Current Conditions
Temp-0.8 C
RH99 %
WindSSW 50 mph
Mauna Kea Observatories Forecast
5 PM HST Friday 23 March (0300 UTC Saturday 24 March) 2018
Fog, ice, precipitation.
Sustained to strong winds
Cloud Cover and Fog/Precipitation Forecast
Clouds are continuing to stream overhead from the west. They are expected to thicken in time and obscure most of the summit sky by late tonight. Precipitation might start fallinglater tonight early, in the morning of Saturday.
Summary of Key Meteorological Variables
Summit temperatures will be near -3C this evening and -2.5 tonight. Winds will be from the WSW at 35-45 mph increasing through the night, with possible higher gusts above 50 mph. Precipitable water is expected to exceed 4 mm, and observing conditions will be poor to unoperable.
The airmasses at the summit will become moister as time goes by this evening and tonight. Instability will also increase in time. As a result fog will be very likely this evening and tonight, and conditions will become unoperable by late tonight through Saturday and part of Sunday. Dropping temperature will result in high risk for ice. Precipitation is also likely from late tonight, early Saturday morning through Saturday in the form of snow/flurries/ice, with a peak expected for Saturday early afternoon. Thunderstorms are possible also, but model project the bulk of the precipitation/system to remain east and south of the Big Island. The environment is expected to dry out some and stabilize a bit late on Sunday and through Monday and Tuesday.

High clouds will continue to stream overhead from the west today, moving eastward, thickening in time and obscuring most of the summit sky by late tonight. Summit sky will be completely cloudy from then through a good part of Sunday, when clouds will start thinning and moving eastward. Summit sky should open on Monday and at least through mid week.

Precipitable water will continue to exceed the 4 mm threshold. It is expected to start lingering close to 4 mm on Monday and possibly decreasing, closer to 3 mm, on Tuesday.

Observing conditions will be poor to unoperable tonight and will worsen late tonight and be unoperable through Sunday afternoon, possibly improving on Sunday evening. Better/drier conditions are expected from Monday and onward.

Not much chance since the morning forecast... The upper level trough NW of the islands is deepening as it approaches the islands' chain. As a result the environment is destabilizing and deep moisture is being advected over the State, from west to east and north to south. Clouds overhead will therefore thicken in time and winds at the surface will be increasing through today, and are likely to reach advisory level by late tonight and through tomorrow. Precipitation is also expected as the system nears the Big Island, starting from early Saturday morning and through that day. Since temperature will be near or below freezing, precipitation in the form of snow flurries is likely. The models project the bulk of the precipitation system to remain southeast of the Big Island, still threats of thunderstorm are possible. Conditions are expected to improve through Sunday as the system moves eastward and lives behind drier and more stable conditions through at least the first half of the coming week.
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 23 - 8 PM60-804-890 / 80-3WSW/35-551-214-18
Sat Mar 24 - 2 AM80-1004-9100 / 100-2.5WSW/35-551-214-18
2 PM80-1004-9100 / 100-1WSW/30-45NaN14-18
8 PM80-1004-9100 / 100-3.5W/35-552-312-16
Sun Mar 25 - 2 AM80-1004-9100 / 100-4WSW/25-401.5-2.510-14
2 PM80-1004-990 / 70-1.5WSW/25-40NaN8-12
8 PM40-604-780 / 30-1.5WSW/25-401-1.46-10
Mon Mar 26 - 2 AM10-305-760 / 20-2SW/25-350.7-1.16-10
2 PM0-20Clear40 / 02.5WSW/20-30NaN6-10
Tue Mar 27 - 2 AM0-20Clear10 / 01WSW/20-300.4-0.83.5-4.5
2 PM0-20Clear20 / 0-1WSW/15-25NaN4-6
Wed Mar 28 - 2 AM0-20Clear0 / 03.5W/15-250.4-0.83-4
2 PM0-20Clear0 / 00.5W/10-20NaN3-5
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
Fri Mar 23 - Sat Mar 24 18:43 19:47 5:09 6:13 N/A 0:59 47 5 58.9 19 38
Sat Mar 24 - Sun Mar 25 18:43 19:47 5:08 6:13 N/A 1:57 58 6 59.3 19 56
Sun Mar 25 - Mon Mar 26 18:43 19:48 5:07 6:12 N/A 2:54 69 7 59.9 18 55
Mon Mar 26 - Tue Mar 27 18:43 19:48 5:06 6:11 N/A 3:47 79 8 59.8 16 41
Tue Mar 27 - Wed Mar 28 18:44 19:48 5:05 6:10 N/A 4:36 88 9 57.9 13 23
Forecast Issued by: Tiziana Cherubini
Next update at 10 AM HST (2000 UTC) Monday 26 March 2018.
Additional Information
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