Current Conditions
Temp8.0 C
RH14 %
WindNE 16 mph
RoadOpen (4x4)
Mauna Kea Observatories Forecast
0830 AM HST (1830 UTC) Tuesday 27 June 2017
Warning(s)
None
Cloud Cover and Fog/Precipitation Forecast
The summit will be dry and stable through the night. Banding high clouds will continue to be visible and stream over the summit today but are expected to thin in time and move northward.
Summary of Key Meteorological Variables
Summit temperatures will be near 8.5 C this afternoon, 3 C this evening and 2.5 C tomorrow morning. Winds will be light to moderate at 10 to 20mph from the NNE. Seeing will average but variable (0.55-0.65 arcseconds). Precipitable water is expected to linger close to 2 mm for the night.
Discussion
The tradewind inversion will continue to cap low-level moisture near 7-8 thousand feet and ensure a dry/stable summit-level air mass through at least the next 2/3 nights. The inversion is expected to weaken and lift afterward. Daytime clouds will be minimal and short-lived through tomorrow, but might become more extensive onward.

Banding high clouds will continue to stream overhead from the Southwest through today, while thinning in time and moving northward. Mostly clear sky is expected for tomorrow. Mid level clouds will instead approach the summit from the Northeast from Thursday. Depending on the development of the associated disturbance, they might thick in time and close a good portion of the summit skies by the end of the week.

Precipitable water will linger close to 2 mm tonight. It will drop closer to 1 mm for Wednesday night and it likely to increase and reach the 4 mm threshold by Thursday and through the beginning of the coming weekend.

Observing conditions will be average but variable tonight and even more variable and less than average on Tuesday night as winds at the surface will pick up some. Conditions might degrade further through the rest of this forecast period because of increasing cloud cover and air masses instability.

Ridging to the North, Northeast of the State will remain in place through this forecast period. Nevertheless an upper level low will approach the island chain from the east starting tomorrow and, depending on its evoultion, is likely to advect clouds over the summit and increase instability in the air masses by Thursday. Surface winds at the summit are also likely to increase through tomorrow because of the tightening of the surface pressure gradients. The tradewind inversion is projected to weaken and lift by Thursday and mid/low level moisture might reach the summit and result in fog and possible drizzle on Thursday and through the beginning of the weekend. If otherwise the low remain far enough and move quickly northward, the inpact on the summit weather might be minimal. More on this with next forecast's updates.
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)
Tue Jun 27 - 2 PM20-407-80 / 08.5ENE/10-20NaN1.5-2.5
8 PM20-407-80 / 03NE/15-250.45-0.751.75-2.25
Wed Jun 28 - 2 AM0-20Clear0 / 02.5NNE/10-200.4-0.71.75-2.25
2 PM0-20Clear0 / 07.5NE/15-25NaN1-1.5
8 PM0-20Clear0 / 03.5NE/20-350.6-10.9-1.3
Thu Jun 29 - 2 AM0-20Clear0 / 02NE/15-250.5-0.91-1.5
2 PM10-307-830 / 07.5NE/15-25NaN3.5-4.5
8 PM30-505-740 / 03ENE/20-300.5-0.94-6
Fri Jun 30 - 2 AM30-504-750 / 102ENE/15-250.6-14-6
2 PM60-804-760 / 207NNE/15-25NaN4-10
Sat Jul 01 - 2 AM60-804-760 / 201ENE/10-200.7-1.14-8
2 PM40-605-760 / 207ESE/5-15NaN4-6
Sun Jul 02 - 2 AM20-406-740 / 01S/5-150.5-0.94-6
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
Tue Jun 27 - Wed Jun 28 19:15 20:29 4:22 5:36 N/A 22:46 23 10 26.5 10 01
Wed Jun 28 - Thu Jun 29 19:15 20:29 4:22 5:36 N/A 23:29 33 11 18.0 6 02
Thu Jun 29 - Fri Jun 30 19:15 20:29 4:23 5:37 N/A 0:10 43 12 07.1 1 51
Fri Jun 30 - Sat Jul 01 19:15 20:29 4:23 5:37 N/A 0:48 53 12 54.7 -2 19
Sat Jul 01 - Sun Jul 02 19:15 20:29 4:23 5:37 N/A 1:26 63 13 41.5 -6 20
Forecast Issued by: Tiziana Cherubini
Next update at 5 PM HST Tuesday 27 June (0300 UTC Wednesday 28 June) 2017.
Additional Information
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This message is also available at the MKWC road conditions page.
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