The weather pattern is changing in preparation for the thunderstorms predicted for the coming two days. Strategically placed clouds at the beginning of the night hampered observations and a few targets could not be measured before they set. Clouds also quickly formed and dissipated all over the sky during the last 1.5 hours of the night, which slowed progress. The entire middle portion of the night was clear, but the seeing deteriorated to 1.5-2.5 arcsec; much worse than during the previous nights of this campaign. In addition, wet air rapidly moved into the area and the humidity, which had been 30-50% on previous nights, rose to nearly 80%. Tomorrow should be interesting.
