This is National Severe Weather Preparedness Week in the U.S., so I wanted to post something a little different than what you may find in the typical tornado safety articles. As a storm chaser, I’m well versed in the interpretation and use of radar, but that’s not always the case with the general public. I think there are a few key lessons that everyone should learn, and everyone should purchase a quality radar app for their mobile phone.
As you can see from the chart below courtesy of NOAA, the majority of tornadoes occur between the hours of 4:00 and 7:00 PM local time. These are peak traffic hours in most cities, as most people are leaving work to head home, going out to dinner, or running errands during these hours.
So what should you do if you’re caught in front of a tornadic supercell on your way home from work? How will you know where to go to get out of the way, or if you should stop at the nearest building to seek shelter?
Surviving the storm starts by planning ahead. If you know there is a good chance for tornadoes in the morning before you even head into work, you can be better prepared for the time after work. You can watch the local news, but a great source to check on a daily basis is the SPC Outlook page. Here you can see when severe storms are expected in your area, many times several days in advance. You can also follow current mesoscale discussions, which are generally issued prior to any watches, as well as the watches themselves. Bookmark this page!
By knowing ahead of time that storms are expected, you may be able to avoid unnecessary travel during the time that storms are impacting your area. Perhaps your boss will let you leave work a little early, or stay late so that you can seek shelter in the office, if need be. You may also want to cancel any dinner plans, as a restaurant usually doesn’t have many good places to seek shelter.
Get A Mobile Radar App
Now to the meat of this article, the mobile radar apps. I’m not talking about the free apps that give you a simple outlook, or a low-resolution radar. I’m talking about apps that provide high-resolution radar with the ability to zoom in and show your position relative to the storms using your phone’s GPS. RadarScope is one of the best ones out there, and is available for the iPhone, iPad and Android phones. Pykl3 is another solid option. These apps are only $10, and you’ll only have to purchase them once. When you get a new phone, you’ll be able to download the app to that phone for free. That’s $10 that could save your life one day!
Learn How To Read Radar Images
Of course a radar app will do you no good if you don’t know what you’re looking at. Below is an image from RadarScope taken of the Moore, OK tornado on 5/20/13. So you see a lot of red, orange, and yellow, where is the tornado? This was a classic supercell with a hook echo. See the backwards J on the southwest end of the storm? The tornado is the little ball on the end of the J hook. They will not always be so well defined, but if there’s a tornado on a supercell, it will be on the southwest end, provided the cell is heading in a generally easterly direction. If it’s going a different direction, you can simply rotate the entire storm; i.e. if it’s heading north, the tornado would be on the southeastern tip.
Knowing the direction the storm is moving is also critical. These apps allow you to loop the radar so that you can see the direction. They also have storm tracks, although these are not always accurate. Sometimes this hook echo may not be very well defined, either. The tornado may be wrapped in rain, and difficult to pick out while looking at the reflectivity. This is when the velocity product comes in handy. This product shows the direction of the winds by red and green pixels. When red and green meet in a localized area, it’s a good indication of rotation, and a possible tornado. An example from Moore is shown below from Pykl3.
If you look at the color bar for the velocity, you’ll notice that on the ends the colors get brighter, then change to blue and green. These colors represent higher wind speeds, and a greater likelihood of a tornado. For more information on reading radar images, Pykl3 has provided a nice little tutorial on their website.
How To Choose An Escape Route
So lets say you’re driving home from work in Moore, OK, and you pull out your radar app and see the top image. The tornado is heading ENE, putting you right in the path. Where can you go to escape? Sure, you can drive east, but you’ll still be in the path, just further away. Your best escape route is perpendicular to the storm track, away from the tornado. So in this case, you can either go north, or south. With all other factors being equal, south is your best escape route. If you go north, you’ll drive right into the core of the storm where heavy rain and large hail could slow you down significantly, and may damage your vehicle, and even force you to stop. In addition, visibilty will be reduced to near zero. So in this example, you should head south out of Moore, and out of the path of the storm. Of course you would need to take other variables into consideration, such as potential traffic to the south. Perhaps a known rush-hour traffic jam is typical on that south escape route, forcing you to head north instead.
If you are much closer to the tornado, you may have to make some other choices, and perhaps should leave your vehicle for a sturdy building. If the tornado is moving slow enough, and the road network allows a quick escape, you can drive east to get further away from the tornado, then make your move to the south. If you are starting just to the north of the tornado, your best option in that case might actually be to the north. If you went south, you’d be crossing the eventual path, and may not be able to get out of the way in time.
What To Do If You’re Already Too Close
If the tornado is in sight, it may be difficult to tell whether you should bail south, north, or just stay put. Use a building or tree as a ground reference, and watch the tornado in relation to that object. If it is moving left to right, you should go left to escape. If it is moving right to left, you should go right to escape. If it doesn’t appear to be moving at all, that means it’s coming right at you. If that’s the case, you must immediately bail south! If you just aren’t sure, and there’s a sturdy building nearby to seek shelter in (preferably underground), then that would be your best option. Lying face down with your hands over your head in a ditch is an absolute last resort option, and not a very good one at that.
NEVER SEEK SHELTER UNDER AN OVERPASS!
NEVER SEEK SHELTER UNDER AN OVERPASS!
NEVER SEEK SHELTER UNDER AN OVERPASS!
Oh yeah, one more thing I forgot to mention, NEVER SEEK SHELTER UNDER AN OVERPASS! I’m not sure how this ever got started, but perhaps is was a result of this video from a Kansas tornado in 1991: http://youtu.be/lHBZylcxIvw. In that case, the people made it out safely, however, the tornado was weak. Others on May 3, 1999 in Newcastle & Moore, OK weren’t so lucky, when 3 deaths occurred near or under highway overpasses. An excellent presentation detailing these events and the reasons an overpass is not a safe place to seek shelter can be found here: http://www.srh.noaa.gov/oun/?n=safety-overpass.
I hope this post helps, and if anyone has any questions or comments, please leave them below and I’d be happy to answer! You may find that you use these radar apps in other situations as well, as I often use them even when I’m not storm chasing to find out when I’m going to be out of the rain on long drives, where expected snow showers are, or if my picnic is going to get rained out. I think it is $10 that is well spent!