Current Conditions
Temp-0.3 C
RH11 %
WindNW 61 mph
RoadOpen
Mauna Kea Observatories Forecast
10 AM HST (2000 UTC) Friday 06 March 2015
Warning(s)
Strong winds
Chance for fog/ice and flurries
Cloud Cover and Fog/Precipitation Forecast
There is a small risk for fog, ice and light flurries through the night. Broken mid/upper-level clouds will continue to block most of the sky throughout the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 0 C this afternoon and -3 C for the night. Winds will be from the west at 50-70 mph for today, tapering to 30-45 mph through the night. Precipitable water is expected to be in the 3-4 mm range, while seeing will exceed 1 arcsecond.
Discussion
Although the tradewind inversion will remain fairly well-defined near 8-9 thousand feet through tomorrow evening, mid/upper-level moisture/clouds passing to the south may allow for short-lived fog, ice and flurries for tonight (though the odds are small). The inversion is slated to breakdown, while this moisture/clouds slips northward, likely saturating most of the air mass between late Saturday evening and Monday afternoon/evening. This will significantly increase the risk for fog, ice, flurries and perhaps convection and heavy snow during that time. The inversion is slated to rebuild again early next week, but the moisture will still remain in the area, which may still allow for more short-lived fog, ice and light flurries during that time. Some afternoon clouds are possible over the next 2 days, will turn extensive for Sunday, then taper a bit for early next week.

Broken mid/upper-level clouds will continue to pass over and especially to the south of the Big Island, contributing to extensive cloud cover throughout the forecast period. There is a very good chance that these clouds will blanket summit skies especially for Saturday and Sunday night.

Precipitable water will linger in the 3-4 mm range for tonight then increase to 6+ for the remainder of the forecast period

Boundary layer and mid/upper-level turbulence will contribute to bad seeing through the next 5 nights.

A very large upper-level trough wil continue to wobble to the north of the state, promote steady, but relatively weak, instability in the area and allow a low to persist to the NNE probably into the second half of next week. It will also allow moderate/strong westerly winds to prevail at the summit through the next week or so. Fortunately, the eastern tip of the low-level ridge to the northwest will linger over/near the Islands, which will help to stabilize the atmosphere and maintain a farily well-defined tradewind inversion near 8-9 thousand feet for another 24-36 hours. This should minimize the risk for more fog, ice and flurries at the summit, despite a persistent band of thick mid/upper-level clouds/moisture lingering just south of the Big Island. That will change as a short-wave trough (SWT), embedded in the large trough, passes to the north and helps reinforce the low to the NNE beginning late tomorrow afternoon. This will reintensify low much closer to the state and pull the band of thick clouds/moisture back over the Big Island, saturating the air mass once again between late Saturday evening and around Monday afternoon. That will significantly raise the stakes on extensive fog, ice and flurries at the summit during that time. There is also a chance for periods of heavy snow and perhaps deep convection in the area mainly around Sunday. Drier conditions will likely return to the summit as the SWT shifts off toward the NE taking the low with it early next week. However, strong winds will continue to be an issue and there is a very good chance that the band of moisture/clouds will persist just SE of the Big Island through much of next week. There is also a possibility that another SWT will drag this band back over the summit area later next week...
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)
Fri Mar 06 - 2 PM70-905-960 / 200W/50-70NaN3-5
8 PM70-905-1020 / 15-3W/40-601-33-4
Sat Mar 07 - 2 AM70-905-1015 / 10-3W/30-451-23-4
2 PM80-1005-1050 / 250W/25-40NaN4-6
8 PM80-1005-1075 / 60-3WSW/30-451-24-6
Sun Mar 08 - 2 AM80-1004-1095 / 90-4WSW/35-501-36-10
2 PM80-1004-1095 / 90-2WSW/50-70NaN8-12
8 PM80-1004-1095 / 90-4WSW/50-701-38-12
Mon Mar 09 - 2 AM80-1004-990 / 75-5WSW/50-701-38-12
2 PM70-904-875 / 40-1W/50-70NaN8-12
Tue Mar 10 - 2 AM60-805-725 / 20-5W/50-701-34-8
2 PM60-804.5-725 / 20-1W/40-60NaN4-8
Wed Mar 11 - 2 AM60-805-725 / 20-6W/50-701-34-8
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
Fri Mar 06 - Sat Mar 07 18:38 19:42 5:24 6:28 19:24 N/A 97 12 17.2 -2 36
Sat Mar 07 - Sun Mar 08 18:38 19:42 5:23 6:27 20:13 N/A 94 13 03.4 -6 17
Sun Mar 08 - Mon Mar 09 18:38 19:42 5:22 6:26 21:02 N/A 88 13 50.5 -9 45
Mon Mar 09 - Tue Mar 10 18:39 19:43 5:21 6:26 21:52 N/A 81 14 39.0 -12 51
Tue Mar 10 - Wed Mar 11 18:39 19:43 5:21 6:25 22:44 N/A 72 15 29.3 -15 25
Forecast Issued by: Ryan Lyman
Next update at 5 PM HST Friday 06 March (0300 UTC Saturday 7 March) 2015.
Additional Information
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