Six LI tornadoes in Saturday storm is a first for the record books, NWS says
Long Island has never had six tornadoes touch down in one day, according to national weather records, but last Saturday that number came blasting through, splintering trees and lifting roofs in both counties.
A quartet was confirmed Monday, and proved destructive for some homeowners and businesses in both counties in mere minutes — a miniature version of the ruinous damage twisters can inflict in the Midwest.
Then Tuesday afternoon, officials said, they had identified a fifth that went through North Bellport. A team of meteorologists from the National Weather Service along with fire and rescue personnel made the "preliminary assessment" after inspecting damage there.
It was determined to be an EF-0, or the weakest level of strength with winds nevertheless up to 85 mph, the weather service said. Three out of the four others were also EF-0.
Tuesday night they confirmed a sixth EF-0, from Hampton Bays to North Sea.
It was a first for the record books, weather service officials said.
A total of 490 twisters have touched down in New York from 1950 to July 31, 2021. But the rotating clouds meteorologists dread seeing on their radar could visit New York more frequently, experts say.
"Since 1950, there has never been more than three tornadoes on Long Island in a single day," Jase Bernhardt, assistant professor of geology, environment, and sustainability at Hofstra University said Monday.
Fueled in part by warming oceans, storms worldwide are growing more intense. The question of whether climate change plays a role is not yet settled but scientists agree that the rise in temperatures helps to boost storms with extra moisture.
"They sort of give storms enough energy to really be powerful and really be able to spin up multiple tornadoes," Bernhardt said.
There is also a heightened reporting of twisters along with social media awareness, said Norman, Oklahoma-based Matthew Elliott, warning coordination meteorologist with the NOAA/NWS/Storm Prediction Center.
But the speed in which nature creates them makes tornadoes, especially the weaker ones such as last weekend's, difficult to predict and track.
On Saturday, the weather service put out alerts for a severe thunderstorm in the late morning but didn't put out tornado alerts until 2:53 p.m., around the time they were touching down in some places.
Challenge of forecasting tornadoes
Only in the last 15 years or so has radar improved to the point that meteorologists now can spot — possibly just a minute or so beforehand — twirling winds signifying smallish tornadoes, or even "debris balls," objects tossed high into the sky, experts said.
Even with that radar, "there are limitations in terms of how much ahead of time we are going to be able to see these," said Nelson Vaz, an NWS meteorologist based in Upton, who inspected the weekend damage that identified the cause as tornadoes and classified them.
Experts applauded the NWS' Upton meteorologists for their expertise, issuing warnings as fast as possible Saturday. Said Vaz: "These things can spin up really quickly. We may only be able to get a minute of lead time. Some spin up so quickly, you may not get any lead time ahead of it."
Twisters blowing in from the sea can give forecasters a little more time to warn the public to take shelter, away from any windows and preferably down in basements. "With some, spinning up off the water and coming inland, we are able to provide some lead time," Vaz said.
Last weekend's six tornadoes on Long Island were either EF-0s or EF-1s, with winds ranging from 40 mph to 112 mph. That total could climb as the National Weather Service completes surveys of the damage done in Shirley, East Islip, Uniondale and other places.
But as destructive as Saturday's tornadoes were, they have been seen in New York before.
What is striking, meteorologists agree, is the number that were spawned Saturday in Nassau and Suffolk, embedded in a line of squalls created within severe thunderstorms that overwhelmed the tristate region.
"Wind events, strong wind events, along cold fronts, are relatively common at this time of year," Elliott said. "What makes this even more unusual this year is just the number of tornadoes that occurred," he said.
Less intense tornadoes seen before
Single, brief and much less intense tornadoes than the acre-eating, often deadly monsters seen in the Midwest are much more common in New York.
Around 85% of New York’s seven-decade total fell into the bottom two rankings for wind speed, Elliott said.
Of Saturday's tornadoes, only the one that swept through the Shirley-Manorville area in Suffolk County was rated as an EF-1.
It has been decades since powerful tornadoes pummeled New York.
Nassau last had two stronger F2 twisters on Sept. 27, 1970, and another on Sept. 18, 1973, Elliott said. That means their winds were no swifter than 157 mph. (The tornado classification system changed in 2007).
And then, said David Robinson, New Jersey state climatologist and a Rutgers University professor, "there also is the timing of it happening in November; it’s definitely more rare but sometimes, it’s actually these late season, like fall type events, where you can get a strong frontal system moving through."
Warmer air fuels storms
The weekend twisters — which ripped the roof off a two-story multifamily residence in Shirley, flipped several small planes at Brookhaven Calabro Airport, sheared off shingles, and collapsed fences — also were powered by the mild air temperatures that have prevailed for much of autumn.
"At this time of year, the ocean water is still a bit warm, so that warm, moist air can (add) basically the energy to create storms," Robinson said.
Had the seas surrounding so much of Long Island been cooler, those twisters may never have developed, as colder water is a natural protective feature, experts noted.
Cold fronts, like the one that sailed through, thanks in part to the weekend's low-pressure Alberta clipper, can help create squalls and thunderstorms. And tornadoes can arise inside thunderstorms.
The sequence begins when thunderstorms, according to NOAA, develop because a cold front lifts the warm air ahead of it, which then condenses into rain drops as it climbs and cools.
How Many Tornadoes Form
Tap the numbers in order.
Unstable conditions produce updraft of warm, moist air.22Mesocyclone forms
The air rises and meets cooler air, causing system to rotate, forming mesocyclone.33The Funnel
Mesocyclone intensies and may form funnel cloud. If funnel cloud extends to ground, it’s called a tornado.
The interplay between the warm and cold air can create spinning air currents within those clouds, NOAA says, and if they rotate vertically, instead of horizontally, they can fall to the Earth as a tornado.
"It's really a good reminder, no matter where you live, a tornado is possible," Elliott said. "Don't assume 'Tornadoes don't happen here.'"
Meteorologists may disagree on whether or even how closely climate change might increase these perils. Another factor, some said, is La Nina, which is forming for the second year in a row.
"You might be able to attribute some of the energy to the fact that the sea surface temperatures are above normal," Robinson said. "But to stick your neck out to say exactly why that happened, is being a bit bold, I think."
Still, La Nina, which arises when the equator’s easterly trade winds intensify, sends the jet stream north, toward the U.S. West Coast, opening the door for more storms — including hurricanes — which tend to head north from the South to the Ohio Valley and the Great Lakes, instead of along the East Coast.
Those rising temperatures are readily seen in Long Island Sound, where yearly temperatures have increased by 11.27% from 1960 to 2020, according to Long Island Sound Study, a research program involving scientists, regulators and advocates.
Determining whether a tornado has in fact touched down can require assessments by not just meteorologists but engineers and physicists, Elliott pointed out.
"We're looking for different severity levels or the magnitude of damage to different things, trees, structural elements," Vaz said. Trees snapped in half are not necessarily the work of a twister.
"Typically, with a tornado, tree falls tend to be kind of convergent, that kind of gives you a signal that there was a rotational wind coming through that is indicative of a tornado," he said.
"A more divergent pattern, or even with things kind of in the same line, is more indicative of straight line winds, that don't have a rotational component."
Surveying blown off roofs, missing siding, and even collapsed buildings can help reveal the wind's speed. "Structural damage really gives us a good idea of mileage."
And, he added: "Spotters are always important to us; the more information we can get into our office, that's really helpful for us to know what's going on."