Current Conditions
Temp2.2 C
RH6 %
WindNE 19 mph
RoadOpen (4x4)
Mauna Kea Observatories Forecast
5 PM HST Wednesday 29 March (0300 UTC Thursday 30 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 1.5 C this evening and 1 C tomorrow morning. Winds will be from the NE at 10-20 mph, with seeing near 0.7-0.75 arcseconds. Precipitable water is expected to be in the 0.8-1 mm range through the night.
Discussion
The tradewind inversion will continue to cap low-level moisture at or below 9 thousand feet and ensure the summit remains dry and stable through the next 5 nights. Daytime clouds will be minimal and short-lived through tomorrow, but could pick up for Friday and Saturday, then taper again for Sunday and Monday.

Skies overhead will remain predominately clear through the next 5 nights.

Precipitable water is expected to linger fluctuate primarily near 0.9-1.1 mm throughout the forecast period.

Strong turbulence and/or shear in the free atmosphere will likely contribute to poorer than average seeing for tonight and likely the opening half of tomorrow night. Seeing is expected to gradually improve as this source of turbulence subsides through the latter night, perhaps slipping toward better than average values for Friday night. However, an increase in boundary layer turbulence will likely contribute to another round of poor seeing for the following 2 nights.

No change since the morning forecast...While the mid-level ridge will remain rather indistinct before restrengthening to the north later in the weekend, the low-level ridge will remain well-established over/near the state into next week. Nonetheless, the presence of the ridge will promote steady/strong large-scale subsidence in the area, which will easily maintain the tradewind inversion at or below 9 thousand feet and ensure a dry/stable summit-level air mass through the next 5 nights. The persistent subsidence, combined with the lack of mid-level moisture will also keep PW near 1 mm during this time. Turbulence in the atmosphere, on the other hand, will change quite a bit over the next 5 nights. Strong northerly flow and free atmospheric turbulence along the western flank of an upper-level trough to the SE will likely contribute to poor seeing through at least tomorrow evening. Calmer upper-level flow should allow for an improvement in seeing as the trough shifts eastward on Friday. However, summit-level winds are expected to pick up as the mid-level ridge strengthens to the north, which could stir up boundary layer turbulence and contribute to another round of poor seeing for Saturday and Sunday night.
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)
Wed Mar 29 - 8 PM0-5Clear0 / 01.5NE/10-200.6-0.90.8-1
Thu Mar 30 - 2 AM0-5Clear0 / 01NE/10-200.55-0.850.8-1
2 PM0-20Clear0 / 07ENE/10-20NaN0.8-1.2
8 PM0-5Clear0 / 02ENE/10-200.55-0.850.8-1
Fri Mar 31 - 2 AM0-5Clear0 / 01.5E/10-200.5-0.70.8-1
2 PM0-20Clear0 / 06ENE/10-20NaN1-1.5
8 PM0-5Clear0 / 01.5ENE/10-200.45-0.651-1.2
Sat Apr 01 - 2 AM0-5Clear0 / 00.5ENE/10-200.45-0.651-1.2
2 PM0-20Clear0 / 05NE/15-30NaN1-1.2
Sun Apr 02 - 2 AM0-5Clear0 / 00NE/20-350.6-10.8-1.2
2 PM0-20Clear0 / 06NE/20-35NaN0.8-1.2
Mon Apr 03 - 2 AM0-5Clear0 / 00.5ENE/20-350.6-10.7-1.1
2 PM0-20Clear0 / 06ENE/20-35NaN0.6-1
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
Wed Mar 29 - Thu Mar 30 18:44 19:49 5:03 6:08 N/A 20:47 7 2 38.8 10 08
Thu Mar 30 - Fri Mar 31 18:45 19:50 5:02 6:07 N/A 21:49 14 3 36.4 13 46
Fri Mar 31 - Sat Apr 01 18:45 19:50 5:01 6:06 N/A 22:52 23 4 35.3 16 31
Sat Apr 01 - Sun Apr 02 18:45 19:50 5:00 6:05 N/A 23:53 34 5 35.0 18 11
Sun Apr 02 - Mon Apr 03 18:45 19:51 4:59 6:05 N/A 0:52 45 6 34.7 18 40
Forecast Issued by: Ryan Lyman
Next update at 10 AM HST (2000 UTC) Thursday 30 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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