May 24, 2023 - Cheyenne, WY Landspout Information

By now, you have probably heard about or seen photos of the landspout that occurred in Cheyenne yesterday. We’ve received numerous questions since about this, along a few common threads. Many people have been wondering, what is a landspout? Why haven’t I heard of this before? Why was there no tornado warning? Why did sirens go off at FE Warren but not in town? We hope this post will help answer these questions and help us all be prepared next time.

First, what a landspout is and how they are different from the more typical tornado most of us are more familiar with? “Landspout” is a term used to refer to a type of non-supercell tornado. The main difference is that the rotation associated with a landspout originates at the ground and rises up to the cloud (base of the updraft), whereas a supercell tornado originates in a rotating updraft of a strong thunderstorm, and moves down to the ground. Landspouts are typically, but not always, very weak and short-lived. Additionally, since there is no rotation at cloud level initially, landspouts are often not detected on doppler radar. While we can predict when conditions are favorable for landspout development, it is nearly impossible to predict precisely where and when they might form, or even to detect them until after they have begun in the current state of our science and technology. Often, the NWS doesn’t hear about these events until after they have already dissipated. Even in a favorable landspout environment like we saw yesterday, most storms will not produce a landspout. 

With that being said, we do want to emphasize that if you see a landspout occurring and feel threatened by it, you should absolutely seek shelter even if a warning has not been issued yet. You may be the first person to see it! If you are observing a landspout from a position of safety, we encourage you to immediately report it to the NWS. We love pictures/videos with exact time stamps and locations!

So why is this the first I might be hearing about landspouts? Well, landspouts really are not that rare across our area. Most of the time though, they occur in rural areas and since they are short-lived and often not damaging, they go unreported. The unusual part now is that we observed two landspouts in two of Wyoming’s largest cities within a week of each other! The other was the May 18 landspout in Laramie. Every Spring the NWS Cheyenne office highlights this exact possibility of landspouts/non-supercell tornadoes and the difference between them and supercell tornadoes in our Skywarn Spotter Talk Training. The image below is taken directly from our training presentation.

Then why was there no tornado warning? The NWS issues a tornado warning if we believe that there is an imminent threat to life and property due to a damaging tornado. While we indicated the potential for landspout formation with a Special Weather Statement in advance of its development, NWS meteorologists are only human. As much as we’d like to, we can’t have eyes everywhere all the time. This landspout only lasted about 2 to 3 minutes, and anyone not outside and looking in that direction at the time would have missed it. Additionally, it originated at the ground so its most dangerous phase was its very initial development when it was completely invisible to doppler radar. By the time we observed the landspout, it was already dissipating. Therefore, we concluded that there was no longer a threat to life and property and decided that a tornado warning would only scare people unnecessarily. Last week in Laramie, we determined there was still a probable threat from the landspout when we were informed of it. That event had a strong enough rotation to pull in a condensation funnel and induce a cloud circulation, and also lasted a little longer compared to the Cheyenne event yesterday. These factors prompted a tornado warning to be issued in the Laramie case, but not the Cheyenne case. This landspout may have posed a brief danger similar to a strong dust devil, but had a warning been issued, the threat would have been long over by the time it was received. 

Why did FE Warren sound their sirens but not those in town? The NWS has a different criteria for issuing a tornado warning than FE Warren does. While we will only issue one if we believe there is an imminent threat to life and property, the base has a different criteria and may also sound the sirens for longer. We understand this can be confusing though, so we encourage civilians to follow NWS warnings and the public sirens in the city when deciding whether or not to take shelter.

How to Report to the NWS:
Social Media (tag us or message us!)
- Twitter: @NWSCheyenne
- Facebook: @US National Weather Service Cheyenne WY
Phone: 1-800-269-6220 or 307-772-2468

Want to learn more about information like landspouts, tornadoes, and severe thunderstorms? Attend one of our spotter talks we host between March and May!

How to Receive Additional Notifications:
- weather.gov/cys

- FEMA app: link here

- Red Cross app: link here

- Your favorite weather app (you may need to turn on notifications!)

Source: Ashley Johnson	Source: Amanda Vroman	Source: Unknown