A dangerous tornado outbreak is expected across parts of the southern and central U.S. today, with intense, long-lived tornadoes possible across Arkansas through the afternoon and evening. All of the counties shaded in red on the map above were under a tornado watch as of 2:00PM CDT.
In addition to the threat for tornadoes, hail up to the size of baseballs and damaging wind gusts of 80 MPH are possible in the strongest storms.
The thunderstorm activity over Arkansas has been battling rain-cooled air and thick cloudcover most of the day, keeping down the amount of instability that's able to take hold across the area. A powerful line of thunderstorms swept through eastern Kansas and Missouri earlier in the afternoon, producing golf ball size hail and potential tornado damage east of Kansas City.
As the sun breaks through the clouds and the atmosphere becomes more unstable, supercell thunderstorms are expected to grow in coverage and intensity over the next couple of hours. There should be several dangerous storms in Arkansas by this evening, all of which will be capable of producing tornadoes.
This map shows the amount of surface-based CAPE across the central United States, and the most instability is located where the sun is breaking through the clouds.
By 6:00PM CDT, the High Resolution Rapid Refresh (HRRR) model shows that storm relative helicity (essentially, the amount of spin in the atmosphere) will greatly increase in the areas where the model is simulating supercell thunderstorms. Values between 300-400 are capable of sustaining strong tornadoes.
It's going to be a dangerous afternoon across much of the central United States, but especially in and around Arkansas. Keep a close eye on the weather and follow updates from the Storm Prediction Center and your local NWS office if you're in the path of the storms.
[Images via SimuAWIPS / NASA / SimuAWIPS / HRRR]