April 14, 2021 - 2:30 pm
April 14, 2021 - 3:30 pm
CategoriesWeather and Climate Systems
Weather and Climate Systems Seminar
Tropopause Polar Vortex Linkages to the February 2021 U.S. Cold Air Outbreak
Wednesday, April 14th
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Tropopause Polar Vortices (TPVs) are coherent vortices along the tropopause, with cyclonic TPVs identified by a local minimum in temperature and local maximum in potential vorticity along the dynamic tropopause. TPVs are most often found in high latitudes poleward of 60ºN but can be transported into the midlatitudes. TPVs are important features in midlatitude and polar synoptic meteorology; common TPV pathways out of the Arctic are via northern Canada and Siberia, and recent research has suggested Cold Air Outbreaks (CAOs) are often linked with TPVs.
February 2021 featured a historic CAO across the United States, both in terms of magnitude and duration. This CAO and associated winter storms had substantial societal impacts, with extensive power and water outages across Texas and parts of Oklahoma, and over 100 fatalities and an estimated $195 billion in damages. Locally, Oklahoma City recorded its longest consecutive stretch of maximum temperatures below 20°F on record (1890-present), its second coldest temperature on record, and in a combination of anomalous cold and multiple snow events its longest duration of snow depth at or above 6 inches (15cm) on record (1949-present).
This presentation will focus on the February 2021 CAO as a case study of a TPV-CAO linkage, highlighting the synoptic evolution of the CAO across North America, the role multiple TPVs had in amplifying the severity of the CAO, the anomality of the TPVs relative to climatology, and potential linkages with a preceding sudden stratospheric warming event and an East Coast winter storm.