NOAA expects El Niño to peak in December
California Gov. Gavin Newsom declared a state of emergency on Monday, Oct. 12, ahead of the El Niño season, to support early statewide preparations for potential winter storms and related events such as flooding and landslides.
The declaration came as NOAA’s winter outlook, released Thursday, projected that a strong El Niño event will steer a series of storms into the West Coast and the southern United States this winter. El Niño is characterized by above-average ocean temperatures in the Pacific that shift weather patterns across the globe, according to the agency. NOAA said the climate pattern will likely peak in strength in December but will affect the Lower 48 states in the winter months.
Under El Niño’s influence, much of the United States will likely be milder and wetter than normal, NOAA forecasters said, adding that snowy weather may not be affected. The agency said the combination of this El Niño’s intensity with record-high global ocean temperatures could allow individual winter storms to produce unusually heavy rains and mountain snows.
The mechanics of the pattern point the jet stream — the west-to-east current of air that steers storms across the continent — toward the southern tier of the United States. NOAA said the typical result is an increase in storms and wetter, cooler weather across southern parts of the country, while northern states become drier and milder than normal. Precipitation along the East Coast is expected to run above average.
How much frozen precipitation falls across the Southeast and parts of the Southern Plains will depend on how cold it gets there and whether cold air coincides with storm tracks, NOAA said. The agency cautioned that no two strong El Niño winters unfold identically, even though most share these general temperature and precipitation trends.