A Black supermoon would be visible tonight, 31 July, that would be completely invisible in the vast night sky.
EarthSky notes that tomorrow's new moon is also a supermoon, this means it will be taking place in conjunction with a lunar perigee - the closet level to Earth in its regular monthly orbit. This new moon is not the second one of the month, so it won't be considered a black moon. A lunar cycle typically takes about 29 days to complete, but our months are slightly longer.
Officially, the Black Moon will occur at 11:13 p.m. EDT, for the Western Hemisphere according to Space.com.
Dependent on which coastline you happen to be on, the Black Moon will occur on both July 31 (for these on the east coastline) or on August 1, indicating it is possibly the next of two new moons or the initial of two. Don't worry though, you'll have a second chance to "spot" the black moon at the end of the month. The remainder of the planet will see the black Moon on August 30.
Some may use black moon to describe the third new moon in a season of four new moons.