Canadian Coast Guard

Environment Canada Marine and Ice

Warning and Forecast Programs

Background

The Meteorological Service of Canada (MSC) of Environment Canada and the regional Meteorological Service Branch offices of Environment Canada operate Canada's weather service. MSC offices offer a broad range of products and services that are designed to help mariners make informed decisions on how weather will affect them. The Canadian Coast Guard (CCG) plays an important role in disseminating forecasts and warnings and in collecting and relaying weather information from volunteer observers and ships.

The constant stream of data coming from volunteer observers, ships, weather buoys, automatic stations, and lighthouses is supplemented by satellite imagery, weather radar and a full set of numerical weather products adapted for marine operations.

Marine Warning Program

Warnings of extreme weather events that pose a threat to life and property at sea such as strong winds, rough seas, storm surges, squall lines and severe thunderstorms, and freezing spray shall be issued for the offshore economic zone including the St. Lawrence Seaway and major inland waters.

Major inland waters are defined as having significant marine activity and where time to reach shore is comparable to the marine weather warning lead time. The criteria for the issuance of weather warnings are based on national guidance, but determined regionally based on appropriate climatology and the character of the regional marine community.

Table 1: National marine warnings

Warnings 1, 2, 3, 4, 5 and 8 are highlighted in the body of the regular forecast using the keywords “IN EFFECT”. Warnings 6 and 7 above are conveyed through special messages (WH) that get top priority on the Canadian Coast Guard communication systems.

Marine Forecast program

Marine forecasts are issued for the offshore economic zone including the St. Lawrence Seaway and major inland waters. The forecast program includes the following: synopsis, weather (warning when appropriate, wind, visibility and precipitation, freezing spray and air temperature as appropriate), extended wind forecast (3 to 5 day forecast), and seastate (except for the Arctic waters). Forecast for localized areas are not considered a basic level of service. A specialized coded forecast (See Table 3, MAFOR) and a NAVTEX compatible format bulletin are also provided on a regular basis. Forecasts for up to 42 hours in advance are normally provided on a regularly scheduled basis at least twice per day as part of a continuous program.

Marine forecast are written to describe the weather for the marine area overall and may not pinpoint local conditions that can occur due to factors such as coastal effects or irregular wind regimes associated with, as example, thunderstorms.