Hmmm - can honestly say I've never though of that before, but can see where it would be very useful.
So - it's done - look for it in the coming update.
The only caveat is that it functions in the analyzer - see the screenshot. There a new HUD display there designed for this and similar purposes. Plus, since folks can run multiple roasts in tandem, I think it would be too much to have the alarms function at the application level, when you might be trying to do other things. So, while you're in the analyzer, it will fire off a "ding" with the HUD alert displaying for a couple of seconds at an interval you choose in the preferences - 15, 30 60 or none (defaulted to none). The HUD will keep alerts from piling up on top of one-another, in case you're away from the roast, plus not interfere with touches if you're doing something else when it alerts.
Note the new dedicated node entry popover - LOTS easier to use.
Hope you like it, and thanks for the idea!