Does anyone know why KFOR-DTV always downgrades its signal from HD to standard def every single time they decide to put a weather map up?

It seems like every time there's something on that channel I want to watch, such as Heroes, if they decide to do a school closing crawler or put up a weather map their signal turns to utter crap.

Is it a technological limitation of that station or are their programmers just asleep at the wheel?