I know, this isn't about Maryland weather, but it was prompted by a query from a Maryland reader of the Sun's weather page about the weather in Alaska.
He asked me for some numbers on what he perceived to be a cool summer in Alaska, based on low temperature readings for the state on our print weather page. I made a quick check of the summer averages for Anchorage and Fairbanks and confirmed his take on it.
June and July in Anchorage both averaged 2.5 to 3 degrees below the long-term temperature averages. Fairbanks had a pretty normal June, but after a sizzling July 4th of 85 degrees (same as Baltimore on the same day), the temperatures fell off a cliff.
July in Fairbanks averaged 60.6 degrees, almost two degrees below normal. And August is averaging 51.4 degrees, a whopping 7.7 degrees below the long-term norms.
So I put in a call to the National Weather Service up there, and eventually found myself chatting with Gary L. Hufford, the regional scientist for the NWS in Alaska. He's in Anchorage, which enjoyed a rare sunny day yesterday (above, from an FAA web cam). He said temperatures in Alaska this summer really have been unusually cold.
Alaskans are "certainly noticing it," he said, "especially because the period of 2002 to last summer. 2007, we've had some incredibly pleasant summers." It was so warm, in fact, that the summers of 2004 to 2006 were very bad forest fire years for the state, as the warm weather speeded drying in the bush and left it prone to fires. But in Alaska, they're adapting, according to one Fairbanks writer, who said this summer is "becoming the most miserable in recorded history."
What seems to have occurred, Hufford said, is a shift to what climatologists call the cold phase of a cycle in the North Pacific Ocean called the "Pacific Decadal Oscillation," or PDO.
I've written about this phenomenon. NASA climatologists said in May the cool phase seems to have begun last fall, and could influence temperature and rainfall patterns in the United States for decades to come, including enhanced hurricane seasons in the Atlantic, milder winters in Maryland, more dry weather in the Southwest and Southeast, and cooler, rainier weather in the northwest.
Hufford said the Arctic Low, a persistent feature of the far northern atmosphere that usually hangs out near Greenland, has shifted west to the northeast corner of Siberia.
"That has ... put us into a lot of flow from the northwest, out of the arctic. And anytime you get air off the arctic, it's not gonna be warm," Hufford said. It also brings persistent cloudiness to the skies over Alaska.
"Everybody's aware of it," he said, "and that's what's getting to them."
The lack of sunshine has impaired the development of wild berries, which Alaskans love to pick in summer. "What berries you get are not very sweet," he said. Hufford also reported a big flock of cranes flying through Fairbanks last week, perhaps a sign of colder weather in the far north and an early fall.
The cool-phase PDO also tends to produce disappointing salmon runs in Alaska, while enhancing them in the northwestern corner of the lower 48 states.
"What really makes it interesting is that we've seen two or three events of snow down to 3,500 feet or so (in the mountains), right in the middle of summer. That's definitely not as usual thing here," he added.
If this really is the start of a cool-phase PDO they're seeing, it's of no small concern to Alaskans. And it's not just because of one summer of bland blueberries and scarce salmon.
When these PDO phases shift, they tend to do so for decades, not the 4- to 7-year cycles typical of the El Nino/La Nina cyclings in the tropical Pacific. The Icebox State could be in for a long haul.
"That's what's concerning us, if this is in fact the PDO," Huffford said.
The last time the PDO shifted into a cool phase was in 1947. And it stayed there until 1976, bringing cooler, cloudier summers.
The big question is how the cool PDO will interact with the longer, global "signal" from global warming. "We're not sure," he said. Maybe they'll cancel each other out for a while. "It's an excellent opportunity to see how the PDO may react with it ... From a scientific standpoint, we're learning."
Inevitably, Alaskans are looking at the cool summer they've experienced and cracking wise.People are saying "What global warming?" when they're desperate for a decent summer day over 60 degrees. "Oh boy, we hear that every day," Hufford said.
Hufford's response is that the PDO is a short-term trend relative to the long-term changes that come with global warming. We're going to see a lot of regional variability like this within the much longer-term, gradual increase in average global temperatures.
Hufford also laments that the cool PDO "is going to cost me money. My wife is not gonna go well into another six months of winter with a cold summer like this. I suspect I'm gonna be hearing about taking a trip to some sun for a while. Here in Alaska, we're real fans of Hawaii."