We are so DOOOOOOMMMMMEDDD.

Massive magma!

The team found that the magma chamber was colossal. Reaching depths of between 2km and 15km (1 to 9 miles), the cavern was about 90km (55 miles) long and 30km (20 miles) wide.

I did a search to try and find what would really happen.  The answers are slightly re-assuring...it won't melt the whole US.  http://io9.com/what-will-really-happen-when-yellowstone-volcano-has-a-508274690

A super eruption might come fast and the Yellowstone magma source is enormous. But don't expect walls of lava pouring across the continent. Lava flows would be likely be "within the vicinity of the park," Lowenstern said, limited to a 30-40 mile radius. When a volcano erupts, he added, at least a third of the liquid rock that's ejected falls right back into the volcano's maw. The rest lands nearby, or goes up into the atmosphere.

Most of the real damage comes from ejecta that's airborne. But it's not fiery death from above. Instead, most damage would come from "cold ash" and pumice borne on the wind. Lowenstern and his colleagues consider it "disastrous" when enough ash rains down that it creates a layer of 10 or more centimeters on the ground — and that would happen in a radius of about 500 miles or so. This ash might reach so far that you'd see a fine dusting of it on your car in New York.

I wonder what would happen to the world's weather if this, the deadly Mount Tambora and the Yellowstone hypermegasupervolcano explode at the same time.

Every ten to 12 thousand years, there's a volcano in the heart of Europe that goes boom. And not any boom, but a let's-kill-everyone-with-billions-of-tonnes-of-magma boom that would cover everything in ash from England and Denmark to the north of Italy.

Now, the supervolcano that can destroy bad teeth, rude waiters, overpriced wine, olive oil, smelly camping sites, disco music, nudist beaches, pasta, David Hasselhoff and Oktoberfest is awakening

It's been 12,900 years since the last eruption. The supervolcano is located under the Laacher See, a caldera lake in the Eifel mountain range, 15 miles from Koblenz and 30 miles from Bonn, the old capital of West Germany.

http://gizmodo.com/5872418/the-supervolcano-that-can-devastate-europe-is-showing-signs-of-awakening

I guess it's about time then, give or take a few thousand years... I'm taking all bets it won't happen in the next 10 years... and give 10-1 odds too.  I get to hold all the money.  And spend it.

More likely to get a giant explosion from the volcano in Iceland:

http://pandawhale.com/post/49397/200-kilometer-long-icelandic-supervolcano-about-to-erupt