Im going to fly to Tucson tommorow. The weather is telling me its going to snow in Denver. So would snow cause a delay or are airliners allowed to take off in this kind of weather?
Don't worry about it
While snow can sometimes cause a delay, airports are really good at snow removal. (Especially airports like Denver that are used to getting a lot of snow.)
According to flydenver.com DIA has 500 trained snow removal people and 270 pieces of equipment to clear 12.2 million square feet of runway, taxiways, etc.
To put that in perspective, a typical highway (2 lanes each way, with shoulders) is around 38 feet wide each way, or 76 feet for both directions. If I've done the math correctly, 12.2 million square feet is about 30 miles of road.
The state of Minnesota knows a thing or two about plowing snow. They use about 1500 drivers and 839 plows to handle 12,000 miles of road. To plow snow the way the Denver airport does it, they would need 200,000 drivers and 108,000 plows.
Here's a YouTube link that shows off some of Denver's bigger snow removal tools.
Chances are, if you can get to the airport you'll be able to fly (but perhaps not on time)
There are two considerations in snow:
Visibility is easily dealt with and most airlines have approved opspecs to takeoff in low visibility (e.g. down to 300 or 500 feet RVR). Heavy snow can reduce visibilities to less than a quarter mile (e.g. less than 1200 feet RVR) so there is quite a bit of margin between between typical snowfall and minimum visibility takeoffs.
Icing is a bit more of a challenge, but is a well defined problem with specific procedures. In snow airplanes will be de-iced with Type I fluid and then treated with an application of Type IV fluid for anti-ice protection. This fluid has a holdover time that you can takeoff within without additional checks. Some of these holdover times can be low (e.g. 5 minutes for specific conditions) but de-ice is usually where the takeoff bottleneck is and once you are treated you can generally take off without too much further delay.
Planes will be able to operate in snow, but departure rates will be less than they would be for a normal good weather day. Departure rates will be limited by runway condition (the airports ability to keep them treated and clean), the throughput of the de-ice facilities and to some degree the aircraft arrival rate (you don't have planes to fly out unless planes are making it in).
Winter ops are normal this time of year (northern hemisphere).
Continuous heavy snowfall can eventually close an airport if it becomes impossible to keep the runways clean, taxi routes become unusable due to drifting snow or snow transitions into sustained freezing rain (or runs out of de-ice fluid, yes IAH I'm looking at you). This is a transient problem and the closure would end as soon as conditions ease and the facilities can keep up with it.
Yes, heavy snow delays departures from the Denver airport (based on personal experience). Of course, nothing horrible: the airport will be cleaned, the plane will be de-iced (twice if your are unlucky enough), and may even catch part of the lost time on the way to destination. Still, it would be unwise to rely heavily on very on-time arrival.
If you need to change into another flight at your destination, and especially if you need to do anything else on time where the airline cannot help (change into unrelated train, or attend important meeting), I would advice to add a few extra hours for the possible delay.
I flew a few times out of some very cold places... on video shoots (I work in film/video). Places like Albany NY, Buffalo, and Wyoming.
Those airports are pre-pared to deal with the snow, so what would fully shut down an airport like say Austin; its business as usual in Albany.
Being in a window seat, and watching a guy in a cherry picker with a fire hose outside your plane spraying down the entire aircraft with I assume a de-freezing chemical solution similar to whats in your windsheild wiper spray; was pretty scary the first time. It was snowing hard. Everything was covered.
But they sprayed us down; and off we went; in a 777 no less.