WEDNESDAY, January 12th, 2022, 9:23 am – There will be heavy rainfall this week in BC as a powerful atmospheric river threatens to unleash significant aggregates that could cause widespread flooding.
Another impressive atmospheric river is flowing along the B.C. coast, bringing waves of moisture and drenching rain this week, posing a serious risk of flooding across the region. In addition to rainfall, melting snow, rising freezing levels and temperatures, as well as weakening infrastructure from disastrous November atmospheric rivers, are all contributing to the potential for flooding. Heaviest rain is likely to occur on Wednesday afternoon and evening, with some areas likely to receive a total of 100-200 mm of rain by Thursday. Rain warnings and special weather details are available, as well as a high current flow advisory. More information on timing and effects to keep an eye on below.
Wednesday/Thursday: Rain, warm temperatures increase flood risk in lower mainland
As rain continues to come in waves across BC, rain warnings and special weather descriptions cover Metro Vancouver and the Lower Mainland, including Vancouver Island, Howe Sound, and the Sunshine Coast. Multiple rounds of rain and Pacific wind returning to the area are helping to pose a threat to local flooding and high stream levels, along with rising temperatures.
The BC River Forecast Center issued a high streamflow advisory and said that areas that experienced flooding in November may be more vulnerable to flooding once again due to erosion and high baseflow conditions.
“The public is advised to stay away from fast flowing rivers and potentially unstable river banks,” the advisory said.
According to officials with Emergency Management BC, sandbags will be provided throughout the area.
A strong southwest current that developed on Tuesday would result in an atmospheric river embedded with a series of lows targeted towards the south coast. A period of heavy rain began in the afternoon when the first system arrived, and will continue through Thursday morning as additional systems hit the coast.
The heaviest rainfall is likely to fall at places with favorable fluctuations near Coast Mountains. The heaviest rain will occur on Wednesday afternoon and evening, which will continue into Thursday morning. This particular atmospheric river can be as strong as Category 3.
Through Thursday, West Vancouver Island will see 100-200 mm of rain, with some local areas potentially 200+ mm, while Metro Vancouver and the Lower Mainland could see 75-125 mm of rain.
This last and strongest system will be closely watched to bring the heaviest rain to the region.
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Rivers are expected to rise on Tuesday and peak on Wednesday or Thursday. Also, the freezing level will rise between 1500-2000 meters, leading to rapid snowfall and flooding.
While January in Vancouver is generally known as a wet month, with an average of 160 mm of rain, this week alone can bring up to 100 mm to the region.
Residents are being urged to clear the base of the hold from snow, and to ensure that appropriate emergency supplies are on hand.
Moreover, a more dry pattern is expected towards the end of this week and till the middle of next week. In addition, there will be an extended break from significant snow and ice for the south coast. However, winter is not over – seasonal temperatures for February are expected to be cooler than that.
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