It's hard to give a definitive answer to this, as so much depends on the existing context. If there already is a dashboard design that you can share with us, it'd help a lot to see that first. However, here's a few pointers to help you think along the right lines:
- Determine the priority that these warnings need to have. To me they sound like urgent notifications that need immediate attention.
- For maximum salience, you want the information to stand out above everything else. In other words, they need to be at the top of the visual hierarchy.
- Using color perception to indicate urgency depends in part on how that user's mental model is trained. Try to use something universal and unambiguous. You've already observed correctly that there can't be any conflict between existing use of the same colors within the interface. Consider also any visual cues the user will see on the device, outside of your application.
- If the device affords it, consider pairing the visual notification with an audio signal and/or vibration pattern.
- Consider animating the notification to help make the notification more salient.
- Consider adding a well-trained icon to give the notification extra urgency.
Like I said, without having seen the rest of the interface, I have to speculate a bit on the use case. It's hard to provide you with a nuanced answer, but in this case I would avoid depending on color perception alone to grab attention. Assuming these indicents will be low occurring, you might consider combining the following elements in your design:
- Use black and white for maximum contrast, supported by an icon.
- Place the alert in a part of the screen where no other notifications pop up. For instance, if the application shows other notifications in the top right corner, don't put the alerts in the same spot.
- Animate the alert.
- Use red in supporting design elements. Works especially well if used on an icon that is richly grounded in the user's mental model (think universal warning signs).
- Consider blurring the background when the alert is showing.
I'd be interested to see what you end up with. Hope this somewhat helps you get going.