Portland, Oregon, has been hot lately. The kind of past-95 degrees hot that glues your clothes to your skin, with multi-day “Excessive Heat Warnings” following on each other’s heels. Several Northwestern communities broke all time heat records late last month and temperatures across the region hovered 10 to 15 degrees above average. A weather map was so garish with red, pink and yellow that one TV meteorologist compared it to a Grateful Dead T-shirt.
So when the long Fourth of July weekend rolled around, some friends and I sought relief in a basin of cold blue lakes high in Washington’s central Cascades. The heat’s signature was everywhere along the Columbia River as we set out on Thursday evening. The grassy hills stepping back from the Gorge’s basalt cliffs were scorched nearly white. As we came around a bend in Highway 97, we saw that they were scorched black as well, where the bright fingers of a grassfire picked their way up through a forest of wind turbines. It took an hour to detour around the blaze. When we finally turned back onto northbound 97, we broke through an endless line of stopped cars and semis awaiting clearance to head south — their headlights stretching across the darkness like a line of flame themselves.
The Junction Fire — which had consumed 2,100 acres by Friday — was one of 1,425 fires that have started in Oregon and Washington so far this season, about double the average for this time of year, says John Saltenberger, fire weather program manager at the Northwest Interagency Coordination Center. “We’re already seeing fire index values (based on heat, humidity, wind and precipitation) you’d typically see in late August.”
But changes in large-scale atmospheric pressure patterns are the primary culprits behind the current heatwave, says Washington State Climatologist Nick Bond, and their causes are hard to pin down. Normally, a ridge of high pressure sits over the Southwest through the early summer, punching up temperatures there before shifting northward in July and leaving a low pressure trough in its wake, ushering in that region’s monsoon cycle thunderstorms while bringing the Northwest into its hottest, driest months. This year, it seems to have shifted a couple of months ahead of time; “It’s like an early onset of summer,” Bond says. “The movement of this high pressure has impacted the whole Western U.S.” Indeed, while the Northwest cooks, the Southwest and southern Rockies have had an unusually wet few months, enjoying additional bumps of moisture from an active Pacific hurricane season. As a result, wildfire potential there is expected to be significantly lower than normal until August. And a strengthening El Niño cycle may pump yet more moisture into the region and much of the Interior West, while threatening to drag the Northwest’s warm, dry times through the winter and into next spring.
Off the West Coast, a swath of water stretching from Mexico to Alaska that is 4 to 6 degrees warmer than the surrounding ocean — which Bond has dubbed “The Blob” — may also be contributing to the disparity, boosting temperatures a short way inland by warming the prevailing winds that comb over the ocean’s surface, while at the same time making it easier for remnants of tropical storms to reach the Southwest. Just how much of a role The Blob is playing in the Northwest’s drought is an open question, says Philip Mote, director of the Oregon Climate Change Research Institute at Oregon State University — one he hopes to answer soon with a massive citizen science computing project. Existing research suggests The Blob was itself caused by more persistent high-pressure conditions that have been parked over parts of the West Coast off and on for the last year and a half, contributing to both the unusually warm winter, and to unrelenting heat last summer — one of the hottest on record for Oregon.
Mote is betting that this summer is on the same track. “We actually have an office pool on the total number of days over 90 that we’ll get in Corvallis. The average is 13, but we’ve already passed that and it’s just July.” But whether that translates into as bad of a fire season as predicted will depend on the number of ignitions, which for large, costly fires in the Northwest tend to come more from lightning than people, Saltenberger says — though you do get spikes on holiday weekends.
Finally up in the Cascades for our own holiday weekend, my friends and I refrain from starting any of our own fires. They’re banned, but it’s also just too hot, even over 6,000 feet. Sweat and floury dust congeal on our calves in brown smears that we dub “trail butter.” Lower Robin Lake, where we camp, is warm enough that I swim its entire perimeter, staying in for over an hour. On our last morning, the sun rises through a weird orange-brown haze. I read later that British Columbia is awash with conflagrations — their clouds of smoke passing through Washington like the ghosts of storms that never arrived.
Sarah Gilman is a High Country News contributing editor based in Portland, Oregon. Follow her @Sarah_Gilman.
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