Dan Robinson
EF5
After all, rainbows are really pretty - they are just too common.
Strange as it sounds, I've done a few rainbow 'chases' in order to get still shots over city skylines and landmarks like the Gateway Arch. To get a good rainbow in a particular spot like that is actually pretty rare. The biggest and most vivid ones are close to sunset, and usually only happen when the trailing stratiform precip of a line of storms has clear skies right behind it. And then you need the storm to move through 30 minutes or so before sunset. Too early, and the rain moves out too soon. Too late and the sun can't break through before it dips below the horizon. Then you need it to happen at the right time of year so the sun angle puts the rainbow in a good spot in the sky for the composition you want. To my knowledge there have only been two or three such events over St. Louis in the past 5 years. I try to keep tabs on when those conditions come together over downtown, and have only caught one good one in 5 years.
But yeah, if you follow right behind a squall line or supercell, you'll see a lot of great rainbows over open fields. It's just getting one to happen where you want one takes forecasting and 'chasing'.