Keeping up with changing forecasts
As you’re reading this, you have access to the weather forecast for the week ahead.
We have access to weather forecasts everywhere now – phone apps, internet, television, newspapers and even on social media. A forecast up to two weeks in advance has never been easier to access.
Erin Hynes wanted to know how often I check the weather to consider it accurate, and how often do I have to evaluate and change the forecast information?
The short answer: It depends.
Several factors go into making a weather forecast, including upper air patterns such as troughs and ridges in the jet stream, the time of year, along with ocean and atmospheric temperatures.
Not surprisingly, I often have more confidence in a fair-weather pattern than one with an active storm track. Complex winter storms change frequently and require plenty of attention and tweaking.
But how accurate is a five, seven, or even 14-day forecast?
The National Oceanic and Atmospheric Administration says a five-day forecast can accurately predict the weather about 90 per cent of the time while a seven-day forecast can accurately predict the weather about 80 per cent of the time.
A forecast of 10 days or longer is only right about half the time.
The weather is constantly changing, especially here in Atlantic Canada. I personally have the most confidence in a forecast within a three-day window. Five-day forecasts often need tweaking. A seven-day forecast is my limit.
Many weather models predict up to two weeks ahead. This is great for watching potential patterns and trends, but not for daily forecasting. A lot of it also comes down to how you present that information to the public.
Let’s take a recent storm for example. When I was looking at the week ahead and building my forecast, weather models began showing signals of a potential weather system around Friday-Saturday. It was showing as a rain-snow system at the time. I included it in my forecast but knew it would require close attention and lots of tweaking.
As the week progressed, confidence in the forecast increased as models started getting a better handle on what might take place. And while weather modelling technology continues to improve each day, models are still just a guide. A lot of it comes down to knowing how local features such as topography and temperature affects the area.
Meteorologist Jim Abraham said it best on Twitter recently: “If the four-day forecast was perfect, meteorologists would only have to work two days a week.”
I hope this answered your question, Erin, and provided a bit more insight into the world of weather.