This 'Rex block' will keep B.C. cold into February
This blocking pattern high over Canada will keep folks across B.C. shivering for the foreseeable future
Winter is here along the West Coast—and it’s in no hurry to leave anytime soon.
A giant blockage in the upper-level pattern over Western Canada will keep this chilly pattern locked over British Columbia through at least the beginning of February.
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A giant Rex block over the West
The jet stream is a region of powerful winds high in the atmosphere around the cruising altitude of passenger jets. We often see troughs and ridges form in the jet stream as it wiggles about, features which drive the vast majority of our weather across Canada.
Sometimes, though, a pattern develops that stifles the free flow of these upper-level winds. These blocks can force the weather to remain stagnant for days at a time.
Once such pattern is known as a Rex block. Named for the meteorologist who first discovered this feature, Rex blocks form when a ridge of high pressure develops north of a centre of low pressure, almost resembling a backwards letter ‘S’ on weather maps.
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Rex blocks are like a kink in a garden hose—once one forms, the flow stops and the weather you have is largely the weather you’ll get until the blockage is cleared and weather systems are able to progress downwind again.
B.C. falls under a Rex block’s spell
The stretch of winter weather enveloping B.C. to end January and begin February is blanketing the region courtesy of a large Rex block setting up over the West Coast.
We’ve got a large ridge of high pressure building over the northern Gulf of Alaska that juts into the Yukon. Meanwhile, a frigid trough is sitting over the southern half of B.C., which is responsible for keeping conditions mighty chilly.
This ridge-trough setup is a classic Rex block—and, as a result, we’re on track to see an extended period of cold temperatures and bouts of wintry precipitation throughout southern B.C. It’s likely that below-seasonal conditions will persist across the region well into at least the first half of February.