“The signal was out there that this is going to be a heavy, significant rainfall event,” says Vagasky. “But pinpointing exactly where that’s going to fall, you can’t do that.”

Flash floods in this part of Texas are nothing new. Eight inches of rainfall in the state “could be on a day that ends in Y,” says Matt Lanza, also a certified digital meteorologist based in Houston. It’s a challenge, he says, to balance forecasts that often show extreme amounts of rainfall with how to adequately prepare the public for these rare but serious storms.

“It’s so hard to warn on this—to get public officials who don’t know meteorology and aren’t looking at this every day to understand just how quickly this stuff can change,” Lanza says. “Really the biggest takeaway is that whenever there’s a risk for heavy rain in Texas, you have to be on guard.”

And meteorologists say that the NWS did send out adequate warnings as it got updated information. By Thursday afternoon, it had issued a flood watch for the area, and a flash flood warning was in effect by 1am Friday. The agency had issued a flash flood emergency alert by 4:30am.

“The Weather Service was on the ball,” Vagasky says. “They were getting the message out.”

But as local outlet KXAN first reported, it appears that the first flood warnings posted from safety officials to the public were sent out ...