Mastodon bots which mirror the NWS warnings back them up
What failed was local officials not succeeding in alerting people — in large part because they had plan or mechanism available to do so with the roughly one-hour warning that current meteorology can provide for specific flash floods like this.
Archived copies of the article:
The first part is the reason for the second part: the alert system isn’t targeted enough so people disable it due to the majority of the alerts being disruptive but not applicable.