Current Conditions
Temp5.8 C
RH39 %
WindSSW 10 mph
Mauna Kea Observatories Forecast
10 AM HST (2000 UTC) Thursday 26 February 2015
Cloud Cover and Fog/Precipitation Forecast
The summit will remain dry and stable, but there is a possibility for lingering patches of mid/upper-level clouds in the area through the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 5 C this afternoon, 0.5 C this evening and 0 C tomorrow morning. Winds will be from the nort at 5-15 mph, with seeing around 0.55 arcseconds. Precipitable water is expected to be in the 3.5-4.5 mm range for the night.
The tradewind inversion will continue to cap low-level moisture at or below 8 thousand feet and keep the summit dry and stable for another 24 hours. The inversion is then expected to fall apart as deep moisture and instability begins to congregate in the area over the following 24 hours. This will likely allow to turn mostly saturated, which will contribute to extensive fog, ice, high humidity, clouds and flurries at the summit for Friday night onward. Periods of heavy snow and convection in the area are also possible during this time, particularly for for Saturday night and around Tuesday/Wednesday of next week. Daytime clouds will be minimal and short-lived for today, but could pick up tomorrow and turn extensive for the remainder of the forecast period.

There is a possibility for patches of lingering mid/upper-level clouds in the area for tonight. Thicker clouds are slated to develop in the area through tomorrow night and are expected to contribute to overcast skies for the remainder of the forecast period.

Precipitable water is expected to linger near 4 mm for tonight and exceed 8 mm for the remainder of the forecast period.

Average-like seeing will prevail as minor turbulence persists in the free atmosphere for tonight. An influx of upper-level turbulence, moisture and instability will contribute to poor/bad seeing and/or inoperable conditions for the remainder of the forecast period.

Although the mid/low-level ridge will promote some degree of subsidence in the area and keep the summit dry/stable for tonight, lots of remnant moisture associated with a decaying low approaching for the east combined with instability from developing large-scale trough digging in from the northwest are expected to meet over the state during following 24 hours. This will help to erode the ridge as the large trough remains quasi-stationary to the northwest of the Islands over the weekend and probably well into next week. The air mass is expected to turn saturated and unstable, which will contribute to overcast skies, extensive fog, ice, high humidity and likely lots of flurries during that time. Two embedded short-waves are slated to further destabilize the atmosphere, which could allow for the development of convection in the area and perhaps periods of heavy snow at the summit mainly for Saturday/Sunday and again around Tuesday/Wednesday. The second short-wave is expected to reorganize the moisture in the area into a cold front and push it off toward the SE late Wednesday/early Thursday. While this could help to improve conditions at the summit by Thursday night, expect nearly inoperable conditions/skies between tomorrow evening and probably Wednesday night.
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 Feb 26 - 2 PM20-406-80 / 05N/5-15NaN4-6
8 PM10-306-80 / 00.5N/5-150.5-0.63.5-4.5
Fri Feb 27 - 2 AM10-306-80 / 00NNW/5-150.5-0.63.5-4.5
2 PM20-405-810 / 04WSW/0-10NaN4-8
8 PM40-605-850 / 25-1.5ENE/0-100.6-18-12
Sat Feb 28 - 2 AM60-804-975 / 50-2SW/5-150.8-1.68-12
2 PM80-1004-1095 / 900SSW/5-15NaN8-12
8 PM80-1004-1095 / 90-3SSE/10-201-28-12
Sun Mar 01 - 2 AM80-1004-1095 / 90-3SSW/10-201-28-12
2 PM80-1004-1095 / 90-1SW/10-20NaN8-12
Mon Mar 02 - 2 AM80-1004-1095 / 75-3SW/10-201-28-12
2 PM80-1004-1095 / 900SSW/10-20NaN8-12
Tue Mar 03 - 2 AM80-1004-1095 / 90-2WSW/5-151-28-12
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
Thu Feb 26 - Fri Feb 27 18:35 19:39 5:30 6:34 N/A 2:29 66 5 50.5 18 09
Fri Feb 27 - Sat Feb 28 18:35 19:40 5:29 6:33 N/A 3:18 75 6 43.0 17 40
Sat Feb 28 - Sun Mar 01 18:36 19:40 5:28 6:33 N/A 4:03 83 7 34.2 16 20
Sun Mar 01 - Mon Mar 02 18:36 19:40 5:28 6:32 N/A 4:46 90 8 23.9 14 15
Mon Mar 02 - Tue Mar 03 18:36 19:41 5:27 6:31 N/A 5:26 95 9 12.3 11 34
Forecast Issued by: Ryan Lyman
Next update at 5 PM HST Thursday 26 February (0300 UTC Friday 27 February) 2015.
Additional Information
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This message is also available at the MKWC road conditions page.
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