CALGARY

30 mm of rain possible for Calgary on Tuesday

Kevin Stanfield
Published Tuesday, June 30, 2020 7:42AM MDT

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CALGARY -- We’re stacking lows, and that brings heavy showers across Alberta.

Are you sick of this trough, yet? It continues to sit over us aloft, and the entirety of its stay has culminated into a rain event that will continue striking up today; firstly, this upper low is strengthening at the base of the trough, and then secondly, a low pressure area is developing near the surface and working through southern Alberta, with a northward track directly to Grand Prairie from there.

So, low aloft, low at the surface: hence the term, “stacked low.” These are often rather strong.

Because low-pressure areas rotate counter-clockwise in the northern hemisphere, that means we’ll be seeing something of a “buzz saw” effect with our precipitation, where it will roll against the foothills and produce potential warning-levels of rain.

As of Tuesday morning, there are only warnings/advisories in place in west-central Alberta (Grand Prairie, Hinton, Whitecourt), where 50-70 mm of rain may fall.

But here’s the thing, there is low model surety on where the heaviest rain can happen, and there are no guarantees that it will happen to Calgary’s northwest; the possibility of our city pushing over 30 mm is very much alive, and heavier precipitation south of us isn’t off the table either.

Beyond and into Wednesday, this surface low will likely have moved into central Alberta, with potential for the entirety of that rain event to pass us by before the noon hour, which could open the city for some fireworks to mark our nation’s birthday.

Here’s the forecast:

Today: