The large‐scale atmospheric structure accompanying New England coastal frontogenesis and associated North American east coast cyclogenesis

• Published in: Quarterly Journal of the Royal Meteorological Society
• Main Authors: Bell, Gerald D., Bosart, Lance F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1989
• Subjects: Greenland; Alaska
• Online Access: http://dx.doi.org/10.1002/qj.49711548907; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49711548907; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49711548907

Abstract An eleven‐case composite is constructed of the large‐scale flow configuration accompanying wintertime New England coastal frontogenesis events which are associated with Atlantic coast cyclogenesis in the United States. The pre‐coastal‐front environment is dominated by anticyclonic activity in the lower troposphere over the eastern Great Lakes. The cold anticyclone moves eastward north of New England while slowly strengthening, and is eventually responsible for the cold south‐easterly flow that participates in the developing coastal front circulation. Coastal frontogenesis commences in an increasingly favourable synoptic‐scale environment for ascending motion and pressure falls with both the passage of the 500 mb ridge axis and the onset of strong 850 mb warm air advection beneath the entrance region of a broad confluence zone at 500 mb. The synoptic‐scale forcing for ascent over the developing coastal front is maximized from the cyclonic shear side of the jet in the base of the 500 mb trough to the anticyclonic shear side of the jet entrance region in the downstream confluence zone. Clearly identifiable departures in both the global‐scale (wavenumbers 0–3) and large synoptic‐scale (wavenumbers 4–8) waves from the long term climatological mean 1000–500 mb thickness field are observed during the evolution of the Atlantic coast cyclogenesis event. The major deviations from climatology in the wavenumbers 0–3 thickness deviation fields are negative anomalies in eastern Asia, the northern Soviet Union and the United States, and positive anomalies over Alaska and Greenland. The global‐scale thickness waves show substantial evolution in their transience and amplitude characteristics following the onset of the cyclogenesis event. The wavenumbers 4–8 thickness anomaly analyses reveal initially quasi‐stationary amplification during the onset of cyclogenesis. As Atlantic coast cyclone development proceeds, however, a pronounced positive thickness anomaly is generated in the western Atlantic and extends into New ...