Edmonton slammed by summer storm for the second time this week

Edmonton went through another stormy day yesterday, after a lightning storm lit up the night there earlier this week.

Summer storms aren't anything new to Edmonton, or anywhere in the Prairies, of course. They're just a sometimes costly, oftentimes dangerous fact of life there.

This week's storms are due to a low pressure system moving through the Prairies. On Tuesday, a lee-side trough set up just east of the Rockies. This trough, which is a region of lower air pressure and higher instability, sets up on the eastern side of the Rockies due to winds blowing down the eastern side of the mountains and heating up. Humid air blown in from the southwest mixes with these warm winds from the mountains and this kicks up storms.

Yesterday was a similar situation, except that there was a cold front added to the mix. Winds blowing down from the mountains did their usual thing of warming up and mixing with humid air. The cold front — which is like a tall, steep wedge of air ploughing across the ground — came through and forced that warm humid air to rise, spawning clouds which quickly turned into the thunderstorms that brought heavy rains and hail to the Edmonton area.

The active weather the prairies have been experiencing this summer is largely due to the position of the jet-stream, which in turn is due to the combined influence of two large atmospheric patterns: the Arctic Oscillation and the El Nino Southern Oscillation. These two patterns already joined forces to give Canada a dry, mild winter, and likely had a large part in the drought the U.S. has been going through this year.

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The effects of climate change are also likely to blame, as weather patterns shift and change with the warming atmosphere. No specific weather event can be definitely blamed on climate change, because as they say, "Weather isn't Climate". However, every weather event that happens gets entered into the climate record, so climate is most certainly weather, and as weather events become more extreme, the evidence is mounting that human activities are having a profound effect on our planet.