You are driving to Knowlton from Montreal. You leave in sunshine but, by the time you reach Granby, it’s a whiteout. How could the weather in Montreal be so different from the weather near Knowlton? The quick answer is that, like fine wine, while there is a common regional character to weather, local geography makes a big difference as to how it is experienced on the ground.

We posed several questions to Andrew Retchless who forecasts our local weather on Facebook at the Retchless Weather Services page. https://www.facebook.com/retchlessweather/

What are the factors that make up our local weather? “Weather systems travel west to east,” he told us. “So we can see the character of the weather that is coming, high pressure, low pressure, warm, hot, cold or very cold. Wet or dry and so on. But our local weather, the detail that we experience, is driven by the interaction of this large weather-system with our local geography.”

What makes our locality so distinct? Andrew told us that the key terrain factors in our area, are the Green Mountains that run north/south just to the east of us. This chain is the northern extension of the Appalachians. The northern tip of this chain includes Killington, Stowe, Jay, Sutton, Echo and Glen. Weather systems, moving east, hit this feature. In the summer, this means that many of the big thunderstorms, that would affect Montreal, weaken as they reach us. In the winter, because the mountains push the air up and cool it, we get more snow than Montreal. Another local feature is the lake. “The closer you live to Brome Lake,” he said, “the more snow you will receive due to the lake effect.”

How did you get into weather? He told us that he had arrived in Magog as a boy from England. Coming from the south of England, the snow here made a huge impression on him. As a result, how weather worked became a life-long interest. Recently retired from a career in teaching at the ETSB, local weather forecasting has become his main occupation.

Tempo often features his forecasts on its Facebook page.