Saturday, 2 May 2015

Risk of dust devils today for southern Quebec


SPECIAL WEATHER STATEMENT has been issued from Environment Canada for the possibility of dust devils in southern Quebec today.

What? Yes you read it right, dust devils. It sounds more like a minor league baseball team as opposed to a weather term, but it is. Late last April I was working outside raking leaves when a rapidly rotating column of dirt and debris went down the street adjacent to my home. It was very visible and  moved quickly with a swoosh, swaying the trees and blasting the street surface with dust and dirt left over from the winter. This was basically a dust devil or thermal. They are rather harmless, but can, in the right conditions, blow over items such as awnings, umbrellas or tents. These rotating columns of air are typically small in nature, no more than 10 to 50 feet wide. They occur just about anywhere but are very common in the southwestern US and desert locations.

They do occur in Montreal, particularly during the spring months. Typically they occur on days like today, strong sunshine, warm and dry. The sun rapidly warms the surface of the earth which causes rolls of air to be displaced. These parcels often get tilted and rotate away. At this time of year there is so much dust and dirt lying around from the winter that is is picked up by the column of air making it visible. They typically last seconds, blowing themselves out. The can reach up to 30 metres (100 feet) in the air and produce winds in excess of 80km/h.

You can read the official statement from Environment Canada HERE.

Other than that, enjoy the sunny, warm weekend as temperatures finally act like May. Highs in southern Quebec will be 22 to 24C (72 to 76F) this weekend with lows of 8 to 10C (48 to 50F). Enjoy!

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