The Government of Yukon Water Resources Branch has released the May 1 Yukon Snow Survey Bulletin and Water Supply Forecast. The May 1 snow survey found that most of the territory was slightly above to well above average for this time of year.
The snowpack has increased in all basins owing to a much wetter than normal April, with most stations recording well above average precipitation that fell as snow. Average monthly temperatures for April varied around normal, however the north and west parts of the territory were notably colder than average. Colder temperatures and cloudier than normal conditions slowed snowmelt, particularly at higher elevation.
The additional snowpack accumulations and the delayed snowmelt, increase the likelihood of a shorter freshet period. This does elevate flood risk, however, the elevated risk is mostly in small to medium sized rivers with lower risk on larger rivers including the Yukon River. While water levels are expected to be above average, peak freshet flood risk to Yukon communities on large lakes and rivers remains low. The current snowpack compared to the historical peak snowpack is more informative of flood risk and more closely matches the April 1 snow survey.
High snowpack is one of several risk factors which influence flood potential during the spring breakup and snowmelt period. Spring weather, the timing and progression of snowmelt, as well as spring precipitation events, are also important drivers of flooding regardless of snowpack levels.
While many parts of the territory are showing well above average snowpack for this time of year, the April snowpack percent of normal is much more indicative of flood risk. However, flood risk is elevated relative to the April assessment as a result of the late onset of snowmelt and additional snowfall.
Every March, April and May, the Government of Yukon conducts Yukon-wide snow surveys to help forecast water levels and flow conditions across the Yukon.
The Snow Survey Bulletin and Water Supply Forecasts provide a summary of winter meteorological and hydrological conditions for major Yukon watersheds.
The bulletin provides long-term snowpack averages, monthly data, and current snow depth and snow water equivalent observations for 52 locations in the Yukon, and five locations in the neighbouring areas of British Columbia and Alaska.
Snow water equivalent is the amount of water released from the snowpack when it melts
Spring freshet, or freshet, is when rivers and lakes rise and peak in response to spring snowmelt. The freshet can last several weeks.
The May 1 snow survey is the last snowpack survey for the season.
Communications Analyst, Environment