Current Conditions
Temp-5.0 C
RH96 %
WindSW 38 mph
RoadClosed
Mauna Kea Observatories Forecast
830 AM HST (1830 UTC) Monday 19 February 2018
Warning(s)
Fog, ice and high humidity
Chance for convection and snow
Moderate/strong winds
Cloud Cover and Fog/Precipitation Forecast
There is a high risk for fog, ice, high humidity, patches of thick clouds and flurries throughout the night. There is a possibility for convection and periods of heavy snow at virtually anytime, particularly this afternoon and toward the end of the night.
Summary of Key Meteorological Variables
Summit temperatures will be near -4 C this afternoon and -6 C for the night. Winds will be from the SW at 25-40 mph, while seeing and precipitable water are expected to exceed 1 arcsecond and 4 mm, respectively throughout the night.
Discussion
Although the upper atmosphere will continue to dry out through Wednesday morning, a fairly saturated mid/low-level air mass combined with lingering instability will likely allow extensive fog, ice, high humidity and perhaps light flurries to plauge the summit for at least tonight. There is also a possibility for isolated convection in the area and periods of heavy snow at the summit, especially for this afternoon and again near sunrise tomorrow. The odds on moisture at the summit and convection in the area is set to diminish as the atmosphere begins to stabilize and dry, while the inversion tries to rebuild through tomorrow night and into Wednesday morning. However, a new influx of deep moisture from the south will begin to erode the inversion later that night. This moisture will continue to stream into the area probably through the week, while fresh more widespread instability builds to the NW late in the week and into the weekend. This will raise the stakes on more periods of inoperable conditions at the summit for the second half of the forecast period. Extensive daytime clouds are expected throughout the forecast period.

While skies will continue to open up of organize clouds through the next 2 nights, there is a possibilty that isolated convection will develop in the area, which could move through and/or send cirrus exhaust into the summit area, mainly for early this evening, near sunrise tomorrow and perhaps again tomorrow evening. Patches of mid-level clouds may also occasionally develop in the area mainly for tonight. Thicker more widespread clouds are expected to build in from the south through Wednesday night and will likely blanket summit skies for at least the following 2 nights.

See table for PW and Seeing forecast. There will be no full MET discussion today.
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)
Mon Feb 19 - 2 PM80-1004-10100 / 90-4SW/25-40NaN6-10
8 PM60-804-795 / 75-6SW/25-400.8-1.64-6
Tue Feb 20 - 2 AM40-604-695 / 60-6WSW/25-400.8-1.64-6
2 PM60-804-890 / 50-1WSW/20-35NaN4-8
8 PM40-604.5-5.560 / 20-3W/15-300.7-1.33-5
Wed Feb 21 - 2 AM20-404.5-530 / 10-3W/15-300.6-12-4
2 PM60-804-675 / 151W/15-30NaN4-8
8 PM50-706-975 / 25-2W/10-200.6-0.94-8
Thu Feb 22 - 2 AM60-806-1075 / 40-3W/10-200.6-14-8
2 PM80-1004-1090 / 800S/5-15NaN8-12
Fri Feb 23 - 2 AM80-1004-1095 / 90-3.5S/5-150.7-1.38-12
2 PM80-1004-1095 / 90-1E/5-15NaN8-12
Sat Feb 24 - 2 AM80-1004-1095 / 90-4SE/5-150.8-1.68-12
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
Mon Feb 19 - Tue Feb 20 18:32 19:37 5:34 6:39 N/A 22:12 20 1 36.5 4 41
Tue Feb 20 - Wed Feb 21 18:33 19:37 5:33 6:38 N/A 23:07 29 2 27.0 8 56
Wed Feb 21 - Thu Feb 22 18:33 19:38 5:33 6:37 N/A 0:04 39 3 19.7 12 50
Thu Feb 22 - Fri Feb 23 18:33 19:38 5:32 6:37 N/A 1:03 50 4 15.1 16 08
Fri Feb 23 - Sat Feb 24 18:34 19:38 5:32 6:36 N/A 2:04 61 5 13.4 18 32
Forecast Issued by: Ryan Lyman
Next update at 10 AM HST Tuesday 20 February (0300 UTC Tuesday 20 February) 2018.
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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