The late-April flood event in eastern Alberta will be remembered for years to come. Although Albertans are accustomed to the Red Deer River rising in June, few people were expecting April flooding in Beiseker, Carbon or Rosebud.
"It had to do with the spring conditions," explained David Watson, a river forecast engineer with Alberta Environment. "We had those colder-than-average temperatures in late-March and early-April and a lot of late-spring snowfall as well, which led to a much above-average snow pack in the Red Deer basin."
Satellite data showed that most of the snow in east-central Alberta melted between April 19 and 20, thanks to a sudden increase in temperatures. All of that snow had to go somewhere, and it found its new home in the prairie creeks and rivers west of Drumheller.
"This year, the snow packs that were measured in the Red Deer River basins as of April 1 showed them to be approximately above-average to much-above-average. They were within the top 20 measurements on record, but, interestingly, they were generally half of what the snow pack levels were measured in 2014."
Watson hesitated to say that the April flood was a one-in-a-million occurrence, but did point out that it was caused by a combination of both high temperatures and the amount of snow in the area.
"It's more the timing of when that snow pack volume got released. We had half of the snow pack levels that we had in 2014 so, even though we had less of a volume it's how quickly that snow pack gets activated."
Watson went on to explain that snow pack in the prairies is different from snow pack in the mountains. On the prairies, high spring temperatures can cause the snow to melt quickly and all at once. In the mountains, the snow melts slowly as temperatures increase gradually throughout the spring.