100+ mm: Major rainfall raises flood risk in Alberta through Sunday
A stalled system will bring an extended period of heavy rain to portions of Alberta through the remainder of the weekend
Flooding is possible through Sunday as a major rainfall event builds over portions of Alberta.
Saturday’s storms around Calgary were a prelude to an extended period of heavy rain across the Edmonton area. Rainfall totals could easily exceed 100 mm in some areas.
Localized flooding is possible as water levels remain elevated following last weekend’s precipitation.
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Significant rainfall set to wash into Edmonton
A low-pressure system stalling near the border between Alberta and Saskatchewan will create a stationary band of precipitation across central Alberta.
We’ll see very heavy rainfall slump across the Edmonton area on Saturday night, with rainfall rates approaching and locally exceeding 5-10 mm per hour.
Downpours will continue across central Alberta into the day Sunday, increasing the threat for localized flooding. High streamflow advisories are in effect for numerous waterways across the region.
Moderate instability and a stationary front may give rise to some thunderstorms across southern Saskatchewan. Small hail, gusty winds, and heavy rainfall will be the primary hazards with these storms.
Cooler temperatures could bring some wet snow above 2200 metres in the Rockies, with the wintry precipitation tapering off by Monday.
Will this rain set any new records?
Rainfall totals may exceed 100 mm across the Edmonton area.
A swath of 50-75 mm of rain may fall across a region extending from Hinton in the west to Lloydminster in the east, and from Red Deer in the south to Athabasca in the north.
While significant river flooding is not in the forecast, localized flooding will remain a concern, especially in urban areas such as Edmonton proper. Downpours can cause ponding on roadways, as well as swift runoff that can overwhelm storm drains.
Given the extent and duration of the heavy rain expected, Sunday could end up as a top-ten rainiest June day in Edmonton. The gauges have to pick up more than 46.7 mm of rain on Sunday to push the date onto that top-ten list.