Sometimes a complete warning will include a second message.

WEA sent 11/26/2022

While researchers and practitioners recommend including an expiration time in the warning message, when an incident will be over or the time by which a threat will be managed cannot always be known. Expiration times are primarily included in weather related WEAs and are updated with new information when conditions change. In the case of an active event requiring a public safety response, including a statement that a follow-up message will be issued later is a strategy is frequently used. This is only effective IF a follow up message is actually provided, telling the message receiver that the conditions are safe for return. In the case of this message sent by the City of Brookfield PD, the alert originator tells the message receiver when the next message will be sent and they they follow through on that plan. Message completeness is frequently described in terms of the contents included in a single warning, a complete message will also close the loop for the community that has been warned.