Photo: BC River Forecast Center
Map showing the percentage of snow cover above normal in major BC basins
A cooler-than-normal spring means that high-altitude snowfall in BC is about twice what it normally is at this time of year, with the risk of flooding moving to larger rivers such as the south and north of Thompson.
The BC River Forecast Center maintained flood monitoring on the North Thompson River and Shuswap region on Friday morning as more rain is expected to fall on the persistent snow in the alpine.
Thompson North and South basins are reporting 232% and 186% of normal snow cover, respectively, according to new data released Thursday.
The Okanagan reports a snow cover of 243% of normal, but now all the snow in the region has melted except the highest. There are no warnings of high flow or flood monitoring in Okanagan or Similkameen, with the risk mainly related to rainfall.
“We’ve been having this dominant weather pattern of storms and unstable rains going on,” said Dave Campbell of the BC River Forecast Center. “Earlier this week we saw places around Kelowna, Mission Creek that we are still very susceptible to and vulnerable to these heavy rain events.”
Campbell says there is still a considerable amount of snow above 1,700 feet. In the Mission Creek Basin, there is a snow cover exploration site at 1,800 feet that is only about halfway up, which keeps the stream full between rain events.
He said entrances to Okanagan Lake, which reached the full pool this week, are now “more or less” at their peak and are expected to decline in the coming weeks.
At Kamloops, Campbell said he did not know when the two arms of the Thompson River would arrive.
“I have ongoing concerns that we could see additional increases through Thompson systems,” he said. “We are in this period of high flows and we are certainly vulnerable to further increases, if we have adverse weather over the next week or two.”
Environment Canada says there are no signs of heat, so the risk of flooding will come from the rain.
“It’s really the rainy part of things. So we’re seeing a lot of precipitation potential. That could include areas in Thompson, especially in North Thompson. We’re looking forward to that,” Campbell said.
A major storm is expected on Friday from the eastern Okanagan to the Alberta border that could cause 20mm of rain and hail.
Unstable weather will continue throughout the southern interior over the weekend.
“There may be continued storm activity until Saturday and Sunday,” said Armel Castellan, a Canadian Environmental and Climate Change warning preparation meteorologist.
As for next week and beyond, Castellan said things look great in the short term, but that they will warm up in July.
“We don’t see any signings for a big or strong heat event in the coming weeks. But the chances of seeing heat in July obviously increase,” he said.
Photo: Environment Canada