YOUNGSTOWN, Ohio (WKBN) – In simplest terms, El Niño is the warming of the Pacific Ocean waters off the coast of South America. The warming has global implications on weather patterns. Those impacts are not usually as pronounced during the summer months. However, there are some trends that can be seen when looking at past warm phases of the El Niño Southern Oscillation (ENSO).
What is El Niño?
The El Niño Southern Oscillation 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.
“When you get SST [sea surface temperature] anomalies in that region, it will strongly impact deep tropical convection, which is thunderstorms. Deep tropical thunderstorms normally sit in the western Pacific and they’ll move eastward,” said Dr. David Dewitt, director of the US Climate Prediction Center (CPC).
These changes in precipitation patterns begin a domino effect across the globe, altering temperatures, jet stream locations, precipitation patterns, and even tropical cyclone formation. There is even research showing impacts on spring severe weather season. Currently, the Mahoning and Shenango Valleys are experiencing a bit of a severe weather “drought” for May, typically one of our more active severe weather months.
Research referenced in a post from Climate.gov shows a correlation between less severe weather during El Niño events for most of the US except Florida and an increase in spring severe weather events for much of the eastern US during La Niña events.
Is this going to be an El Niño influenced summer?
The CPC issues long-range climate forecasts, including forecasting El Niño or La Niña conditions. CPC forecasters began seeing signs of a developing El Niño earlier this year. An El Niño Watch was issued in April 2023 by CPC and continued in the May 2023 update.
“The evolution of the past month certainly is strong along these lines of having an El Niño event in the next couple of months,” said Dewitt.
Currently, sea surface temperature anomalies are beginning to approach the El Niño threshold in the crucial area of the central Pacific. Forecasts show continued strengthening through the summer. Weak to moderate El Niño conditions being reached as summer 2023 begins is very likely. The current CPC outlook calls for a 90% chance of El Niño conditions developing and persisting into the 2023-2024 winter season.
What may a developing El Niño mean for our summer temperatures in the Youngstown area?
The strength of the El Niño plays a critical role in general impacts locally.
“One of the risks that we have with a weak to moderate El Niño during the summer time is a cooler than normal pattern across much of the united states,” said meteorologist Richard Redmond, lead forecaster at the National Weather Service Pittsburgh office.
Redmond has been with the local NWS forecast office since the early 1990s. He’s been watching El Niño impacts locally for decades and is following the currently developing one closely.
The weak to moderate level El Niño conditions he mentions are expected to be reached by summer 2023 as the strengthening of the SST anomalies continues. In fact, the current forecast from the CPC calls for the El Niño threshold bring crossed with continued warming possible into Fall 2023.
Even if this were to result in a cooler-than-normal summer, that doesn’t mean it’s all cold. When referencing a season as warmer or cooler than normal, the number used is the average for the entire three months. Meteorological summer runs from June 1 – Aug. 31. Occasional temperature extremes in the warmer or cooler direction almost always occur during different parts of a season.
For some perspective, if you had a high of 80° and a low of 60° every day of the summer, the average temperature for that summer would be 70°. Obviously, the will be a lot more fluctuations over three months. Even with some extremes, the average can still come close to the same figure referenced above. For example, if day one has a high of 65° and a low of 45°, then day two has a high of 95° and a low of 75°, the average temperature for the two days would still be 70°.
“I would say temperature-wise, we’re probably going to be close to a normal summer with, like you said, intrusions of heat and humidity, times where we’re going to be a little cooler, cooler nights,” said Redmond.
The current outlook for the summer season from the Climate Prediction Center has our area outlined in the agency’s “equal chances” shade, meaning forecasters are not seeing a statistical lean toward either warmer or colder than normal temperatures in our region.
What may a developing El Niño mean for our summer precipitation in the Youngstown area?
Pittsburgh National Weather Service lead forecaster Richard Redmond believes there is a stronger deviation possible when discussing precipitation. “I think the one thing that does stick out in the data is there’s a threat for a pretty dry summer,” said Redmond.
While it remains possible modeling doesn’t yet have a good grasp on the strength of the developing El Niño event, Redmond is seeing strong correlations to drier-than-normal conditions in our region based on past events. He thinks a drier-than-normal summer is very likely.
“The models are picking up on some of this, showing a drier-than-normal pattern. Historical data shows drier conditions in the Ohio Valley and some of the experimental data from our drought partners shows drier than normal conditions for the upper Ohio Valley,” Redmond added.
Wintertime impacts during strong El Niño events favor drier than normal conditions in our region. The summer impacts can be a bit less pronounced. But if current trends are any indication, then this would be a drier season. Meteorological summer begins June 1, and the first several days of meteorological summer are now showing up in the model data. May 2023 is expected to be one of the driest on record. We are currently sitting as the 6th driest on record with just two days to go, both of which are expected to be dry.
A model output for the first 10 days of June shows very little precipitation in our area. Obviously, the data can change as days go on and models adjust to current patterns as newer data is collected. However, the trend we are seeing in the data currently shows continued drier-than-normal conditions. Take a look at this model output of potential rainfall between now and June 9.
Pittsburgh National Weather Service’s Richard Redmond’s assessment, however, contradicts the forecast from the US Climate Prediction Center. Redmond is expecting our summer weather to be drier than normal. The CPC summer precipitation outlook shows our area in their leaning wetter than normal category.
What impacts would be expected in the Youngstown area in an El Niño influenced winter?
Localized impacts from El Niño and La Niña are typically much more pronounced during the winter season. Currently, the CPC has a 90% chance of El Niño conditions developing and persisting into the 2023-2024 winter season. The strength of the El Niño is crucial to what impacts we see in our region. For a look at the possible winter-time impacts and an examination of what impacts El Niño may have on the upcoming winter season, check out Part 2 of the series.