High Streamflow Advisory: South Coast, North Shore, and Howe Sound
Issued: 02 December 2015 4:00 PM
The BC River Forecast Centre is issuing a High Streamflow Advisory for:
- North Shore including Seymour, Lynn, Capilano, and Coquitlam rivers and surrounding small streams
- Howe Sound including the Stawamus River and surrounding small streams
The first in a series of powerful storms with high winds and high rainfall totals will affect the South Coast Wednesday overnight and through the day on Thursday. Although model uncertainty still exists regarding precipitation totals and the track of the storm, rainfall totals of 80 to 180 mm are expected Wednesday overnight to Thursday evening for the North Shore and the southern areas of Howe Sound. At higher elevation, snow is expected due to cooling temperatures on Thursday.
Rainfall is expected to ease Thursday night through Friday. Temperatures are expected to cool on Friday ahead of another storm expected to arrive on the South Coast by Saturday morning. Further details on the storm track and timing are available at the Environment Canada weather blog.
The B.C. Storm Surge forecast indicates a moderate risk of flooding in low-lying coastal areas in the Lower Mainland due to elevated tidal conditions around midday on Thursday. Tidal conditions are expected to ease after Thursday’s high tide. Details of storm surge forecasts are provided at the B.C. Storm Surge website.
Smaller streams on the North Shore are expected to see rapidly rising water levels by early morning Thursday, while larger systems will see increases by mid-morning Thursday and peak water levels by late-afternoon or evening Thursday.
Streamflows on major streams in the North Shore and southern sections of Howe Sound are expected to increase to flows where low-lying areas may see minor flooding and streams will be flowing fast. Smaller streams at higher elevations may reach or exceed bankfull conditions due to heavy rain and the expected added pulse of runoff from snowmelt on the North Shore and Howe Sound.
The public is cautioned to stay clear of rivers during rain events due to quickly flowing water and potentially unstable riverbanks.
The River Forecast Centre will continue to monitor conditions and will provide updates as conditions warrant.