The heavy rain and flooding that Connecticut and Long Island experienced this weekend have been billed as a “once-in-a-lifetime” storm. But officials from the National Weather Service say they’re becoming more common and harder to predict.
More than 10 inches of rain fell within hours on Sunday night. It destroyed roads, homes and businesses. Two people died in the flood.
Connecticut Gov. Ned Lamont declared a state of emergency. Members of Long Island’s federal delegation are urging New York Gov. Kathy Hochul to do the same.
Nelson Vaz, the warning coordination meteorologist with the National Weather Service in New York, said the NWS had predicted heavy rain and the potential for flash flooding before the weekend started.
But he said the heaviest rain can be the hardest to predict. That’s why many people were caught off guard by the 10 inches of rain that poured down in places like Oxford.
“When you look at a kind of a distribution of possibilities, that type of rainfall really falls on the tail end of these very, very, very low probabilities,” Vaz said. “You're talking about 1% or less chance. And sometimes those types of rainfall amounts actually don't even show up in the distribution of what we see in the weather models.”
The state of weather technology also hinders the ability to predict the worst of heavy rain storms.
“Unfortunately, right now, the skill of science is not at that point where we can predict those types of rainfall rates and those types of amounts,” Vaz said.
According to data that Vaz paraphrased from the Intergovernmental Panel on Climate Change, there’s a strong correlation between a warming planet and heavier rain storms.
The hotter the atmosphere, the more moisture. And the more moisture, the more rain.
“What they've seen is a 40% increase in these top 1% extreme rainfall events over the last 60 years,” Vaz said. “And the projections are going out with a continuing warming planet. And especially for the northeastern United States, is a continuation to see potentially another 40% increase in these in these heaviest 1% rainfall event days.”
Vaz’s job is not only to forecast the weather. He also coordinates with working with public safety and the media to keep the public informed of major weather developments.
He said the best way to get the most up-to-date weather information is to monitor the NWS and take the alerts seriously.
“When you're getting those types of alerts, you really want to pay attention,” Vaz said. “Move out of lower areas. Move out of basement apartments, get to higher ground.”
