Nass River High Streamflow Advisory

From: Chapman, Allan R ENV:EX
Sent: Monday, May 26, 2008 16:16
Subject: High Streamflow Advisory: Skeena, Nass, Bulkley
Importance: High

High Streamflow Advisory: Northwest rivers, including:

* Skeena River (Terrace)
* Nass River
* Bulkley (Smithers)

Issued: 26May2008 4:00PM

Temperatures for the past three days have been above normal in the Northwest, with daily high temperatures above 24 degrees at Smithers yesterday and today. This warm weather has accelerated melt of the ripe snowpack, and has caused the Bulkley River, Skeena River, Nass River, and others to rise over the past 60 hours. With the continuing snowmelt produced from the warm weather today, rivers in the northwest are expected to continue to rise overnight and Tuesday, and may reach levels tomorrow or Wednesday where localized flooding occurs.

The Skeena River has a current discharge of 4380 cubic metres per second (m3/s), and is rising. It will be near 4800 m3/s Tuesday (at a 2-year return period), and may rise beyond that. The June 2006 peak on the Skeena was 5200 m3/s.

The Nass River has a current discharge of 3250 m3/s. It will be near or above a 2-year return period discharge of 3480 m3/s Tuesday.

The Bulkley River has increased in water level 15 cm since Saturday. Its current discharge is 520 m3/s. It will be at or near a 2-year return period discharge of 560 m3/s Tuesday. This will match the water level experienced on May 20.

Temperatures are forecast to fall to seasonal normals by Wednesday, which will ease snowmelt rates. However, Environment Canada is forecasting light rain in the Skeena / Nass basins Wednesday and Thursday (4-6 mm).

There is abundant snowpack remaining in the Skeena and Nass basins. Following the late spring and delayed melt, and the hot weather of the Victoria Day weekend, snowpacks are very ripe. Temperatures near normal or only slightly above normal are sufficient to keep snowmelt progressing, and will keep water levels on the Skeena, Nass, and Bulkley rivers, and other rivers in the northwest, high.
________________________________
Allan Chapman, P.Geo.
Head, River Forecast Centre
BC Ministry of Environment
4th Floor, 395 Waterfront Crescent, Victoria BC V8W 9M2
PO Box 9362 STN PROV GOVT
Tel: 250-387-9472, Fax: 250-387-8897
Website: http://www.env.gov.bc.ca/rfc/ <https://spring.gov.bc.ca/exchweb/bin/redir.asp?URL=http://www.env.gov.bc.ca/rfc/>

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