A very strong El Niño is likely to shape the coming US winter, according to the official winter outlook from the National Oceanic and Atmospheric Administration. NPR reports on what forecasters expect region by region.

NOAA's outlook covers December through February. It favors warmer-than-average temperatures across the northern US, including northern California, the Pacific Northwest, the Midwest and much of the East. Wetter-than-average conditions are most likely across the southern US, from California to Florida, and along the East Coast.

"A very strong El Niño will likely bring a southward and eastward shift to the jet stream," said Ken Graham, director of NOAA's National Weather Service. He warned that heavy rain on dry soil can cause flash floods and mudslides.

El Niño is a natural pattern that begins when a vast area of the eastern Pacific near the equator warms. That releases heat into the air and shifts weather around the world, NPR reports.

Forecasters caution that the outlook shifts the odds but does not promise any outcome. "In the winter months it doesn't mean you won't have snow," Graham said, according to NPR. "It doesn't erase the risk."

NOAA expects drought to ease or end in the Southwest, the southern Great Plains, the Southeast and parts of the East Coast. Drought may grow in parts of the northern Rockies and in northeastern Oregon and eastern Washington.

NPR reports that rain in the Southwest will not end the water crisis on the Colorado River. Lake Powell and Lake Mead remain at record lows, said climate scientist Daniel Swain.

NOAA says this year it will use "Particularly Dangerous Situation" wording in some blizzard and ice storm warnings. The next outlook update is due on November 19.

What we know: NOAA's outlook favors a warmer North and a wetter South and East this winter.
What we don't: How the season will actually play out in any one place, since outlooks only shift the odds.