Current Conditions
Temp2.5 C
RH14 %
WindSW 0 mph
RoadOpen (4x4)
Maunakea Observatories Forecast
10 AM HST (2000 UTC) Wednesday 19 January 2022
Warning(s)
Increasing winds
Cloud Cover and Fog/Precipitation Forecast
The summit will remain clear, dry and stable, but there is a chance that humidity will increase toward 60% by the end of the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 2.5 C this evening and -3 C tomorrow morning. Winds will be from the NNW at 10-20 mph for today, increasing to 20-35 mph through the night. Seeing will be near 0.8-1 arcsecond, while precipitable water is expected to exceed 4 mm for the night.
Discussion
A fairly well-defined inversion will continue to cap low-level moisture at or below 9 thousand feet and ensure the summit steers free of fog and precipitation through the next 5 nights. However, there is a possibility that summit-level humidity will increase toward 50-70% mainly toward the end of tonight and again over the latter part of the weekend. Daytime clouds will be minimal and short-lived throughout the forecast period.

Skies overhead will remain predominately clear of organized high clouds through the next 5 nights. However, there is an outside chance for the development of lenticular clouds over the Big Island summits mainly for tomorrow night and again for Saturday and Sunday night.

Precipitable water is expected to increase to 4+ mm for tonight and probably most of tomorrow night, then slip into the 2-3 mm range for Friday night and settle in near or just below 2 mm for the following 2 nights.

Increasing winds will likely contribute to steady boundary layer turbulence as well as strong free atmoisoheric turbulence, resulting in poor/bad seeing throughout most of the forecast period. There is a small chance for a minor dip in the winds, which may allow for a brief modest improvement in seeing for Friday night.

A very broad/intense westerly jet will maintain a zonal orientation in the western Pacific, while a the easterly tip of rather deep ridge to the south extends over the state probably well into next week. This ridge will promote steady large-scale scale subsidence in the area, which will help maintain a well-defined inversion at or below 9 thousand feet and ensure a dry/stable summit-level air mass throughout the forecast period. The westerly jet will also keep high clouds passing well to the north of the state, allowing mostly clear skies to prevail at the summit during this time. Unfortunately, a mid-level low developing in the eastern Pacific is expected to tighten the wind gradient over the next 24 hours, resulting in a rapid/significant increase in summit-level winds particularly between midnight and early tomorrow afternoon. There is a chance that winds will begin to gradually weaken as the low dissipates over the next 24 hours. However, energy pouring out of the the right jet exit region will help tighten the wind gradient along the eastern flank of the ridge beginning Friday night. There is a chance that winds will increase toward 50-70+ mph for Saturday and Sunday night. Regardless, moderate/strong winds will contribute to boundary layer turbulence and mostly poor/bad seeing throughout the forecast period. A rather stable air mass, combined with the strong winds and pockets of mid-level moisture passing throughout may also allow for the development of lenticular clouds over the Big Island summits, mainly for tomorrow evening and again over the weekend.
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)
Wed Jan 19 - 2 PM0-20Clear0 / 02.5NNW/10-20NaN2-4
8 PM0-5Clear0 / 0-3NNW/15-300.6-14-6
Thu Jan 20 - 2 AM0-5Clear0 / 0-3NNW/20-350.8-1.24-6
2 PM0-20Clear0 / 03N/35-50NaN4-6
8 PM0-5Clear0 / 0-0.5NNE/35-501-23.5-4.5
Fri Jan 21 - 2 AM0-5Clear0 / 0-0.5NNE/30-451-23.5-4.5
2 PM0-20Clear0 / 05N/15-30NaN2-4
8 PM0-5Clear0 / 00N/10-200.5-0.92-3
Sat Jan 22 - 2 AM0-5Clear0 / 0-1NNW/15-300.6-12-3
2 PM0-20Clear0 / 02NNW/30-45NaN2-3
Sun Jan 23 - 2 AM0-5Clear0 / 0-3NNW/40-601-21.5-2.5
2 PM0-20Clear0 / 01NNW/35-50NaN2-3
Mon Jan 24 - 2 AM0-5Clear0 / 0-2N/50-701-31.5-2.5
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
Wed Jan 19 - Thu Jan 20 18:16 19:23 5:43 6:50 19:47 N/A 94 10 09.8 16 51
Thu Jan 20 - Fri Jan 21 18:16 19:24 5:43 6:50 20:41 N/A 88 10 58.7 12 00
Fri Jan 21 - Sat Jan 22 18:17 19:24 5:43 6:50 21:35 N/A 81 11 46.5 6 35
Sat Jan 22 - Sun Jan 23 18:18 19:25 5:43 6:50 22:28 N/A 72 12 33.9 0 47
Sun Jan 23 - Mon Jan 24 18:18 19:25 5:43 6:50 23:23 N/A 62 13 21.9 -5 07
Forecast Issued by: Ryan Lyman
Next update at 5 PM HST Wednesday 19 January (0300 UTC Thursday 20 January) 2022.
Additional Information
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