WA Heat Map 0702

High temperatures predicted for western Washington on June 28.

Historic high temperatures hammered the Northwest in June's final days, smashing some long-standing records, straining the grid, and causing deaths in a region accustomed to moderate summer temperatures and little need for air conditioning.

The Bonneville Power Administration’s grid held up well during the heat wave, coming close to shedding load only in one area, but Spokane, Washington-based Avista was forced to implement rolling outages and calls for electricity conservation.

Portland reached 116 degrees Fahrenheit on June 27, breaking all-time temperature records of 112 set the day before and 108 on the previous day. Salem, Oregon, also recorded the highest temperature in its history on Sunday, 112 F.

Seattle smashed its all-time record, first when it hit 104 on June 27 and then when it rose to 108 the next day. It also had its first-ever three-day back-to-back triple-digit highs, with June 26 reaching 102 degrees.

The heat extended into British Columbia as well, with the small town of Lytton on June 29 seeing 121 F, Canada's highest-ever recorded temperature. The town was destroyed the next day by a fast-moving wildfire.

With water supply and snowpack above average in spring, utilities that rely on hydropower were well-positioned going into summer to handle supply issues from the anticipated increase of load from running fans and air conditioners. The main worry was whether the grid was up to the task.

In the run-up to the heat, which started June 26, utilities requested that customers conserve power to help avoid the need for rolling blackouts to keep the grid on line.

BPA and its partners were in good shape to muster resources for the heat. This included the agency restricting planned maintenance on its transmission system from June 28 through June 29; the 1,207-MW Columbia Generating Station returning to service after its 25th refueling; and spill for fish on the lower Columbia and Snake rivers transitioning from spring to summer operations, which increased federal hydropower generation from those facilities.

In addition, the U.S. Bureau of Reclamation was on target to refill the Grand Coulee reservoir in early July, freeing up the remaining water flow to pass through the system for power and nonpower uses.

"Even with streamflows below average levels, we are in a good position to serve our customers over this very hot weekend," Suzanne Cooper, BPA senior VP of power services, said in a statement. "I want to thank our partners at the Bureau of Reclamation and the U.S. Army Corps of Engineers for the work and coordination they provide at the region's 31 federal dams to ensure reliable operations."

Despite the lower-than-average water year, there is plenty of water behind Grand Coulee Dam and some snowpack left in the Canadian Rockies, BPA said. Unlike 2015 and 2001, years with a similar volume of water, the shape of this year's runoff has been slower, with snow gradually melting above Grand Coulee.

BPA spokesman Doug Johnson told California Energy Markets that the Tri-Cities area of Washington was the only place where the agency came close to having to shed load. That was avoided by monitoring the temperatures of transformers, control houses and other equipment across its system, and taking actions such as flushing radiators and watering equipment to bring temperatures down when they approached dangerous levels.

"Thanks to these efforts and electricity reduction measures taken by retail customers in the area, electrical service was available throughout the heat wave," Johnson said.

Especially hard hit by the heat was Avista, which had to implement "temporary unplanned power outages" during the afternoon and evening of June 28 as temperatures tied a 105-degree record in Spokane and put a "strain on the electric system" with a new load record, the utility said in a news release.

The earliest outages were unplanned because events transpired quickly, triggered by constraints on the distribution system due to the heat and high load as people ran air conditioners and fans.

The utility called for voluntary conservation between 1 p.m. and 8 p.m. from June 28 through July 1 to help with the situation. It also proactively shifted some load to accommodate increased usage in some areas and postponed some routine work to ensure the system was available.

By 8 p.m. on June 28, about 5,700 Avista customers in parts of Spokane were without power, down from around 8,200 earlier in the day.

Over the course of the week, the number of protective outages Avista employed in the Spokane and Lewiston, Idaho, areas decreased due to the efforts to reduce the strain on the electric system. The utility dropped from a high of 24,000 customer outages on June 28 to 8,660 on June 29. On June 30, Spokane had no protective outages while Lewiston had 603. No outages were called July 1, and monitoring is continuing in some areas of Spokane and Lewiston that are at higher risk of being impacted.

"While we plan for the summer weather, the electric system experienced a new peak demand, and the strain of the high temperatures impacted the system in a way that required us to proactively turn off power for some customers," Dennis Vermillion, Avista president and CEO, said in a statement. "This happened faster than anticipated."

The fast pace of that first day meant Avista was unable to alert customers in a timely manner, a situation it sought to address in the following days.

Puget Sound Energy spokesman Andrew Padula told CEM the utility's system "held up through the extreme heat though we saw some localized outages."

"The majority of the outages were a result of tree limbs coming into contact with our wires and heat-related equipment failure," Padula said.

Temperatures were 30 to 40 degrees above normal, and resulted in about seven times the volume of work orders "as we would see on a typical June day," Padula said.

PacifiCorp customers in Oregon experienced some outages on June 27 and 28, but all were restored by late on the second day. The largest of these was on June 27 in areas surrounding Medford and Talent, affecting more than 30,000 customers. The cause of the outage in both cases was equipment failure.

Scattered minor outages were also seen in Portland General Electric territory in Multnomah, Washington and Clackamas counties.

Deaths in the region due to the heat numbered in the hundreds. The toll in Oregon alone reached 79, the Oregon state medical examiner's office said July 1, with most occurring in Multnomah County.

In Canada, B.C. Chief Coroner Lisa Lapointe said in a statement that her office received reports of at least 486 "sudden and unexpected deaths" between June 25 and June 30. Normally, she said, about 165 people would die from all causes in the province over a five-day period.

The province had seen only three heat-related deaths in the past three to five years before this heat wave. "This, frankly, took many of us off guard," she said.

In Washington's King County, 13 people have been reported dead from hyperthermia, or dangerous overheating, the county medical examiner's office said on June 30.

And the heat is not over. Six Western states remain under heat alerts as of July 1, with extreme temperatures likely to continue from eastern Washington and Oregon to Montana and south into Nevada and Northern California.

The most extreme heat will be centered over eastern sections of Washington and Idaho, where temperatures of 110 degrees and higher are possible again, the National Weather Service said.

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News Editor - Clearing Up

Rick Adair has been with NewsData since 2003, and is news editor for Clearing Up and editor for Water Power West. Previously, he covered environmental and energy issues in the Lake Tahoe area. He has a doctorate in earth sciences.