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Article
Synoptic-Scale Analysis of Freezing Rain Events in Montreal, Quebec, Canada
Weather and Forecasting
  • Gina M. Ressler, The Weather Network
  • Shawn M. Milrad, McGill University
  • Eyad H. Atallah, McGill University
  • John R. Gyakum, McGill University
Submitting Campus
Daytona Beach
Department
Applied Aviation Sciences
Document Type
Article
Publication/Presentation Date
4-1-2012
Disciplines
Abstract/Description

Freezing rain is a major environmental hazard that is especially common along the St. Lawrence River valley (SLRV) in southern Quebec, Canada. For large cities such as Montreal, severe events can have a devastating effect on people, property, and commerce. In this study, a composite analysis of 46 long-duration events for the period 1979–2008 is presented to identify key synoptic-scale structures and precursors of Montreal freezing rain events. Based on the observed structures of the 500-hPa heights, these events are manually partitioned into three types—west, central, and east—depending on the location and tilt of the 500-hPa trough axis. West events are characterized by a strong surface anticyclone downstream of Montreal, an inverted trough extending northward to the Great Lakes, and a quasi-stationary area of geostrophic frontogenesis located over Quebec. Central events are characterized by a cyclone–anticyclone couplet pattern, with a deeper surface trough extending into southern Ontario, and a strong stationary anticyclone over Quebec. East events are characterized by the passage of a transient well-defined cyclone, and a weaker downstream anticyclone. In all cases, cold northeasterly winds are channeled down the SLRV primarily by pressure-driven channeling. Northeasterly surface winds are associated with strong low-level temperature inversions within the SLRV. Additionally, west events tend to have a longer duration of weaker precipitation, while east events tend to have a shorter duration of more intense precipitation. The results of this study may aid forecasters in identifying and understanding the synoptic-scale structures and precursors to Montreal freezing rain events.

DOI
https://doi.org/10.1175/WAF-D-11-00071.1
Publisher
American Meteorological Society
Additional Information

Dr. Milrad was not affiliated with Embry-Riddle Aeronautical University at the time this article was published.

Citation Information
Gina M. Ressler, Shawn M. Milrad, Eyad H. Atallah and John R. Gyakum. "Synoptic-Scale Analysis of Freezing Rain Events in Montreal, Quebec, Canada" Weather and Forecasting Vol. 27 Iss. 2 (2012) p. 362 - 378
Available at: http://works.bepress.com/shawn_m_milrad/18/