This article has been updated.
Cape Cod in Massachusetts had at least a passing resemblance to Kansas on Tuesday morning as one or more tornadoes and several violent downbursts ripped through the region.
A popular hotel in the populous Mid-Cape section, the Cape Sands Inn, had its roof torn off, with the building suffering serious damage. Eyewitness video captured the moment the roof was dislodged in the town of Yarmouth:
When the tornado came through, Nicole Walsh was at a movie theater with her daughter not far from where it touched down. “Suddenly the wind just hit. It seemed like it had to be blowing close to 100 mph,” she said.
Additional widespread damage was reported farther east in Harwich, Orleans and Chatham, where an 82 mph wind gust was reported. In Harwich, a state of emergency was declared where 90 percent of homes were without power Tuesday afternoon. More than 50,000 residents across the Cape remained without power Tuesday evening.
Tornadoes are very rare in Cape Cod. Tuesday’s twister was just the fourth on record to strike the area since 1950.
The twister formed in the last of multiple waves of storms that tore across the area between Monday and Tuesday.
An initial round of severe storms prompted tornado warnings on Cape Cod late Monday night, accompanied by damaging winds and a few reports of downed trees. Storms redeveloped over New York City overnight, pressing east around sunrise. The first rotation appeared within storm cells over Long Island Sound about 10 a.m.
At 11:13 a.m., the National Weather Service issued a tornado warning for northern parts of Martha’s Vineyard and the Elizabeth Islands. The main area of rotation threaded the needle between the two land masses, zipping ominously up Vineyard Sound and lingering just offshore of the Mid-Cape. The tornado warning was extended to include most of Cape Cod at 11:38 a.m.
A prominent “rear flank downdraft” developed, marking an area where cool, dense air from above blasted to the ground south of the circulation. A wind gust of 69 mph was recorded at 11:35 a.m. as the downdraft passed over Vineyard Haven.
The mesocyclone — the dangerous, rotating part of the thunderstorm — whirled just offshore until about 11:50 a.m. Around the same time, a powerful rear flank downdraft surge shoved the rotating mesocyclone north toward land. This helped to tighten the storm’s spin, and a tornado dropped over Yarmouth less than five minutes later. This was the twister that badly damaged the Cape Sands Inn. The tornado warning had been in effect for 15 minutes by this point.
An 11:54 a.m. radar scan revealed a TDS, or tornado debris signature, over West Yarmouth. In the atmosphere, the radar could see debris, which is shaped differently than the typical raindrops or hailstones that radar is used to detecting.
Based on this, it looks like the tornado touched down initially along Main Street/Route 28 about a mile west of the Bass River, near the Whydah Pirate Museum. Several people captured video of the circulation as it crossed the Bass River.
It’s unclear how long that initial tornado remained on the ground, but it probably was about five minutes. The debris associated with the first tornado moved northeast. At the same time, extreme winds developed south of the tornado in the rear flank downdraft, bringing gusts of 60 to 90 mph to the surface. A gust of 90 mph was recorded at Kalmus, on the banks of Lewis Bay; it’s uncertain if this was from the tornado itself or from the exceptional winds of the rear flank downdraft.
A second debris signature appeared on radar at 12:01 p.m. just south of West Dennis near the West Dennis Yacht Club and Kelleys Pond. This may have been another touchdown of the first tornado, but based on radar data it appears that the storm “recycled,” and a second circulation farther south took over. That same circulation may have produced a third touchdown near Harwich Port at 12:08 p.m.
Shortly afterward, radar showed rotation intensity decreasing. This may be misleading, however; as storms move away from the radar, the radar beam shoots higher into the clouds since it leaves the radar at an angle. In this case, the circulation was shallow, so the beam may have “overshot” the strongest rotation as the storm progressed farther east toward the Outer Cape.
The thunderstorm responsible for the trail of damage was nestled in wave of low pressure drifting over the region. The storm didn’t take the form of a typical supercell thunderstorm, its “hook echo” more closely resembling the stinger of a giant scorpion.
It’s likely that much of the damage on the Outer Cape may have been due to straight-line winds rather than additional tornadic touchdowns.
Tuesday’s setup didn’t feature a large weather system; instead, a more localized “mesoscale” whirl — between 50 and 100 miles wide — had a structure that mimicked a miniature nor’easter.
Here is some more imagery from the storm.