Friday, September 20, 2024

Soggy set up ahead as back-to-back systems hit B.C.’s central, northern coasts

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A very wet and unsettled pattern will set up over coastal B.C. this weekend, a pattern that is much more reminiscent of what would happen during late fall.

Visit our Complete Guide to Fall 2024 for an in depth look at the Fall Forecast, tips to plan for it and much more!

An area of high pressure that has dominated the region for these final days of summer will be compressed and pushed south, as a low pressure system tracks towards central and northern B.C. this weekend. Some of the harder-hit areas could be in line for 100 mm through Sunday.

Baron - BC atmospheric moisture Saturday - Sept20

Baron – BC atmospheric moisture Saturday – Sept20

Conditions will remain dry Saturday across southern parts of the province, though temperatures will be a degree or two on the cool side of seasonal. By Sunday, there’s a chance for rain showers to reach the Lower Mainland.

Friday overnight through Sunday:

Heavy rain is expected to push into British Columbia later Friday, impacting much of the central and northern coast through the weekend. The set up will be considered a weak atmospheric river.

As much as 75-100 mm of rain could impact communities, including Bella Bella, heightening the risk for localized flooding in areas that see significant amounts.

Baron - BC rain accumulations - Sept20Baron - BC rain accumulations - Sept20

Baron – BC rain accumulations – Sept20

Monday through Wednesday:

Another atmospheric river is forecast to bring heavy rain to the north and central coast for the start of next week, and this event will be stronger than the weekend system, but will track a bit further north.

Heavy rain, with upwards to 150 mm is expected for the northern coast and Haida Gwaii, with lesser amounts forecast for Bella Bella and Bella Coola compared to the weekend system.

Baron - BC atmospheric moisture Monday - Sept20Baron - BC atmospheric moisture Monday - Sept20

Baron – BC atmospheric moisture Monday – Sept20

High pressure protects the Lower Mainland and southern Vancouver Island once again, with some showers possible later on Wednesday on the tail end of the atmospheric river.

SEE ALSO: Atmospheric Rivers: Expert explains the good and bad of these extreme storms

Atmospheric rivers are, for the most part, what you might imagine from the name — rivers in the sky. They’re long, narrow bands in the atmosphere that carry large amounts of water vapour, usually from the tropics where water and atmospheric moisture are abundant.

Baron - BC rainfall outlook - Sept20Baron - BC rainfall outlook - Sept20

Baron – BC rainfall outlook – Sept20

Thursday through Friday:

The active pattern brings another system to coastal B.C. late next week, and has the chance to bring the most rain to southern areas that remain protected from these previous back-to-back systems.

Overall however, a drier than normal pattern will dominate for the South Coast region through the end of September, and into the beginning of October, as well.

WATCH: British Columbia’s 2023 Fall Forecast: What an El Niño pattern means for fall storms

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