Why does wind cause digital broadcast drop out?

It was windy again this week in the Sacramento area, and once again the digital broadcast just disappeared. Does anyone know why this happens?

I live about 15 miles from the various transmitters in very flat terrain. Every time we get high winds (40-50 mph) the digital signal just drops out on my set top receiver. The antenna is amplified and in the attic, and the analog broadcast comes in just fine with minor "snow".

This happens during nearly every wind event -- there is something much less robust about the digital signal. Anyone know why this happens? Anyone know what the industry is doing to address this?