Subjective and objective forecast evaluations of upper-level aircraft turbulence were conducted during the period 23 January through 31 March 2003. The Integrated Turbulence Forecast Algorithm (ITFA) generated forecasts using observations of turbulence, the Rapid Update Cycle (RUC) gridded forecasts, and a physically-based fuzzy logic technique. Forecasters at the NOAA/NWS Aviation Weather Center (AWC) provided detailed subjective evaluations through electronic questionnaires developed by the Forecast Verification Branch (FVB) of the NOAA Forecast Systems Laboratory (FSL) and the Research Applications Program (RAP) of the National Center for Atmospheric Research (NCAR). The FSL Real-Time Verification System (RTVS) provided objective verification statistics.

Objective scores show that the ITFA products have skill in forecasting upper-level turbulence. The subjective evaluations show the same trends; that is, for events associated with favorable objective scores, the forecasters were more likely to assess the guidance favorably. The agreement between the objective and subjective numbers improves when the most active days are chosen. However, for days with little or no organized turbulence areas, there was little relationship between the objective and subjective evaluations. This demonstrates that the ongoing objective verification is useful for evaluating ITFA, particularly for the overall performance and for significant events.

The subjective evaluations taken alone indicate that the forecasters were satisfied with ITFA as a useful forecasting tool. Several commented that ITFA is useful as part of a suite of tools. When forecasters were dissatisfied with ITFA guidance, they tended to suggest that the forecast turbulence volumes were too broad and too severe. There was also a tendency for the eastern region, particularly the Northeast, to get relatively high scores, with the Great Basin area receiving some of the lowest.