Analysis and characterization of Convective Monsoonal Surges into the Northern Great Basin

The North American Monsoon (NAM) is characterized by a northward surge of moisture into the desert southwest of the continental United States primarily during the summer months. While the NAM primarily affects states such as Arizona and New Mexico, sporadic surges of moisture can infiltrate northward into Nevada, Utah, and southern Idaho. The intent of this research is to better understand the synoptic and mesoscale processes that lead to monsoonal outbreaks in regions of the northern Great Basin. Primary focus and research of the monsoon is centralized over northern Mexico as well as the southwestern portions of the U.S. An enhanced understanding of mechanisms and triggers of the monsoon into the Northern Great Basin region is needed. Case studies analyzed using NCAR-NCEP reanalysis along with NARR (3-hourly data) from 1 Jan 1979 (limit of NARR) to present day for various meteorological fields are used. Algorithms used return periods of events in which we see this specific circulation trigger convection in the Northern Great Basin. Results are to enhance the understanding of the influence of extratropical flow which enables surges to propagate into the interior west along with an improved understanding of features in mid-latitude circulation that enable monsoonal moisture to penetrate to higher latitudes. This includes examination of Rossby wave breaking events both upstream and downstream of the study area for the influence in disrupting typical zonal flow and enabling meridional flow that allows for southerly surges.