1987 In Alaska -- The Eleventh Straight Warm Year
Is it really getting warmer in Alaska?
Certainly the year just past, like the ten before it, was warm. It's also had some precipitation extremes -- wet on the south coast, with some months having up to three times their normal precipitation at Yakutat, but rather dry in the Interior, where Fairbanks, for instance, had its second driest year on record. Southeastern was also warm, with Juneau having above-freezing average temperatures in every month, and January, February, November, and December all more than five degrees above normal. Even Anchorage, where June and July were admittedly cool and cloudy, finished the year almost three degrees above normal. The lack of really cold weather was also noticeable -- both Barrow and Fairbanks temperatures just brushed minus forty in January, while Barrow had three days of 40 below averages in February. Neither station had so much as a forty below minimum temperature during the rest of 1987.
Both temperatures and precipitation are what would be expected with more air coming from the south and less from the north than usual. This is a time, however, when we may need to look a little more closely at what "usual" means, because 1987 was in fact quite normal relative to the last ten years.
In an attempt to keep track of what was going on with Alaskan weather, I have been keeping a record of mean annual and mean winter temperatures averaged over four Alaskan stations -- Anchorage, Fairbanks, Nome, and Barrow. These four stations have had only minor moves since 1953, so while a little warming might be blamed on city growth toward the respective airports, the changes recorded since 1954 should be reasonably accurate. All four stations, individually and averaged, have been noticeably warmer since the winter of 1976-77 than they were before that time. The average temperature for the combined stations over the last eleven years has been almost three degrees warmer than for the 23 years from 1954 through 1976. The change was abrupt and did not coincide with a period of rapid growth, so it is probably real. A similar warming appears to have occurred in Southeastern, but starting a year earlier. This year's average temperature is only half a degree above the eleven-year normal, so it simply represents a continuation of the existing warm period.
Even the lack of very cold weather is typical. Fairbanks from 1953-54 through 1975-76 averaged about 6 days a winter with average daily temperatures of 40 below or colder, and more than a day a winter with the average daily temperature 50 below or colder. Since the 1976-77 winter, no winter has had more than four days averaging 40 below or colder (the average for the last 11 years has been 2 days a winter), and 50 below averages simply have not occurred. The absence of very cold weather has been even more pronounced in the last four years -- the last time Fairbanks had a daily mean temperature lower than 40 below was January 1984, and the lowest daily average temperature then was only 41 below.
Are we seeing the anticipated carbon dioxide warming? Not directly, but carbon dioxide could have something to do with the changes in the upper winds which do appear to be responsible. The average winds over Alaska about two miles up generally blow more from the south than from the north, but the speed of these south winds was almost 50 per cent higher over the last eleven years than it was over the previous 23. The higher speed means more warm air brought into the state before it has time to cool off.
Has anything like this happened before? Changes in the locations of all of the weather stations I'm using make direct comparisons chancy, but there was a similar 11-year warm period from 1934 through 1944. Unfortunately the winds two miles up were not being measured then. It is still quite possible, though, that this year, or the year after this, or 1990 will see a return to more "normal" weather.
Meanwhile, enjoy our new climate!
