Washington Post: “When will spring come? Or has it already? Look up where you live. All across the east, naturalists are exasperated. As the rest of us luxuriated in this winter’s uncommon mildness, gardeners and wildlife biologists watched with rising pique as one of the earliest springs in recent memory threw nature’s rhythms out of whack. Ignorant of the human calendar, nature instead responds to the gradual accumulation of heat at the beginning of each year. If the daily average temperature is above freezing, that sends a signal to plants and animals that life is again preparing to grow. Each year, the USA National Phenology Network — phenology is the study of seasonal change — keeps track of when leaves sprout as heat accumulates across the country. This year’s winter weather pattern cleaved the country in half. As a ridge of high atmospheric pressure warmed the east, a low pressure system kept conditions cooler and wetter than usual across the west, said Michael A. Crimmins, a climate science professor at the University of Arizona…”