UPDATE: Thanks to a commenter, here is an article with more videos from this thunderstorm.
This YouTube video showed up in my mailbox this morning, as a "Top 5 Most Viewed" video, and it now has over one million views:
I did some research (for our news story) to determine what wind conditions caused this incredible event. On Aug. 14, winds were sustained as high was 41 mph gusting to as high as 60 mph from the north-northwest during a thunderstorm between 2:45 and 4:00 p.m. local time at both Calgary International (graphed below) and Calgary/Springbank airports:
According to Google Maps & Street View, the location of the driver would have had a north-northwest wind behind him, which meant it was blowing perpendicular to the street sign's horizontal support bar -- not unlike what happened when winds perpendicular to the Tacoma Narrows bridge ("Galloping Gertie") caused it to crash in 1940 (except then it caused twisting, not simple bouncing up and down). This is my guess anyway, I'm by no means an expert on Aerostatic Fluttering; if you are, leave me a comment below. One YouTube commenter said that the bad engineering of signs spanning too many lanes contributed to the problem.
Two days of rare September severe thunderstorms in Pennsylvania have dropped tornadoes and funnel clouds, and I was able to chase some of them.
There are quite a few notable low pressure systems or "cyclones" worldwide today. One of them, Typhoon Meranti, is the biggest in a while.
On the evening of September 5, 1996, as Hurricane Fran approached the North Carolina coast, I embarked on my first-ever hurricane storm chase trip.
Twenty years ago, Hurricane Fran roared into eastern North Carolina, and I was there -- and I've got the VHS tapes to prove it.
Until yesterday, Hurricane Wilma was the last Hurricane to strike the state of Florida, 11 years ago.
Hurricane Irene caused over $16 billion in damage in 2011. A the 5-year anniversary, I look back on my experiences with the storm.