A significant threat of tornadoes exists today across the south, with several tornadoes expected from a band including Eastern Louisiana into Western Alabama. Storm mode is the thing to watch, but instability is much higher than yesterday with comparable wind shear, so this is an obvious environment capable of strong tornadoes. Let’s dig in.
Tornado threat is obvious: The environment is highly supportive of tornadoes today, with 0-1km SRH values of 200-350 common through the day. Additionally 0-3km CAPE values are on the high end of supportive, with values over 150 across much of the region into the afternoon expected.
- Both of those indices are considered extremely supportive of tornadoes. In the case of 0-1km SRH, we look for values of over 100 for tornadoes and for 0-3km CAPE, anything over 100 I am very intrigued by. Obviously we’re well above both today.
- Soundings show lots of curvature in the low-levels, indicating lots of spin in the lowest levels of the atmosphere.
The limiting factors: As with any big, primed atmosphere — the main question today will be storm mode. Lots of shear typically also means lots of forcing — which means lots of storms. This is the most obvious and apparent problem with today’s environment.
- There is little to no capping, so the degree of forcing is likely to result in numerous storms.
- Lots of storms means lots of interactions — crowded storm modes tend to mean storms can interfere with one another which can interfere in the tornado process for all but the strongest cells.
- Getting a strongest cell is a problem in these situations, because the continual interference between cells means they’re dealing with a less unstable and more chaotically sheared environment than you’d otherwise expect.
- Still, with today’s environment being so favorable, this seems likely only to put a top-end on the overall number of tornadoes today but not limit them entirely.
The tornado threat should be the dominant threat today: Hail won’t be a huge factor today given lower overall instability and very curved low-level hodographs. Damaging winds along the advancing line on the front will be a concern, but tornadoes will even be the dominant concern there.
- The threat should wane into the nighttime hours, as the wave in the jet stream departs and the shear weakens.
- Even if storm modes are very crowded to linear, there will still be a tornado threat within the line/line segments.
As always, be sure to share this post and/or any official forecasts to raise awareness if you live in these areas or if you have friends who live in these areas. Advance warning is a life-saver, and we can all do our part in spreading awareness with accurate information when significant weather threatens.