On October 19, 2017, the National Oceanic and Atmospheric Administration's Climate Prediction Center released its U.S. Winter Outlook.
The outlook noted a 55–65% chance that a La Niña would develop.
According to CPC Deputy Director Mike Halpert, any such La Niña was expected to be "weak and potentially short-lived", but it could still affect the season.
He also noted that La Niña years normally result in colder-than-average, wetter winters in the northern tier of the United States and the inverse conditions across the south.
In terms of precipitation, wetter-than-average conditions were favored across the majority of the northern United States, including a region spanning from the northern Rocky Mountains to the eastern Great Lakes in addition to the Ohio Valley, Hawaii, and western and northern Alaska.
Drier conditions were anticipated across the entire southern United States.
Above-average temperatures were favored across the southern two-thirds of the contiguous United States and along the east coast, as well as in Hawaii and the northern and western parts of Alaska.
The outlook favored below-average temperatures in the northern tier, from Minnesota to the Pacific Northwest region as well as southeastern Alaska.
The remainder of the country was assigned equal chances of either above or below-normal temperatures or precipitation.
The drought outlook noted that drought was likely to remain in parts of the northern Plains, with recovery likely to the west.
The development of limited regions of drought was possible in regions that did not receive rainfall associated with tropical systems during the 2017 Atlantic hurricane season.
On October 19, 2017, the National Oceanic and Atmospheric Administration's Climate Prediction Center released its U.S. Winter Outlook. The outlook noted a 55–65% chance that a La Niña would develop. According to CPC Deputy Director Mike Halpert, any such La Niña was expected to be "weak and potentially short-lived", but it could still affect the season. He also noted that La Niña years normally result in colder-than-average, wetter winters in the northern tier of the United States and the inverse conditions across the south. In terms of precipitation, wetter-than-average conditions were favored across the majority of the northern United States, including a region spanning from the northern Rocky Mountains to the eastern Great Lakes in addition to the Ohio Valley, Hawaii, and western and northern Alaska. Drier conditions were anticipated across the entire southern United States. Above-average temperatures were favored across the southern two-thirds of the contiguous United States and along the east coast, as well as in Hawaii and the northern and western parts of Alaska. The outlook favored below-average temperatures in the northern tier, from Minnesota to the Pacific Northwest region as well as southeastern Alaska. The remainder of the country was assigned equal chances of either above or below-normal temperatures or precipitation. The drought outlook noted that drought was likely to remain in parts of the northern Plains, with recovery likely to the west. The development of limited regions of drought was possible in regions that did not receive rainfall associated with tropical systems during the 2017 Atlantic hurricane season.
2017–18 North American winter