Current Conditions
Temp7.7 C
RH10 %
WindNNE 13 mph
RoadOpen (4x4)
Mauna Kea Observatories Forecast
9 AM HST (1900 UTC) Thursday 11 February 2016
Warning(s)
None
Cloud Cover and Fog/Precipitation Forecast
The summit will remain clear, dry and stable through the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 7 C this afternoon and 2.5 C for the night. Winds will be from the NW at 20-35 mph, with seeing around 0.7 arcseconds. Precipitable water is expected to be in the 0.7-0.9 mm range for the first half of the night and 0.6-0.8 mm range for the second half.
Discussion
A well-defined tradewind inversion will continue to cap low-level moisture at or below 7 thousand feet and ensure a dry/stable summit-level air mass through the next 5 nights. Daytime clouds will be minimal and short-lived throughout the forecast period.

Skies will remain predominately clear through the next 5 nights.

Precipitable water is expected to start out near 0.8 mm for this evening, but slip toward 0.7 mm by the end of the night and likely settle in near 0.6-0.65 mm for the remainder of the forecast period.

Lingering boundary layer/low-level turbulence will contribute to poor seeing for one more night. Calm skies and deep subsidence should allow for seeing to settle in near 0.4-0.5 arcseconds for the remainder of the forecast period (there is a possibility it will dip toward/below 0.4 arcseconds early Saturday morning).

A deep ridge is expected to fill in from the west over the next 24-36 hours, then linger over the state into the early part of next week. This ridge will promote steady/strong large-scale subsidence in the area, which will easily maintain a well-defined tradewind inversion and ensure a dry/stable and clear summit-level air mass throughout the forecast period. While north/northwesterly flow along the eastern fringe of the ridge may continue to stir up boundary layer turbulence and contribute to poor seeing for tonight, seeing is slated to settle in near 0.4-0.5 arcseconds once calm skies embedded in the ridge fills in over the area for the following 4 nights. PW is also set to benefit from this deep persistent subsidence and settle in near 0.6-0.65 mm, particularly after tonight.
WRF Astronomical Observing Quality Guidance
Cloud Cover and Precipitable Water Analyses
MK CN² Profiles
5 Day Forecast Summary (Graphical Trend)
HST Cloud Fog/Precip Temp Wind Seeing PW
Cover (%) Height (km) Probability (%) (Celcius) (Dir/MPH) (Arcseconds) (mm)
Thu Feb 11 - 2 PM0-20Clear0 / 07NW/20-35NaN0.8-1.2
8 PM0-5Clear0 / 02.5NW/20-350.55-0.850.7-0.9
Fri Feb 12 - 2 AM0-5Clear0 / 02.5NNW/20-350.55-0.850.6-0.8
2 PM0-20Clear0 / 010N/10-20NaN0.6-1
8 PM0-5Clear0 / 05.5NE/10-200.4-0.50.55-0.7
Sat Feb 13 - 2 AM0-5Clear0 / 05E/5-150.35-0.450.55-0.7
2 PM0-20Clear0 / 010ENE/5-15NaN0.6-1
8 PM0-5Clear0 / 010E/10-200.4-0.50.55-0.75
Sun Feb 14 - 2 AM0-5Clear0 / 04.5ESE/10-200.4-0.60.55-0.75
2 PM0-20Clear0 / 09SE/5-15NaN0.6-1
Mon Feb 15 - 2 AM0-5Clear0 / 03.5SSE/5-150.4-0.60.55-0.7
2 PM0-20Clear0 / 09NW/5-15NaN0.6-1
Tue Feb 16 - 2 AM0-5Clear0 / 03.5NW/5-150.35-0.550.55-0.7
Rise and Set times for the Sun and Moon
Night (HST) Sun Set Twilight End Twilight Beg Sun Rise Moon Rise Moon Set Illumination (%) RA DEC
Thu Feb 11 - Fri Feb 12 18:28 19:34 5:38 6:44 N/A 22:00 18 0 53.8 3 32
Fri Feb 12 - Sat Feb 13 18:29 19:34 5:38 6:43 N/A 23:01 28 1 49.0 7 48
Sat Feb 13 - Sun Feb 14 18:29 19:35 5:37 6:42 N/A 0:01 39 2 44.7 11 35
Sun Feb 14 - Mon Feb 15 18:30 19:35 5:37 6:42 N/A 1:00 50 3 41.0 14 38
Mon Feb 15 - Tue Feb 16 18:30 19:35 5:36 6:41 N/A 1:59 61 4 37.8 16 47
Forecast Issued by: Ryan Lyman
Next update at 5 PM HST Thursday 11 February (0300 UTC Friday 12 February) 2016.
Additional Information
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This message is also available at the MKWC road conditions page.
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