The cruelty of this particular April, in the number of tornadoes recorded, is without equal in the United States. The record for the month has been shattered, and preliminary assessments say that of the four biggest clusters ever recorded, two have occurred in the last three weeks.

What is happening here? With every passing day, it seems, more precise digital tools emerge to clarify the inner heart of a storm cell in rampage. And yet, for all that solid information, the natural world can still seem murky, unpredictable and downright scary when it roars into full-throated chaos.

Tornadoes in particular, researchers say, straddle the line between the known and the profoundly unknowable.

“There’s a large crapshoot aspect,” said Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research in Boulder, Colo. “A little quirky thing can set one off at one time, and another time not.”