Weather Report for April 27, 2014

The forecast storm system moved through Arizona during the afternoon and left behind a thin coating of snow/ice on Mt. Bigelow. Surprisingly, the sky was totally clear by the end of evening twilight and even more surprisingly, the humidity was below 80%. So, on a night that was expected to yield little or no data, observations were continuously made throughout the night. Skies were clear until the last two hours of the night when thin cirrus moved over the site. The last surprise of the night was the seeing, which was not great (1.5-2.5 arcsec), but better than expected given the fact that the temperature dropped around 20 deg (F) from the previous night.