Weather Report for October 13, 2012

Yesterday's low pressure system moved away from Arizona very rapidly and the sky was mostly clear by sunset. The humidity stayed high for most of the night and about an hour and a half of observing was lost just before midnight as the mountain formed a thin, but opaque cloud cap. After that, the humidity backed off but the seeing degraded to 2-3 arcsec. Earlier in the night, the seeing had been 1.5-2 arcsec. More than 10 blazars were successfully observed in generally clear skies. It was the coldest night of the season so far with the temperature dropping to 36 deg F.