Per the FAA, DEN is still closed, but some of the secondary Denver airports have opened and are seeing air traffic.

I suspect one big problem with DIA is going to be the access road - Pena Blvd. For DEN to re-start operations, it'll be necessary for vital employees (TSA, ATC controllers, ground employees, etc.) along with crews and passengers to get to the airport safely. Anyone who has driven Pena Blvd will know what a mess it can be during snow.

With the size of DIA, there is also a lot of snow to be cleaned off not only the runways, but the taxiways and ramps. I understand many planes are stuck there at the moment and they'll need good de-icings as well.

Hopefully JetBlue and all of the other carriers will be able to add some extra flights into DEN to accomodate the passengers who (1) are already there and (2) that were scheduled on flights that have been cancelled over the past few days. JetBlue has at least one aircraft stuck in Denver which will need a good de-icing .

In fact, the last flight to land before the airport closed was a JetBlue A320 from JFK.

With all of the scheduled flights later today already full to begin with, it's going to be difficult, thus the need for some extra capacity. I expect the majors to not only run some additional flights, but to upgauge equipment on some routes to larger widebody aircraft when possible.

If you're in Denver or trying to get out of Denver, I wish you the best of luck!