Current Conditions
Temp0.1 C
RH100 %
WindW 16 mph
RoadClosed
Maunakea Observatories Forecast
5 PM HST Friday 03 December (0300 UTC Saturday 4 December) 2021
Warning(s)
Extensive fog/ice and flurries
Chance for convection and heavy snow
Strengthening winds
Cloud Cover and Fog/Precipitation Forecast
Extensive fog, clouds, ice and occasional flurries will continue to plague the summit through the night. There is an outside chance for convection and heavy snow toward the end of the night.
Summary of Key Meteorological Variables
Summit temperatures will be near -4 C this evening and -6 C tomorrow morning. Winds will be from the SW at 30-45 mph for this evening, increasing to 40-60 mph as the night progresses. Seeing and PW are expected to exceed 1 arcsecond and 4 mm, respectively, through the night.
Discussion
The atmosphere near the Big Island will remain saturated and unstable, allowing extensive fog, ice and flurries to plague the summit probably through the next 5 nights. There is also a possibility for convection in the area and periods of heavy snow at virtually anytime throughout the forecast period, but particularly between this afternoon and Saturday evening and again between Sunday afternoon and Tuesday morning. Extensive daytime clouds are expected throughout the forecast period.

Banding overcast clouds are set quickly develop overhead through today and will blanket summit skies throughout much of the next 5 nights.

Precipitable water is expected to linger near or exceed 4 mm throughout the forecast period.

A saturated/unstable air mass, combined with turbulent skies and eventually building boundary layer turbulence will contribute to bad seeing through the next 5 nights.

No change since the morning forecast...A strong low developing to the north will bring fresh widespread instability to the area and reorganize the residual moisture in the area into a rather deep/broad frontal band over the state. This band is set to stall out over the Big Island as the low becomes quasi-stationary to the north through tomorrow, then will begin to intensify and broaden as tropical moisture is drawn in from the south in response to the strengthening/deepening of the low between late Saturday night and Monday evening. The low will begin to weaken and retrograde westward thereafter, likely shifting the frontal band to the west of the Big Island around Wednesday/Thursday. Nevertheless, this frontal band will ensure that the air mass near the Big Island remains saturated/unstable, allowing extensive fog, ice and snow to plague the summit throughout the forecast period. Convection in the area and heavy snow are possible at virtually anytime throughout the forecast period, particularly as frontal band develops through tomorrow evening. A break in the convection is possible as the frontal band slides subtly eastward, but the influx of deep tropical moisture combined with building instability could bring more widespread/vigirous convection to the area and heavy snow at the summit between between Sunday evening and Tuesday morning. In addition to this, a very tight wind gradient along the southern fringe of the low will continue to settle in over the Big Island, strengthening summit winds over the next 48 hours. While winds may slowly subside as this tight wind gradient slips westward a tad thereafter, winds will may continue to top 50 mph through Monday morning and contribute to periods of blizzard-like conditions and/or deep drifts during that time (perhaps even into Tuesday morning).
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)
Fri Dec 03 - 8 PM60-804-9100 / 75-4SW/30-451-28-12
Sat Dec 04 - 2 AM80-1004-9100 / 90-6SW/40-601-38-12
2 PM80-1004-10100 / 95-3SW/60-80NaN8-12
8 PM80-1004-10100 / 75-5.5SW/70-901-38-12
Sun Dec 05 - 2 AM80-1004-10100 / 75-5SW/70-901-38-12
2 PM80-1004-10100 / 80-2SW/60-80NaN10-15
8 PM80-1004-10100 / 95-4SSW/40-601-310-15
Mon Dec 06 - 2 AM80-1004-10100 / 100-4SW/30-451-310-15
2 PM80-1004-10100 / 1001SSW/30-45NaN10-15
Tue Dec 07 - 2 AM80-1004-10100 / 95-2S/15-301-210-15
2 PM80-1004-995 / 902SSW/15-30NaN10-15
Wed Dec 08 - 2 AM60-804-890 / 650SSW/15-300.8-1.68-12
2 PM0-204-675 / 255SE/10-20NaN4-8
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
Sun Dec 05 - Mon Dec 06 17:52 19:00 5:26 6:34 N/A 19:40 6 19 00.6 -26 12
Mon Dec 06 - Tue Dec 07 17:52 19:01 5:26 6:35 N/A 20:47 13 20 05.0 -24 47
Tue Dec 07 - Wed Dec 08 17:52 19:01 5:27 6:35 N/A 21:52 22 21 05.6 -21 47
Wed Dec 08 - Thu Dec 09 17:53 19:01 5:27 6:36 N/A 22:54 32 22 01.5 -17 37
Thu Dec 09 - Fri Dec 10 17:53 19:02 5:28 6:36 N/A 23:51 42 22 53.1 -12 41
Forecast Issued by: Ryan Lyman
Next update at 10 AM HST (2000 UTC) Monday 6 December 2021.
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