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Flood updates Wednesday: Peak of 16.4 ft. forecast at 10 a.m. Thursday
Updated: Aug 13
‘As we move through the day, the pace of information will increase,’ NWS Juneau meteorologist says; major flood stage expected to arrive about 5:45 a.m. Thursday
See Thursday's updates here: Flood updates Thursday: Forecasted crest moved later between 10 a.m. and 2 p.m.
By Mark Sabbatini and Jasz Garrett
Juneau Independent
9:30 p.m. Wednesday
Back Loop Bridge closed at 8:30 p.m., and Mendenhall Loop Road is closed to through traffic between Montana Creek Road and Mint Way, according to the Alaska Department of Transportation and Public Facilities. Access remains open to River Road and View Drive for local traffic.
The Mendenhall River was at about 8.5 feet at 9:10 p.m. and expected to reach the minor flood stage of nine feet within the hour, Andrew Park, a National Weather Service Juneau meteorologist, said in an online update.
"We’re going to progress rapidly to the various flood stages tonight," he said.
The major flood stage of 14 feet is expected to occur between 5 and 6 a.m. Thursday, with a crest of 16.4 feet still predicted at about 10 a.m., although forecasters say the waters may peak anytime between 8 a.m. and noon.
7 p.m. Wednesday
A more specific peak flood forecast for the Mendenhall River of 16.4 feet at about 10 a.m. Thursday was issued by Britton Musall, a National Weather Service Juneau meteorologist, in an online video update at about 6:40 p.m. Wednesday.
"It could be as early as 8 a.m. or as late as noon," he said, matching the estimated range NWS Juneau officials have been providing since early Wednesday afternoon.
The current forecast time is three hours later than predictions earlier during the day. Musall, in a follow-up interview after his webcast, said "the main reason that we pushed back the crest timing was based on the rate of release from Suicide Basin."
"The rate was a little bit slower than we had initially anticipated," he said.
6 p.m. Wednesday
A joint request for assistance from the State of Alaska was filed today by the City and Borough of Juneau and the Central Council of the Tlingit and Haida Indian Tribes of Alaska, according to a CBJ press release. The request is "in anticipation of a potentially imminent and record level glacial lake outburst flood, or jökulhlaup, from Suicide Basin above the Mendenhall Glacier."
The two local government entities also "issued preemptive emergency disaster declarations as a proactive measure to protect life, property, and critical infrastructure."
Gov. Mike Dunleavy, in a post on his official Facebook page on Tuesday, stated "My administration is closely monitoring the conditions at Suicide Basin and is standing by to respond to any flooding that could occur." State disaster declarations have been issued for record floods each of the past three years.
The flood forecast remains unchanged from a 1 p.m. National Weather Service Juneau update that predicts a crest of 16.1 to 16.6 feet between 8 a.m. and noon Thursday. The Mendenhall River was at 7.36 feet at 5 p.m. Wednesday.
3:30 p.m. Wednesday
The Mendenhall River is now expected to crest between 8 a.m. and noon — three hours later than previous estimates — with the peak water level remaining between 16.1 and 16.6 feet, according to a 3 p.m. update by National Weather Service Juneau.
The river is expected to be at the major flood stage (14 feet or higher) between 5:45 a.m. and 1 p.m. Thursday.
The river was at 6.87 feet and rising about 0.22 feet an hour as of 3 p.m. Wednesday, according to the Suicide Basin monitoring website.
12 p.m. Wednesday
Officials are urging people in flood zones to evacuate by 3 p.m., and the National Weather Service Juneau’s forecast for the timing and level of a Mendenhall River flood crest remains unchanged as of late Wednesday morning.
Nicole Ferrin, a warning coordination meteorologist with the National Weather Service, said the Mendenhall River is expected to crest at 16.1 to 16.6 feet between 5 and 9 a.m. Thursday. The river is expected to reach a major flood stage of at least 14 feet after midnight Thursday and remain in that stage for about eight hours.
“We are seeing a steady rate of rise on the lake gauge right now and the basin is dropping rapidly,” she said during a joint press briefing by emergency response officials at 11 a.m. Wednesday. “It's dropped about 25 feet since the release started. ”
The Mendenhall River was at 6.06 feet and the water level in Suicide Basin at 1,321.58 feet at 11 a.m., according to the Weather Service’s monitoring website for the basin.
Ferrin cautioned the community that even after the Mendenhall Lake crests, it can take about an hour to an hour and a half for the Mendenhall River’s lower levels to do so.
She said in the unlikely event of a HESCO barrier breach, the weather service will issue a flash flood warning. Juneau residents in the evacuation zone would receive an emergency alert on their cellphones like they did when the basin filled and began releasing water Tuesday.
Ryan O’Shaughnessy, the city’s emergency program manager, reemphasized the importance of evacuating. He asked people to leave the flood zone by 3 p.m. He said the Unified Command is confident in the infrastructure installed, but that the community should be prepared if the HESCO barriers fail.
“Folks would only have minutes before the area could be inundated,” he said.
O’Shaughnessy said a flash flood warning would contain instructions to shelter in place.
“Many of the homes in the area are only one story. Even in a two-story event, this is very fast-moving water,” he said. “There's no amount of water that folks can walk through or drive through in this flood scenario that is considered safe.”
Ken Murphy, a safety officer for the Alaska Department of Transportation and Public Facilities, encouraged people to take a breath and look around before leaving the house.
“We are going to do this together as a team,” he said. “Slow is fast.”
The emergency shelter at the Floyd Dryden Gymnasium opened at 7 p.m. Tuesday. Loren Jones with the American Red Cross of Alaska said a family of six stayed overnight. He said the gym has the capacity for up to 75 people and can accommodate pets kept separate from owners.
Capital Transit will continue to serve the evacuation areas until 5 p.m., said Denise Koch, public works director for the City and Borough of Juneau.
Koch said city workers are performing repairs to some HESCO barriers near encampment sites by Vintage Boulevard and Clinton Drive that have knife damage. She said there was also a warming fire at an encampment near Don Abel Building Supply, but no damage to barriers occurred.
Koch said HESCO barriers will continue to be monitored on foot until the lake stage reaches 14 feet, and then they will be inspected via drones provided by state DOT officials.
The Back Loop Bridge will be closed at 8:30 p.m. Wednesday and the pedestrian crossing at the Brotherhood Bridge is expected to be closed at about 5:15 p.m., said Travis Eckhoff, a DOT incident commander for the flood.
The Mendenhall Glacier Visitor Center is scheduled to be closed at 4 p.m. and the entire glacier recreation area will be closed this evening, said U.S. Forest Service Deputy Forest Supervisor Barb Miranda.
6:30 a.m. Wednesday
The Mendenhall River is rising at the rate forecast when the glacial lake outburst flood from Suicide Basin started Tuesday afternoon, with the river expected to crest between 16.1 and 16.6 feet at about 7 a.m. Thursday, said Andrew Park, a National Weather Service Juneau meteorologist, during a livestreamed update at 5:40 a.m. Wednesday.
"But there is a window of about 5 a.m. to 9 a.m., somewhere in there," he said.
The Mendenhall River was at 5.3 feet and rising about 0.1 feet per hour as 6 a.m., according to Suicide Basin’s monitoring website. But Park said the rate of rise is expected to increase after the river reaches minor flood stage at about 3 p.m. Wednesday.
"Then the river starts really increasing, picking up pace, going into moderate flood stage (of) 10 feet around five in the afternoon," he said. "And then late tonight (or) early Thursday morning, that's when we are going to forecast that major flood stage of 14 feet, and that's when the river really becomes a scary place and a really dangerous situation."
The river should drop quickly after cresting, dropping below the "action" stage of eight feet by about 3 p.m. Thursday, Park said.
An evacuation advisory by the City and Borough of Juneau is in effect for flood zone areas and a Weather Service flood warning is in effect until 4:30 a.m. Friday. An emergency evacuation shelter is open at the Floyd Dryden campus at 3800 Mendenhall Loop Road.
City facilities, parks and trails along the Mendenhall River are closed Wednesday and Thursday.
An updated safety briefing by city, weather service and other officials is scheduled at 11 a.m. It will be livesteamed by KTOO. Updated information is also available at CBJ’s flood preparedness website and the Suicide Basin monitoring website.
"As we move through the day, the pace of information will increase, and as we go into tonight especially expect hourly updates as we watch this river and make sure we're not missing anything," Park said.
• Contact Mark Sabbatini at editor@juneauindependent.com or (907) 957-2306. Contact Jasz Garrett at jasz@juneauindependent.com or (907) 723-9356.
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