Current Conditions
Temp2.6 C
RH31 %
WindNE 41 mph
RoadOpen (4x4)
Mauna Kea Observatories Forecast
4 PM HST Thursday 21 June (0200 UTC Friday 22 June) 2018
Cloud Cover and Fog/Precipitation Forecast
Summit skies will be predominantly clear tonight.
Summary of Key Meteorological Variables
Summit temperature will be near 4.5C this evening and 3.5C tonight and tomorrow morning. Precipitable water will linger close to 2.5m through the night. Winds from the NE will be increasing in speed through this evening and possibly reach the moderate 15/20 to 25/30mph range. Seeing will be average but variable, more so as the night progresses.
The tradewind inversion will continue to cap the bulk of the low level moisture below summit level through the forecast period. The inversion is expected to rise and weaken some from late tomorrow and through the weekend as an upper level disturbance approaches the Hawaii from the East, as a result moisture might increase some and so daytime clouds.. The tradewind inversion is not expected to completely vanish.

Summit skies will be predominantly clear throughout the forecast period. Some high clouds might start being visible along the Eastern horizon late on Sunday.

Precipitable water will be lingering close to 2.5 mm tonight and 3 mm on Friday night. It is expected to quickly drop to the 1 to 1.5 mm range for the following two nights, possibly dipping even more and lingering close to 1 on Monday night.

Observing conditions will be average but variable tonight as winds at the surface increase some and stear some boundary layer turbulence. These conditions are likely to worsen some tomorrow night (more variability) and return as average observing conditions for the remaining nights.

Not much is changed since the morning forecast... The current weather scenario is dominated by a strong surface high passing north of the Hawaiian's chain. This will ensure atmospheric stability but will also thight the gradients and increase surface wind speed at the summit for the coming 2/3 days. So far the projection is for moderate winds and the latest cycle confirmed it. Also an upper level low is expected to approach the island from the East by late tomorrow and wear off to the north, leaving the islands on its left, by Sunday. It is not expected to greatly affect the summit weather if not for a temporary increase in clouds over part of the sky by the end of the weekend. Tredewind inversion will also weaken some during its transition, but should remain strong enought to cap low level moisture below summit level.
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)
Thu Jun 21 - 8 PM0-20Clear0 / 04.5NE/10-150.55-0.952.5-3
Fri Jun 22 - 2 AM0-20Clear0 / 03.5NE/15-250.45-0.852.25-2.75
2 PM0-20Clear0 / 09ENE/15-25NaN1.5-2.5
8 PM0-20Clear0 / 02.5E/20-300.55-0.953-4
Sat Jun 23 - 2 AM0-20Clear0 / 02E/15-250.6-13-4
2 PM0-20Clear0 / 08NE/10-20NaN1-2
8 PM0-20Clear0 / 02NE/15-250.5-0.91.5-2
Sun Jun 24 - 2 AM0-20Clear0 / 01NE/15-250.4-0.81-1.5
2 PM0-20Clear0 / 08NE/10-20NaN1-2
Mon Jun 25 - 2 AM10-307-80 / 02ENE/15-250.4-0.81-1.5
2 PM10-306-80 / 08NE/10-20NaN1-2
Tue Jun 26 - 2 AM20-406-80 / 02E/10-200.4-0.80.9-1.3
2 PM10-307-80 / 07SE/10-20NaN2-3
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
Thu Jun 21 - Fri Jun 22 19:14 20:28 4:20 5:34 N/A 2:05 70 13 37.3 -5 19
Fri Jun 22 - Sat Jun 23 19:14 20:28 4:20 5:34 N/A 2:44 79 14 26.2 -9 37
Sat Jun 23 - Sun Jun 24 19:14 20:28 4:21 5:35 N/A 3:25 87 15 15.4 -13 28
Sun Jun 24 - Mon Jun 25 19:14 20:28 4:21 5:35 N/A 4:07 93 16 05.2 -16 40
Mon Jun 25 - Tue Jun 26 19:14 20:28 4:21 5:35 N/A 4:51 97 16 56.0 -19 07
Forecast Issued by: Tiziana Cherubini
Next update at 10 AM HST (2000 UTC) Friday 22 June 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.
NWS Hawaiian Islands Synoptic Discussion and Guidance
Honolulu National Weather Service Data and Products