Current Conditions
Temp10.3 C
RH6 %
WindNE 12 mph
RoadOpen (4x4)
Maunakea Observatories Forecast
10 AM HST (2000 UTC) Tuesday 28 June 2022
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 10 C this afternoon and 5 C for the night. Winds will be from the ENE at 10-20 mph for today, increasing to 15-30 mph through the night. Seeing will be near 0.6-0.7 arcseconds, while precipitable water is expected to be in the 0.8-1 mm range for the night.
Discussion
A distinct tradewind inversion will continue to cap low-level moisture near 8-9 thousand feet and ensure a dry and stable summit-level air mass through at least Friday evening. There is a chance that an influx of deep low-level moisture will raise/erode the inversion and increase the risk for periods of fog, high humidity and light ice around sunrise Saturday and especially for that night. Daytime clouds will be minimal and short-lived through Friday, but could pick up over the weekend.

Skies overhead will remain predominately clear through at least Thursday evening, but there is a possibility for scattered high clouds along the western skies during this time. These clouds are set to creep eastward beginning Thursday night, and could begin to move over the summit as that night progresses, only to break up through Friday night. Patches of deep clouds may develop in the area for Saturday night.

Precipitable water is expected to linger near 0.8-0.9 mm for the next 2 nights, increase into the 1.5-2 mm range for Thursday night and probably most of Friday night, only to jump to 4+ mm for Saturday night.

Despite relatively calm/stable skies in the free atmosphere, increasing boundary layer turbulence will begin to degrade seeing through tonight and probably contribute to poor/bad seeing for the next 3 nights (particularly Thursday and Friday night). Winds are set to abruptly diminish on Saturday, but an unstable/moist air mass will limit much improvement in seeing for Saturday night.

The mid/surface ridge will continue to sit to the north of the state and promote steady/strong large-scale subsidence in the area into the early part of the weekend. This subsidence will easily negate the effects of the tropical upper-tropospheric to the west, maintain a well-defined inversion near 8-9 thousand feet and ensure a dry/stable summit-level air mass through at least Friday evening. The TUTT is actually expected to shift further westward, which could allow a weak upper-level ridge to develop to the east over the next several days. This should allow for predominately clear/calm skies to prevail overhead as the sub-tropical jet also slips off toward the west for the next few nights. However, summit-level winds are set to subtly pick up as the mid-level strengthens and expands to the north over the next 48 hours. A tropical wave/disturbance is also expected to fill in from the east on Thursday, and could significantly tighten the wind gradient and contribute to an abrupt increase in summit-level winds beween Thursday afternoon and late Friday morning. Regardless, this increase in winds will strengthen boundary layer/low-level turbulence and probably result in poor/bad seeing mainly for Wednesday, Thursday and Friday night. There is also a fairly high risk that remnant moisture/instability from this tropical wave will push through the Big Island, erode the inversion and increase the risk for fog, convection and light rain between sunrise Saturday and early Sunday morning.
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 (%) (Celsius) (Dir/MPH) (Arcseconds) (mm)
Tue Jun 28 - 2 PM0-20Clear0 / 010E/10-20NaN0.8-1.2
8 PM0-10Clear0 / 05E/10-200.5-0.70.8-1
Wed Jun 29 - 2 AM0-10Clear0 / 05E/15-300.55-0.850.8-1
2 PM0-20Clear0 / 010E/15-30NaN0.8-1.2
8 PM0-10Clear0 / 04.5ESE/15-300.6-10.7-0.9
Thu Jun 30 - 2 AM0-10Clear0 / 04.5ESE/15-300.7-1.10.7-0.9
2 PM0-20Clear0 / 08.5E/20-35NaN1-2
8 PM0-20Clear0 / 03.5E/30-450.8-1.41.5-2
Fri Jul 01 - 2 AM10-309.5-100 / 02.5E/25-400.8-1.61.5-2
2 PM20-409-100 / 06ENE/25-40NaN1.5-2.5
Sat Jul 02 - 2 AM10-309-1015 / 5-1ENE/25-400.8-1.61.5-2.5
2 PM60-804-1075 / 252ENE/15-30NaN4-8
Sun Jul 03 - 2 AM20-404-1065 / 20-1.5SE/5-150.7-1.34-8
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 28 - Wed Jun 29 19:15 20:29 4:22 5:36 6:01 19:23 0 6 48.2 26 13
Wed Jun 29 - Thu Jun 30 19:15 20:29 4:23 5:36 N/A 20:12 2 7 40.1 25 20
Thu Jun 30 - Fri Jul 01 19:15 20:29 4:23 5:37 N/A 20:58 5 8 31.0 23 17
Fri Jul 01 - Sat Jul 02 19:15 20:29 4:23 5:37 N/A 21:40 10 9 20.3 20 13
Sat Jul 02 - Sun Jul 03 19:15 20:29 4:24 5:37 N/A 22:18 16 10 07.8 16 14
Forecast Issued by: Ryan Lyman
Next update at 5 PM HST Tuesday 28 June (0300 UTC Wednesday 29 June) 2022.
Additional Information
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