Canada has a new weather alert system and I’m writing this blog post because I know I’m going to need to share it with folks in the future.

The systems categorizes weather events based on the above matrix, which represents an intersection of the forecasted impact of the event and the confidence of the forecast. I like the simplicity of the colour coding, because that gets my attention and will always cause me to read more in the forecast description. I like that they have factored confidence into the determination. I alos know that most folks will just see the colours without knowing what’s behind it.

Environment Canada has a very helpful page that explains how the system works. They also have a very helpful page that lists the types of weather effects that help them make a determination of the level of impact. These are important resources and worth bookmarking.

However, severe weather is not a spectator sport in Canada and so I’m making my own set of heuristics to deal with it when I see these alerts based on the impact guide.

From reading the guide, it is very clear to me that red alerts are going to be few and far between but if I see one it will likely be accompanied by notices sent through the provincial and local emergency messaging systems, including Alertable. I will immediately stop what I am doing and take steps to secure my safety. Orange events are likely to be very damaging and should cause me to take immediate action to prepare for impacts. Yellow events will be the most common and will probably only require me to make a contingency plan.

A second set of heuristics comes into play, especially here on the west coast where sever weather effects can be very local. I’ve relied on these practices for most of the last 24 years that I have lived on this island.

• When there is a warning of any kind it triggers me to monitor the situation using a variety of information sources, starting with Environment Canada. I supplement this information with the ensemble modelling forecasts used on apps like Windy, which aggregates many different forecast models.
• I immediately look to local meteorologists like Chris Doyle who shares his insights at Ensembleator on Bluesky. Losing twitter was a big blow to having access to real time weather scientists working in our local areas. Chris has moved to Bluesky and he is my go to.
• I pay attention to actual weather conditions around me and notice changes. There is no substitution for local knowledge. I find all the time on Bowen Island that, for example, newcomers who live on south facing slopes see warnings for severe outflow winds, experience nothing more than a few gusty breezes and then complain about how inaccurate weather forecasting is. Meanwhile folks on the north end of the island will have lost power or had tress come down.
• I check things frequently because reality changes often and forecasts are not 100% accurate, especially on the coast. No forecast on teh west coast will be local enough for your particular situation so you HAVE to rely on a variety of information.
• I DO NOT rely on the bevy of other phone apps to guide my decision making in any one given moment. These are largely modelled forecasts and not subjected to local interpretation by humans unlike the Environment Canada forecasts. For longer term warnings such as expected wind storms, rain or snow fall, I watch the trends as the forecasts are released every hour or so, using the information that comes through Environment Canada, Accuweather, Windy and the Weather Network. Watching how a forecast changes across many different apps gives you a better sense of what might happen than looking at one event 36 hours away and assuming that is the truth. Reality and forecasts converge over time, but they always start differently. That is the nature of complexity.
• And of course, understand that weather predictions begin to vary wildly beyond three days, especially for changeable weather. These are not predictions. They are probabilities, verging into possibilities, verging into assumptions made fqrompast climate data. There is no such thing as a long term forecast that guarantees conditions.

These actions are, of course, on top of the base level of preparedness I have for damaging events from weather, wildfire and earthquakes. This includes having go-bags and first aid kits in our home and cars, having 60 litres of freshwater stored, and having agreed upon out-of-region phone contacts through which we can coordinate communication if we are separated during an emergency.