Weather Report for October 21, 2017

A complex, breezy weather night due to a cold front that moved through the area at around midnight. Mt. Bigelow produced a cloud cap twice within three hours as the front moved through. In all, about two hours of observing were lost waiting for the orographic clouds to dissipate. Prior to the front's passage there were occasional very thin cirrus clouds and seeing of 1.5-1.8 arcsec. After the front moved through, the temperature dropped sharply and the seeing blew up to 2.5-3 arcsec. The sky remained clear after the second cloud cap dissipated at about 0030 local time.