North American extreme precipitation events and related large-scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends

Abstract

This paper surveys the current state of knowledge regarding large-scale meteorological patterns (LSMPs) associated with short-duration (less than 1 week) extreme precipitation events over North America. In contrast to teleconnections, which are typically defined based on the characteristic spatial variations of a meteorological field or on the remote circulation response to a known forcing, LSMPs are defined relative to the occurrence of a specific phenomenon-here, extreme precipitationand with an emphasis on the synoptic scales that have a primary influence in individual events, have medium-range weather predictability, and are well-resolved in both weather and climate models. For the LSMP relationship with extreme precipitation, we consider the previous literature with respect to definitions and data, dynamical mechanisms, model representation, and climate change trends. There is considerable uncertainty in identifying extremes based on existing observational precipitation data and some limitations in analyzing the associated LSMPs in reanalysis data. Many different definitions of "extreme" are in use, making it difficult to directly compare different studies. Dynamically, several types of meteorological systems-extratropical cyclones, tropical cyclones, mesoscale convective systems, and mesohighs-and several mechanisms-fronts, atmospheric rivers, and orographic ascent-have been shown to be important aspects of extreme precipitation LSMPs. The extreme precipitation is often realized through mesoscale processes organized, enhanced, or triggered by the LSMP. Understanding of model representation, trends, and projections for LSMPs is at an early stage, although some promising analysis techniques have been identified and the LSMP perspective is useful for evaluating the model dynamics associated with extremes.

A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events

“…Previous studies adopted various approaches and criteria for the identification of precipitation extremes. Common criteria, applied to daily or multiple-day precipitation amounts, are (i) absolute thresholds, (ii) percentile-based thresholds, and (iii) monthly or annual maxima (Zhang et al, 2011;Barlow et al, 2019). Also, with regard to their spatial characteristics, several approaches have been used to define extremes, including (1) individual grid points (e.g., Pfahl and Wernli, 2012), (2) area averages for specific regions of interest (Martius et al, 2006;De Vries et al, 2018), (3) spatially smoothed fields using a spatially-moving average within a defined radius (Skok et al, 2009;Raveh-Rubin and Wernli, 2015), and (4) spatially coherent objects that consists of multiple co-located extreme precipitation grid points (Moore et al, 2015(Moore et al, , 2019Mahoney et al, 2016).…”

The Climatic Analysis of Summer Monsoon Extreme Precipitation Events over West Africa in CMIP6 Simulations

“…With the introduction of the new state-of-the-art Coupled Model Intercomparison Project, Phase 6 (CMIP6; Eyring et al 2016) which is made up of models with higher spatial resolution and additional physical complexity relative to the phase 5 (CMIP5; Taylor et al 2012) models, it is a useful exercise to assess the performance of CMIP6 models in representing daily summer monsoon rainfall characteristics over West Africa. Other studies (e.g., Akinsanola and Zhou, 2019a, b;Barlow et al 2019) have opined that these improvements may not necessarily improve model representation of the current climate and precipitation characteristics on regional-scales. It is entirely possible that model performance may vary over regions and across CMIP6 models as differences exist in how they represent physical processes and according to their numerical resolution.…”

Meteorological Environments Associated With California Wildfires and Their Potential Roles in Wildfire Changes During 1984–2017

“…Despite the broadly explored relationship between meteorology and fire activity, the potential effect of meteorological environments in general and large‐scale meteorological patterns (LSMPs) in particular, on California wildfires based on comprehensive historical records remains relatively unexplored. LSMPs are recurrent meteorological patterns defined relative to the occurrence of a specific phenomenon, such as heat waves (Grotjahn et al., 2016) and extreme precipitation (Barlow et al., 2019). LSMPs have a spatial scale larger than mesoscale systems but smaller than the scale of modes of climate variability that are often near‐global (Grotjahn et al., 2016).…”