Cities like Dallas, Fort Worth, and Shreveport are under the gun for what could be an interesting bout of severe weather this afternoon, with storms potentially producing very large hail, damaging winds, and strong tornadoes. If you live in the area, make sure you have a way to receive warnings and a plan if you need to take life-saving action.
The Storm Prediction Center has issued an enhanced risk for severe weather (three on a scale from zero to five) across two regions this afternoon—the most significant threat exists across parts of Texas and Louisiana, where very large hail (baseball-size or larger) and tornadoes are possible today. A similar threat exists over the enhanced risk in central Kansas.
Down near Dallas and Shreveport, there’s enough wind shear available to storms that some of the tornadoes could be strong and long-lived. A tornado watch is in effect for much of central and northern Texas through 10:00 PM CDT for counties shaded in red; the Storm Prediction Center says that a few tornadoes are “likely,” within the watch area, and some of the tornadoes could be intense. In addition to the tornado threat, areas in the watch area are at risk of seeing damaging winds in excess of 75 MPH and hail larger than baseballs.
A 10% risk for significant tornadoes is in place across northeastern Texas, northern Louisiana, and southern Arkansas, with Dallas, Fort Worth, and Shreveport in the area of greatest risk. The black hatching indicates the possibility of “significant” tornadoes, which could cause damage rated EF-2 or higher on the Enhanced Fujita Scale.
The risk for tornadoes today (and tomorrow!) has caused some consternation on social media, with people getting increasingly anxious over the threat for tornadoes. We’re approaching that time of the year where every date has a tragic tornado event associated with it—late April is a pretty ugly period in tornado history. Every tornado is dangerous if it hits you, but it’s important to keep some perspective between normal springtime weather and a notable outbreak that makes even seasoned weather geeks anxious.
Here is the climatological risk for significant tornadoes on April 24 between 1982 and 2011. A 0.35% probability means that, historically, there’s a 0.35% chance of a significant (EF-2 or stronger) tornado occurring within 25 miles of any point in the shaded area on April 24 based on the number of strong tornadoes that touched down in the area over that 30-year period. Greater probabilities indicate that, based on the weather over the past 30 years, tornadoes are most common on April 24 in these areas.
In other words, tornadoes are possible today exactly where they commonly occur on April 24. By no means will it be a noteworthy outbreak that results in dozens of scars across the earth, but a single tornado hitting the wrong place at the wrong time can create great losses in life and property. Today is one of those days where residents should keep a close eye on forecasts, radar, and warnings, but also take a deep breath and remember to keep things in perspective.
That being said, let’s talk about the TOR:CON.
The elephant in the room over the past couple of days has been a renewed interest in The Weather Channel’s TOR:CON (tornado condition) index, created and mostly maintained by the great Dr. Greg Forbes. The TOR:CON is a proprietary metric they developed a while back that uses forecast data and subjective analysis to assess the risk for at least one tornado within 50 miles of a given point. For example, if the TOR:CON for northern Arkansas is a 5, it means there’s a 50% chance of seeing one tornado within 50 miles of northern Arkansas.
It’s useful, vague, and somewhat confusing to casual viewers—three qualities everyone loves in meteorology.
Now, I’ve mentioned before that I don’t outright object to the TOR:CON—unlike some of the network’s other experiments (rhymes with “winter storm names”), this one is well-intentioned and has some practical use in communicating the threat for tornadoes in a given area on a given day. However, there’s been an uptick in chatter among meteorologists over the past couple of weeks about the TOR:CON confusing people.
James Spann had a pretty righteous rant on Periscope last night where he talked about this index confusing his viewers because nobody seems to be on the same page. One guy says there’s a low risk for tornadoes, another station uses the Storm Prediction Center’s “enhanced risk” language, another says there’s no risk for tornadoes, and The Weather Channel says that the TOR:CON is a 6 out of 10. Conflicting terminology is a pretty big problem these days—your forecasts can differ all they want, but at least use the same terms in doing so. As we saw last month, even news stations in disaster-prone Oklahoma City can’t use a standard set of terms and scales to communicate the risk of dangerous weather to their viewers.
My advice to you would be to use the TOR:CON at your own risk. The index directly conflicts with the Storm Prediction Center’s probabilities of severe weather, which runs on a completely different scale that’s based on a different definition. On top of that, many local television meteorologists each do their own thing, so you could have six or seven competing sources all giving you different information. It’s great for the ratings game—confusion breeds forced loyalty—but potentially deadly when it comes to severe weather safety.
When in doubt, stick with the Storm Prediction Center. They’re not always right (nobody ever is), but they’re experts in severe thunderstorms and tornadoes. They’ve usually got a pretty good handle on what’s going on.
If you’re in an area expecting severe weather today (or any day, really), make sure you have a way to receive severe thunderstorm and tornado warnings from the National Weather Service when they’re issued. Invest in a weather radio. Don’t park under an overpass during a hailstorm or when a tornado threatens, and remember that the only time you should evacuate a building ahead of a tornado is if it’s a barn, an outhouse, or a mobile/prefab home. If you’re under a warning, take shelter in the lowest part of the building and put as many walls between you and the outdoors as possible.