src/Base/Logger/StdioLogger.php
public function alert($message, array $context = array(), $traceShift = 0)
    {
        $this->log(LogLevel::ALERT, $message, $context, $traceShift);
    }
public function alert($message, array $context = array(), $traceShift = 0)
    {
        $this->log(LogLevel::ALERT, $message, $context, $traceShift);
    }
Action must be taken immediately.

Example: Entire website down, database unavailable, etc. This should
trigger the SMS alerts and wake you up.

@param string|mixed $message
@param array        $context
@param int          $traceShift

@return void