Arrival of heavy rain means risk for structures, boats and avalanches even higher after record snow

This story has been updated to note Thane Road is closing at 6 p.m. Friday.

The record snowfall is over, but the heavy lifting and danger of it remains — and may get much worse with heavy rain forecast through Monday that will result in high weight loads on structures and boats, and increase the potential for avalanches, according to officials.

One to two inches of rain are forecast each day Friday through Monday, according to a warning issued Thursday afternoon by the National Weather Service Juneau. Warming temperatures means the snow level will be about 3,000 feet on Friday and rise to more than 4,000 by Sunday.

Snow will become heavier as it absorbs the rain, making it more difficult to move,” the NWS Juneau notice states. Also, conditions are expected to be icy, heavier snow may affect susceptible properties and vessels, snowmelt may block drainage and thus cause flooding on streets, and snowmelt from high elevations will add to the runoff.

“The City and Borough of Juneau asks residents to provide assistance with clearing drains on or near their property to reduce the risk of flooding. Residents are also asked to please keep fire hydrants clear and shovel snow off their vessels in the harbors,” the statement adds. “Local avalanche forecasters with CBJ, DOT, and AEL&P are expecting an increased risk of avalanches in known avalanche paths through this event.”

Thane Road, which was opened at 3 p.m. Thursday following intermittent closures during the week, is scheduled to be closed again indefinitely stating at 6 p.m. Friday, according to the state Department of Transportation and Public Facilities.

“The closure will remain in effect until weather conditions allow for Avalanche Hazard Mitigation work or until the hazard naturally decreases,” a statement by the department issued Friday notes. “Conditions will continue to be monitored during the closure period.”

Nine boats in Juneau’s harbors have sunk and one boat shelter was destroyed as of early Thursday afternoon due to the weight of snow on them and other vessels are still at risk because they haven’t been cleared by their owners, said Harbormaster Matthew Creswell.

“We’re very busy calling people tell him to get down and clean them,” he said. “Our staff is having to drop what they’re doing every hour to and run and shovel off a boat that’s in the process of sinking. And that impedes our time to be able to do proper snow removal because people aren’t shoveling their boats and we’re having to drop what we’re doing to save their vessels.”

“The heavy rain starts (Friday) afternoon and evening…and that is the problem. That’s not going to wash the snow away. The snow is going to absorb the rain, and we’re going to see much more weight on houses and vessels. That’s a big concern for us, that’s a real thing and we’re worried how the weekend’s going to look.”

While vessel owners are responsible for clearing their boats of snow, harbor staff are being forced to do so when vessels are in immediate danger of sinking due to environmental and other public safety concerns, Creswell said.

A three-day storm that began about two weeks ago, which left more than 30 inches in some parts of town, affected boats in the downtown harbor most, he said. But with a second storm between Sunday and Wednesday of this week, which also resulted in more than 30 inches of snow in some areas, means the accumulation at all local harbors is probably between five-and-a-half to seven feet.

As of midnight Wednesday, a few hours before the worst of the second storm ended, Juneau’s official snowfall for January was tied for the second-highest ever at 69.2 inches, including two days that set accumulation records on those dates, according to NWS Juneau. The record for snowfall in January in Juneau is 75.3 inches set in 2009.

Snow weight has also damaged some commercial and residential structures, with some businesses including the Mendenhall Mall closed for hours or a daylong period immediately after this week’s storm ended to allow for snow removal from roofs.

Heavy snow accumulation in past years did the most damage to accessory buildings, storage sheds and other structures that aren’t built to residential or commercial building codes, said Charlie Ford, a CBJ building code official who’s lived in Juneau for 19 years. At the same time, the current threat is worse than locals have had to cope with in recent years.

“This is right up there with the worst I’ve seen,” he said. “It used to happen more often, Back in the ‘80s and ‘90s it seemed like every winter we’d get a couple of weeks of this stuff. But it’s been a long time since I’ve seen it been this bad, probably 12 years or so.”

People should measure snow loads on the ground near structures to determine weight loads on roofs, rather than the roofs themselves due to the risk factor, Ford said.

“The ground snow load in Juneau is 70 pounds,” he said. “So if you go out into your yard and do a 12-inch-by-12-inch sample, and put it in a garbage bag or something and weigh it, and if it’s over 70 pounds then you should start being concerned.”

Ford said that advice came from a CBJ structural engineer, who also stated in an email snow loads “will not be the same across the borough depending on heat loss, exposure to wind and those days when it was sunny exposure to sun.” Also, another indicator is “if doors swing fine, windows open fine and no other signs of distress the conditions are likely fine. however if suddenly doors are hard to open, ceilings are sagging, then get someone to remove snow.”

It’s a problem also occurring in other parts of Alaska receiving heavy snow, with the Anchorage Daily News reporting Thursday that local officials say up to 1,000 commercial buildings are at risk of roof collapse.

Avalanche danger in the Juneau vicinity, which has been level four (“high”) out of five most of the week, is forecast to remain that way Friday due to “warmer temperatures in place and with a large system coming in with large volumes of precipitation on a weak snowpack,” according to an advisory issued at the city’s website.

Tom Mattice, the city’s avalanche forecaster, has stated the volume of snow is sufficient a large snowslide could reach structures.

DOT stated it has hired additional employees from other communities, as well as a private contractor, to remove snow on state-owned roads. The department is also urging residents to take steps to ease the work for state, city and private work crews.

“If you can, please clear driveway culverts and storm drains on or near your property.” a DOT advisory notes. “These efforts will go a long way to improve drainage as temperatures rise, the snow starts to melt and the rain returns. Your assistance in keeping drains and culverts clear is incredibly appreciated. Street flooding prevention helps avoid property damage and ensures traffic – including emergency vehicles or maintenance crews – can move through the community.”

Also people should avoid shoving snow onto roads or right-of-way points, and clearing the left side of driveways gives plows space to dump snow and reduces the chance of berms blocking access. Clearing mailboxes helps ensure emergency response agencies can correctly identify addresses.

• Contact Mark Sabbatini at mark.sabbatini@juneauempire.com or (907) 957-2306.