Daniel Keyser
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View article: Features and Processes Influencing the Evolution and Forecast Skill of Strong Low-Skill Arctic Cyclones
Features and Processes Influencing the Evolution and Forecast Skill of Strong Low-Skill Arctic Cyclones Open
Strong Arctic cyclones (ACs) characterized by low forecast skill of intensity, hereafter referred to as strong low-skill ACs, may pose challenges to human activities in the Arctic. The purpose of this study is to increase understanding of …
View article: A Climatological Analysis of the Linkages between Tropopause Polar Vortices, Cold Pools, and Cold Air Outbreaks over the Central and Eastern United States
A Climatological Analysis of the Linkages between Tropopause Polar Vortices, Cold Pools, and Cold Air Outbreaks over the Central and Eastern United States Open
Coherent vortices in the vicinity of the tropopause, referred to as tropopause polar vortices (TPVs), may be associated with tropospheric-deep cold pools. TPVs and associated cold pools transported from high latitudes to middle latitudes m…
View article: Antecedents for the Shapiro–Keyser Cyclone Model in the Bergen School Literature
Antecedents for the Shapiro–Keyser Cyclone Model in the Bergen School Literature Open
Two widely accepted conceptual models of extratropical cyclone structure and evolution exist: the Norwegian and Shapiro–Keyser cyclone models. The Norwegian cyclone model was developed around 1920 by the Bergen School meteorologists. This …
View article: Composite Vertical-Motion Patterns near North American Polar–Subtropical Jet Superposition Events
Composite Vertical-Motion Patterns near North American Polar–Subtropical Jet Superposition Events Open
A polar–subtropical jet superposition is preceded by the development of a polar cyclonic potential vorticity (PV) anomaly at high latitudes and a tropical anticyclonic PV anomaly at subtropical latitudes. A confluent large-scale flow patte…
View article: Composite Synoptic-Scale Environments Conducive to North American Polar–Subtropical Jet Superposition Events
Composite Synoptic-Scale Environments Conducive to North American Polar–Subtropical Jet Superposition Events Open
A polar–subtropical jet superposition represents a dynamical and thermodynamic environment conducive to the production of high-impact weather. Prior work indicates that the synoptic-scale environments that support the development of North …
View article: Linkages between Extreme Precipitation Events in the Central and Eastern United States and Rossby Wave Breaking
Linkages between Extreme Precipitation Events in the Central and Eastern United States and Rossby Wave Breaking Open
Linkages between extreme precipitation events (EPEs) in the central and eastern United States and synoptic-scale Rossby wave breaking are investigated using 1979–2015 climatologies of EPEs and upper-level potential vorticity (PV) streamers…
View article: Recurrent Synoptic-Scale Rossby Wave Patterns and Their Effect on the Persistence of Cold and Hot Spells
Recurrent Synoptic-Scale Rossby Wave Patterns and Their Effect on the Persistence of Cold and Hot Spells Open
The persistence of surface weather during several recent high-impact weather events has been pivotal in generating their societal impact. Here we examine Hovmöller diagrams of the 250-hPa meridional wind during several periods with particu…
View article: A Climatology of Extratropical Cyclones Leading to Extreme Weather Events over Central and Eastern North America
A Climatology of Extratropical Cyclones Leading to Extreme Weather Events over Central and Eastern North America Open
Cool-season extreme weather events (EWEs) (i.e., high-impact weather events that are societally disruptive, geographically widespread, exceptionally prolonged, and climatologically infrequent) are typically associated with strong extratrop…
View article: Antecedent North Pacific Jet Regimes Conducive to the Development of Continental U.S. Extreme Temperature Events during the Cool Season
Antecedent North Pacific Jet Regimes Conducive to the Development of Continental U.S. Extreme Temperature Events during the Cool Season Open
This study considers the development of continental U.S. extreme temperature events (ETEs) during the cool season (September–May), where extreme temperatures are defined in terms of percentiles and events are defined in terms of the spatia…
View article: Extratropical Cyclones: A Century of Research on Meteorology’s Centerpiece
Extratropical Cyclones: A Century of Research on Meteorology’s Centerpiece Open
The year 1919 was important in meteorology, not only because it was the year that the American Meteorological Society was founded, but also for two other reasons. One of the foundational papers in extratropical cyclone structure by Jakob B…
View article: A Composite Perspective of the Extratropical Flow Response to Recurving Western North Pacific Tropical Cyclones
A Composite Perspective of the Extratropical Flow Response to Recurving Western North Pacific Tropical Cyclones Open
This study investigates the composite extratropical flow response to recurving western North Pacific tropical cyclones (WNP TCs), and the dependence of this response on the strength of the TC–extratropical flow interaction as defined by th…