Latest Forecast for Mauna Kea Observatories
5 PM HST Thursday 10 January (0300 UTC Friday 11 January) 2019
Cloud Cover and Precipitation Forecast
The summit will remain clear, dry and stable through the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 4.5 C this evening and 4 C tomorrow morning. Winds will start out from the NNE at 5-15 mph, switching to a more ENE direction through the night. Seeing will be near 0.4-0.45 arcseconds, while precipitable water is expected to be in the 1-1.5 mm range for the night.
A strong well-defined tradewind inversion will continue to cap low-level moisture at or below 8 thousand feet and ensure the summit remains dry and stable through the next 5 nights. Daytime clouds will be minimal and short-lived throughout the forecast period.
Skies will remain predominately clear through the next 5 nights.
Precipitable water is expected to increase toward 1.2-1.4 mm for tonight, slip back toward 1 mm through Friday night, then dip toward 0.7-0.9 mm for the following 3 nights.
Very calm/stable skies with relatively laminar north to northwesterly flow will prevail in the free atmosphere, which should allow seeing to settle in near 0.4-0.45 arcseconds probably throughout the forecast period.
No change since the morning forecast...A fairly deep mid/low-level ridge will continue to sit almost directly over or just north of the Big Island and promote steady/strong large-scale subsidence in the area well into next week. This subsidence will help maintain a well-defined inversion near 7-8 thousand feet and ensure the summit remains dry/stable and relatively warm through the next 5 nights. Skies will also remain predominately clear as a zonal westerly jet well north of the state continues to shuttle high clouds away from the area during this time. This should also allow relatively weak/laminar northwesterly flow to prevail aloft, minimizing turbulence in the free atmosphere during this time. Weak (not dead) winds at the summit should also promote some sort of mixing at the summit, which should allow seeing to settle in near 0.4-0.5 arcseconds probably for the remainder of the week and into next week. PW, on the other hand, may spike toward 1.5 mm as a patch of mid-level moisture passes through for tonight. However, the deep subsidence in the area should help PW drive toward 1 mm by tomorrow night and 0.8 mm for the following 3 nights.