I have many more pictures that I may add if there is a need. Right now I'd like to mention another discussion. I belong to a Miata forum and they have an "off topic" area like most. I started a discussion there. A guy named Ted offered this.
The term "dust devil" isn't much used in the eastern US because it's something that happens mainly on open arid land with intense solar exposure. Microburst is closer but incomplete because it refers specifically to a small focused downdraft. I don't know if there's a term other than the broad "waterspout" for a mini tornado that follows streams but I've seen them. They wobble and sometimes flick up onto the banks briefly before dissipating or returning to water. And little twisters (dust devils where it isn't very dusty) happen. In the 1970s I was working at a manufactured housing plant in North Carolina when one touched the holding yard. A doublewide half sitting on tires & hitch was tipped over while a big unbound stack of 2x4s right beside it was undisturbed
Ted's suggestion was that a little twister came off the warm water of the creek and traveled up the ramp and destroyed the canopy.
Meanwhile, there is a meteorologist there that says that it is not possible that wind did this damage.
I don't know what you saw, but your description doesn't match the the atmospheric physics that would be at work here.
Yes, you need a thermal differential to form a devil, but Rocky mountain stream temperature would be very cold before a "sharp cold front", say 40F. Even if a cold front was 20F, and you had a 20 degree differential, and it persisted long enough to possibly form a vertical column of air: the horizontal wind speed associated with the sharp cold front would be very high and too strong to enable the vertical updraft due to a thermal differential to form/maintain itself. Plus, the speed of stream water would also dampen any vertical updraft over the stream. It would carry the base of the vertical column of rising air, down stream, stretching it out of shape to its death.
But let's say in this case, a creek-devil did form. That the temperature differential between water and air was high enough to create an updraft. Plus, the motion of the water was weak enough to not stretch the column of air. Plus the motion of the air was strong enough to move the creek-devil on shore to the campground canopy/picnic table. This creek-devil (surface based and not dropping down from a cloud on this sunny day) would then need to be large enough to destroy the canopy AND lift/flip the large heavy table yet not displace the the items under the canopy. Recall, OP said they were still in place. Being the lightest items in the destruction zone they should have been thrown to the far corners of the earth had wind (horizontal or rotational) been at work here. (Google Beaufort wind scale for empirical effects due to wind speed).
Two things make this operational/research meteorologist think this was not a wind driven event:
No displacement of items under the canopy despite canopy destruction and table movement.
No indication of weather according to OP to cause a wind event: sunny, not windy, not stormy.
So the meteorologist says that it had to be vandals. Looking at the destruction and the fact that it happened in my front yard in the middle of the day makes it impossible for me to believe that vanals are even a remote possibility.
Does anybody have any idea about what happened?