Outdoor warning sirens have sounded several times in recent weeks without the threat of a tornado warning, prompting many people to wonder why.
The sirens can sound during numerous severe weather conditions, not just for possible tornadoes, but Plano’s Department of Emergency Management said Wednesday's activation was "accidental, a result of human error."
The severe thunderstorm in the area around 11 p.m. did not meet the criteria for sirens to be sounded, the DEM tweeted. Staff is reviewing procedures.
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Several residents responded to the DEM’s tweet, saying they sought safety in bathtubs.
The outdoor warning system is designed to alert people outdoors to seek shelter and information inside. The city’s website lists two major reasons why sirens are sounded:
- The National Weather Service issues a tornado warning that includes Plano in the path.
- A severe thunderstorm warning is issued and winds are predicted to be greater than 73 miles per hour.
Hail under a severe thunderstorm warning can also trigger sirens. Verified reports of half-dollar sized hail (1¼ inches in diameter) or forecasted to be the size of a ping-pong ball (1½ inches) or golf-ball (1¾ inches) or larger.
Plano officials said the criteria is similar to other North Texas cities and follows National Weather Service guidelines.