red alert

noun

1. (in military or civilian defense) the most urgent form of alert, signaling that an enemy attack is believed to be imminent.
2. the signal or alarm sounded for this alert. Compare blue alert, white alert, yellow alert.
3. a signal or warning that a critical situation is developing or has occurred.
4. the period during which a state of crisis or danger is declared to exist.

Word History and Origins

Origin of red alert¹

First recorded in 1960–65

Example Sentences

However this second Dana weather system is not expected to be as dramatic as the red alert on 29 October, when the Valencia region in particular suffered an unprecedented loss of lives and material damage.

From BBC

Catalonia in north-eastern Spain, particularly the coast near Tarragona, has also been placed on red alert until Wednesday evening.

From BBC

However this second “Dana” weather system is not expected to be as dramatic as the red alert on 29 October, when the Valencia region in particular suffered an unprecedented loss of lives and material damage.

From BBC

Particularly, at the fact the official red alert sent to mobile phones came at 8pm - far too late.

From BBC

Meanwhile, the Spanish authorities have extended a red alert for torrential rain on the southern coast.

From BBC