It seems as though I write a La Niña story every few years. Oh, wait, I do. It is a periodic phenomenon that happens like clockwork along with El Niño. The National Oceanic and Atmospheric Administration (NOAA) recently issued its winter forecast for the United States, and La Nina was prominently featured. What does the presence of La Niña mean for weather in the coming months and could the U.S. Presidential Election be affected?
Before I answer that question, let’s do a little “101” on La Niña. The term literally means the “little girl” in Spanish and describes decreased sea surface temperatures in the eastern and central equatorial Pacific. It is the “cold sibling” counterpart to El Niño, which is represented by warm sea surface temperatures. They both are a part for the larger El Niño- Southern Oscillation (ENSO). Through broader connections to the jet stream and other atmospheric processes, El Niño and La Niña affect seasonal weather patterns around the globe including U.S. rainfall, temperatures, and hurricane activity.
In a press release this week, NOAA said, “winter forecast for the U.S. favors warmer, drier conditions across the southern tier of the U.S., and cooler, wetter conditions in the North, thanks in part to an ongoing La Niña.” The division of NOAA’s National Weather Service that issues seasonal outlooks is the Climate Prediction Center. This expected pattern is typical of teleconnection patterns associated with La Niña though it is important to mention that each one is different. For the period December 2020 to February 2021 (meteorological winter), the probability of warmer and drier conditions in the Southern tier of the U.S. could be bad news for snow lovers. However, it is important to remember these are not forecasts for day-to-day variability. I often find that some people consume these outlooks incorrectly and interpret them to mean “warm and dry” every day of the winter. That’s not the case.
The news is not good for the states west of the Mississippi River either. NOAA CPC’s winter drought outlook predicts developing, continuing, or worsening drought conditions for much of the region. Parts of southern Georgia and northern Florida and the Midwest are also included. La Niña conditions tend to support more Atlantic hurricane activity, on average. As we move into mid-October, there is typically a decline in hurricane activity, but it doesn’t go to zero. Colorado State University hurricane expert Phil Klotzbach recently tweeted, “CSU calls for above-normal Atlantic #hurricane activity with next 2-week forecast (10/14-10/27).”
Ironically, I wrote a similar article in 2016 around the time of the U.S. Presidential election. Research has shown that rainfall, extreme temperatures and snowfall can suppress turnout among new or less-intense voters. While it is generally thought that adverse weather conditions favor Republicans and hurt Democrats, there are contradictory findings in the literature, but common sense tells us that weather has some impact on elections.
Currently, the U.S. is seeing record early-voting and mail-in ballots, which could neutralize weather impacts. If you are planning to vote in the next two weeks, the NOAA CPC precipitation outlook is below. Unfortunately, it is a bit too far out to know if any part of the country will be dealing with a hurricane on Election Day. Candidly, it is really challenging to attribute any specific day of weather in the next few weeks to La Niña, but hopefully you have a better sense of what it means as we approach the winter season.