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Weather: A cooler pattern settling in

Forecast covering the period from April 21 to April 28

This map shows the total amount of precipitation that fell over the Prairies during the seven-day period ending April 14 and captures the precipitation from last week’s storm system. With the moisture streaming in from the east, you can see that eastern Manitoba received the greatest amount, in the 30- to 40-mm range. A second area of increased precipitation was in Saskatchewan, which got 15-30 mm.

If you’re going to fail, then fail spectacularly. That’s what happened with the last forecast. Thanks to the retrograding upper low that impacted our region for most of the week of April 12-16, the forecast fell apart as the atmosphere underwent a shift to a much cooler pattern. The question is, just how long will the cool weather last?

Looking at the big picture, this forecast period will begin with a large trough of low pressure across Eastern Canada and a steep ridge of high pressure over the West Coast. This places us in a fairly strong northwesterly flow, which leaves the door wide open for outbreaks of cool air as areas of arctic high pressure slide southeastward. Each time one of these highs pushes southward, an area of low pressure will spin up, bringing with it the chance of rain or snow.

After a cool start to the week of April 19-23, milder air will temporarily move in around mid-week before an area of arctic high pressure pushes in for the weekend. Ahead of this feature we will likely see a quick shot of rain or more likely snow sometime Thursday or early Friday. Expect daytime highs in the low single digits, with overnight lows falling to around -5 C. Milder air will try to move in to kick off the week of April 26-30 as an area of low pressure is forecast to track through the Dakotas. We will have to keep an eye on this system as it has the potential to bring a quick shot of significant precipitation to our region Monday or Tuesday. Confidence in this system is not that high due to its quick speed and uncertain track.

Once this system goes by, the weather models show a more seasonable pattern developing as the western ridge and eastern trough flatten out and weaken. This would allow temperatures to moderate, with highs making it back into the mid-teens with overnight lows falling to within a couple of degrees of 0 C.

Usual temperature range for this period: Highs, 5 to 18 C; lows, -6 to +3 C.

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.



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