Jenna Ladd | April 18, 2018
By-in-large, spring weather has been arriving earlier each year in the United States. For instance, the frost-free season was 10 days longer between 1991 and 2011 than it was from 1901 to 1960.
This may come as a shock to Midwesterners, who saw several inches of snow fall this Sunday, April 15th. So what’s going on?
Among some other factors, the Greenland Block has a lot to do with the snowy spring of 2018, according to Dr. David Mechem of the University of Kansas. Mechem, a professor of geography and atmospheric science, explained that there is a persistent atmospheric area of high pressure above Greenland which funnels cold air from the poles straight into the mid-latitudes of North America. He told KCUR that the block was in place throughout February and March and is finally starting to break down, which would bring long-awaited warmer temperatures to the midwest.
Further research is needed to establish exactly what kind of effect climate change has on spring weather, but scientists are noticing some changes. Winter storms (even if they happen in April) have increased in frequency and intensity in the Northern hemisphere since 1950 according to the National Climate Assessment. Nor’easter winter storms plague the eastern U.S. and are caused by the the cold air from the Arctic and warm air from the Atlantic interplaying. This year, that region of the U.S. saw several Nor’easters in very quick succession, which is unusual. A recent study in the journal Nature Communications found that as the Arctic’s climate continues to warm at an alarming rate, winter storms becoming more likely in the eastern U.S.
The good news is that as the Greenland block continues to break down, residents of the mid-latitudes can expect spring to finally arrive. The bad news is that unpredictable spring weather can be expected to continue coming years as the climate continues to change.