Determining the difference between a microburst and tornado damage
(WHSV) - When severe weather strikes, damaging winds are a common threat. There are various types of winds that do different things in thunderstorms. For example, how can you tell if an area was hit by or tornado versus just damaging, straight-line winds?
Straight-line winds are well, straight, and damage is more outward. They are caused from a violent downdraft in a thunderstorm. Tornado winds spin, so impact on the ground is different. Usually, tornadoes are not confirmed until the next day or two after the event. That’s when the National Weather Service comes out and surveys damage.
If damage is all pointed in the same direction, that is when you know the event was a straight-line wind event. The wind hits objects at one angle and blows them over.
Here’s what was determined from the July 6, 2022 storm that hit from Churchville to Staunton:
Steve Zubrick with the National Weather Service says it’s a myth that changing wind directions must be from a tornado. “You can get changing wind direction in micro burst and as the micro burst starts hitting, you’ll notice an increase in wind speed, the tree top start bending, perhaps branches are breaking off, leaves are being stripped off. And this can last for thirty seconds up to a minute.
The National Weather Service is still looking into how strong the winds were in the storm. But they have determined this was a straight-line wind event and there is no evidence of a tornado.
Notice all the trees are knocked down in the same direction. This characterizes “straight” line. Straight line winds can be just as powerful as a tornado. Severe thunderstorm winds can typically be as strong as 60mph which is enough to take down trees. However in extremely strong severe storms, straight-line winds can be as strong as 60-110mph. Yes, straight-line winds can be that strong. It’s more unusual but it does happen.
Tornado damage is more scattered about. If you have trees falling in all different directions, that’s when you know a tornado came through. Tornadoes have wind flow into it versus out like damaging winds. Tornadoes will pick up things and throw them around while straight line winds go direct.
Notice how trees have fallen in all different directions. That indicates the winds were spinning. Debris would be more scattered over a larger area, pieces of things would be lofted and carried away.
WHAT IS A DOWNBURST?
Downburst - This is a general term to describe macrobursts and microbursts. Basically localized strong wind from downdrafts. Downbursts are very powerful winds that race down and out from a thunderstorm. These downbursts spread out once they hit the ground. Powerful downbursts can have winds as strong as 60-110 mph. The damage can look similar to that of tornado, and are sometimes misinterpreted as tornadoes.
In this video below from Chris Jackson, you can see the powerful downdraft of the rain and it spreads outward in all directions. This can lead to changing wind directions which is usually mistaken for tornadoes. You can have changing wind directions with a downburst. Storms can also have multiple downbursts, not just one.
Microburst - These also come from downdrafts but are more confined in space. Microbursts are powerful downdrafts that race down to the ground in less than 2.5 miles in diameter. These kinds of winds cause all sorts of trouble for aviation especially when taking off or landing as these bursts of wind cause rapid increases and decreases in airspeed performance. These can be extremely hazardous and lead to a lot of damage.
STRAIGHT-LINE VS. TORNADO DAMAGE
Straight -line wind damage is on the left. It’s more concentrated in a smaller area here. It’s really only tree damage. This is from Staunton, July 6, 2022.
The photo on the right is from a tornado in Timberville on October 31, 2019. There’s more damage that’s spread out. The barn roof has two large pieces thrown into the field. The wood is all strewn out on the ground and in opposite directions. The debris field is more spread out. Debris is carried with a tornado.
With a downburst or a microburst the damage is going to be pushed outward.
Copyright 2022 WHSV. All rights reserved.