Green Up Day: A sign of spring for Fairbanks

Published: May. 11, 2020 at 6:43 PM AKDT
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On Sunday many of us celebrated the great mothers of the world, including Mother Nature, as the National Weather Service declared "Green Up Day" in Fairbanks.

The commemorative day is determined as the date "when leaf buds on birch and aspen trees open enough to produce a faint, yet distinct green flush through the boreal forest canopy."

"Green Up is very unique in Fairbanks in that the leaves open up over just a several day period," Jim Brader said, Meteorologist for the Fairbanks National Weather Service. "I don't think there is probably any other place in the United States that is like that, where all the leaves basically open up at once."

The term "Green Up Day" was coined by late bioscience librarian at UAF Jim Anderson in 1974, who looked over the western flank of Chena Ridge from his office at the University of Alaska Fairbanks. He kept records of each "Green Up Day" since, before his passing in 2007, when the National Weather Service took over the records.

"He was a person with a lot of curiosity," Brader said of Anderson. "Ted Fathauer, who was a long-time forecaster here at the Fairbanks office, and Rick Thoman, who also was, studied 'Green Up' and worked with Mr. Anderson and they came up with a formula of basically thawing degree days, where you start to have temperatures above freezing. So, they actually came up with a predictive model who could use to predict the date 'Green Up' might occur."

The downside to the luscious views, "Green Up Day" also coincides with allergies, as pollen is released from the newly budding leaves. However, the leaves can also help with the dry climate in the Interior.

"It also somewhat affects the weather, because once leaves start to come out, they start to admit moisture into the air," Brader added. "We typically have very dry air and then after 'Green Up', it adds moisture to the air."

This year's Green Up Day of May 10 falls in the "near normal date range" of May 5-12, while last year's was early, occurring on May 1st.

The latest Green Up day recorded since 1974 was May 26th in 2013, with the earliest coming April 26th in 2016.

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