MOBILE, Ala. (WKRG) — The National Oceanic and Atmospheric Administration has issued its U.S. Winter Outlook. This forecast corresponds to the December 2023 to February 2024 timeframe.
What is El Niño?
El Niño, the climate pattern characterized by weak trade winds and warmer-than-normal sea surface temperatures over the equatorial Pacific, is expected to flex its muscle during the winter months. This “warm phase” of the larger El Niño Southern Oscillation (ENSO) influences global weather patterns. For instance, a strong El Niño phase in the Northern Hemisphere summer months generally leads to increased wind shear over the Caribbean and western Atlantic Basin. This tends to suppress tropical activity, assuming all other factors are equal.
Typical El Niño Winter
The effects from El Niño are more easily observable during the winter months when ebbs and flows in the jet stream tend to be more variable. During winters with a strong El Niño in place, we most often observe a “split flow” pattern over North America where the cold, Arctic air is kept farther north and east. Meanwhile, the southern branch of the jet stream (Subtropical Jet) tends to be more active driving Pacific storms across the Southern U.S.
As a result, El Niño winters are more likely to be wetter than normal across the southern third of the continuous United States. Drier-than-normal winters are more often observed over parts of the Tennessee and Ohio Valleys and parts of the Great Lakes.
The polar jet stream tends to stay north at higher latitudes under the presence of El Niño in the winter. This causes warmer-than-normal conditions over the Midwest, Central and Northern Plains, and the Northern Rockies.
The official winter outlook from NOAA falls mostly in line with a typical El Niño winter. For the Gulf Coast, there is a higher-than-normal chance for a wetter winter. This is thanks to the anticipated subtropical jet set up over the southern one-third of the U.S. This could be significant considering the ongoing drought over the southern U.S. In terms of temperatures, the Gulf Coast has an equal chance of having a cooler or warmer than normal winter season.