I was in the pattern at St. Louis Downtown Parks airport several years ago flying on a very nice afternoon.
Both patterns were full for 30L and 30R as the airport hosted two major college flight training programs at the time. There must have been a dozen aircraft in the air between the two runways with more arrivals coming in from the south practice area as well as aircraft departing for it.
The tower gal came on the radio and announced that the winds had just shifted and she was changing the runways to 12L and 12R.
She was brilliant. I still don't know how she got all of us turned around in that aerial ballet, but she did a very professional job with the help of many of us in the air. There was some confusion on the part of some of the newer pilots, but it worked out very well.