The primary goal of IMPROVE-2 (Improvement of Microphysical PaRameterization through Observational Verification Experiment), which was conducted over the central Oregon Cascades from 26 November through 22 December 2001, was to simultaneously and comprehensively measure both basic-state and cloud and precipitation microphysical fields in a variety of weather systems. The data will not only help verify and improve bulk microphysical parameterizations, but it will also help improve our understanding of orographic precipitation processes. Part I in this series of talks will present the motivation and setup of the experiment, while part II will give an overview of cases observed during the field study and some preliminary results.

During the one month period of IMPROVE-2 an active weather pattern setup over the eastern Pacific, with a series of frontal systems making landfall along the Pacific Northwest coast. This resulted in over 2 meters of snowfall over the Oregon Cascades during the first two weeks of the experiment alone. The first part of the experiment was highlighted by a significant trough passage on 28-29 November (IOP1), which produced ~ 0.3-1 m of snowfall over the mountains. The S-Pol radar provided information on particle types, while the NOAA P-3 aircraft mapped out the low-level flow using the tail Doppler radar, and the University of Washington Convair-580 aircraft collected microphysical measurements aloft. Other significant events, which targeted more post-frontal regimes, will be highlighted. Some of the case studies are being simulated down to 1.3 km resolution using the Penn State-NCAR mesoscale model (MM5). These modeling results will be compared with observations.