Anomalous November storm triggers unprecedented mini-swarm of tornadoes damage parts of Long Island and Connecticut – Thousands without power

Multiple tornadoes struck several Northeast states on Saturday in an unprecedented November outbreak, snapping trees and leaving behind pockets of structural damage to homes and businesses.

The mini-swarm of tornadoes occurred as an intense, tightly wound impulse swept across the region, drawing energy from near record-warm Atlantic Ocean waters. A strong cold front accompanying the disturbance incited a line of powerful thunderstorms, some of which began to rotate as they slid through Long Island and into southern New England.

Radar imagery showed numerous instances of debris lofted amid this rotation, prompting the National Weather Service to issue a total of 12 tornado warnings across New York, Connecticut, Rhode Island and Massachusetts.

At one point, two simultaneous tornadoes were probably ongoing near Islip in Long Island. The Weather Service office in New York City is conducting damage surveys near Mastic and Shirley on Sunday to determine whether and where tornadoes touched down and to assign damage ratings. In Shirley, a shopping center suffered heavy damage from the storms.

In Connecticut, three probable tornadoes struck Cheshire, Branford and Plainfield, with radar imagery showing rotation and debris. In Cheshire, a trampoline was blown into power lines, while snapped trees damaged some property and cut electricity to thousands. The Weather Service is also surveying the damage in this area on Sunday.

Ryan Hanrahan, a broadcast meteorologist in Hartford, said this activity in Connecticut was unprecedented. “Since records began in 1950 we’ve never had tornadoes this late in the season,” he tweeted.

Tornado warnings were also issued in Providence, R.I., and in Cape Cod and Martha’s Vineyard in Massachusetts.

Across the four states, more than 5,000 people were without electricity Sunday morning, according to Poweroutage.us. The Weather Service received more than 50 reports of storm damage in the region, mostly from downed trees.

Saturday was the second day in a row that the Weather Service issued multiple tornado warnings in region, after two on Friday as the first of two cold fronts swept through. The Weather Service office in Albany confirmed that a tornado rated EF1 on the 0-to-5 Enhanced Fujita scale for twister damage, with 90 mph winds, touched down near Millbrook, which is roughly midway between New York City and Albany.

Unusual storm activity amid a record-setting year in the Northeast

The tornado activity on Friday and Saturday continued what has been a historic year for severe weather in the Northeast. Several Weather Service offices in the region have issued record numbers of warnings for severe storms and tornadoes.

Ordinarily, severe storms are on the decline in the Northeast during its cold season, which spans the period from October through March. Storms at this time of year require heat to destabilize the atmosphere, and its supply dwindles into the winter months. During this entire period, the Northeast typically sees only around two tornadoes each year on average.

Number of November tornadoes on average. By NOAA
Number of November tornadoes on average. By NOAA

But a number of highly unusual tornado events have rocked the region since Oct. 1, climaxing in Saturday’s event.

Three Weather Service offices have issued record-setting numbers of tornado warnings since Oct. 1:

1. The New York City Weather Service office, which also covers northern New Jersey, extreme-southeast New York state, all of Long Island and the southern half of Connecticut, issued five tornado warnings Saturday. That warning count single-handedly exceeds any previous October-to-March period and represents a third of the cold season warnings ever issued (since records began in 1986). The office has also issued more tornado warnings this month than any since September 2012. And, for the year, the office has issued a record-tying 16 tornado warnings.

2. The Binghamton, N.Y., Weather Service office, which also serves Syracuse, Wilkes-Barre, Ithaca and Utica, has issued five tornado warnings since Oct. 1, two more than any previous cold season, and it’s only mid-November. One-third of the cold season tornado warnings that the office has ever issued have been in the past six weeks.

Tornado warning counts by month at the New York City and Binghamton National Weather Service offices. By Iowa Mesonet
Tornado warning counts by month at the New York City and Binghamton National Weather Service offices. By Iowa Mesonet

3. The Boston Weather Service office, which also covers much of Rhode Island, northern Connecticut and eastern Massachusetts, has issued seven tornado warnings since Oct. 1. Before this year, it had issued only six in all other years — one in 2020 and the rest in 2018. The 22 tornado warnings it has issued in 2021 are, by far, a record.

Tornado warning counts by year at the Weather Service office in Boston. By Iowa Mesonet
Tornado warning counts by year at the Weather Service office in Boston. By Iowa Mesonet

The ocean cools more slowly than land, meaning a warm Atlantic can act as the fuel required for tornadoes even as the sun’s energy wanes. When water adjacent to the coast is warmer than normal, this fuel availability increases.

Over the past week, coastal waters offshore the Northeast have been three to six degrees warmer than normal.

As water temperature in the North Atlantic continues to rise, cold season tornadoes could increase over the region. [WP]