It was a late-May afternoon in central Oklahoma and big time
thunderstorms were expected to form soon. I was there as part of a
30-person tornado research team - a Vermont weatherman's
dream-come-true. Our goal? Bring 10 vehicles as close as we safely
could to tornadoes to gather meteorological data. The armada
consisted of three large flatbed trucks outfitted with Doppler
radar arrays able to scan thunderstorms and pinpoint any tornadoes
within them. Also in tow were a dozen or so pickup trucks carrying
deployable (but very heavy) weather instrument pods that we
intended to put in the path of oncoming twisters to directly
As we chitchatted in the searing heat, a team member came over
the CB radio to announce that a Tornado Watch had been issued - not
for Oklahoma, but for Vermont!
Over the next couple of hours, I remained glued to the radar
imagery coming in, reveling in the irony that I had come all the
way to the Great Plains to witness tornadoes, and now they were
happening back on my home turf.
The Vermont storm began as an ordinary thunderstorm, but quickly
became severe. Eventually, it transitioned into what is known as a
supercell thunderstorm. Supercells are the rarest and most powerful
brand of thunderstorm, respected and feared for their ability to
produce enormous hail, damaging straight-line winds, rapid-fire
lightning, intense rain, and of course, tornadoes. Unlike
hurricanes, which can cause corridors of wind damage hundreds of
miles across, supercells focus their rage on much smaller areas.
Tornadoes are rarely more than a mile wide, but their rotating
winds can lash the earth at speeds exceeding 200 mph - fast enough
to rip the asphalt from the road.
As the Vermont supercell slowly drifted east-southeast, it
exhibited all the telltale signs of strong rotation. Accordingly,
the National Weather Service issued a tornado warning, and shortly
thereafter the storm produced a brief, weak tornado in West Glover,
with estimated winds of about 70 mph. It knocked down about 45
trees and blew over a chimney before it petered out.
While rare, tornadoes do form in the Northeast. Unlike in the
Plains, where the spring months tend to carry the highest risk for
the dangerous whirls, high summer is the most likely time for them
here. During this time of the year, the high sun angle and long
days often result in sultry surface temperatures.
If the air above this warm layer is cold enough, the atmosphere
is unstable and therefore favorable for the strong vertical air
currents needed to drive thunderstorms. These updrafts can begin to
rotate if the horizontal winds they move up into are strong enough,
and/or change direction in just the right way. These ingredients
come together earlier and more often in the Plains due to the
earlier onset of the warm season there.
The delicate balance of forces within supercell thunderstorms
can be disturbed by mountainous terrain. This may offer some
protection from tornadoes in the more rugged sections of the
Northeast, but it does not make this region immune.
Indeed, Vermont, New Hampshire, and Massachusetts average one
tornado per year. Maine and Connecticut average two, and Rhode
Island, perhaps owing to its small size, averages less than one.
New York is a bit more active with 10 a year. To put this in
perspective, Oklahoma, at the heart of Tornado Alley, averages 62
twisters annually. It is interesting to note however that when the
average number of tornadoes per 10,000 square miles is considered,
Connecticut is the hotspot of the Northeast, with 3.6 per year.
On June 1, 2011, one the deadliest tornado outbreaks in recent
history occurred in New England. Several supercell thunderstorms
erupted that afternoon ahead of a cold front, spawning a total of
seven tornadoes. The strongest of these was in central
Massachusetts. It was on the ground for over an hour, resulting in
a 39-mile trail of destruction. The tornado tore through the city
of Springfield, destroying about 500 buildings and causing three
Given how infrequently tornadoes occur here in the Northeast, it
may be tempting to not give them much thought. But as past events
show, not only do they happen, but they can be deadly. For this
reason, always heed the watches and warnings issued by the National
Should a tornado warning be given for your area, head for the
basement or a central room in your house.
Chris Bouchard is a meteorologist at the
Fairbanks Museum and Planetarium in St. Johnsbury, VT.
The Outside Story is assigned and edited by Northern
Woodlands magazine and sponsored by the Wellborn Ecology Fund of
New Hampshire Charitable Foundation. Illustration by Adelaide