After an unsettlingly warm winter across North America, budding trees are coming to life earlier than usual, setting them up for the next arctic outbreak, which is spreading across the country now. (see first few minutes of video above) The Washpost piece below is specific to DC’s cherry blossoms, but the problem applies to apple, cherry and other growers across the states. As fast-warming winters encourage early blooms, they also risk exposing the trees to damage from cold snaps that remain common into March at the mid-latitudes where the ornamental cherry trees have long thrived. A close call is in the forecast this weekend, with temperatures possibly dropping into the upper 20s in Washington. – Winter is warming faster than any other season in the northern hemisphere, and that is sending confusing signals to cherry trees and other plant life. While hibernating for winter, the trees keep track of how long temperatures spend below about 45 degrees. Once the weather starts to warm, though, they start another count, Walsh said, gauging whether it’s safe to begin growing again based on how much temperatures rise. Increasingly mild winters mean the cherry trees risk blooming so early they could still face damaging hard freezes, as occurred in Washington in 2017. That year, the Tidal Basin blossoms were on the verge of a mid-March peak bloom, almost two weeks earlier than average, when temperatures dropped into the lower to mid-20s on back-to-back mornings. That wiped out nearly half of Washington’s cherry blossoms. When temperatures remain that cold for several hours, it harms the blossoms if the buds have begun to flower. Even colder temperatures, as well as sunlight reflecting off snow cover, can also damage cherry trees’ bark and internal tissue, Walsh said. Temperatures are forecast to skirt the danger zone for blossom damage this weekend, with lows expected in the upper 20s to near 30 early Sunday... |