Stalled Systems Turn up the Heat
Here's a look at the current jet stream position and the stalled high over the US Midwest.
Published Thursday, July 13, 2017 11:58AM ADT
Last Updated Thursday, July 13, 2017 12:18PM ADT
It’s still very hot out west…and even more importantly very dry, especially across the BC interior. At the supper hour yesterday, the relative humidity was 16% in Kamloops. Daytime high temperatures will continue to be above norm, ranging from 27 to 35 until at least next Wednesday with not a drop of rain in sight and very little moisture in the air.
Why is this happening?
The stalled pattern responsible for the hot, dry weather is called a “heat dome”. A heat dome is the result of a couple of factors: a dramatic northern bulge on the jet stream and an area of high pressure system south of the jet. That area acts like a dome, and under the dome, you have sinking air. As the air sinks, it is compressed and it warms, eventually becoming trapped under itself. Day after day, the air gets warmer and warmer and becomes more and more difficult to dislodge. Sinking air also keeps a cap on the atmosphere reducing the likelihood of any shower formation.
This “heat dome” has been in place south of the border for about a month now. It’s not quite as hot as it was in Nevada but still very warm. Daytime highs will range from 38 to 43 for the next 10 days in Las Vegas!
Heat domes are not rare, but their size and duration vary, making some more dangerous than others.
The deadliest heat wave in Canadian history occurred from July 5th to the 17th, 1936; temperatures exceeded 44 C in Manitoba and Ontario and claimed the lives of 1,180 Canadians.
Right now, we don’t have to worry about the heat dome out west, but our thoughts and prayers go out to those who are dealing with the hot, dry conditions.