What was supposed to be a rainy day has turned out to be a snowy day in Bozeman and southwest Montana in general. Up to 4" of fresh snow could fall in town, with up to 9" of snow in the southern mountains by Thursday night.
If you're in the mood to miss your flight out of Bozeman or sit around the gate area for an extra 45 minutes before your flight - ask a local what time you should show up at the airport. There's a very decent chance they'll give you crappy, non-detailed, and not particularly accurate advice.