Flood Warnings and Advisories

High Streamflow Advisory – Vancouver Island and South Coast

ISSUED: 10:00AM September 23, 2020

The River Forecast Centre is issuing a High Streamflow Advisory for:

  • West Vancouver Island
  • North Vancouver Island
  • Sunshine Coast
  • Howe Sound and Sea-to-Sky including the Lillooet River
  • North Shore Mountains
  • Metro-Vancouver
  • Fraser Valley tributaries including the Chilliwack River

A series of storms is expected to impact the British Columbia coast over the next several days. The first system begins today and will continue into Thursday, with following systems passing again later Friday and into the weekend.
Environment and Climate Change Canada has issued a Special Weather Statement for the region, with forecasted rainfall totals for the first storm in the 25-40mm range for Vancouver Island, with amounts exceeding 100mm over West Vancouver Island, and 30-50mm for the South Coast with higher amounts in the mountains.
These storms will mark a significant shift in streamflow runoff conditions which have been dominated by drier summer patterns for the past several weeks. Rivers are expected to rise rapidly in response to rainfall on Wednesday, with peak flows from the first storm expected late-Wednesday or Thursday, with larger rivers expected to reach peak levels later on Thursday or into Friday. Current hydrologic modelling is indicating the potential for streamflow in the 2-year to 5-year flows in some areas which can lead to localized issues and minor flooding.
Additional storm cycles into the weekend will bring additional periods of high streamflow; advisories will be updated to reflect anticipated conditions as we approach the weekend.

The River Forecast Centre continues to monitor conditions and will provide updates as conditions warrant.

Contact for Media Relations, Ministry of Forests, Lands, Natural Resource Operations and Rural Development:
Tel: 250 356-7506

Levels of Warnings/Advisories:

  1. High Streamflow Advisory: River levels are rising or expected to rise rapidly, but that no major flooding is expected. Minor flooding in low-lying areas is possible. This is the lowest level.
  2. Flood Watch: River levels are rising and will approach or may exceed bankfull. Flooding of areas adjacent to affected rivers may occur. This is the intermediate level.
  3. Flood Warning: River levels have exceeded bankfull or will exceed bankfull imminently, and that flooding of areas adjacent to the rivers affected will result. This is the highest level.

Links:

  1. Home of River Forecast Centre
  2. Current Streamflow Conditions and Flood Forecast Modeling
  3. Map of Current Streamflow Return Periods for All WSC Stations
  4. CLEVER Model 10-day Forecasts of Discharges and Return Periods
  5. COFFEE Model 5-day Forecasts of Discharges and Return Periods
  6. Back to page of Flood Warnings and Advisories