PENNSYLVANIA, USA — Last year was an El Niño winter, and for 3 consecutive years before that, it was La Niña. So, let's look at what another La Niña winter could mean for us here in Northeastern and Central PA.
We were in the ENSO-Neutral climate pattern this summer, with a La Niña Watch issued for the fall. It's taking longer than expected, but a transition to the La Niña phase is still predicted to happen by November, and once it’s here, it should last through the rest of the winter and possibly even into early spring of 2025.
El Niño and La Niña are two opposing climate patterns in the Pacific Ocean that can affect weather worldwide.
Trade winds, which blow east to west, typically push warm surface waters toward Asia. But El Niño and La Niña are phases that break these normal conditions, making the ocean temperatures warmer or colder than average.
During El Niño, trade winds weaken.
During La Niña, they are stronger than usual. The phases change generally every two to seven years.
Scientists call these patterns the ENSO cycle; it is just one factor affecting weather patterns.
The NOAA Climate Prediction Center forecasts a La Niña pattern this winter.
Meteorologists with the National Weather Service who forecast for Northeastern and Central PA explain that we don't typically see a lot of coastal storms or Nor'Easters during a La Niña winter. Those can sometimes be the bigger snow producers here in Pennsylvania. Forecasters say La Niña winters favor lower-precipitation systems and mixed precipitation storms.
These storms are fast-moving over the Great Lakes, but there could also be a lot more of them. That is why the Climate Prediction Center has all of Pennsylvania leaning towards above-average precipitation for the winter months of December, January, and February. La Niña winters also favor late-season snowfall in March and April.
La Niña winters here in the northeast tend to feature above-average temperatures, too, and the Seasonal Temperature Outlook has Pennsylvania under a 40 to 50 percent chance of seeing above-normal temperatures for December, January, and February.
Of course, other variables impact winter weather, so it is important to remember that a La Niña phase does not provide an exact forecast.
