The following video is streaming on YouTube, showing the roof collapse from inside the stadium early Sunday morning:
Below is the text of my original post from Sunday morning:
The roof of the Metrodome (home of the Vikings) in Minneapolis has collapsed this morning, apparently the result of the weight of heavy snow bearing down on the structure.
Here is a photo of what the Metrodome usually looks like (date unknown):
And here is a photo of what it looked like this morning after the collapse:
Flattened, I guess you could say, like a pancake...
According to an article in Wikipedia, "the roof is made of two layers of Teflon coated fiberglass fabric, and is an air-supported structure supported by positive air pressure. It requires 250,000 ft³/min (120 m³/s) of air to keep it inflated. It is reputed to be the largest application of Teflon on Earth."
Here is a photo of what the inside of the teflon roof looks like when properly inflated:
The region has been hammered by heavy snow over the past 24 hours, with blizzard to near blizzard conditions at times. As of 7am CST this morning, 15.7 inches of snow had fallen at the Minneapolis/St. Paul airport. Here is the latest snow depth map as produced by the NWS Snow Project:
A detailed graph of the activity at Minneapolis shows the snow fell in a relatively short period of time, and with a heavy "water equivalent" (or water content of the snow, which makes it more dense and heavy).
Fortunately this occurred at a time when the stadium was empty (other than a few support personnel that thankfully were not injured). It may, however, add more fuel to the controversy over the use of what some view as "non-permanent" materials in sporting and other public structures. Some of you may recall the collapse of the Dallas Cowboys Training Facility in strong thunderstorm winds back in May of 2009.
That facility was made out of a similar material, also supported by forced air, and was no match for the strong downburst winds of a severe thunderstorm. Many in the meteorological community, particularly those involved with warning and protecting the public during severe weather events, came out in force after that event and called for further review of the use of this type of structure where large numbers of the public meet.
Yesterday the Vikings management postponed today's game to Monday, which does indicate an awareness on their part as to the magnitude of the severe winter weather conditions that had been affecting the region. Thank goodness that move was made, or other support personnel would have been inside the stadium preparing for today's game when the collapse took place.
UPDATE 9:30 AM: Perhaps I gave the NFL & Vikings management too much credit in the last paragraph of my post. According to this article from KSTP, the game was postponed because the Giants were stranded in Kansas City due to the snowstorm, not out of concern for conditions in Minneapolis itself...