Warns are not easy to distinguish on low-contrast and/or on indirect sun-light. Use more "yellowish" color for Warn's please. What about #FFCC33?
Accessibility: We might also want to differentiate by Saturation and Value to make it more "readable" to color-blind people.
Since 0.15 Beaker uses the default Bootstrap warning colour #F89406 which is quite readable I think.