Part one of our series dove into the potential impacts of a developing El Niño on our summer season. In Part 2, we dive into how it can shape our weather for winter 2023-2024. El Niño impacts are typically much more pronounced during the winter season. How those impacts play out in our region hinges on the strength of the El Niño event.
What is El Niño?
The El Niño Southern Oscillation (ENSO) is the name of the revolving cycle of warmer and colder surface waters of the equatorial Pacific Ocean. It is classified as an El Niño event when waters are warmer than average. The name La Niña is assigned to the colder-than-normal counterpart. Both patterns alter global temperature and precipitation patterns.
When ocean waters are anomalously warm, the likelihood of rising air and thunderstorm development increases in the vicinity of the anomaly. As the exchange of warmth and moisture from the water to the air above occurs, it rises up into the atmosphere. That rising air leads to lower pressure, thunderstorm development and wetter conditions. Away from the warmer waters at the equator will be a zone favoring higher pressure, sinking air, and drier conditions. These circulation patterns are called “Hadley Cells” and result in a domino effect of localized climate anomalies for temperatures and precipitation across the world.
Is this going to be an El Niño-influenced winter?
The U.S. Climate Prediction Center (CPC) currently has the likelihood of El Niño conditions developing and persisting into the 2023-2024 winter season at 90%. The strength of the El Niño event later this year will be crucial to understanding how our winter will be impacted. Current conditions show warming is underway, with much of the globe seeing anomalously warm surface water temperatures.
“El Niño impacts vary seasonally and, in fact, the strongest impacts for the U.S. conus [contiguous United States] are in the fall and into winter,” said Dr. David Dewitt. Dewitt is the director of the Climate Prediction Center, the entity tasked with long-range climate forecasts that include El Niño/La Niña forecasts. The CPC issued an El Niño watch in April as waters in the eastern equatorial Pacific Ocean started warming, signaling a change.
“The evolution so far in this event would be what I call typical. And by typical, I mean anomalies start on the South American coast and propagate westward,” said Dewitt. “That doesn’t always happen and so the models tend to do better when you get these eastern Pacific events.”
Forecast models show sea surface temperature anomalies crossing the El Niño thresholds early this summer. The data suggests continued warming of the equatorial Pacific Ocean waters will occur later this year. Strong warming is already occurring in the eastern Pacific Ocean, just off the coast of South America.
Also watching the warming is Pittsburgh National Weather Service Lead Forecaster Richard Redmond. Redmond has been with the National Weather Service since the early 1990s. He is impressed with how the developing El Niño is progressing so far. He feels there is a chance the models are underdoing projections of the strength the El Niño event setting up.
“If you see the water off the coast of Peru, it’s almost 7 degrees above normal. That’s incredible warmth,” said Redmond.
While the strength of the developing El Niño remains a big question, it is looking highly likely El Niño conditions will be an influence on our winter. This CPC table shows the likelihood of varying levels of sea surface temperature anomalies through the rest of the year. The current data shows a high likelihood of, at least, a weak El Niño in place by meteorological winter, running Dec. 1, 2023, through Feb. 29, 2024. The CPC has the chances of a stronger El Niño event by that time of year between 48% to 77%.
How would a weak El Niño impact winter weather in the Youngstown, Ohio area?
Weaker El Niño events typically result cooler than normal conditions and can be snowier in our region.
“Generally, in a neutral to weak El Niño phase, we see a cooler than normal pattern in the Ohio Valley. Again, because the sub tropical jet is not as strong, the polar jet is able to make intrusions down into the Ohio Valley,” said Redmond.
More frequent visits from the polar jet stream means more frequent bouts of cold, Arctic air reaching the region. Those cold snaps pulling colder air of the lakes results in lake effect snows which increases snow totals.
A recent example of a weaker El Niño event with colder conditions is winter 2014-2015.
That winter season is currently our 13th snowiest on record, with 79 inches total at the airport.
Walking though the colder months shows several top 10 records broken during that winter. November 2014 is the eighth snowiest on record. There was a lull in snow in December 2014, resulting in December 2014 being the second least snowy, with only 0.7 inches. We made up for that lack of snow in January and February 2015. January 2015 is the eighth snowiest on record.
February 2015 is both the coldest February on record and the third snowiest. The overall winter season, December 2014 through February 2015, is our sixth coldest on record.
The video below is a look at what the sea surface temperature anomalies looked like during the 2014-2015 winter season.
Even if we ended up going into winter with a weak El Niño in place, that doesn’t guarantee a cold, snowy winter. There are many other variables that can play a role. However, a weaker El Niño event would favor colder, and potentially snowier, conditions.
How would a strong El Niño impact winter weather in the Youngstown, Ohio area?
There are signals Pacific Ocean waters may trend warmer, resulting in a more moderate to strong El Niño event by winter. That scenario would look much different for the area.
A stronger El Niño event favors a much warmer winter for our area. The typical stronger El Niño pattern also generally results in drier conditions in our region.
“The sub-tropical jet is stronger, the polar jet can’t intrude as far south in the United States, so we see a warmer than normal and generally drier than normal pattern,” said Redmond.
This is the typical scenario associated with an El Niño winter, warmer and drier, in our region. With the stronger sub-tropical jet blocking the polar jet from invading the U.S. as frequently, much of the northern U.S. trends warmer. The southeastern U.S. typically experiences cooler than normal temperatures during a moderate to stronger El Niño event.
With a more active sub-tropical jet, storms more frequently take a southern track. That results in less Alberta clipper style systems or storms rising north along the Appalachian Mountains. Northeast Ohio and northwest Pennsylvania are typically drier in this pattern, while the southern U.S. is generally much wetter than normal during the winter.
The most recent strong El Niño influenced winter was 2015-2016. Total snow that winter season was 49.9 inches. November 2015 is the third warmest on record and is in the top ten for lowest total snow with only a trace. December 2015 is the warmest on record and the third least snowy. That winter season, December 2015 through February 2016 is our 10th warmest on record. We also had our fourth warmest March on record in 2016.
The video below is a look at what the sea surface temperature anomalies looked like during the 2015-2016 winter season.
Which scenario is more likely for the 2023-2024 winter season?
So which scenario will win out? It’s still a bit too soon to tell.
“We’re seeing lots of discrepancies in the model data, not sure exactly what it wants to do once we get into the fall and winter on how strong the El Niño will be,” said Redmond. “That makes a big difference to what we can expect in the Ohio Valley.”
At this point, the focus is on trends. The general leaning in available data is for at least a moderate El Niño by the winter. But there are signs this could be the beginning of a stronger El Niño event. One of those signs is the location where the warming is beginning, of the coast of Peru in South America.
“The eastern Pacific events tend to be stronger,” said Dewitt, of the CPC. He added that these impacts typically result in larger climate impacts across the globe.
The current trends being seen in the Pacific Ocean lean toward a high likelihood of this coming winter being an El Niño winter. There are signs this setup has the making of being a stronger El Niño event later this year. The result of that would likely be a warmer and drier winter in northeast Ohio and northwest Pennsylvania. That said, we still have seven months to go and a lot could change.
Right now, the CPC says El Niño is likely to form between now and July. Data from the climate prediction center suggests the chance of a strong El Niño event in place during meteorological winter, Dec. 1 through Feb. 29, is at 48%. This is something StormTeam 27’s team of meteorologists will be monitoring for you throughout the rest of this year.
What does a developing El Niño mean for summer in the Youngstown area?
Did you miss part one of this series, discussing what a developing El Niño would mean for summer conditions in the Mahoning and Shenango valleys? You can view part one of this two-part series, discussing potential impacts to summer 2023, here.