Weather Report for May 7, 2016

Unsettled weather settled in over Arizona tonight. Orographic clouds were the major problem, as thunderstorms to the west of the observatory never got closer than about 100 km. Only a handful of brighter blazars could be observed for polarization during short gaps in the cloud cover. No photometry was attempted. Observations were impossible after 0100 local time when it became totally overcast. The seeing was 2-4 arcsec and the temperature took yet another nosedive to near freezing by the end of the night. Pretty impressive weather for southern Arizona in May. The forecast has more of the same for tomorrow night.