Current Conditions
Temp-1.5 C
RH99 %
WindSSE 47 mph
Mauna Kea Observatories Forecast
4 PM HST Monday 19 March (0200 UTC Tuesday 20 March) 2018
Chances for fog this evening
Cloud Cover and Fog/Precipitation Forecast
High clouds from the WSW will continue to cross the summit sky through this evening possibly breaking down and clearing through the first part of the night.
Summary of Key Meteorological Variables
Summit temperatures will be near -3 C this evening and -2.5 tonight. Winds will be from the WNW at 25-35 mph with possible higher gusts. Precipitable water is expected to still exceed 4 mm, and observing conditions will continue to be poor.
The latest sounding shows a saturated low level atmosphere (below 700mb) and a wet profile above. It is likely that moisture will linger at the summit level into the evening hours today, and there is also a small chance for thunderstorms to develop along the slope later this afternoon/evening. The mid level airmasses are expected to dry some during the second half of tonight, through tomorrow and possibly Wednesday, and the atmosphere to slightly stabilize. The airmasses will destabilize again and moisture will increase from mid week and onward as a front will interest the area through the coming weekend.

High clouds from the WSW will cross the summit sky today and will be breaking down through this evening, possibly leaving mostly clear skies during the second half of the night (~ after 10pm) . More high clouds, from the west will approach the area tomorrow evening and will thicken in time, blanketing at least half of the summit sky then. Sky will be completely covered by Thursday and through the coming weekend. Expect extensive daytime clouds through the forecast period.

Precipitable water will continue to exceed 4 mm throughout the forecast period perhaps lingering close to 4mm tonight.

Observing conditions will remain very poor throughout the next five nights as surface wind increase and remains sustained to strong throughout, while moisture and clouds will continue to still interest the area.

Not much is changed since the morning forecast... The high pressure North of the State will slowly shift Southeastward through this week increasing surface gradients and resulting in stronger, moderate to sustained, at times strong, winds at the summit throughout. A low pressure system to the NW is advecting moisture and high clouds over the summit. These clouds are expected to break down some through late today while a new bout is expected for tomorrow evening. Conditions will start degrading further as a front will be approaching the State from the West on Thursday. More organized clouds, deep moisture and inclement weather will therefore interest the area then, continuing this spell of poor observing conditions at the summit of Mauna Kea.
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 Mar 19 - 8 PM60-805-760 / 20-3WSW/25-401.3-1.710-14
Tue Mar 20 - 2 AM10-305-740 / 0-2.5WNW/25-401-1.44-8
2 PM40-604-750 / 102WNW/25-40NaN6-10
8 PM50-705-740 / 0-3.5NW/25-400.7-1.14-8
Wed Mar 21 - 2 AM60-805-730 / 0-2NW/20-351.1-1.54-8
2 PM40-604-760 / 52.5NW/20-30NaN6-10
8 PM30-505-740 / 0-1NW/15-250.6-18-12
Thu Mar 22 - 2 AM30-505-730 / 0-1.5WNW/15-250.6-18-12
2 PM50-704-770 / 201W/15-25NaN10-14
Fri Mar 23 - 2 AM80-1004-880 / 50-2WSW/15-251-1.410-14
2 PM80-1004-890 / 600WSW/20-35NaN10-14
Sat Mar 24 - 2 AM80-1004-995 / 90-3SW/30-451-1.414-20
2 PM80-1004-9100 / 90-1SSE/25-40NaN14-20
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 Mar 19 - Tue Mar 20 18:42 19:46 5:13 6:17 N/A 21:02 9 2 15.5 8 00
Tue Mar 20 - Wed Mar 21 18:42 19:46 5:12 6:16 N/A 21:59 16 3 07.9 12 03
Wed Mar 21 - Thu Mar 22 18:42 19:47 5:11 6:15 N/A 22:58 25 4 02.7 15 30
Thu Mar 22 - Fri Mar 23 18:42 19:47 5:10 6:14 N/A 23:58 35 4 59.7 18 06
Fri Mar 23 - Sat Mar 24 18:43 19:47 5:09 6:13 N/A 0:59 47 5 58.9 19 38
Forecast Issued by: Tiziana Cherubini
Next update at 10 AM HST (2000 UTC) Tuesday 20 March 2018.
Additional Information
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