El Nino Pattern Drives Diverse Winter Weather Forecasts Across US

A strengthening El Nino pattern is expected to shape winter weather across the United States, with forecasters warning of regional differences including warmer conditions in the Midwest, increased rainfall in parts of the South, and a reduced chance of prolonged cold in the Pacific Northwest.

According to the Climate Prediction Center, there is more than an 80% chance that a strong-to-very strong El Nino will continue in the Northern Hemisphere until at least spring. Sea surface temperatures in the eastern Pacific have risen more than four degrees Celsius above normal.

NBC Chicago reported that El Nino occurs when weakened Pacific trade winds allow warmer ocean water to move eastward toward the Americas. The pattern can shift the Pacific jet stream southward, affecting temperature and precipitation patterns across the country.

The University of Illinois said El Nino winters in Illinois generally trend warmer and drier, with below-average snowfall often occurring during those years. The Climate Prediction Center seasonal outlook also indicates above-average temperatures could continue through meteorological fall and December.

In the Pacific Northwest, KPTV meteorologist Mark Nelsen said the upcoming winter is likely to be milder than average, although a single snow or ice event remains possible. He noted that seasonal forecasting involves uncertainty because multiple climate factors influence winter outcomes.

The forecast discussion identified El Nino as a major driver of the expected pattern, with warm Pacific waters altering the position of the jet stream. KPTV reported that very strong El Nino events can sometimes bring wetter conditions farther north than typical patterns suggest.

In South Carolina, forecasters expect the El Nino pattern to increase moisture across the southern United States. AccuWeather lead long-range forecaster Paul Pastelok said the strength of the event raises confidence for a wetter winter in the region.

"The intensity of the El Niño that is coming on, a very strong, near-record or record El Niño, builds the confidence that we should see a lot more moisture in the southern tier of the nation, unlike what we saw last year and other years prior to that," said Paul Pastelok, AccuWeather lead long-range expert.

South Carolina officials said additional rainfall could help areas affected by drought, though higher river levels may create flooding concerns. The state experienced its driest fall-spring period in 131 years of record keeping before summer rainfall provided partial improvement.

"Summer rainfall has been beneficial, but not enough to completely recover from the long-term drought impacts. During the hot summer months, at least one inch of rainfall is needed per week to offset losses from evaporation," said the SC Drought Response Committee.

The World Meteorological Organization said El Nino events usually last around 18 months and can influence extreme weather risks. The organization also noted that climate change may increase the intensity of some related impacts.

"Amplify associated impacts because a warmer ocean and atmosphere increase the availability of energy and moisture for extreme weather events such as heatwaves and heavy rainfall," said the World Meteorological Organization.