The Role of Wave Breaking in the Development and Subseasonal Forecasts of the February 2021 Great Plains Cold Air Outbreak

Abstract

The February 2021 Great Plains cold air outbreak (CAO) was a high-impact weather event involving numerous power outages, traffic incidents, widespread winter storm warnings, and various cold-related fatalities (BBC News, 2021;NWS, 2021a). Texas was impacted particularly hard due to the failures of power generation, natural gas supply, and water infrastructure (Doss-Goslin et al., 2021). Based on certain metrics, this event was the second most severe Great Plains CAO since 1950(Millin et al., 2022. Given the high degree of severity, there is great importance in understanding potential sources of atmospheric predictability in both observations and models that could improve forecasts of such events on the subseasonal-to-seasonal (S2S) timescale (i.e., 2-8 weeks; e.g., Vitart & Robertson, 2018).The stratospheric polar vortex, which is the boreal wintertime cyclonic circulation 10-50 km high in the atmosphere near the North Pole, has links to Northern Hemisphere CAO development. If vertically propagating planetary-scale waves break in the stratosphere, the stratospheric polar vortex will weaken and warm; if the westerly circulation reverses then a major sudden stratospheric warming occurs (

The Dynamical Footprint of Year‐Round North American Weather Regimes

“…A key interest of weather regimes is that they link to anomalous regional surface weather, and have been fruitfully leveraged for studying weather extremes (e.g., Amini & Straus, 2019; Lee et al., 2019; Millin et al., 2022; Yiou & Nogaj, 2004) and medium‐range to sub‐seasonal and seasonal predictability (e.g., Büeler et al., 2021; Cortesi et al., 2021; Lee et al., 2022; Millin & Furtado, 2022; Molina et al., 2023; Nabizadeh et al., 2022; Vigaud et al., 2018). Weather regimes have also proved valuable in other contexts, including climate dynamics and variability (e.g., Barrier et al., 2013; Madonna et al., 2017; Straus et al., 2007), energy meteorology (e.g., Grams et al., 2017; van der Wiel et al., 2019), climate model evaluation (e.g., Dorrington et al., 2022; Fabiano et al., 2020), and changes in atmospheric dynamics under climate change (e.g., Fabiano et al., 2021; Mallet et al., 2017).…”

Reply to: Response to limited surface impacts of the January 2021 sudden stratospheric warming

“…Recent work suggests that localized tropospheric wave breaking in the Siberian and Labrador Seas 4 , as well as vertical mixing 5 of radiatively-cooled surface air in Canada due to broad snow cover 6 , may have contributed to the severity of the cold air outbreak. CESM2(WACCM6) has 100 km horizontal resolution, with limited vertical resolution in the boundary layer.…”