Weather warning side companies like Weather Watch or Instant Weather. These side companies are not associated with the government in any way. Environment Canada defines a advisory as ""an alert to cover a wide array of deteriorating weather conditions,"" a watch as ""when conditions favour that severe weather forming"" and a warning as ""severe weather is actually occurring or is imminent."" . Additionally, Environment Canada breaks down weather alerts based upon the specific type of hazardous weather. These alerts are regionally issued throughout Canada and include, but are not limited to, winter storms, extreme temperature, ice, thunderstorms (including tornadoes), wind, tsunami, tropical
Weather forecasting if more than , the larger the change in weather can be expected. If the pressure drop is rapid, a low pressure system is approaching, and there is a greater chance of rain. Rapid pressure rises are associated with improving weather conditions, such as clearing skies. Along with pressure tendency, the condition of the sky is one of the more important parameters used to forecast weather in mountainous areas. Thickening of cloud cover or the invasion of a higher cloud deck is indicative of rain in the near future. High thin cirrostratus clouds can create halos around the sun or