There is and the national weather service alerts that night for the area should have triggered such alerts twice, according to another article I read.

It was around midnight on Friday, July 4, when the first few thunderstorms began dumping heavy rainfall in central Texas. About an hour later, the first Flash Flood Warning was issued by the National Weather Service at around 1:14 a.m. This warning also included the “considerable” tag, which should have triggered wireless emergency alerts to go out to cell phones and NOAA Weather Radios.

Then at 3:35 a.m., the original warning was upgraded and included the verbiage, “Move to higher ground now. Act quickly to protect your life.” Less than 30 minutes later, the warning was upgraded again to a Flash Flood Emergency and would have triggered the wireless emergency alerts once again.

The problem seems to have been that the region where the floods were most dangerous has very spotty cell service. That combined with the fact that some people apparently turn their phones off at night prevented those alerts from reaching a lot of people. Also, the kids at Camp Mystic were not allowed to have phones with them during their stay.