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- Title
Synoptic-Scale Analysis of Freezing Rain Events in Montreal, Quebec, Canada.
- Authors
Ressler, Gina M.; Milrad, Shawn M.; Atallah, Eyad H.; Gyakum, John R.
- Abstract
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.
- Subjects
SAINT Lawrence River Valley; MONTREAL (Quebec); QUEBEC (Province); SYNOPTIC meteorology; FREEZING rain; HAZARDS; ANTICYCLONES
- Publication
Weather & Forecasting, 2012, Vol 27, Issue 2, p362
- ISSN
0882-8156
- Publication type
Article
- DOI
10.1175/WAF-D-11-00071.1