89th American Meteorological Society Annual Meeting

Sunday, 11 January 2009
A composite-based diagnostic study of Colorado lee cyclogenesis
Phoenix Convention Center
Doug A. Koch, University of Northern Colorado, Boulder, CO; and P. Nutter and E. Thaler
Although theoretical studies have examined the interaction between baroclinic waves and a mountain barrier, lee cyclogenesis remains a major forecasting challenge, especially along the Colorado Rockies. The goal of this research is to bridge the gap between theory and forecasting to expand upon the tools that are applicable to the analysis of Colorado cyclone events in an operational setting. Correlation-based analogs are used to construct composites of March cyclone events. The composites are partitioned according to both the direction from which the upper-level waves initiate (northwesterly vs. southwesterly), as well as the outcome that occurs (cyclone development vs. non-development).

An investigation into the key differences between the composites gives new insight into the processes that govern Colorado lee cyclogenesis. We utilize a novel framework for numerically solving the QG omega, height tendency, Zwack-Okossi development, and ageostrophic circulation equations. In particular, QG vertical stretching is an important mechanism in the cyclone formation process. Emerging results from this research will be presented at the 8th Annual AMS Student Conference.

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