Question

What is a black blizzard?

Answer 1

During the drought in 1930s , the unanchored soil turned into dust, which was blew by prevailing winds away in huge clouds that sometimes/often blackened the sky.
These billows of dust were named black blizzards or black rollers.

Explanation:

They traveled across country, reaching as far as the East Coast and striking cities (New York City and Washington, D.C). On the Plains, they often reduced visibility to 1 metre (3.3 ft) or les

Here you can see a black blizzard from 1934 - South Dakota