As the resident sydlexian geographer i will point out that as you probably know that hail, thunderstorms and tornadoes are products of mesoconvective systems or a single mesoconvective complex, see diagram.
Black, brown even green clouds are common with the phenomena so it is not surprising that the skies were that color.
I will also point out that thunderstorms are not systems such as a depression or anticyclone, they can develop within the systems and can span from local to regional scale. This is why you suddenly hit pitch black. You were merely entering the area.
"That article is primarily about the Springfield area which was hit by tornados, but the storm they are discussing came right through where I live (about 50 miles south)."
If they were struck my tornadoes you can see on the diagram that you were facing the tail end of the system. Which explains the strong wind and small pellets of hail.
Also note the 15km wide which was cut off on the top. They are known for dense cloud cover and if that suddenly passed over you any sunlight would be drowned out.
Also for interest sake:
