Icing Product Alaska (ipa) Follow-on Assessment: Final Results

Abstract

The QA PDT was tasked to complete a follow-on quality assessment of the Icing Product Alaska Forecast (IPA-F) algorithm developed by the In-Flight Icing (IFI) PDT at the National Center for Atmospheric Research. The purpose of this second assessment was to compare the performance of the IPA-F to the current suite of Alaska icing forecast products, including the Forecast of Icing Probability (FIP), the Forecast of Icing Severity (FIS), and the gridded Alaska Aviation Weather Unit (AAWU) icing product. The results of this study are intended to assist the Technical Review Panel in determining the readiness of IPA-F to be transitioned into operations. The study was conducted on data from the autumn of 2016, with particular emphasis on the area of responsibility for the AAWU. The forecasts were compared to each other as well as to observations, including pilot reports (PIREPs), aviation routine weather reports (METARs), and upper-air soundings. In general, the assessment findings include: - IPA-F outperformed FIP/FIS and the gridded AAWU forecast. - IPA-F improvement was the greatest for higher probability thresholds and higher severities of icing (moderate or greater). - IPA-F captured more moderate or greater (MOG) icing events than the gridded AAWU forecasts while forecasting that severity over a smaller area. - IPA-F forecasted larger areas of high probability and zero probability of icing than FIP; FIP forecasted a larger area of low probability of icing than IPA-F. - IPA-F forecasted a larger area of MOG icing than FIS