Document Type

Article

Publication Date

1-1-2014

Abstract

A first observational and modeling study of a dryline and associated initiation of deep convection over the high plains of southeastern Wyoming is presented. Radar and station measurements show that the dryline is a well-defined convergent humidity boundary with a modest density (i.e., buoyancy) gradient. Its development, intensity, and movement are regulated by the terrain, diurnal land surface and boundary layer processes, and synoptic-scale evolution. At least one of the thunderstorms that emerged from the dryline became severe. Weather Research and Forecasting Model (WRF) simulations accurately reproduce measured aspects of this dryline, as well as the timing and location of convection initiation. The WRF output is used further to characterize the dryline vertical and horizontal structures and to examine convection initiation processes.Adryline bulge over a local terrain ridge appears to be an essential ingredient in convection initiation on this day: just north of this bulge the surface convergence and buoyancy gradient are strongest, and deep convection is triggered. In this region especially, the WRF simulation produces horizontal convective rolls intersecting with the dryline, as well as small cyclonic vortices along the dryline. In fact, the primary storm cell initiates just downwind of one such vortex. Part II of this study describes the finescale vertical structure of this dryline using airborne Raman lidar data.

DOI

10.1175/MWR-D-13-00049.1

Comments

© Copyright 2014 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act September 2010 Page 2 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyrights@ametsoc.org.

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