Much of the southern half of the United States is likely to see a warmer, drier winter than usual, while the northwest could be cooler and wetter, according to a preview released this week by the National Oceanic and Atmospheric Administration’s Climate Prediction Center.
And while some portions of the Northeast and Mid-Atlantic could be warmer than normal, forecasters said large portions of those regions fell into a category that could go either way, depending on how regional patterns shift.
It’s difficult to predict the weather beyond seven days, and seasonal forecasts such as this one cannot predict the amount of snow or rain that will fall this winter. These forecasts look at probability, providing a range of possible outcomes and their likelihoods, rather than a single prediction.
A few factors go into a winter forecast like this, including climate trends, computerized models and other weather patterns. But the forecast is highly influenced by what’s known as the El Niño-Southern Oscillation, a climate pattern involving sea surface temperatures across the Equatorial Pacific. It has three phases: La Niña (below-average temperatures), El Niño (above-average) and a neutral phase.
NOAA meteorologists predicted that much of this winter’s weather would be driven by La Niña, which means cooler-than-normal water temperatures in the tropical Pacific Ocean can play a significant role in weather across the entire country.
Bob Henson, a meteorologist and writer for Yale Climate Connections, called this year’s outlook a “classic La Niña pattern.”
Mr. Henson noted that no matter the pattern, in winter, cooler weather is typical to the north and milder conditions are typical to the south. But, he said, “La Niña tends to accentuate that.”
Here is a summary of the Climate Prediction Center’s winter weather trends across the continental United States.
Midwest
The Midwest tends to be cold, often bone-chillingly so, in winter, and the upper Midwest — including North Dakota, South Dakota and Minnesota — could be colder and snowier than usual. Nebraska falls within the part of the country that could be colder than usual. Much of the rest of the region has an equal chance for above-, near- or below-normal precipitation and temperatures.
Great Lakes
The Climate Prediction Center is forecasting wetter-than-average conditions for all the states surrounding the Great Lakes, particularly eastern Illinois, Indiana and western Ohio.
Northern Michigan has a shot at being cooler than normal, while there’s an equal chance for above-, near- or below-normal temperatures across a large part of the rest of the region.
California
The winter outlook is more skillful in some parts of the country than others, and the reliability has been historically low in California, said Jeanine Jones, the interstate resources manager for the California Department of Water Resources.
Warm, dry weather is expected in Southern California this winter, according to this year’s outlook, and La Niña does tend to bring these conditions — but not always.
“A couple of the top 10 wettest years in Southern California were actually La Niña years,” Ms. Jones said.
A mild winter could heighten wildfire risk and worsen pre-existing drought conditions.
Northwest
The Northwest trends cooler and wetter in the winter, and this year odds are in favor of below-normal temperatures across Washington, northern Idaho and Montana.
The entire region is predicted to be wetter than normal, particularly a large portion of Montana.
New England
The Climate Prediction Center did not find a strong signal for specific weather trends across most of New England and concluded that the region could see above-, near- or below the normal amount of precipitation that it usually gets.
Temperatures could also go one of three ways for northern New England, though there’s a chance for warmer-than-usual weather in Massachusetts, Connecticut and Rhode Island.
New England is known for its snow, and a wet pattern often comes from storms coming off the Atlantic Ocean, but when cold air drops down from Canada, drier conditions can unfold. These systems cannot be predicted several months out.
Mid-Atlantic
The signal is also weak in much of the Mid-Atlantic, though there’s a chance for above-normal temperatures in southeastern New York; eastern Pennsylvania; New Jersey; West Virginia; Virginia; Delaware; Maryland; and Washington, D.C.
Western Virginia is leaning toward above-normal precipitation, but it’s unclear what winter will bring in terms of precipitation to the remaining part of the Mid-Atlantic, including New York.
Southwest
The odds are good there will be above-normal temperatures, particularly in portions of Arizona, New Mexico and far West Texas.
Arizona, New Mexico and most of Texas are at risk of an unusually dry winter, and drought conditions ” rel=”noopener noreferrer” target=”_blank”>are expected to persist across the Southwest, NOAA said.
Southeast
Florida’s winters are usually mild and sunny with a few cold snaps, and the Climate Prediction Center is forecasting a warm and mostly dry winter for the state.
In the rest of the region, the odds are tipped toward drier, warmer weather across the Gulf Coast, including southern Louisiana, Mississippi and Alabama. Chances are also leaning toward above-normal temperatures and below-normal precipitation in most of the Carolinas.
Amy Graff is a Times reporter covering weather, wildfires and earthquakes.
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