Don’t get too used to the unseasonably warm weather across most of the U.S. in November and December. Frigid temperatures and some heavy storms are predicted for the New Year, from January through March, according to the National Oceanic and Atmospheric Association’s (NOAA) Climate Prediction Center, which updated its El Niño forecast last week.
NOAA Deputy Director Mike Halpert explained that the current 2015-2016 El Niño, announced last March, has the potential to be a record-setting event, equally or even more powerful than one of the strongest El Niños on record in the winter of 1997-98. That El Niño was called “one of the most significant climatic events of the century” by the NOAA.
El Niño, meaning “Little Boy” or “Christ Child” in Spanish, was coined by fisherman from the West Coast of South America in the 19th century to describe the Pacific Ocean’s tendency to become warmer every few years. It causes extreme weather globally.
The warm and balmy December days that we’ve been enjoying have nothing to do with El Niño, Halpert said. “We are seeing a positive arctic oscillation (AO) since the beginning of November, and while it has certainly been mild across the country, it is not really something that we could necessarily attribute to El Niño. The AO is probably playing a bigger role at this time.”
In short, AO is the term used to describe the cold winds that circulate counterclockwise around the Arctic at around 55°N latitude. When it is in a positive mode, these winds remain confined mostly to the Arctic region instead of moving south.
So what can we expect come January through March? Quite possibly severe flooding.
“The winter does favor above normal precipitation across the entire southern part of the U.S., from California to Florida and along the East Coast to southern New England,” Halpert said. “During the handful of stronger El Niño episodes that we have seen over the past 50 years, regions across the southern United States have experienced periods of heavy precipitation and flooding. This includes California and along the Gulf Coast. During both the 1982-1983 and 1997-1998 episodes, we saw a significant increase in the number and intensity of extreme weather events which resulted in numerous instances of flooding.”
What about snow? It’s “trickier” to predict snow patterns, Halpert explained. “We have seen a couple of El Niño winters that had really big bonanzas, and it becomes a matter of: Is there enough cold air in place as the storminess hits? It is really something that we cannot make any kind of forecast on.”
For a more detailed look at how El Niño could affect the U.S. this winter, see NOAA’s National Integrated Drought Information System assessments, called “El Niño Impacts and Outlook.” Here’s a synopsis of predictions for each region in the U.S. (in alpha order), based on past El Niños:
Alaska – Warmer than normal statewide, with some consensus for increased chances for wet conditions over the southern mainland and Southeast.
Eastern Region – Increased frequency of nor’easter coastal storms, above-average snowfall, with regions along the coast experiencing six inches more than usual. In DC, eight of the ten greatest 2-day snowfalls since 1950 have happened during El Niños.
Great Lakes Region – Warmer than average winter leading to minimal ice cover on the Great Lakes, causing reduced winter recreation as well as increased survival of agricultural pests.
Hawaii/U.S. Pacific Islands Region – Tropical cyclone activity in the western north Pacific is expected to be above normal. In the southwest Pacific, the chances for cyclone activity are elevated for a majority of the Pacific Island countries.
Midwest – Increased chance of above-normal temperatures, except for southern Missouri, far southern Illinois and Kentucky. States along the Great Lakes have an increased chance of below-normal precipitation.
Missouri River Basin – Above normal temperatures for much of the region. Below-normal precipitation is favored for the headwaters of the Missouri River. Above-normal precipitation is favored for areas of the southern Rockies.
Southeast Region – There is an increased chance of below-normal temperatures across the southern portion of the region, including much of Alabama, Georgia and Florida, along with a strong probability of above-normal precipitation throughout the Southeast, especially in the southern and eastern portions of the region
Southern Plains – Above-normal precipitation, below-normal temperatures, slightly higher probability of snowfall and sleet events.
Western U.S. – Above-normal temperatures and below-normal precipitation are anticipated in the Pacific Northwest and northern Rockies. There is a 50% chance that winter precipitation totals will be in the top 33% of historic values across southern California, Arizona and New Mexico.