Aviation Safety Letter 3/2004

Local Area Weather Manuals

by Bob Robichaud, Meteorological Service of Canada

"Highly recommended reading," that's what the author of an article in issue 2/97 of the Aviation Safety Letter (ASL) had to say about the Meteorological Service of Canada's (MSC) publication called Aviation Weather Hazards of British Columbia and the Yukon. Therefore, it is fitting that when MSC was approached by NAV CANADA to document and publish local aviation weather across the country, they used this publication as a model.

When NAV CANADA announced a new approach to delivering aviation weather briefings by centralizing flight-briefing services, one of the users' concerns was the possible loss of local area knowledge. To ensure that this type of information was systematically captured and retained, NAV CANADA started the Local Area Knowledge Project (LAKP) and contracted the MSC to produce a series of weather manuals to document this local knowledge. A series of six manuals have been published, each corresponding to a specific graphic area forecast (GFA) domain, with the exception of The Weather of Nunavut and the Arctic, which covers two GFA domains.

The most critical component to the project was the interview process. To conduct these interviews, MSC meteorologists traveled across the country and sat down with pilots and other aviation professionals to discuss local weather. The meteorologists would ask the pilots to indicate where they would routinely encounter elements such as low cloud, restricted visibility, turbulence, icing, strong winds and other aviation weather hazards. Reference was made to different seasons and various types of synoptic situations. To supplement the forecasters' notes, pilots were urged to actually draw on navigation charts to accurately show where hazards were encountered. Although the main focus was "Seasonal Weather and Local Effects," several other interesting sections were added to supplement the manual, including "Basics of Meteorology," "Aviation Weather Hazards," "Weather Patterns," and "Airport Climatology."

Here is an excerpt from The Weather of Atlantic Canada and Eastern Quebec: "Cape Breton often experiences some of the worst turbulence encountered in the Maritime Provinces. [.] Southeast winds ahead of low pressure systems will be quite violent here, due to mountain waves. [.] They occur near Chéticamp and extend out to about 3 miles from the mountain peak. Here severe turbulence, downdrafts [.] and wind speeds as much as double those of surrounding areas can be expected. The downdrafts on the northwest side of the mountains will hit the water and flow outward, much like microbursts, producing patterns on the water that are readily seen from the air. Local pilots call these patterns "cat tracks" or "cat paws"."

The production of these aviation weather manuals should prove to be beneficial to pilots, flight service specialists, meteorologists, and flight dispatchers alike. They can be downloaded free of charge from the NAV CANADA Web site at www.navcanada.ca/, under flight planning, local area weather manuals.

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