Climatology and ENSO-Related Variability of North American Extratropical Cyclone Activity

Abstract

The climatology and interannual variability of North American extratropical cyclones are examined using 6-hourly sea level pressure data from the NCEP-NCAR reanalysis for the period 1950-2002 and ECMWF 40-yr Re-Analysis (ERA-40) data from 1971 to 2000. The climatology includes an evaluation of the seasonal frequency and intensity of storms as well as an analysis of extreme event intensity. ENSO variability is evaluated by ENSO phase with emphasis on boreal winter. Results show an enhanced East Coast storm track during El Niño as well as an equatorward shift in storm tracks in the North Pacific for storms generated from both the NCEP-NCAR reanalysis and ERA-40 datasets. Observed precipitation close to a storm's center is used to determine which phase of the ENSO cycle is associated with the most productive storms and where they occur. During El Niño winters, a precipitation maximum is located east of the Appalachians and is associated with an enhanced East Coast storm track. During La Niña winters, the precipitation maximum shifts to the Ohio Valley and is associated with an enhanced Great Lakes storm track. Along the U.S. west coast, there is a precipitation maximum in the Pacific Northwest during La Niña winters, which is due to a storm track west of Washington State.

Meteotsunamis in the northeastern Gulf of Mexico and their possible link to El Niño Southern Oscillation

“…Previous studies have shown that the frequency and intensity of tropical cyclones and winter cold fronts in this area are affected by climate variability. For example, Eichler and Higgins (2006) found Gulf of Mexico cyclogenesis occurred more often during the warm El Niño Southern Oscillation (ENSO) phase, because of strengthening of the southern branch of the jet stream over North America (Smith et al 1998) and increased sea surface temperature in the Gulf of Mexico (DeGaetano et al 2002). Thompson et al (2013) corroborated the previous findings and identified a multidecadal increase in storm frequency from early to late twentieth century along the Gulf of Mexico and over the southeastern coast.…”

The role of linear wave refraction in the transient eddy–mean flow response to tropical Pacific SST anomalies

“…The midlatitude response is characterized by a southward shift and zonal extension of the Pacific jet and storm track into the southwestern USA during El Niño (EN), and a northward deflection of the jet and storm track during La Niña (LN; Hoerling and Ting, 1994;Trenberth and Hurrell, 1994;Straus and Shukla, 1997;Compo and Sardeshmukh, 2004;Orlanski, 2005;Eichler and Higgins, 2006), with corresponding changes in precipitation systems (Schubert et al, 2004b,a;Seager et al, 2005bSeager et al, , 2008Herweijer et al, 2006;Cook et al, 2007;Seager, 2007). ENSO also affects the Atlantic and Europe, but the response is not as robust as in the Pacific (e.g.…”

The role of meteorological processes in the description of uncertainty for climate change decision-making

“…Between seasons, precipitation processes transition from predominantly one type to the other. Midlatitude or extratropical cyclones (1000 km scale) are a major mechanism for precipitation in the Great Lakes (Eichler and Higgins 2006). The most active period of extratropical cyclones is January through March with storms originating from "Alberta clippers" or from cyclogenesis in the lee of the Rocky Mountains (Eichler and Higgins 2006).…”

“…Midlatitude or extratropical cyclones (1000 km scale) are a major mechanism for precipitation in the Great Lakes (Eichler and Higgins 2006). The most active period of extratropical cyclones is January through March with storms originating from "Alberta clippers" or from cyclogenesis in the lee of the Rocky Mountains (Eichler and Higgins 2006). The transition from the cool to warm season is accompanied by a northward shift of extratropical storms (Eichler and Higgins 2006).…”

“…The most active period of extratropical cyclones is January through March with storms originating from "Alberta clippers" or from cyclogenesis in the lee of the Rocky Mountains (Eichler and Higgins 2006). The transition from the cool to warm season is accompanied by a northward shift of extratropical storms (Eichler and Higgins 2006). In the warm season, there is an increase in the amount of moisture entering the continent from the Gulf of Mexico, which is strongly linked to precipitation (Schubert et al 1998).…”