As strong El Niño develops off the Pacific, experts say Vermont impact is tough to tease out

Particularly warm water forming along the coasts of North and South America have caught the eyes of weather watchers across the globe, but the impacts on Vermont are murky for now.

The warming and associated weather patterns are known as El Niño, a natural climate phenomenon where strong winds that normally push warm waters from east to west are weakened and often reversed, causing the water in the western Pacific to be pushed back east toward the Americas.

It is only the warm phase that is part of the larger El Niño-Southern Oscillation cycle, or ENSO, that occurs every two-to-seven years and typically lasts for nine to 12 months, according to the National Oceanic and Atmospheric Administration. As a typical El Niño unfolds, heavy rainfall and flooding is predicted to emerge across parts of South America and in the Southeast of the U.S., while warmer and drier winters will develop in the northern regions. 

In the coming months, a “super” El Niño is expected to develop, with the conditions being heightened. 

“The current El Nino has a 63% chance of being very strong, and so our confidence in certain weather and climate outcomes is higher than normal,” Michelle L’Heureux, a physical scientist at the NOAA’s Climate Prediction Center, told VTDigger. 

However, with Vermont being removed from the source region in the tropical Pacific, the El Niño impacts will likely be more “muted,” Lesley-Ann Dupigny-Giroux, Vermont’s state climatologist, told VTDigger. 

According to official three-month forecasts from NOAA’s Climate Prediction Center, Vermont has a 40% to 50% chance of above normal temperatures this summer. The outlook, stretching from July to September, also shows that southern Vermont has a 33% to 40% chance of leaning above normal seasonal precipitation, while the rest of Vermont is predicted to be safe from irregular rainfall. 

Dupigny-Giroux wrote in an email that weather phenomena in the north Atlantic and arctic have more direct impacts on Vermont and the Northeast. But the state is keeping a close eye on the developing El Nino events and comparing them with other past strong events dating back to the 1870s, she said. 

Johnna Infanti, another meteorologist and seasonal forecaster at NOAA’s Climate Prediction Center, called the impact of El Niño on summertime temperatures and precipitation over New England “difficult to untangle,” adding that “it can be easily overshadowed by local and shorter-term weather patterns and long-term trends.” 

Seasonal forecasts rely on computer models and local conditions, such as soil moisture, as well as multiyear trends in temperature and precipitation.

The impacts from El Niño are generally stronger in winter across the U.S., according to Infanti. This can lead to milder winters over New England, with some potential for above-normal precipitation, particularly along the coast. Vermont being more inland, he said a reliable signal for the state’s precipitation “is difficult to tease out.” 

Despite projections for above-normal temperatures and precipitation in Vermont, NOAA’s seasonal forecasters note that there are always limits to every forecast. 

“Much of the variability of seasonal temperature and precipitation is unpredictable,” Dan Collins, meteorologist and seasonal forecaster at NOAA’s Climate Prediction Center, told VTDigger. “Despite predictable tilts in the odds toward above or below normal temperatures or precipitation, we can only predict the probability that these will occur.”  

Monitoring the local impacts of El Niño closely, Vermont Emergency Management officials are preparing for any local emergency situations that should arise.

“We work around the parameters of what may happen in your typical El Nino situation,” said Eric Forand, Vermont Emergency Management’s director, in an interview. “We’re looking at all hazards and trying to compare for any eventual outcome of Mother Nature.” 

As Vermont prepares for possible increased precipitation and temperatures, Forand said the state has plans, policies and procedures in place, whether it’s activating the emergency operations center or having connections with other agencies that might need assistance. 

Given the state’s history of summer flooding in recent years, he advocated that all Vermonters should be ready for any scenario. 

“You should plan for all hazards events,” Forand continued, “meaning that you should have a to-go bag, an escape route, a plan to go somewhere and how to communicate, whether it’s a wildfire or a flood or snow event or a wind event.” 

While Vermont may experience minor impacts from El Niño during the summer, north Atlantic weather patterns are strongest in the winter months and the full effect of the weather anomaly will likely not be felt until then, Infanti said.

Read the story on VTDigger here: As strong El Niño develops off the Pacific, experts say Vermont impact is tough to tease out.