Gustnado vs. Tornado

Today, we got quite a few reports of “possible tornadoes” including one spotted by several law enforcement officials in Whiteside Co. The National Weather Service Forecast Office in Davenport will be looking at any damage there on Friday, in order to determine what kind of damage was done there.

In the meantime, we received quite a few unconfirmed reports of tornadoes in Ogle County. After examination of storm photos, this was not a tornado…but a gustnado. What’s that you say? Let’s go in-depth.

TORNADO¬†First let’s look at this example of a tornado. The storm is moving from left to right so picture yourself looking north into the storm.
More often than not, a severe storm with a tornado will produce heavy rain and hail with strong, gusty wind coming down from high within the storm. Then, once the rain and hail comes to an end, a tornado will exist at the bottom of the storm’s updraft. Finally, as the storm moves from left to right the rear-flank downdraft (often called the RFD) comes in to produce additional wind damage.

So that’s a tornado…most likely NOT what we had tonight.

Instead, let’s look at the diagram of a gustnado. Again, the storm is moving from left to right. Instead of the rain and hail coming first, a swirling vortex is seen BEFORE the storm. GUSTNADOIn all of the photos I’ve observed today, this vortex was not attached to the storm iteself. Instead, the wind moving out on the front side of the storm began swirling and created a gustnado (in short, a tornado on the gust front).

After seeing photos of the gustnado and hearing reports, it’s likely this was a strong one tonight! Trees and power lines were taken down in its path…and if a survey team assesses the damage, it’s likely to be classified as a gustnado with a rating on the Enhanced-Fujita Scale (the scale used to rate tornadoes).


Posted under severe weather, weather geek

This post was written by qni_it on May 30, 2013

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