Latest Forecast for Mauna Kea Observatories
5 PM HST Monday 14 May (0300 UTC Tuesday 15 May) 2012

Warnings
Small chances for fog/ice

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

Summary of Key Meteorological Variables
Summit temperature will be near 0 C this evening and -1.5 C tonight. Precipitable water will be in the 3 to 4 mm range. Winds will be light at 5 to 15 mph with seeing ranging between 0.5 and 0.6 arcsec.

Discussion
The latest sounding shows a slighly weakening tradewind inversion, which might lift some through this evening and tonigth as a result of a dissipating front sweeping through the area. Therefore low level moisture could be advected up to the summit level this evening and result in short episoded of fog/ice and/or high relative humidity. The inversion will strengthen from Tuesday morning and will remain established well below summit level for the rest of this forecast period, ensuring dry and stable conditions.

Broken, dissipating high clouds will 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 by the second half of tonight. Summit sky will be predominantly clear for the rest of the foreasting period.

Precipitable water will range between 3 and 4 mm tonight, and between 2.5 and 3.5 mm on Tuesday and 2 and 3 mm on 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 the atmosphere should be relatively turbulence-free this week, exception done for some shear aloft through tonight. 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.

Not much is changed since the morning forecast... The trough interesting the eastern central pacific area is slowly shifting southeastward. Although its influence is limited, it will affect the tradewind inversion through tonight by weakening the inversion some. Therefore low-level moisture will possibly slip up the summit level and short episodes of high relative humidity and fog/ice are possible. 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.