In an exceptionally rare close-up video, an apparent tornado was captured within a snow squall in Scotland on Tuesday.
Michael Peterson, a Scottish farmer, witnessed the bizarre phenomenon while tending to his sheep this week. The video was taken in Sandness, on the western tip of the Shetland Islands, which are located in the North Sea between the United Kingdom, Iceland and Norway.
Moderate snow was falling at the time amid an Arctic blast that’s forced school closures and prompted the issuance of alerts from the U.K. Met Office. A yellow warning for snow and ice remains in effect for the Shetland Islands and the remainder of mainland Scotland until Friday morning.
“Some roads and railways likely to be affected with longer journey times by road, bus and train services,” they wrote. “Some injuries from slips and falls on icy surfaces [are possible, and] probably some icy patches on some untreated roads, pavements and cycle paths.”
Is it a legitimate tornado?
While video alone isn’t usually enough to fully explain the dynamics behind a vortex, in this case we can make a couple observations.
- The tornado appears to be spinning counterclockwise, the sun is emerging behind the tornado and snowflakes in the foreground are moving left to right. That indicates the parent storm cloud was likely rotating counterclockwise and that, from the vantage point of the camera, we’re likely looking west-northwest. Tornadoes usually rotate counterclockwise in the northern hemisphere and occur on the backside of thunderstorms (or, on occasion, snow squalls).
- There is a visible funnel above the whirling confetti of snow at the base of the vortex. That indicates the twister was likely a bona fide tornado and may have exhibited connection to the cloud base above.
Therefore, while we can’t conclude definitively, we can assert it probably was a tornado rather than a run-of-the-mill snow whirl. It’s unclear if any damage was reported, but a rough eyeball estimate from the video would put winds in the sub-90 mph range.
The meteorological setup
A weather satellite shows low pressure near the Shetland Islands on Monday. (NOAA/NASA)
A strong updraft has to be present to vertically stretch a vortex and form a tornado. Robust updrafts are tough to come by in the wintertime, since rarely is sufficient relative warmth and moisture available for a cloud to grow vertically.
However, on Monday, a small low pressure system worked east through the North Sea, tugging frigid air from the Arctic southeast in its wake. This bone-chilling air passed over lukewarm waters. Air heated by the milder waters below rose into the cold air mass above, forming pockets of snow showers. That could explain how enough upward motion was present to cook up a tornado.
It’s impossible to know if this was a mesocyclonic tornado or a landspout, however. The former describes a twister born from cloud-based rotation. A landspout snakes its way from the ground up. If a preexisting whirlwind was near the ground, a convective cloud (or an updraft-fed cloud) above it could stretch it into a tornado.
There is no way to know which mechanism, if either, may have been responsible here.
Is there a precedent for this?
As crazy as it may sound, there have been instances of snow tornadoes:
On Jan. 24, 2022, a waterspout beneath a snow squall moved ashore on Andros Island, Greece. A potent winter storm had been battering the Mediterranean Coast.On Feb. 17, 2019, a tornado touched down from a snow shower in Tinian, New Mexico. The twister was documented by local photographer Antonio Chiquito.A small snow shower produced a confirmed EF1 tornado in southern Ontario on Nov. 23, 2013. No thunder or lightning was detected. Local radar confirmed the cloud was made out of snowflakes and ice pellets. The tornado damaged a farm with winds estimated around 90 mph.There are also rumors that a tornado may have snaked its way down from a snow squall near Whitefish Bay, Wis., in 1987, but there doesn’t seem to be any literature available to support that.
The overall pattern
Beyond the snow tornado, much of northwest Europe and the United Kingdom recently have been battling below-average temperatures.
A negative Arctic Oscillation, or a southward deviation of the jet stream, which is allowing bitter Arctic air to spill south in periodic insurgences, is to blame. That can be traced back to a disruption of the polar vortex in mid-February.
On Wednesday, satellite images showed the northern half of Scotland blanketed by a fresh dusting of snow:
While nowhere near a record, Kinbrace in Sutherland, Scotland, fell to 4.3 degrees on Wednesday morning. That was the lowest temperature recorded all winter anywhere in the United Kingdom. That’s also the lowest March temperature observed in the U.K. since 2010.
Meanwhile, Londoners awoke Wednesday to snow for the first time since December 11. A few additional snowflakes are possible early Friday.
Source: washingtonpost.com
