Could someone please explain the ongoing Heath Dome (i.e. Texas) while there is low atmospheric pressure?

My (poor) knowledge of meteo is based on the association btwn low pressure and clouds/rain/storm vs High Pressure and heath/no wind/sunshine

Having heard about todays record temperature in Dallas, I checked the map so to discover a low wide pressure area

https://preview.redd.it/x79jvmfkcpkb1.png?width=1057&format=png&auto=webp&s=241f9b7927b7e58fd621da6c9d6166c45e81bded

Because we had something similar in Southern Europe, I kindly ask for some hint to better understand why the heat dome is associated with low pressure