Hey Canada: Don't get comfortable, things change Thursday
theweathernetwork.com
Monday, May 14, 2018, 9:37 PM - It's taken a while to get everyone on board, but Tuesday will bring yet another round of above seasonal temperatures to most of Canada. Heading toward and into the long weekend may be a different story for some; more on that below.
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Weather highlights:
- High temperatures sit above seasonal coast-to-coast on Tuesday, with exception of northern Ontario
- Ridging in the west keeps the heat on for B.C., Alberta
- Late-week trough developing in the east will mean a return to cooler, unsettled weather
Most Canadian weather-watchers (and isn't that most of us?) are probably at least a bit familiar with the role of the jet stream in driving weather across our country. While there are a number of different key jet streams around the globe, the ones that we focus on most for Canada's warm months are the polar and subtropical jets, with the polar being the one that drives most of our weather from west to east across the country.
Early this week, that jet stream is in a more zonal phase across much of the country; that is, it's pretty 'flat' across the eastern half of the country, rather than featuring big ridges of high pressure or troughs of low pressure. The one exception is in the west, where the jet is climbing well to the north, and bringing the warmth with it. All in all, that makes for some quiet, mild weather conditions across the country.
Watch below: Temperature pattern this week
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We're looking at above-average temperatures from Vancouver to St. John's once again on Tuesday - something that will be a welcome sight for many Canadians who've been waiting out a lackluster spring.
The only exception is northern Ontario, where temperatures will be slightly below seasonal. In southern Ontario, showers are expected overnight into Tuesday morning, though temperatures will remain above the seasonal average through the afternoon as skies clear. Some showers will also accompany the warmth in the Maritimes Tuesday.
Home to the core of the heat, some spots in Western Canada will be surpassing the 30-degree mark on Tuesday. Southern and central cities on the Prairies to the 30-degree mark as well.
Long weekend warmth? Not so fast
Before you pull out the shorts and swimsuits for the unofficial kick-off to summer, this mild pattern doesn't look set to last as we head through midweek and beyond. As you can see in the temperature pattern clip above, cooler air starts to work its way into eastern Canada once again after midweek. That's thanks to a developing trough over the Great Lakes - the gradual response of the jet stream to the ridging in the west. Unfortunately, that means a return to cooler temperatures and unsettled weather for the latter half of the week, with long range model guidance suggesting most of the country east of Manitoba will see a few rounds of precipitation between Wednesday and Victoria Day.
In the West, the ridge will prove stubborn, sending most low pressure systems riding up well to the north for most of the week and keeping conditions hot and dry for most of the Prairies and B.C. This is good news if you're craving the warmth, but potentially bad news for those with flooding concerns in the B.C. Interior as mild temperatures keep pressure on the seasonal snow melt.
