As of 10:30am, Wednesday July 27, the River Forecast Centre is upgrading to a Flood Watch for the Lillooet River, including:
• Pemberton
• Lillooet Lake
• Lillooet River and tributaries
The River Forecast Centre is issuing a High Streamflow Advisory for:
• Sea-to-Sky rivers and creeks, especially glacially influenced
A province wide heat wave is in effect. Pemberton reached 37.1°C on Monday and 39.1°C on Tuesday (+5.1°C higher than yesterday’s Environment and Climate Change Canada’s (ECCC) forecast for Tuesday). Overnight low temperatures remained at 14.4°C on Tuesday morning and 15.1°C on Wednesday morning. The Lillooet River watershed is comprised of unmonitored very high elevation snow and glacial contributions which can delay peak flows into the summer months. The recent hot weather is significantly melting high elevation snow and glaciers in the region. The Lillooet River near Pemberton (08MG005) hydrometric station rose overnight to 578 m3/s as of 6:30am this morning – an increase of about 75 m3/s from the previous day’s melt-related peak. The river has reached above a 2-year return period flow (564 m3/s) at Pemberton.
Hot weather remains in the forecast for the upcoming week. Current Pemberton ECCC Weather Forecast Max/Min are as follows; Wednesday: 35°C/16°C, Thursday: 35°C/13°C, Friday: 34°C/13°C, Saturday: 33°C/13°C, Sunday: 32°C/16°C. The Lillooet River is expected to continue rising this week and could reach above a 5-year return period flow (709 m3/s) or higher at Pemberton. The upcoming flows will be the highest recorded flows for late-July since measurements began on the Lillooet River near Pemberton in 1914.
Other rivers and creeks in the Sea-to-Sky region with high elevation snow and glacier contribution are experiencing significant rises due to the heat wave.
Although rivers and creeks in the Sea-to-Sky are unlikely to reach peak flood levels experienced typically from rain and rain-on-snow events in the fall, the upcoming flows are expected to be highest experienced in late July. Extreme caution should be taken for those travelling to the backcountry during the current heat event.
The public is advised to stay clear of the fast-flowing rivers and potentially unstable riverbanks during the high-streamflow period.
Details of the COFFEE and CLEVER Model forecasts can be found at:
The River Forecast Centre continues to monitor the conditions and will provide updates as conditions warrant.
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