''Weather Whiplash'' The Story of May So Far

     The central continent as a whole has had very extreme weather in the last couple weeks. The battle between winter and summer has been much more intense than we are used to. There is a term for this: weather whiplash. Unofficially, this term describes the extreme and sudden turn from one extreme to the next (drought to flood or summer to winter or vice versa). Here's a brief discussion of the extremes we have felt so far.

     Although we may not want to remember, the month of May began with very chilly conditions and even snowfall. Areas west of Lake Manitoba started the month with an intense snowstorm which dumped in excess of 30 cm in some areas. After the storm, record cold temperatures were felt in some areas. Dauphin dropped to -15.4°C on May 2, breaking the old record of -11.7°C in 1966. That also made it the coldest temperature ever recorded in May in the city, smashing the old record of -12.2°C on May 1, 1958 and May 7, 1907. Records began in 1890 there (however there is a lot of missing data).

     A seperate system, dubbed Winter Storm Achilles, brought record snowfall south of the border from May 1-3. Parts of Iowa, Minnesota and Wisconsin were pummeled with more than 20 cm. All-time May snowfall records were broken in Minnesota (45 cm in Blooming Prairie), Wisconsin (43 cm in Rice Lake), Iowa (30 cm in Chariton) and Missouri (15 cm in Warrensburg). In addition, Arkansas received the first May snowfall in state history with 5-10 cm in the northwestern part of the state. The storm also dumped copious amounts of snowfall in northern Ontario. 10 cm fell in Geraldton and 5-10 cm in Thunder Bay.

Image source Jeff Masters. Amounts in INCHES

     Only days later, a dramatic shift to summer-like weather took place here in southern Manitoba as temperatures rose to the mid twenties on May 6-7. However, it was brief. Well below normal weather settled back a few days later as we went back down the temperature roller coaster.

     Highs struggled to reach 10°C on May 11, then bottomed out on the morning of the 12th. Winnipeg dipped to -7.3°C, not quite breaking the old record of -10.0°C in 1918. At the same time, record high temperatures were being seen in the BC Interior as temperatures exceeded 30°C. In northern Ontario, a snowstorm pummeled the region with over 30 cm in spots. Chapleau recorded 32 cm while Timmins got 26 cm.

     Only a day later, we got slapped with mid-summer-like temperatures in Manitoba with highs in the high twenties and low thirties in some instances. Winnipeg's high of 27.5°C was almost 35 degrees warmer than it was the morning before! Gretna reached a record high 31.9°C, a full 36.5 degrees hotter than the previous morning! It was a similar story south of the border with some areas challenging their record for greatest 1-day warmup. Aberdeen, South Dakota reached 33.3°C May 13, a 39°C warmup from the previous morning low of -5.6°C.

     It was even hotter yesterday south of the border. According to Jeff Masters, temperatures reached highs never seen this early in the year. Sioux City, Iowa hit 41°C yesterday, the hottest temperature ever in May. This is just 2 weeks following its first ever snowfall in May on May 1! Perhaps most extraordinary was in Omaha, Nebraska. After tying for the coldest temperature for so late in the season on May 12 (0°C) they reached the hottest temperature for so early in the season just 2 days later with a high of 38°C! Hard to find a better example of weather whiplash than that...

     Back here at home, enjoy today and tomorrow's mild  and generally pleasant conditions. A rainy weekend may be in the cards. I'll try to have a post about it on Friday.