Forecast region

In Canada, the Meteorological Service divides the country into several forecast regions for the purpose of issuing routine text forecasts and weather warnings, as Canada's provinces and territories do not use a common second-level administrative division scheme similar to the division of states into counties and parishes in the United States. Due to the localized nature of some weather phenomena, such as freezing rain storms and tornadoes, some forecast regions that have been found to be more prone to such phenomena are further divided into sub-regions, especially in the Prairie provinces. Parts of Northern British Columbia, Northern Quebec, Labrador, and the territories do not belong to any forecast region, owing to the lack of any significant population in those areas.

With the implementation of Specific Area Message Encoding into the Weatheradio Canada service in 2007,^[1] each forecast region and sub-region has been given a unique six-digit code known as a Canadian Location Code, or CLC.^[2] These codes are programmed into SAME-capable weather radio receivers the same way FIPS county codes are programmed into receivers in the United States, enabling them to only activate and sound an alert when the MSC issues weather warnings for the forecast regions that have their codes programmed into the receivers. Outside of Nunavut and the Northwest Territories, CLCs are assigned using the format 0paabb, where 0 is a constant, p is a province or provincial or territorial grouping, aa refers to a specific forecast region, and bb, if nonzero, refers to a sub-region. In Nunavut and the Northwest Territories, where population densities are much lower than elsewhere in the country, the format is 09aaa0, where aaa refers to the forecast region. On the water, CLCs are assigned using the format 00aaab, where aaa refers to the forecast region, and b, if nonzero, refers to a sub-region. CLCs are also assigned to the areas of international waters for which Canada issues maritime navigation and weather warnings. For specific types of warnings, such as air quality alerts, coastal flood warnings and tsunami warnings, CLCs of the format 0p0aaa have been assigned.