I live near the crash location. The mountains they were crossing at the time have the highest peaks in the area. That area will frequently see mountain wave and turbulent air during front passage.
The other point is they took off from the valley North of the mountain ridges, flew South over and along the ridges, then tried to cross over again to head North. It appears that they took off, ran into heavy precip and chose to turn South to escape the precip. I wonder if they had any sort of onboard weather. I wonder what their preflight weather briefing - radar especially - consisted of.
The afternoon of the crash saw pockets of extreme precip in this area. It has been my experience that some ATC locations are better than others at assisting with wx alerts and deviation. Years ago Atlanta center warned me about a buildup along my route and advised I seek assistance from tri cities approach as they handed me off to tri cities. Tri cities told me they didn't see anything worse in front of me than where I was. I didn't have onboard wx. I proceeded to fly into an embedded CB black cloud, occasionally lit by lightning, precip so extreme water came into the plane from where I have never seen it before and I couldn't even hear the radio from the noise. I got onboard wx after that flight. At the time of the crash they were likely talking to tri cities depending on their altitude - under 10k tri cities, over 10k Atlanta center.
Some days it is just better to be VFR. This may have been one of those days.