Warnings
Blizzard-like conditions.

Cloud Cover and Precipitation Forecast
Moderate to heavy snow, ice, thick clouds, and extensive fog is penciled in for tonight. Thunderstorms (possibly severe) are also expected primarily between noon and midnight.

Summary of Key Meteorological Variables
Summit temperatures will be near -2 C this afternoon, -4 C tonight, and -6 C tomorrow morning. Precipitable water is expected to > 10 mm for the night. Summit winds will exceed 50 mph through the night, with shear near 10 to 20 mph.

Discussion
The atmosphere near the summit is expected to be saturated and unstable for the next 24 hours. As a result, moderate to heavy snow, extensive fog, thunderstorms (possibly severe) and ice are all penciled in between noon today and sunrise/noon tomorrow. The inversion is now expected to slowly build in at 6-8 thousand feet while summit-level humidity plummets toward 10% for Saturday night, and possibly into Sunday night. While this would normal call for dry and stable conditions, I will still say there is a chance for fog and ice on those nights due to the close proximity of wet/unstable conditions. Slight instability is expected to build in aloft while a band of moisture moves in from the southeast. Thus, the odds on fog and precipitation will increase slightly for Monday and Tuesday night.

Thick clouds will block all of the sky for tonight. Fortunately, all of these clouds are slated to drift east of the Big Island after noon tomorrow. Thus, only residual summit/mid-level clouds will likely linger around the area for that night. These clouds should be very minimal and short-lived as strong winds will tend to tear them apart. Another patch of post-frontal scattered mid/upper-level clouds are expected to build in just west and/or over the summit for Sunday night. This may increase cloud cover slightly for that night. Then more high clouds are expected to become more organized to the southwest and possibly move over the summit for next week Monday, Tuesday, and especially Wednesday night.

Precipitable water is expected to increase to more than 10 mm for tonight then rapidly decline toward 0.75 mm for Saturday night. It is then projected to increase to 3-4 mm for Sunday and Monday night, then drop toward 2.5-3.5 mm for Tuesday night. Again, there is still a bit of uncertainty for Saturday night's forecast, in which case PW could be much more than the given value.

Observing won't be possible tonight (due to the blizzard-like conditions) and probably tomorrow night (due to the winds and the possibility for fog). Nonetheless, expect bad/lousy seeing due to wind shake and slight instability/turbulence aloft for Saturday night. Improving conditions (i.e. drop in winds) and weak to moderate shear/turbulence in the free atmosphere will likely for average seeing for the following three nights.

A relatively strong cold-front will continue to march through the Islands over the next 24 hours. It is expected to pass through the Big Island probably between midnight and sunrise tomorrow. While the atmosphere near the Big Island is somewhat stable at the moment, that will likely change probably within the next 3 hours or so. For one, southerly winds ahead of the front will continue to draw moisture up from the tropics and help saturate the atmosphere. Secondly, the front/low will continue to push colder temperatures aloft over the Big Island. Third, daytime heating will well aid in developing afternoon convection/thunderstorms, which could be severe given the building moisture and the instability in the area. Lastly, deep organized convection ahead of the front will likely pass through the Big Island probably between this early evening and midnight tonight. Consequently, I expect summit-level humidity will continue to hover near 80-100% probably for the next 24 hours. I also expect moderate to heavy snow to blanket the mountain probably down to 11 thousand feet during this time. And as winds are projected to top 50 mph, blizzard-like conditions are penciled in for the night. All in all, I wouldn't recommend that anyone should be at the summit over the next 18-24 hours. Latest model runs have shown very consistent results for the following 4 nights, which, for the most part, are positive. Summit-level humidity is expected to rapidly decline as the front drifts east of the Big Island around noon tomorrow. While this seems reasonable, I still have a few problems with this projection as I suspect residual mid-level moisture will still linger in the area. Yes, strong winds may help the drying process, but these winds will probably limit observing for that night. Sunday/Monday could be OK as most of the moisture will have dissipated and the inversion will have reestablished itself at 8-10 thousand feet. But come Tuesday, tonight's front is expected to retrograde back westward and over the Big Island. This extra mid/low-level moisture combined with the a new source of instability (i.e. another trough to the west) could bring another round of fog to the summit for that night.

Astronomical Observing Quality Guidance
Vertical Profiles from MM5 (vertical coordinate is pressure in mb):

Tonight's (Friday Night) Collage	NOT AVAILABLE
Thursday Night's Collage (available after 0800 HST on Thursday)	Seeing Cn2
Friday Night's Collage (available after 0800 HST on Friday)	Seeing Cn2