Warnings
Chance for fog and light snow for the night.
Possibility for afternoon thunderstorms.

Cloud Cover and Precipitation Forecast
There is a chance for light snow and periodic fog through the night. There is a good chance for a partial clearing for the first few hours of tonight, but more

Summary of Key Meteorological Variables
Summit temperatures will be near 3 C today, -1 C tonight, and -1.5 C tomorrow morning. Precipitable water is expected to be in the 5 to 7 mm range for the night. Winds will be from the South at 20 to 30 mph for today, and SW at 15 to 25 mph for tonight, 25 to 35 mph tomorrow morning. Shear is expected to be between 50 to 60 mph tonight and 35 to 45 mph tomorrow morning.

Discussion
While the tradewind inversion will persist at 7-8 thousand feet during the next 24 hours, mid-level moisture will continue to move in from the west through Saturday. Nonetheless, there is a chance for isolated thunderstorms this afternoon, and periodic fog/uniform light snow throughout tonight. Instability will move in from the northwest tomorrow, which will help to erode the inversion and saturate the atmosphere around noon tomorrow. A band of deep/strong convection will then pass through the Islands tomorrow night and into Saturday. Thus, isolated thunderstorms are again likely tomorrow afternoon. This will be followed by moderate to heavy snow, extensive fog, ice, and widespread thunderstorms for tomorrow night and possibly into noon on Saturday. Snowfall after that should be light/minimal, but isolated thunderstorms, periodic fog, and ice will likely continue for the next 3 nights.

A temporarily relief in the thick uniform high clouds is expected to occur probably for the next 12 hours. While scattered to broken mid-level clouds will likely linger in the area, the skies may actually be visible for the first half of tonight. However, more thick clouds are slated to slide in from the northwest during the second half of the night, and block 90-100% of the sky between 3-5 am tomorrow and sunrise on Saturday. There is a chance for clearing as most of the high clouds shift off toward the east during the following 2-3 nights. But, residual slow-moving mid-level clouds will still linger in the area probably through Tuesday night. In addition to this, more high clouds are expected develop over the Islands and/or move in from the southwest on Tuesday/Wednesday of next week.

Precipitable water is expected to increase from 5-7 mm for tonight to more than 10 mm for tomorrow night. Large uncertainties for the following 3 nights as the latest model run has PW dropping toward 1 mm as the dry side of a low shifts over the summit. I find that to be highly suspicious and thus decided that PW will likely be more than 4 mm for the following 3 nights (although there is a possibility that it could dip toward 3 mm on Sunday night).

Observing may actually be possible this evening, however, seeing will likely be poor/bad due to the moisture aloft and moderate turbulence/shear in the free atmosphere. Moreover, thick clouds are expected to move in during the second half of the night. While I still don't think observing will be possible on Friday and Saturday night (due to snow/thunderstorms/fog/ice/winds/clouds and fog/ice/winds, respectively), seeing will be terrible and highly variable on either night as pockets of turbulence, moisture, and instability persist in the free atmosphere. Weak to moderate shear is expected for Sunday and Monday night, but pockets turbulence could still linger in the area for those nights. Thus, seeing will probably be still variable (although not to the same extent) and poor/bad.

Aside from tomorrow night, the forecast for the next 5 nights are rather difficult...A deep strong trough is still slated to dig in over the Islands later tomorrow and cut-off into cold-core low on Saturday. In the process it will send a band of thunderstorms/convection through the Island chain, with this band passing over the summit tomorrow night. This will create blizzard-like conditions as winds top 50 mph, extensive fog make for very poor visibility, and moderate to heavy snow blankets most of the mountain above 11 thousand feet. Still the atmosphere will likely be highly unstable and very saturated probably between noon tomorrow and noon on Sunday. Thus, isolated thunderstorms, similar to the Jan 25 hailstorm, are possible particularly during the afternoon hours when daytime heating/forcing is most prominent. At any rate, Friday night is pretty much figured out. As for tonight...summit-level humidity has temporarily decreased as most of the mid-level moisture has slid northward, which has me a little stumped. I still expect humidity to steadily increase as the trough digs in from the northwest and pushes this moisture over the Islands during the next 24 hours. In addition to this, another round of thick clouds will also drop through the Islands for tomorrow and into Saturday. Now for Saturday night and onward...the big question for those nights is: where is the cut-off low going to be situated? Every other model run places the low 200-300 km east of the Big Island, situating the summit on the dry/stable side of the low; while the other runs places the low over or west of the Big Island, situating the summit on the wet/unstable side. While I do think the former projection is possible given the trough's trajectory, the global model does not take into account one crucial factor: the affects of our rock and its mountains. Time and time again the mountain has served as a ramp to incoming unstable low/mid-level clouds that helps to maintain a moist environment at the summit days after a low passed through and lingers just east of the Island. Furthermore, another trough is still expected to dig in behind this weekend's trough/low and reinitiate the deep southwesterly flow probably through the middle of next week. Consequently, I don't think conditions will improve much after the front/band passes through the summit on Friday night. Precipitation will likely be limited, but fog, high humidity, ice, and isolated thunderstorms will likely continue.

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

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