Dynamic forcing and mesoscale variability of heavy precipitation events over the Sierra Nevada mountains

AMS Citation:
Reeves, H. D., Y. -L. Lin, and R. Rotunno, 2008: Dynamic forcing and mesoscale variability of heavy precipitation events over the Sierra Nevada mountains. Monthly Weather Review, 136, 62-77, doi:10.1175/2007MWR2164.1.
Date:2008-01-01
Resource Type:article
Title:Dynamic forcing and mesoscale variability of heavy precipitation events over the Sierra Nevada mountains
Abstract: The aim of this research is to investigate the causes for an isolated maximum in precipitation that is typically found along the northern half of the Sierra Nevada mountains of California, in the vicinity of Plumas National Forest (PNF), during moderate to heavy precipitation events. Particular attention was paid to the role various mesoscale (i.e., <200 km) terrain features may have played in localizing the precipitation at PNF. Numerical simulations and sensitivity experiments for two cases of heavy precipitation at PNF reveal that the extent to which terrain acts to focus precipitation is case sensitive. In the first case, the upstream flow was characterized by a strong horizontal gradient in wind speed and moisture. This gradient led to differential deflection of airstreams incident to the range and, consequently, localized convergence and enhanced rain rates at PNF. This localized enhancement occurred regardless of whether any terrain variations were present in the simulations or not. The second case was characterized by more a horizontally uniform upstream flow and showed a much stronger sensitivity to terrain variations, in particular, short- and long-wavelength undulations along the leading (west) edge of the Sierra Nevada range. When these undulations were removed, no localized maxima in precipitation occurred.
Subject(s):Forcing, Mesoscale processes, Precipitation, Mountain meteorology
Peer Review:Refereed
Copyright Information:Copyright 2008 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 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.
OpenSky citable URL: ark:/85065/d7pg1rz6
Publisher's Version: 10.1175/2007MWR2164.1
Author(s):
  • Heather Reeves - NCAR/UCAR
  • Yuh-Lang Lin
  • Richard Rotunno - NCAR/UCAR
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