The Yukon government issued a flood warning for the Southern Lakes region at 10 a.m. Tuesday.

Bennett Lake, Tagish Lake and Marsh Lake have exceeded the 10-year return period level and continue rising.

Return period refers to the expected frequency at which a specific level or flow will be exceeded based on statistical analysis of historic records.

For example, the two-year return period is expected to be exceeded once every two years on average, but has a 50-per-cent chance of being equalled or exceeded in any year.

All three lakes rose 10 centimetres or more in the last 24 hours, the government said.

Bennett Lake, Tagish Lake and Marsh Lake are fewer than 45, 50, and 60 centimetres away from the 2007 peak, respectively.

The snowpack in the Upper Yukon River Basin was historically high at 196 per cent of normal on April 1.

A cold spring resulted in delayed melt and a 215 per cent of normal snowpack on May 1.

“While much of the snowpack has melted, snow remains in the higher elevation headwaters that continues to contribute to the Southern Lakes,” the government said in a statement.

The well-above-average temperatures experienced over the preceding days has hastened the rate of snowmelt in the headwaters of the Southern Lakes, pushing already historically high inputs even higher.

Current forecasts indicate a break in the current heat event across southern Yukon for Wednesday, with a chance of showers, but a return to well above seasonal temperatures by the coming weekend. Continued rapid snowmelt is expected.

“Rates of water level rise are likely to remain elevated for the next week in the Southern Lakes in response to this warming,” the government said.

“Water levels near or above the 2007 peak flood level are likely, given the current trajectory, and could be reached as early as this weekend.

“As the snowpack depletes, rates of rise are expected to decrease, assuming minimal precipitation.

“Precipitation will have an acute impact on water level increases and peak water levels in the coming weeks.”

Flood-prone property owners are advised to have a plan in place in the event of a flood. (See Yukon.ca for more information.)

“We will continue to monitor conditions and will provide updates as conditions change,” the government said.

A high streamflow or water advisory means that river or lake levels are rising or expected to rise rapidly, but that no major flooding is expected.

Minor flooding in low-lying areas is possible.

Flood watch means that river or lake levels are rising and will approach or may exceed bankfull or flood stage.

Flooding of areas adjacent to affected rivers and lakes may occur.

“Flood warning means that river or lake levels have exceeded or will exceed bankfull or flood stage imminently, and that flooding of areas adjacent to the rivers and lakes affected will result,” the government said.

For flood response information, the Yukon Emergency Measures Organization can be contacted at 667-5220 or EMO.yukon@yukon.ca