May have to be careful here…not sure. Once METAR took over in 1996 everything went to <= 12kft ceilometer observations. A few of the larger airports did augment higher levels in, but I’m not sure how consistent that has been. BOS has had a 25kft ceilometer for awhile now, and does consistently augment, but I’m not sure how the high level coverage compares to the pre ASOS days with manned SA obs. At least Fish was smart enough to use BOS.
@vortex95 would probably know more on that
Here’s CON. A big “drop off” in cloudiness in 1996 once the ceiling reporting stopped at 12kft.
It’s pretty stupid seeing obs reported as CLR/Fair when it’s totally overcast at 15kft.