An unusually warm June in Alaska has glaciers melting so fast that they have in places destroyed the salmon fishing.
Mark Hem in the tiny community of Chitina in the east-central part of the state reported the Copper River near flood stage on June 30 just days before he announced his business – Hem Charters – was shutting down for a week because high water made the river’s popular dipnet fishery dangerous.
One man died earlier this year after falling off a ledge along the river and being swept away in the always fast, muddy current. Dipnetting is a 49th state tradition that dates back thousands of years to when the first Athabascan Indians discovered they could weave nets of spruce roots or sinew, attach them to long poles, and dip salmon out of the waters of silt-laden glacial rivers.
Today the nets are made of nylon with handles and hoops of aluminum, but the fishing technique remains the same. And strong runs of Chinook (king) and sockeye (red) salmon to the Copper have produced good early season catches for dipnetters.
But the unusual run of warm, sunny weather most residents have been enjoying is now putting a damper on the resident-only fishery.
Temperatures across much of the state were in the 80s, which USA Today on Monday categorized as “scorching” though the state has seen much warmer.
The state-record high of 100 degrees was set in June 1915 in Fort Yukon, a Central Alaska community of 600 people living miles north of the Arctic Circle. The surrounding Yukon River flats are the only place on the globe where such high temperatures have been recorded in the Arctic, according to the U.S. Fish and Wildlife Service.
Fort Yukon’s climate is like something from another planet with its 178-degree swing from temperatures that climb as high as 100 degrees in summer and drop to as low as 78 degrees below zero in winter.
The Alaska hot streak has inevitably fired up global-warming fears although the temperatures of the moment are way, way above the averages predicted by any climate-change models.
Still, the state has seen a significant climate shift in the last few years. Alaska witnessed its warmest year in 2016 and 2018 came second, according to the National Oceanic and Atmospheric Administration (NOAA). So far 2019 is following the trend.
The National Weather Service reported Anchorage, the state’s largest city, witnessed its warmest, driest June ever, and the month added to a run of 16 that have now ended with average temperatures above the norm – sometimes significantly above the norm.
The June 2019 average temperature of 69.1 degrees was more than 6 degrees above normal, the agency reported, even though the monthly high temperature of 82 degrees was 3 degrees short of a record set in 1969 and trailed the records for 2015 and 2016.
High temperatures on 12 days hit 70 degrees or more, according to weather service records. Only 11 years ago, Anchorage went the entire summer with only two days – a sixth of those of this June – warming to or above 70 degrees, according to the National Weather Service.
Alaska weather is prone to huge variations that appear to be driven in significant part by what is happening in the atmosphere above the polar ice cap where spins the “polar vortex.”
“It sounds like it could be some sort of alien death-ray or an extremely powerful washing machine,” NOAA says on its website, but it’s really just a broad expanse of cold, low-pressure air that tends to stay parked over the sea ice.
It is best known for its winter antics when – as NOAA observes – it can weaken and “send cold air southward” to turn the country’s heartland bitter cold.
“Normally, when the vortex is strong and healthy, it helps keep a current of air known as the jet stream traveling around the globe in a pretty circular path. This current keeps the cold air up north and the warm air down south,” the agency says.
“But without that strong low-pressure system, the jet stream doesn’t have much to keep it in line. It becomes wavy and rambling. Put a couple of areas of high-pressure systems in its way, and all of a sudden you have a river of cold air being pushed down south along with the rest of the polar vortex system.”
Alaskans are well familiar with what happens when the polar vortex falters in winter: High-pressure air settles along the U.S. West Coast to form a barrier shiting the normally west-to-east flow of the jet stream more north and south.
As a result, weather systems passing near Hawaii in the tropics can end up getting pushed north into Alaska. They cool off along the way, but they still arrive packing a lot of warm, moist air as they did in March of this year when April seemed to have arrived a month early.
Elsewhere in the country, it was the opposite. “Glancing blow of Polar Vortex will bring another blast of deep arctic cold to smother Michigan,” MLive Michigan headlined at the time.
Usually, the vortex is more stable in the summer, and the so-called Arctic oscillation – that punch of cold air south – isn’t as extreme. Not this year, however.
“Now we are in late June,” he wrote in his last blog post, “and there are still no signs of the positive tropospheric polar cap geopotential heights (PCHs) waning and disappearing. In fact, the high latitude blocking predicted for late June is impressive for any time of year but especially for the summer. And with the warm/positive tropospheric PCHs continuing to show strong persistence, it is still not obvious to me what other than synoptic or internal variability can reverse the warm/positive PCHs to cold/negative PCHs.
“I feel that the probability of a summer characterized by a negative AO and warm tropospheric PCHs has only increased. A negative AO/NAO and Greenland blocking continue to favor seasonable to cool temperatures in the Northeastern US and Western Europe.”
Translation? The polar vortex has lost control of the atmosphere; the disruptions in the jet stream will continue; and more cold, polar air will leak north into the mid-continental U.S. while warm, tropical Pacific air is pulled north into Alaska.
Cohen’s temperature predictions have Central Alaska painted red, for hot, for most of July and nearly all of Alaska painted pink, for warm.
So pon’t put the shorts away just yet. Go buy some more sunscreen. And take care of the pets.
Warm weather in Alaska is notorious for causing heat stroke (hyperthermia) in dogs. The Iditarod Trail Sled Dog Race warns mushers to be on the lookout for it any time the temperature climbs above zero because dog produce a lot of heat while running.
“Astoundingly, muscular exertion may increase metabolic heat production by as much as 60 fold,” writes Iditarod veterinarian Stuart Nelson. “Development of life-threatening hyperthermia is our greatest temperature-related medical concern.”
Large-breed dogs that have yet to thermoregulate their metabolism to adjust to warm weather are very vulnerable, and the faster they move the more vulnerable they become.