2017-18 winter outlook map for precipitation Photo: NOAA

The long-term winter forecasts have nearly as much uncertainty as annual almanacs did in centuries past. Recent predictions of the season ahead have had mixed results. But their long-term modeling has helped homeowners and governments alike prepare for the snow and ice – or lack thereof.

La Niña is likely to reverse the effects of El Niño for the season, U.S. official said.

“If Niña conditions develop, we predict it will be weak and potentially short-lived, but it could still shape the character of the upcoming winters,” said Mike Halper, deputy director of the Climate Prediction Center at NOAA.

The northern tier of the continental U.S. will be wetter, the South drier, according to the regular seasonal prediction by the National Oceanic and Atmospheric Administration.

The wetter precipitation bands in a large rounded “W” shape from Washington and Montana and the Northern Rockies over to the Midwest, Great Lakes, and Upstate New York. The drier is a less curved swath from southern California eastward across Arizona, New Mexico, Texas, Louisiana, Alabama, Mississippi, Florida and up to the Carolinas.

The southern two-thirds of the country are forecast to be slightly warmer, they add. The only cooler parts are the Pacific Northwest corner of Washington, across Idaho and Montana to the Dakotas, they add.

Drought is likely to persist in the northern swath of the Great Plains. (Alaska and Hawaii are also likely to be wetter and warmer, as well).

The factors that went into the prediction are the Arctic Oscillation, which adds considerable uncertainty to forecasts beyond two weeks, and the Madden-Julian Oscillation, which may affect rain on the West Coast.

NOAA said their predictions are meant to give overall projections – but don’t necessarily reflect snowfall totals or number of freezing precipitation events.

“While the last two winters featured above-average temperatures over much of the nation, significant snowstorms still impacted different parts of the country,” they announced. “Snow forecasts are generally not predictable more than a week in advance because they depend upon the strength and track of winter storms.”

The last two winters in the U.S. have been in the top 10 records for warmth.

An updated winter outlook will be available in roughly one month, on Nov. 16.