High Streamflow Advisory

– South Coast and Vancouver Island (Maintained)

UPDATED: 11:00 AM December 18, 2018


The River Forecast Centre is maintaining a High Streamflow Advisory for the South Coast and  Vancouver Island including:

  • Metro Vancouver – including the Serpentine and Nicomekl Rivers and local streams
  • Howe Sound – including the Stawamus River and tributaries along the Sea-to-Sky Highway
  • Sunshine Coast – including watersheds around Gibsons and Sechelt
  • North Shore – including the Seymour River and watersheds around North Vancouver and West Vancouver
  • Fraser Valley (North) – including mountainous tributaries from Coquitlam to Harrison
  • West Vancouver Island – including tributaries around Gold River, Zeballos, Tofino and surrounding areas
  • Central Vancouver Island – including the Sproat and Somass Rivers and areas surrounding Port Alberni
  • East Vancouver Island – including tributaries around Campbell River, Courtenay, Parksville, Nanaimo and surrounding areas
  • Southern Vancouver Island – including the Cowichan River, Chemainus River and surrounding tributaries

A series of powerful Pacific storms has impacted British Columbia for the past week, with several weather stations recording over 300 mm of precipitation.  Freezing levels have ranged between 1000 to 1500 m resulting in significant snow accumulation over higher terrain. Rivers and creeks on Vancouver Island and the South Coast have been high, but have not resulted in flood levels.

Rainfall is expected to continue through Tuesday evening, and ease overnight and into Wednesday.  Another strong storm is forecast to arrive on Thursday bringing moderate to heavy precipitation to Vancouver Island and the South Coast.  Freezing levels are expected to reach 2000 m on Thursday, increasing the risk of a rain-on-snow event for the lower elevations.  Flows are expected to peak late Thursday or Friday. Additional storm systems are possible into the weekend.

Continued periods of high streamflow are expected on rivers this week. Brief periods between storms will allow for river levels to ease during these gaps in heavy rainfall.

The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.

 

A High Streamflow Advisory means that river levels are rising or expected to rise rapidly, but that no major flooding is expected.  Minor flooding in low-lying areas is possible.

A Flood Watch means that river levels are rising and will approach or may exceed bankfull.  Flooding of areas adjacent to affected rivers may occur.

A Flood Warning means that river levels have exceeded bankfull or will exceed bankfull imminently, and that flooding of areas adjacent to the rivers affected will result.

High Streamflow Advisory – South Coast and Vancouver Island

ISSUED: 2:00 PM December 12, 2018

 

The River Forecast Centre is issuing a High Streamflow Advisory for the South Coast and  Vancouver Island including:

  • Metro Vancouver – including the Serpentine and Nicomekl Rivers and local streams
  • Howe Sound – including the Stawamus River and tributaries along the Sea-to-Sky Highway
  • Sunshine Coast – including watersheds around Gibsons and Sechelt
  • North Shore – including the Seymour River and watersheds around North Vancouver and West Vancouver
  • Fraser Valley (North) – including mountainous tributaries from Coquitlam to Harrison
  • West Vancouver Island – including tributaries around Gold River, Zeballos, Tofino and surrounding areas
  • Central Vancouver Island – including the Sproat and Somass Rivers and areas surrounding Port Alberni
  • East Vancouver Island – including tributaries around Campbell River, Courtenay, Parksville, Nanaimo and surrounding areas
  • Southern Vancouver Island – including the Cowichan River, Chemainus River and surrounding tributaries

A series of powerful Pacific storms continue to impact British Columbia. Following heavy rainfall yesterday, another storm is expected to arrive to south-west BC overnight Wednesday into Thursday. Moderately heavy rainfall is expected with this storm, along with a slight rise in temperatures. Over higher terrain, precipitation is expected to remain as snow, however mid-elevations (<1400m) may see minor melt of snow that has accumulated over the past day. An additional storm is expected to arrive later on Friday.

Streamflow is expected to rise in response to these storms, with high flows expected on Thursday. Rivers will have a reprieve later on Thursday or into Friday, before another round of precipitation arrives. Current hydrological modelling is indicating the potential for streamflow in the 2-year to 5-year return period range, and possibly higher, over the Thursday-Friday period.

The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.

 

ENDED – High Streamflow Advisory

ENDED – High Streamflow Advisory – Howe Sound, Sunshine Coast, North Shore, Fraser Valley (North), Squamish River, Sea-to-Sky, Fraser Valley (South)

ISSUED: 9:30 AM November 28, 2018

 

The River Forecast Centre is ending a High Streamflow Advisory for the South Coast including:

  • Metro Vancouver – including the Serpentine and Nicomekl Rivers and local streams
  • Howe Sound – including the Stawamus River and tributaries along the Sea-to-Sky Highway
  • Sunshine Coast – including watersheds around Gibsons and Sechelt
  • North Shore – including the Seymour River and watersheds around North Vancouver and West Vancouver
  • Fraser Valley (North) – including mountainous tributaries from Coquitlam to Harrison
  • Squamish River
  • Sea-to-Sky – including tributary watersheds along the Sea-to-Sky corridor north of Squamish to Whistler
  • Fraser Valley (South) – including the Chilliwack River and surrounding tributaries

Rainfall eased on Tuesday, following a significant atmospheric river event on Monday. Rivers have peaked from the runoff from this event, and levels have eased.

The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.

 

A High Streamflow Advisory means that river levels are rising or expected to rise rapidly, but that no major flooding is expected.  Minor flooding in low-lying areas is possible.

 

A Flood Watch means that river levels are rising and will approach or may exceed bankfull.  Flooding of areas adjacent to affected rivers may occur.

 

A Flood Warning means that river levels have exceeded bankfull or will exceed bankfull imminently, and that flooding of areas adjacent to the rivers affected will result

High Streamflow Advisory (DOWNGRADED)

High Streamflow Advisory (DOWNGRADED) – Howe Sound, Sunshine Coast, North Shore, Fraser Valley (North)

High Streamflow Advisory (MAINTAINED) – Squamish River, Sea-to-Sky, Fraser Valley (South)

UPDATED: 11:40AM November 27, 2018

 

The River Forecast Centre is downgrading a Flood Watch to a High Streamflow Advisory for the South Coast including:

  • Metro Vancouver – including the Serpentine and Nicomekl Rivers and local streams
  • Howe Sound – including the Stawamus River and tributaries along the Sea-to-Sky Highway
  • Sunshine Coast – including watersheds around Gibsons and Sechelt
  • North Shore – including the Seymour River and watersheds around North Vancouver and West Vancouver
  • Fraser Valley (North) – including mountainous tributaries from Coquitlam to Harrison

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

  • Squamish River
  • Sea-to-Sky – including tributary watersheds along the Sea-to-Sky corridor north of Squamish to Whistler
  • Fraser Valley (South) – including the Chilliwack River and surrounding tributaries

A series of intense Pacific storms impacted the South Coast and Vancouver Island yesterday and overnight. Observed rainfall totals for this event, since Sunday afternoon, have been in the 60-170 mm range through the Howe Sound, Sunshine Coast, and North Shore Mountains.

Rivers have been responding to this rainfall, with peak levels being experienced in most rivers on Monday, or early on Tuesday. Some river systems, including the Mackay Creek, Seymour River, Stawamus River, upper Coquitlam River, and upper Stave River reached between 2-year and 10-year return period flows. River levels in other areas generally remained below 2-year flow.

Precipitation is expected to continue through Tuesday, with significantly reduced rainfall rates than were observed on Monday. River levels in most areas are expected to remain elevated through Tuesday, however significant additional rises are not expected at this time.

The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.

 

Flood Watch!

Flood Watch – Howe Sound, Sunshine Coast, North Shore, Fraser Valley (North)

High Streamflow Advisory – Squamish River, Sea-to-Sky, Fraser Valley (South)

UPDATED: 11:30 AM November 26, 2018

 

The River Forecast Centre is maintaining a Flood Watch for the South Coast including:

  • Metro Vancouver (NEW) – including the Serpentine and Nicomekl Rivers and local streams
  • Howe Sound – including the Stawamus River and tributaries along the Sea-to-Sky Highway
  • Sunshine Coast – including watersheds around Gibsons and Sechelt
  • North Shore – including the Seymour River and watersheds around North Vancouver and West Vancouver
  • Fraser Valley (North) – including mountainous tributaries from Coquitlam to Harrison

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

  • Squamish River
  • Sea-to-Sky – including tributary watersheds along the Sea-to-Sky corridor north of Squamish to Whistler
  • Fraser Valley (South) – including the Chilliwack River and surrounding tributaries

A series of intense Pacific storms is impacting the South Coast and Vancouver Island. Heavy rain has occurred overnight and this morning across the region, and is expected to continue through the day on Monday. Observed rainfall totals so far have been in the 20-60 mm range through the North Shore Mountains and Howe Sound.

Heavy rain is expected to continue throughout the day today. Environment and Climate Change Canada has issued rainfall warnings for the region, indicating the potential for 60-80 mm of rainfall through Tuesday morning, and amounts up to 90-120 mm over higher terrain.

River levels are expected to rise rapidly in response to this rainfall throughout Monday and overnight into Tuesday. Shallow snow accumulations at mid-elevations over the past few days are expected to melt with warmer temperatures, and will contribute additional runoff to streams. Additional heavy rainfall is expected to continue throughout the day. Peak flows are expected late Monday and into Tuesday.

Hydrologic modelling of current weather forecasts is indicating the potential for flood levels in streams and rivers in the Howe Sound, Sunshine Coast, North Shore, Fraser Valley (North) and Metro Vancouver areas.

The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.

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