Latest Forecast for Mauna Kea Observatories
10 AM HST (2000 UTC) Tuesday 13 March 2018
Cloud Cover and Precipitation Forecast
Extensive fog, ice, thick clouds and light/moderate stratiform snow will continue to plague the summit today and through the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 0.5 C this afternoon, -0.5 this evening and 0C tonight. Winds will be from the SSW at 20-35 mph. Seeing and precipitable water are expected to exceed 1 arcsecond and 4 mm, respectively, through the night.
The airmasses over and around the Big Island will continue to be saturated and unstable, allowing extensive fog, ice and flurries/rain to plague the summit through at least Thursday night, perhaps even through Friday and the weekend nights. Short periods of heavy snow and convection are also possible at times through tomorrow. Moisture should decrease some Friday and Saturday but airmasses will be slow to dry, and more moisture could be advected over the area starting late on Saturday, early on Sunday. Extensive afternoon clouds are expected through Friday, but may taper some over the weekend.
Broken to overcast thick clouds will continue to pass over/linger near the summit, blanketing skies probably through Wednesday night. Clouds are expected to start thinning on Thursday and through Friday shifting eastward allowing skies to start opening up for that night and and through Saturday night.
Precipitable water will continue to exceed 4 mm throughout the forecast period.
A mixture of abundant moisture (particularly in the low-levels), strong mid-level turblence, boundary layer turbulence and/or instability will contribute to poor/bad seeing probably through Thursday night. There is a small/moderate chance for some improvement as the atmosphere begins to stabilize on Friday and Saturday night.
The deep moisture over the State will continue to plague the summit while slowly moving east-northeastward, advected and organized by the short-wave trough to the NW. An upper level low to the SW of the State associated with the shortwave will dissipate over the area by tomorrow/Thursday, therefore the air mass near the Big Island will remain saturated and unstable, allowing inoperable conditions to plague the summit probably through Thursday night. Blizzard-like conditions, with strong winds, extensive fog, heavy ice/rime and periods of moderate/heavy snow and convection along the eastern slopes and to the SW are also possible mainly as the low moves through the aread through tomorrow afternoon. There is a possibility that the air mass will warm-up a bit and winds will taper as the low rapidly dissipates then. A weak ridge building in from the SE will eventually settle in over the southern half of the State and perhaps begin to stabilize the air mass a bit by Friday, but there is a good chance that moisture will get caught up in the ridge and persist (while slowly detraining into the surrounding atmosphere) in the area well into the weekend.
Expect blizzard-like conditions probably through tomorrow and part of Thursday mostly fog and light rain into Friday night, with a slight overall improvement on Saturday.