A Space Weather Forecaster Tells Us How to Aurora Chase
There are a few important things you should keep in mind.
Weather forecasting, while critical to modern life, has never struck me as a particularly cool job. Sure, sometimes they get to stand in front of an impressive video display or report live as hurricane-level winds bear down, but ultimately the weatherman is not a figure of tremendous cultural esteem. Being a space weather forecaster, though, sounds incredibly badass. Turns out it’s also important to our daily lives, even if we don’t often realize it.
“People are going to hear about the potential impacts of space weather, but you'd never experience them too often,” Shawn Dahl, the Space Weather Prediction Center service coordinator and senior space weather forecaster at the National Oceanic and Atmospheric Administration (NOAA), tells me. “That's because when we get these levels of storm possibilities, we pick up the phone and contact all these industries, including the satellite community, the space launch community, the power grid, and so on because they need to take action to keep their systems working.”
Space weather affects many things. When the sun emits large quantities of energy (through a coronal mass ejection or solar flares, to name a couple phenomena), the winds produced by that emission create a shockwave, which can interact with the Earth’s magnetic field—and that’s what we call a geomagnetic storm, which is, according to NOAA, “a major disturbance of Earth's magnetosphere.” When those storms take place, they can, depending on their intensity, affect the power grid, radio systems, satellite navigation systems, and even spacecraft operations and aviation issues.
That’s why Dahl and his team monitor the sun 24 hours a day, seven days a week. If the systems pick up any space weather activity—or if they notice something visually through their ground-based observatories—they put out a warning and call up the industries affected to have them prepared ahead of time.
But people shouldn’t get too concerned about it. If anything, they should enjoy the benefits and “focus on the spectacular,” as Dahl puts it. That’s because along with bringing disturbances and potential outages, solar activity—and in particular, geomagnetic storms—is also responsible for one of the most glorious natural phenomena humans can witness from their own backyard. Namely, the northern lights.
As a side product of their space weather forecasting efforts, Dahl and his team are able to figure out, thanks to their models, when and where the aurora is going to be visible.
We sat down with Dahl to learn more about his space weather job, as well as insider’s tips and knowledge stargazers should know the next time they plan an outing to see the northern lights.
Editor’s note: This story has been edited for length and clarity.
Thrillist: I’m curious—what got you into this very specific job in the first place?
Shawn Dahl: I have a big interest in the sun and space weather because I really love astronomy. It's a hobby of mine. I developed it when I was in eighth grade when a total solar eclipse went right over my hometown in North Dakota. I also always had an interest in weather just because of the weather changes that happened in North Dakota and it all kind of came together over time.
What about it was (and is) so attractive to you?
It's the challenge—the difficulty of doing space weather forecasting and trying to get industries, sectors, government, and the general public to understand what all this means. They hear so many different words and some of them sound kind of frightening. I like that challenge of forecasting along with the challenge of making people understand what it is they need to know and prepare for any extreme significant space weather event.
Do you get a lot of people asking worried questions when there is some sort of ominous-sounding space weather news?
Yeah, we do. Usually we see these questions in comments on our social media pages. It’s people expressing that they don't exactly understand what's happening because they think it's affecting other things that it's necessarily not.
Such as?
I don't mean this in any derogatory way whatsoever because it's complicated, but some FEMA response staff were recently querying me about whether there was going to be any problem with the appliances because of this geomagnetic storm we were experiencing. I told 'em, “Nope, you're good to go. That's not a concern.”
A wide variety of things can happen with space weather—it can affect communication frequencies, GPS accuracy, satellite communications, the power grid, and aviation issues.
On top of that, though, space weather and geomagnetic storms are also responsible for causing the northern lights. How do you predict a geomagnetic storm and therefore are able to draw up an aurora forecast?
What we actually forecast is geomagnetic storms based on what we see taking place in the sun. Certain events can be associated with something called a coronal mass ejection, for instance, or CME for short. That's a blast of solar material and strong magnetic fields that head out from the sun.
The difficulty of doing this job is forecasting something from 93 million miles away. It's not easy, but that’s how we’ve been able to put this together—analyzing that imagery for the CMEs, trying to model them and map them on when they might arrive on Earth, and if so, how strong they might be when they get here. The thing about this business is we could have quiet conditions for three days and then we see a CME, and now all of a sudden we're forecasting a strong geomagnetic storm just like that. You don't see that in terrestrial weather, right? We have these surprises that happen because we don't know when some of these events are imminent.
As per aurora forecasts, a lot of the information we provide can get translated directly to that, or even some of our models and things we say translate to that.
What’s the timeline and accuracy for space weather forecasting?
Our space weather forecasts that are available to the public go out three days, so it's a three day forecast that goes out twice a day, and it's focused on three primary things: solar flares, solar radiation storms, and geomagnetic storms.
Auroras depend directly on geomagnetic storms. How accurate are aurora forecasts, then?
It's pretty good overall for those models that do it. We can look for how strong the magnetic field in that CME is, what the orientation of that magnetic field in the CME is, and how fast it is at that point. That all adds up, and that's when we can start to put out geomagnetic storm warnings and increase our forecast confidence tremendously, because now we see the structure of it, but we have to wait until it gets a million miles to Earth before we actually have any idea of what that CME is like.
But once we get to that point, once we see it—the other night, I took my wife and drove out at just after nine o'clock because we reached G3 levels. I looked at the solar wind and saw that it was very favorable. We were well connected, so I thought we might have a chance to glimpse the northern lights along the horizon.
The NOAA aurora model always gives a good idea of where the northern lights might be visible from the US.
Yeah, but that model always shows the aurora much further north than people are capturing. We're going to have to figure out how to adjust that because digital technology has become so good that even if you don't see it at all or just catch a glimpse of what you think is the aurora, use your digital technology and suddenly you have this extraordinary rural picture. So don't take it for granted. You're not going to see it just within the firm line on our model.
That’s a good tip. So where would you say is the aurora actually visible depending on the storm’s intensity?
I think anybody living along the northern tier of the country, if we're hitting a G1 storm, then it's a possibility. With a G2 storm, now those northern tier become the northern states, and it becomes potential. Once you get to a G3 storm, now you're dipping down potentially into the lower Midwest slightly south of those more northern states and becoming closer into those central Midwest states. If you get a G4 storm, now it's potentially seen from northern California, maybe even further south. And with a G5 storm, the aurora can clearly be seen across the United States, even in Hawaii, if things add up right.
If I’m based in the US, what’s the best state travelers should go to for aurora sightings? Where are my odds going to be best, all things considered?
That's kind of a tough call, but obviously Alaska. Additionally, I would say the upper peninsula of Michigan, Northern Wisconsin, Northern Minnesota, and northeastern North Dakota is a really good area to see the aurora when weather patterns are cooperating.
Can you give me other useful pieces of advice for all the aurora chasers and travelers out there? What tools and websites should they keep monitored to boost their viewing odds?
First, obviously, monitor our website—we're the nation's official source for space weather information.
Everything people need to know, as long as they have a better understanding of what these things mean, they can now forecast for themselves on the aurora and know when to run out or feel that they have a good chance of seeing it.
Pay attention and learn more about coronal holes because that feature is very predictable. They’re a good thing to key in on because on our webpage we have a 27-day outlook and you can look at some of these geomagnetic numbers and get an idea. If you're planning a long-range trip and want to go to Iceland and see the aurora, maybe plan it around when a prominent coronal hole is coming back around.
The other thing is to always be outside of city lights, and be aware of other things going on. Is the moon present or not? Where are you compared to a city? Which direction do you need to go?
Finally, the prime-time hours are usually within a couple hours of local time of midnight.
Ready to go stargazing?
Here are all the best stargazing events that you can get out and see this month or you could stay in and stream the northern lights from home. If you're just getting started, check out our guide to astronomy for beginners or easy stargazing road trips from big US cities.