P1.0
A Case Study of Offshore Flow Inducing Vortices in the Lee of the Olympic Mountains in the Summertime
Emily L. Niebuhr, University of Wisconsin Madison, Madison, WI; and M. H. Hitchman and M. L. Buker
Weather in the Pacific Northwest during summer is usually dominated by a high pressure system in the Northeast Pacific that typically brings mild and dry weather to the region and northerly flow. However, the interaction of synoptic events with the coastal mountains and the diurnal cycle of land heating and cooling on the Olympic, Cascade and Vancouver Island Mountains can contribute to the formation of disturbances in this fair weather pattern and different wind patterns. One such phenomena is the Puget Sound Convergence Zone, where west northwesterly winds flow around the Olympic Mountains to the north and south, and converge in their lee over Puget Sound, with a northward-migrating precipitation zone typically forming in the afternoon. Although this phenomena has been examined in several studies, few studies have focused on the case of flow patterns resulting from large-scale offshore flow in this region during the summer. This paper presents observational and mesoscale modeling analyses of such a case during 14-15 August 2002, employing the University of Wisconsin Nonhydrostatic Modeling System (UWNMS). In this event there was low-level flow down the Straits of Georgia, through Puget Sound, and then offshore south of the Olympics. Some of this flow continued around the Olympic mountains northward while the rest interacted with a more direct southward flow from Vancouver Island and flowed down the Washington coast. The complexity of evolution of the resulting vortices in the simulations is described and validated by station data. Physical processes most relevant to this phenomenon will be discussed.
Poster Session 1, All Submissions
Sunday, 29 January 2006, 1:00 PM-5:00 PM
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