It is of some interest to note that this year looks like being one of the unusual ones in which freezing conditions in Fairbanks (mean daily temperature below 32 °F) give way to thawing conditions (mean daily temperature above 32 °F), with no period of back and forth. This occurs in about 10 percent of years and last happened in 2007. For comparison, a sudden transition in the opposite direction in the autumn happens in about 15 percent of years - a little more often, because the autumn cooling is more rapid than the spring warming.
Friday, April 18, 2014
Sudden Onset of Thawing
After a slightly delayed start, the thawing season has suddenly gotten under way in the interior, and in only a few days the snow depth at Fairbanks airport has dropped in half (from 20" on Sunday to 10" today). The year-to-date accumulation of thawing degree days, defined as the excess of the daily mean temperature above 32 °F, will be above normal in Fairbanks after today. The chart below shows the annual thawing degree day accumulation through April 17; I think there is a strong connection here between earlier onset of thawing and El Nino conditions in the preceding months.