During the period of December 2000 through April 2001, regular surface observations, nearby upper air observations, and ETA-model data were archived at Plymouth State College (PSC) to evaluate low-level aircraft icing forecasts in a mountain environment at Mt. Washington, New Hampshire. In addition, the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) deployed a Rosemount ice detector and rotating multi-cylinders on the summit of Mt. Washington to gather in situ icing data. We evaluated corresponding Air Force Weather Agency (AFWA) MM5-based operational forecasts for 15-km and 45-km resolutions, RUC-based Aviation Weather Center (AWC) operational NNICE and experimental VVICE forecasts, PSC-generated forecasts using ETA input and techniques outlined in the 1997 Air Weather Service FYI Icing publication, and National Center for Atmospheric Research (NCAR) IIDA results.

An initial study (Stanley et. al., 2002) presented primarily yes/no forecast verifications based on the actual surface observations from the summit of Mt. Washington. In this paper, we report on the NCAR IIDA results that were not previously reported and present additional verification results for all of the nowcasts and forecasts, based on the ice detector data that provide not only more objective "yes/no" verification criteria, but also information on icing intensity.