There’s a common expression in Whistler: if you don’t like the weather, wait five minutes.
While that may be true in a typical year, recent weather patterns have left Whistler and the Pacific Coast with mostly grey, wet, and cold weather for spring and summer, which is anything but typical.
According to David Jones, a climatologist with the Environment Canada Weather Office, this has been a most unusual year.
“It’s been a pretty crappy summer so far,” he said. “We had a pretty good month of May generally, it was warmer and sunnier than normal — and I’m generalizing about the South Coast — but June really went into the crapper. Which June can do — it’s really a bipolar month in that it can be really good or really bad, but it is rare that it would carry so far into the month of July.”
Even the sunny periods were unusual, said Jones. At the beginning of July the Lower Mainland and southern Vancouver Island were reporting record high temperatures for about a week before the colder, wetter weather system returned.
The system is the result of an Alaskan low pressure system that drifted to the south and stalled off the coast of British Columbia.
“That system just set up shop out there, and has been spinning off storms and clouds and lots of precipitation,” said Jones. “In the last week or so, before the nice weather came again, a system came in and just stalled on top of us. Usually it would push off after a few days as a high pressure system would move in.”
The result was seven straight days of rain, which ties the second-most consecutive days of rain in July. The actual record is 14 days of rain in 1993, but Jones thinks that’s probably a mistake. The last time Whistler reported seven days of rain was in 1991.
The good news is that weather patterns are changing.
“We’re into more of a typical summer weather pattern now, and should be sunny through Saturday as this ridge of high pressure sticks with us. Beyond that we could see a weak front possibly crossing on Sunday, not a big soaker, then we’ll get some more high pressure weather from offshore,” said Jones. “It will be warm, but not hot by any stretch of the imagination. It could get warmer mid-week, but things are looking a little cooler than normal — really nice summer weather actually, but not the heat we’ve seen in the last few years.”
Whistler’s latest rain cycle broke up just as an Environment Canada study proved that humans are causing critical climate change, with human activity influencing rainfall.
The study, authored by Xuebin Zhang and Francis Zwiers looked at precipitation data from 1925 to 1999, compared it to 14 complex climate models by computer, and discovered that rainfall has shifted north from regions at the equator to Canada and Europe, as well as to the tropics below the equator.
While the authors of the study expected to find that human activity had some influence on weather patterns, they were surprised by how much impact those changes would have on regions that are most sensitive to rain, like northern Africa. According the report, human activity is strengthening the water cycle, moving more water vapour away from warm areas and pushing it towards the poles. That has the effect of making wet areas wetter, and dry areas drier.
The buildup of greenhouse gases and sulphate aerosol concentrations are responsible for these conditions, and have a greater impact on climate than events like volcanic eruptions. The authors are recommending a global response to address the issue, as well as enhanced strategies within Canada.
The study will be published in Nature magazine this week. This is the first time that rainfall has been used to measure human impact on climate change. Previous reports have made similar connections between greenhouse gas emissions and climate change by looking at ocean temperatures and air temperatures.