Updated | 5:55 a.m Friday
The National Weather Service in Juneau canceled a flood warning for the Mendenhall Lake area.
Mendenhall Lake water level crested at 10.92 feet about 4:30 p.m. Thursday, and since has been steadily falling.
~ Tripp J Crouse, KTOO
Updated 8:25 a.m. Thursday
The National Weather Service issued a flood warning for the Mendenhall Valley area Thursday morning.
General forecaster Jessica Voveris said a glacial dam release from Suicide Basin is causing levels of Mendenhall Lake and River to rise.
“Our current stage sensors coming in at the lake were actually at 8.99 feet (at about 8 a.m. Thursday). Flood stage is 9 feet,” Voveris said. “So this is obviously very concerning event as far as issuing a warning. We’ve got that the crest is expected at the river level to be 11.9 feet around 10 p.m. Thursday.”
The glacial dam outburst also is causing the temperatures of the lake and river to decrease, which increases the risk of hypothermia.
“This one we think will come close to the record event but will not be greater than or about 12 feet, so we’re thinking the crest will be less than that, but it does have the potential to be close to that record,” Voveris said.
The flood impact should be less farther from the lake, she said
The flood warning is in effect until 10 a.m. Friday.
~ Tripp J Crouse, KTOO
Original post | 11:14 a.m. Wednesday
National Weather Service issued a flood watch for the Mendenhall Lake and Mendenhall River starting Thursday afternoon and lasting through Friday afternoon.
A glacial dam release is underway.
Hydrologists say Suicide Basin, located higher up on the ice field from Mendenhall Glacier, is now emptying into Mendenhall Lake.
“Late last night, the water level on the web cam images that we get from Suicide Basin started to show the water level going down,” said Nicole Ferrin, who’s with the National Weather Service office in Juneau. “Subsequently, the lake levels started rising.”
Water levels at Mendenhall Lake are at 6 feet and rising. Flood stage is 9 feet.
At that level, water will cover Mendenhall Lake Campground and the Skaters Cabin Road between Skaters Cabin and the West Glacier Trailhead.
View Drive will be covered at 10.9 feet.
National Weather Service says the lake could crest at 12 feet by Thursday night, with water levels dropping rapidly after that.
Uncertainty about the volume of water being released can affect their forecasts about water levels and timing.
~ Matt Miller, KTOO
