Current Conditions
Temp-1.5 C
RH19 %
WindNE 25 mph
RoadOpen (4x4)
Mauna Kea Observatories Forecast
5 PM HST Friday 24 March (0300 UTC Saturday 25 March) 2017
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 -0.5 C this evening and -1 C tomorrow morning. Winds will be from the north ENE at 10-20 mph, with seeing near 0.6 arcseconds, while precipitable water is expected to be in the 0.9-1.1 range for the night.
Discussion
The tradewind inversion will continue to cap low-level moisture primarily near 6-7 thousand feet and ensure the summit remains dry and stable through the next 5 nights. Daytime clouds will be minimal and short-lived throughout the forecast period.

Skies overhead will remain predominately clear of organized clouds through the next 5 nights. However, there is a possibility for high clouds along the northern skies, which may occasionally/briefly stray over/through the area mainly for Sunday and Monday night.

Precipitable water is expected to linger near 1 mm for tonight, briefly increase to 1.2-1.3 mm for tomorrow night, slip back to 1 mm for Sunday night and probably 0.8-0.9 mm for the early part of next week.

Moderate turbulence in the free atmosphere may keep seeing near more average-like values for tonight. A minor increase in boundary layer turbulence may contribute to slightly poorer than average seeing for tomorrow night, but seeing is set to improve toward more average-like values or better as calmer skies prevail for Sunday night and especially early part of next week.

No change since the morning forecast...A new ridge filling in from the west will settle in to the north of the state and instill strong/fresh large-scale subsidence in the area well into next week. This subsidence will maintain the tradewind inversion near 6-7 thousand feet and ensure the summit steers free of moisture over the next 5 nights plus. There is a possibility that summit-level winds will pick up a bit as the ridge strengthens and drifts northward mainly between late tomorrow morning and Sunday afternoon (perhaps again around Monday afternoon/evening). This could result in a period of boundary layer turbulence and thus poorer than average seeing for tomorrow night. Besides this, there is a possibility for minor upper-level turbulence along the western side of a passing trough, which could could contribute to more average-like seeing for tonight and Sunday night. This source of turbulence should subside as a more zonal westerly flow prevails aloft, allowing for an improvement in seeing for the early part of next week.

Please Note: There will be only be a brief update in the forecast on Monday, March 27, Prince Kuhio Day. The normal forecast schedule will resume on Tuesday, March 28.
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)
Fri Mar 24 - 8 PM0-5Clear0 / 0-0.5ENE/10-200.5-0.70.9-1.1
Sat Mar 25 - 2 AM0-5Clear0 / 0-1E/10-200.5-0.70.9-1.1
2 PM0-20Clear0 / 05E/15-25NaN1-1.5
8 PM0-10Clear0 / 0-1E/15-250.55-0.851-1.5
Sun Mar 26 - 2 AM0-10Clear0 / 0-1.5ENE/15-250.55-0.851-1.5
2 PM0-20Clear0 / 05SE/10-20NaN1-1.5
8 PM0-20Clear0 / 01SE/10-200.5-0.70.9-1.1
Mon Mar 27 - 2 AM0-208-90 / 01SE/5-150.5-0.70.9-1.1
2 PM0-208-90 / 06.5ESE/10-20NaN0.8-1.2
Tue Mar 28 - 2 AM10-308-90 / 01.5SSE/10-200.45-0.650.7-1
2 PM20-408-90 / 06.5SW/5-15NaN0.8-1.2
Wed Mar 29 - 2 AM0-20Clear0 / 01NE/5-150.45-0.650.7-1
2 PM0-20Clear0 / 06.5ENE/15-30NaN0.8-1.2
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
Sat Mar 25 - Sun Mar 26 18:43 19:48 5:07 6:11 5:18 16:48 4 23 01.6 -7 33
Sun Mar 26 - Mon Mar 27 18:44 19:48 5:06 6:11 6:03 17:45 1 23 54.4 -3 14
Mon Mar 27 - Tue Mar 28 18:44 19:49 5:05 6:10 6:49 18:45 0 0 48.0 1 20
Tue Mar 28 - Wed Mar 29 18:44 19:49 5:04 6:09 N/A 19:45 2 1 42.7 5 54
Wed Mar 29 - Thu Mar 30 18:44 19:49 5:03 6:08 N/A 20:47 7 2 38.8 10 08
Forecast Issued by: Ryan Lyman
Next update at 10 AM HST (2000 UTC) Monday 27 March 2017.
Additional Information
For public road conditions and snow report message please call (808) 935-6268.
This message is also available at the MKWC road conditions page.
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