Weather Report for September 21, 2017

Once again, a promising night is turned to ruin by orographic clouds. Patchy clouds around the mountain dissipated during evening twilight, allowing for about 3 hours of observations in clear skies with seeing of 1.5-2 arcsec. At a little past 2300 local time, the sky became opaque within minutes and remained in this sorry state until a half hour before dawn. This was enough time to get a few more bright blazars before the sky became too bright. The satellite image adds insult to injury by promoting the notion that the entire state of Arizona is cloudless. Fake news!