Latest Forecast for Mauna Kea Observatories
10 AM HST (2000 UTC) Monday 14 May 2012

Warnings
Small chances for fog/ice

Cloud Cover and Precipitation Forecast
Small chances for moisture to linger around the area during the first part of the night resulting in short episodes of fog. Otherwise the atmosphere at the summit should be predominantly stable. Thin high clouds will quickly move southeastward.

Summary of Key Meteorological Variables
Summit temperature will be near 5 C this afternoon, -0.5 C this evening and -1 C tonight. Precipitable water will be in the 3 to 5 mm range. Winds will be light at 5 to 15 mph with seeing ranging in the 0.5-0.6 arcsec.

Discussion
The tradewind inversion might weaken and lift through today and tonigth. Therefore low level moisture could be advected up to the summit level tonight and results in short episoded of fog/ice and/or high relative humidity. The inversion will rebuild through Tuesday morning and will remain established well below summit level for the rest of this forecast period, ensuring dry and stable conditions at the summit. Afternoon clouds are possible today.

Broken, thin patches of high clouds might still interest the summit sky late today and through the first half of the night. They are expected to quickly move southeastward and out of the area afterward. Summit sky will be predominantly clear for the rest of the foreasting period.

Precipitable water will range between 3 and 5 mm tonight, and between 2 and 3 mm on Tuesday and Wednesday night. It will continue decreasing and linger close to 2 on Thursday night and close to 1.5 mm on Friday night.

Light winds will persist at the summit throught most of the forecast period. Meanwhile, but for some shear aloft for today and tonight, the atmosphere should be relatively turbulence-free this week. Observing conditions will therefore be in the average to better than average range for most of this forecast period, but for some variability to seeing for tonight.

The trough interesting the eastern central pacific area is slowly shifting southeastward. Although its influence is limited, it will affect the tradewind inversion today and tonight by weaking it some. This will result in low-level moisture possibly slipping up the summit level and short episodes of high relative humidity and fog/ice. The conditions will improve through the night and as the system moves further east, and the ridge rebound northward on Tuesday, stable and dry conditions will follow and will characterize the rest of this forecast period.