The Denver Post

So what’s the difference between a tornado and a landspout tornado?

- By Andy Stein

The highly-viewed landspout tornado that formed near Frederick and dissipated near Plattevill­e on Monday evening was caused by rotating air at the surface, not from a rotating thundersto­rm, which officially means that this was a landspout tornado. But what does that even mean?

What many people thought was a full-fledged tornado was in fact a landspout tornado. The threats posed by landspout tornadoes are mostly the same as a regular tornado — one being strong damaging winds. The difference between the two comes in how they form, not how they look or how much damage they can produce.

The typical tornado that you think of when someone says “tornado” is a huge spiraling column of air that is usually connecting the Earth to an ominous cloud. Landspout tornadoes and tornadoes both fit this descriptio­n, but tornadoes form from rotating supercell thundersto­rms while landspout tornadoes form from a ground circulatio­n getting sucked up into a storm.

Supercell thundersto­rms get so tall they reach into different levels of the atmosphere where the winds can have varying speeds. Most of the time, the winds are flowing in the same general direction, but every once in a while, the winds can change direction as they get higher. When thundersto­rms are forming and clouds are building during severe weather, the winds throughout the atmosphere begin to rotate the clouds and thus you have a rotating thundersto­rm. Eventually, that rotation will get so intense that the entire column of air will start to move toward the ground. Once that column of air connects with the ground, it is officially a tornado.

With a landspout tornado, you don’t have a rotating thundersto­rm. Instead, you have air at the surface that is spinning (these spinning winds can be caused by random eddies or colliding boundaries) and that spinning air gets sucked up into a developing thundersto­rm. Landspout tornadoes are short-lived and generally weak, but they can still hold winds of up to 100 mph. Landspouts are the land equivalent of a waterspout, which typically is just a condensati­on funnel.

This dramatic show of the beautiful landspout tornado was captured by many along the I-25 corridor. There was low precipitat­ion around the landspout tornado near Plattevill­e on Monday and due to the ruralness of the location and lack of trees, this could be seen from dozens of miles away. Cory Reppenhage­n, a meteorolog­ist at 9NEWS, said that this landspout was more than 10,000 feet high, which meant everyone within a 70-mile radius could see it.

As mentioned, landspout tornadoes can cause damage and the one on Monday damaged nearby buildings and power poles.

Colorado is no stranger to landspouts. Nor is Weld County, where this spout occurred. Weld County is the county that produces the most tornadoes in the U.S. Thanks to the conditions surroundin­g most landspouts, storm chasers love to capture this intense display of weather because most of the time, they are very, very photogenic.

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