With roads across much of the country still bearing the evidence of this week’s nor’easter, it may be hard to imagine that spring is on the horizon. But after a false start earlier this month, spring is coming, climate scientists say – and it’s likely to be a warm one.
In its spring outlook, released on Thursday, the National Oceanic and Atmospheric Administration (NOAA) forecasts above-average temperatures for much of the United States. Temperatures are likely to be particularly warm in the south-central Plains and the Eastern US, NOAA indicated. The northern Plains and the Northwest, meanwhile, may experience some cooler-than-average temperatures, The Weather Channel's three-month outlook suggests.
After a winter of unusually high precipitation, the warm spring brings with it the possibility of flooding in parts of the country, particularly in northern North Dakota or Idaho’s Snake River basin, NOAA said.
“Snowpack is heavy in the West and northern plains, and if our long term warm-up coincides with spring rains, already saturated soils will not be able to absorb the increased water, which would lead to increased runoff and potential flooding,” explained Dr. Tom Graziano, the director of NOAA’s Office of Water Prediction, in the release.
In California, where near-record precipitation and deep snowpack have reduced the geographic extent of drought from 73 percent three months ago to just 8 percent, infrastructure like the Oroville Dam is already struggling to cope with the runoff.
But the unexpected rain and snow across the country meant that only 3 percent of the contiguous US experienced severe to exceptional drought in February, the lowest percent in 7 years. And those drought conditions are expected to improve across much of the country, including the Gulf Coast and mid-Atlantic, as spring progresses.
Looking forward, it will be a hot start to summer, according to Todd Crawford, the chief meteorologist with The Weather Channel. He expects that heat to slacken slightly going into July and August, though other factors may limit the cooling power of El Niño, he adds.
"Typical transitions from La Niña to El Niño conditions result in cooler summers overall, especially late; our forecast reflects this warmest-early, coolest-late idea, but is not particularly cool given the recent pronounced global-scale warming [and] historically-low Arctic sea ice levels," Dr. Crawford said.
Individual weather events could lead to brief periods of warmer or cooler weather within these projected trends, The Weather Channel indicated.
On the whole, temperatures have been warming within the US and globally over the past few years. 2016 was the second-warmest year in the US on record, according to NOAA’s National Centers for Environmental Information. These higher temperatures have been matched at global level: 2016 followed 2014 and 2015 in setting records for average temperature. And these rising temperatures were accompanied by rising average rainfall, leading to costly flooding events.
For many, it’s a sign of a changing climate.
“A single warm year is something of a curiosity,” Deke Arndt, NOAA’s chief of global climate monitoring, told The New York Times in January. “It’s really the trend, and the fact that we’re punching at the ceiling every year now, that is the real indicator that we’re undergoing big changes.”
That warming may make events like this year’s early spring more commonplace. After winters with less snow, the typically sudden transition from winter to spring tends to start earlier and last longer, a new study led by the University of New Hampshire finds.
Having a longer “vernal window,” though pleasant, can present challenges – like more insects and a “false start” to the growing season – that may need to be addressed going forward.
“While these earlier springs might not seem like a big deal – and who among us doesn’t appreciate a balmy day or a break in dreary winter weather – it poses significant challenges for planning and managing important issues that affect our economy and our society,” Jake Weltzin, a United States Geological Survey ecologist, said in a statement last month.