Threat of Okanagan flooding rises with temperatures

The Okanagan is the only area in B.C. with a lower than normal snowpack level as of May 1, but not even it is spared the risk of flooding, according to the BC River Forecast Centre.

“Every region is at risk for flooding, even if the snowpack is below normal. The weather conditions during spring play a critical role in the rate at which the snow melts,” reads the report.

“For example, gradual warming under dry conditions is ideal to lessen the flood risk. A lengthy cold period with high amounts of precipitation followed by a sudden extreme heat wave could lead to catastrophic conditions, especially if additional rain follows.”

The risk is born from colder April temperatures continuing into May and, across the province, delayed snowmelt. If a heat wave happens at the end of the month or in June, that’s where the issue will arise.

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The Okanagan’s snow basin is currently 83 per cent of normal, up nearly 10 per cent from a month earlier. In contrast, the Liard snowpack in Northern B.C. is at 413 per cent of normal. When every region is accounted for, however, it averages out to 113 per cent of normal, which is a rise from 99 per cent a month earlier.

These high numbers are likely due to April being colder than normal throughout the province. The BC River Forecast Centre said that temperatures ranged from -4.5 C to – 1.5 C below normal across the province.

Penticton, for example, saw the 4th coldest April with records dating back to 1907. Examples of recent years with colder than normal April temperatures are 2008 and 2011.

It’s what happens in the days ahead, however, that makes the most difference and they pointed out that spring weather is hard to predict.

Communities and residents vulnerable to flooding are being warned that they should prepare accordingly.