The AIRPACT air-quality forecasting system was developed in 2000-2001 to provide air-quality managers in the Puget Sound region with timely forecasts of high pollutant conditions and to allow for the potential notification of sensitive populations. AIRPACT used MM5 forecasts from the University of Washington with the CALMET/CALGRID photochemical modeling suite, with PAVE being used for automated generation of web-based animation graphics. Forecast results for critical pollutant species, along with the emissions that were used in for simulation, were provided automatically via the project website at www.airpact.wsu.edu. An automated verification system was included, providing comparisons of predictions against observations on an hourly basis for available air-quality monitoring sites. Verification graphics were typically posted to the website the following day. The initial AIRPACT system was operated through 2002-2003, providing abundant experience in the challenges and benefits attending operation of a high-resolution air-quality forecast and verification system.

The original system is updated in AIRPACT-2 with the following enhancements:

· The expanded 4-km domain ranges from covering Vancouver, BC in the north and Salem, OR in the south, and from the Pacific coast in the west to beyond the crests of the Cascades in the east. · Air-toxics chemical and particulate species have been added as tracers to provide for comparisons against current measurement programs for air-toxic species. The specific air toxics include formaldehyde, acetaldehyde, 1,3 butadiene, benzene, perchloroethylene, PM2.5 from diesel sources, from woodsmoke, and a PAH tracer. · A SMOKE-based emissions generation sub-system replaces the original highly idiosyncratic implementation.

This presentation describes the design of the enhanced AIRPACT-2 air-quality forecasting and verification system. Preliminary results are provided in terms of the evaluation of AIRPACT-2 for photochemical pollutants and selected air toxics.