It is going to be a day with lots of weather to pay attention to with severe weather with tornadoes possible in the South and heavy rain and flash flooding possible further to the west in Eastern Oklahoma and Western Arkansas. The severe weather threat will ramp up this afternoon and last into the nighttime hours. Let’s take a deeper dive.
A Potent Atmosphere
The atmosphere today will be quite potent with strong low level shear, strongly unstable low levels, and a close link up of the LCL and LFC. All of these are favorable for tornado formation.
- The 0-1 KM SRH values today are above 200 m2/s2 and in some cases over 250 m2/s2. This is more than enough for tornadoes.
- The low-level instability is quite large as well, most models are showing over 100 j/kg by the late afternoon and early evening hours.
- The temperature/dewpoint spreads are tiny, meaning the cloud bases will be very low. Lower cloud bases mean tornadoes are much easier to come by for the atmosphere — especially when the LCL/LFC are linked up tightly with lots of low-level instability. This enhances the lifting/stretching potential which is a key component to tornado formation.
- HP storm modes are pretty likely with the storm relative hodographs pretty centered in the middle of the hodograph.
Crowded Storm Modes Again
The usual fly in the ointment in the South is always crowded storm modes it seems. The more storms crowd up, the more they tend to interact with each other which disrupts the tornado production process. This never entirely precludes tornadoes — but if storms crowd up too fast, too early it can limit the number of tornadoes.
- Storms are initially semi-discrete, meaning they will have some small distances between them. In this early stage, storms will be more favorable for tornado formation.
- Look for tornado potential to maximize in the late afternoon and early evening before the atmosphere stabilizes. Any storm that has clean inflow to its south and southeast will have potential to produce tornadoes.
- If storms crowd up too fast, the atmospheric instability is not terribly impressive due to temperatures not cooling that much aloft. This would limit instability in a big way. Thus, I think the atmosphere will be more sensitive to storm interference today.
Moisture will be plentiful in the South today. We talked about how the warm Gulf of Mexico will tend to favor severe weather setups anytime a storm system moves through and this one is no different. Near 70 dewpoints in February isn’t historically that typical.
The storm system responsible for today’s event will be centered over Western Oklahoma this evening with the main energy ejecting eastwards us usual. You look for lift on the eastern flank of troughs and subsidence (sinking air) on the western side. Given how far back the main system is though, the air aloft isn’t as cool as it would be if the system were closer to the storm area — this will limit instability some.
My favorite model on storm days is the HREF. Instability probabilites show the potential for 1000 j/kg surface cape is somewhat likely this evening.
The HREF isn’t incredibly bullish on generating updraft helicity tracks — which is sometimes a signal that the tornado potential may not be as high as you’d expect given an environment. I find this a lot more reliable on the Plains than the South though.
Excessive rainfall and flash flooding is possible (and ongoing!) across portions of eastern Oklahoma/Texas and especially into Arkansas. The drought conditions that were present in this region a few months ago have all but disappeared.
