NOAA officials released their winter weather outlook for the 2018-19 season Thursday, predicting a mild winter for much of the United States. The reason: El Niño.
NOAA forecasters say El Niño has a 70 percent to 75 percent chance of developing. While a weak El Niño is expected, it is still likely to influence the weather pattern across the United States.
Typical El Niño winters bring wetter conditions across the southern United States with a warmer, drier pattern for much of the north. El Niño is an ocean-atmosphere climate interaction linked to periodic warming in sea surface temperatures in the central and eastern equatorial Pacific.
Storm Center 7 Chief Meteorologist McCall Vrydaghs said El Niño winters in the Miami Valley typically tend to be drier with slightly less than normal snowfall.
During the last weak of El Niño in the winter of 2014-15, the Miami Valley saw record low snowfall amounts during December, but wound up only slightly below average for the entire winter. The temperature trend saw wild swings from month to month.
February 2015 went in the record books as the fourth coldest in Dayton. Vrydaghs said while the average temperature for the entire winter may be above normal, there could still be some brief outbreaks of cold at times like in 2015.
Other climate patterns that can affect winter weather are challenging to predict on a seasonal time scale.
The Arctic Oscillation influences the number of arctic air masses that penetrate the South and could result in below-average temperatures in the eastern part of the United States.
The Madden-Julian Oscillation can contribute to heavy precipitation events along the West Coast, which could play a large role in shaping the coming winter, especially if El Niño is weak as forecasters predict.
NOAA’s seasonal outlooks give the likelihood that temperatures and precipitation will be above, near or below average, and how drought conditions are expected to change.
Vrydaghs says the outlook does not project seasonal snowfall accumulations
The outlook does not project seasonal snowfall accumulations.
Snow forecasts are generally not predictable more than a week in advance. Even during a warmer-than-average winter, periods of cold and snowfall are still likely to occur.