Winter Weather Regimes in the Northeast United States

Abstract

The method of k-means cluster analysis is applied to U.S. wintertime daily 850-hPa winds across the Northeast. The resulting weather patterns are analyzed in terms of duration, station, gridded precipitation, storm tracks, and climate teleconnections. Five distinct weather patterns are identified. Weather type (WT) 1 is characterized by a ridge over the western Atlantic and positive precipitation anomalies as far north as the Great Lakes; WT2, by a trough along the eastern United States and positive precipitation anomalies into southern New England; WT3, by a trough over the western Atlantic and negative precipitation anomalies along much of the U.S. East Coast; WT4, by a trough east of Newfoundland and negative precipitation anomalies along parts of the U.S. East Coast; and WT5, by a broad, shallow trough over southeastern Canada and negative precipitation anomalies over the entire U.S. East Coast. WT5 and WT1 are the most persistent, while WT2 typically progresses quickly to WT3 and then to WT4. Based on mean station precipitation in the northeastern United States, most precipitation occurs in WT2 and WT3, with the least in WT1 and WT4. Extreme precipitation occurs most frequently in WT2. Storm tracks show that WT2 and WT3 are associated with coastal storms, while WT2 is also associated with Great Lakes storms. Teleconnections are linked with a change in WT frequency by more than a factor of 2 in several cases: for the North Atlantic Oscillation (NAO) in WT1 and WT4 and for the Pacific–North American (PNA) pattern in WT1 and WT3.

Power‐law behaviour of hourly precipitation intensity and dry spell duration over the United States

“…So a possible reason for the non-exponential waiting times is persistent regime behaviour (Franzke et al, 2015). This would imply that the regional climate models have deficiencies in reproducing the observed regime behaviour over the United States (e.g., Roller et al, 2016). Whether this is due to deficiencies in regime behaviour over the United States in the driving GCMs or due to the dynamical downscaling is an open research question.…”

A General Methodology for Climate‐Informed Approaches to Long‐Term Flood Projection—Illustrated With the Ohio River Basin

“…Both patterns are characterized by a low-pressure trough to the west and a high-pressure ridge to the east, which draws warm moist subtropical air into the region, often associated with the phenomena known as an atmospheric river or tropical moisture export (Knippertz & Wernli, 2010;Nayak & Villarini, 2017). This pressure configuration has been explicitly linked to extreme floods in the region by composite analysis and weather typing (Nakamura et al, 2013;Robertson et al, 2015) and is related to the negative phase of the Pacific/North American (PNA) teleconnection pattern (Roller et al, 2016). Its converse, which is related to the positive phase of the PNA, causes cyclonic circulation that inhibits tropical moisture transport and results in drier conditions during the winter season (Ning & Bradley, 2014).…”

Persistent precipitation extremes in the Yangtze River Valley prolonged by opportune configuration among atmospheric teleconnections

“…Revisiting power spectral properties of well‐acknowledged teleconnection modes, Feldstein () unravelled the diversity in time‐scale of atmospheric teleconnections, which span from synoptic to multi‐decadal scales. On this basis, follow‐up analysis examined implications of synoptic teleconnections on weather anomalies/extremes, with emphasis placed on the statistical relationship between occurrence of one‐day extremes and active phases of teleconnections (Archambault et al., ; Franzke and Woollings, ; Li et al., ; Harding and Snyder, ; Ohba et al., ; Roller et al., ). In contrast, little attention has been devoted to influences of synoptic teleconnections on persistence (duration) and intensity of extremes.…”