After nearly a year of anticipation, the climate phenomenon known as El Niño has arrived, U.S. climate scientists said Thursday.
It is marked by warmer-than-normal ocean temperatures along a stretch of the central Pacific that can have a significant impact on weather around the globe, bringing extra rain some places and drought in others. In Maryland, its impact can vary, but it is associated with snowy winters and fewer Atlantic hurricanes.
Conditions in the Pacific have suggested a developing El Niño since last March. In May, climatologists predicted 90 percent chances the pattern would set in by last fall. But though the Pacific waters warmed, other atmospheric conditions were meanwhile not indicative of El Niño until recently.
So far, it is considered a "weak" El Niño, Mike Halpert, deputy director of the Climate Prediction Center in College Park, told the Associated Press. That could mean few noticeable impacts.
The El Niño will do little to reverse an ongoing drought in California, as had been hoped, because it arrives at the end of that region's rainy season, Halpert said.
This is the globe's first El Niño since March 2010. There have been two occurrences of La Nina, a related climate pattern associated with cool waters in the Pacific, since then, from June 2010 to March 2011 and August 2011 to February 2012.
But for most of 2012 and all of 2013 and 2014, the globe has been under "neutral" conditions, with neither an El Niño or a La Niña.
El Niño's impact on Maryland can be difficult to predict. The region's geography between mountains and ocean, with the Chesapeake Bay in the middle, prevents dramatic climate fluctuations.
It does correlate with snowy winters, though. While about 18-20 inches of snow falls in an average winter in Baltimore, closer to 27 inches fall in an El Niño year, according to an analysis by the National Weather Service's Baltimore/Washington forecast office.
The record-breaking 77 inches of snow that fell in winter 2009-2010, for example, came during a moderate El Niño, the last one to occur. So did the third and fourth snowiest winters, 2002-2003 and 1963-1964. But the second-snowiest Baltimore winter, 62.5 inches in 1995-1996 came during La Niña, known for mild winters here.
Of course, this El Niño is arriving late in the season to have much of an impact on snowfall. Whether this El Niño will be around come next winter is impossible to reliably predict.