Update, 5:30 a.m. Monday:
The NWS Juneau has canceled the flood warning for Mendenhall Lake and River. Water will continue to recede through the morning.
Water levels reached a crest height of 10.77 feet late Sunday night at 11:30 p.m., lower than the 11 to 11.5 feet expected.
As of 3 a.m., the Mendenhall River gauge was back below flood stage at 8.67 feet.
Update, 10:45 p.m. Sunday:
The National Weather Service reports that as of 10:15 p.m, Mendenhall Lake is at 10.6 ft and continuing to rise. All estimates remain the same.
A Facebook post from NWS also advises mariners to be aware that trees and debris have been reported in the river and could become hazards once they are washed out into the ocean.
Update, 3:45 p.m. Sunday:
The National Weather Service reported that flood waters had officially reached flood stage as of 3:15 p.m. Flood stage is 9 feet, and current estimates continue to predict a crest of 11 to 11.5 feet between 1 a.m. and 7 a.m. Monday morning.
Update, 11:45 a.m. Sunday:
In a statement posted on Facebook on Sunday morning, the National Weather Service Juneau addressed concerns circulating on social media related to whether high tide will impact flooding during the glacial release.
“The flood inundation maps created in 2014 take into consideration a high tide of 20 feet. While the Mendenhall River is expected to crest near 4 a.m., which is at high tide for the Juneau area, we are only expecting a 15.54 foot high tide,” the post reads.
The city continues to distribute sandbags and sand to residents of streets that have experienced flooding in the past. Bags can be picked up at the Valley Library while sand is available at Dimond and Melvin Parks from 9 a.m. to 5 p.m.
Residents can check the inundation maps to see whether their streets will be impacted at moderate flood stage. Here are directions for how to use the map:
• Scroll down, click “Activate MNDA2 FIM Gauge”
• Zoom out and reposition the map
• Maximize the opacity gauge
• Click the numbers under Stage(ft) on the left-hand side to see predicted inundation levels
In a Facebook post, the city warns that low-lying areas expected to be impacted by flooding shortly will be closed for safety reasons.
“All members of the public should avoid the Mendenhall River until further notice for the safety of yourself and others. Banks are unstable and slippery with recent snow,” the post reads.
Original story:
The National Weather Service has issued a flood warning due to glacial outburst flooding on Mendenhall Lake and River.
Based on the estimated current volume of Suicide Basin, water levels are expected to be much lower than this past summer’s flood.
“This one is definitely going to be different because of the late season and the fact that we’ve got snow on the ground — certainly not expecting major flooding like we saw in August,” said Nicole Ferrin, the warning coordination meteorologist with NWS Juneau Saturday morning.
During the Aug. 6 record-breaking outburst flood, the river crested at 15.99 feet. Flood waters damaged 289 homes.
The current warning is in effect until Monday morning. Ferrin said they predict Mendenhall Lake will continue to rise through Sunday and crest early Monday morning between 1 a.m. and 7 a.m. The crest height is predicted to reach between 11 and 11.5 feet.
“When we had the major record flood event back in August that reached almost 16 feet, so we’re talking five feet less than that,” she said.
At the predicted moderate flood stage, low-lying areas will flood, including View Drive. There could be more than a foot of water on Skater’s Cabin Road and the West Glacier trail, and up to three feet of water in parts of the Mendenhall Campground.
At the predicted crest, some parts of View Drive could also start to flood and homeowners along Meander Way may see water seeping into their backyards. But most homes in the Mendenhall Valley should be spared from flooding.
City and Borough of Juneau Emergency Programs Manager Tom Mattice said residents on View Drive should be considering their options for evacuation.
“The residents on View Drive definitely need to be concerned. It’s never any good news, but we hope that the flood goes as predicted,” he said. “People need to be taking evacuation seriously and have their plans in place at this point in time.”
Ferrin said it’s important residents stay updated from now until at least Monday morning.
“Residents that live along the river should always be aware of what the current conditions are. Monitor your surroundings, pay attention to what’s going on,” Ferrin said. “So take the time now, between now and early Monday morning to get ready for that crest.”
The city is distributing sandbags to homeowners that live in areas impacted by August flooding at the Mendenhall Valley Public Library from 9 a.m. to 4 p.m. daily through Tuesday.
Experts had predicted another release this fall from Suicide Basin, a glacial lake that dams meltwater and rainwater behind a spur of the Mendenhall Glacier and drains periodically.
In a 10 p.m. update, the NWS predicted that water levels would reach minor flood stage — 9 feet — early Sunday afternoon.
Homeowners in the Mendenhall Valley can get a better idea of potential flood impacts in their neighborhood by consulting the National Weather Service flood maps.
According to the city, View Drive, Skater’s Cabin Road, Kaxdigoowu Héen Dei/Brotherhood Bridge Trail and Dimond Park pedestrian bridge will be closed to traffic beginning Sunday afternoon.
