The Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting model, or OVATION, is a model used to depict the intensity of the aurora. NOAA compiles a 30-minute forecast to give an idea of where the aurora is currently active around the globe. One misconception about the OVATION model is that it depicts the chances of seeing aurora activity. The truth is, it is the chance of seeing overhead aurora activity, meaning you are looking up at the aurora rather than to the aurora. This is where the app can help you.
The app color codes the OVATION model in the following way: 1-9% in light gray, 10-19% in dark gray, 20-29% in dark green, 30-39% in bright green, 40-49% in yellow, 50-59% in orange, and anything 60% or greater in red. The app relies on these percentages to give you a more accurate idea of when you can start to see aurora activity, beginning with the arc.
You should begin to be able to see the arc at around a 5-6% chance of overhead activity. Depending on your seeing conditions (clouds, fog, haze, etc.), this value could be higher or slightly lower. The app’s goal is to get you in the ballpark. Once your location transitions into higher percentage chances of overhead activity, the app will update the probability. It is important to note that, while the OVATION model is the chance for overhead activity, the app’s probability is based on seeing ANY aurora activity; the arc is the beginning of this activity. From experience, once your location is on the edge of the dark green portion of the app’s OVATION depiction, you should start to see more elevated aurora activity with overhead aurora activity highly likely once your location is in the yellow band.
Free Versus Subscription
In the free version of the app, you will get the latest OVATION forecast for what is possible right now. You can toggle the northern and southern hemispheres by using the toggle switch in the left-middle of the screen. This setting saves so you do not have to switch it every time you open the app. The subscribed version is a little more in-depth.
With the subscription version of the app, you can toggle the OVATION window to view one hour ago, 30 minutes ago, now, 30 minutes from now, and one hour from now. This gives you the ability to look back on the OVATION forecast and see what is coming in the next hour. It is important to note that, in times of increased solar wind speeds, this timeframe may be less than one hour.