Discussion
While there is a good possibility that the upper air mass will continue to slowly dry out, the inversion is expected to fall apart, allowing the low-level cloud field to deepen over the next 2-3 nights. As a result, humidity will continue to linger near 60-80% and there is a moderate/high risk for periods of fog/ice at the summit mainly over the next 2 nights. Light flurries/rain is also possible mainly around Tuesday evening. The inversion will begin to rebuild, decreasing the risk for moisture at the summit through Wednesday night, and will likely allow humidity to settle back in near 10-20% over the following 2 nights. Extensive daytime clouds are expected through Tuesday, then will taper over the next 2 days, then become minimal and short-lived for Friday and over the weekend.
Scattered mid/upper-level clouds will continue to build in from the SW, passing over/near the summit area for tonight. There is a possibility that more broken mid/upper-level clouds will pass through the area for tomorrow night, then shift eastward on Wednesday, leaving mainly residual pockets of mid-level clouds in the region for that night. Mostly clear skies will prevail Thursday and especially Friday night.
Precipitable water is expected to exceed 4 mm probably into Thursday evening, but could slip toward 2 mm by sunrise Friday and to 1 mm by later that night.
Despite mostly calm/laminar westerly flow in the free atmosphere, a weak/elevated inversion, combined with linger mid-level moisture will likely contribute to poorer than average seeing over the next 2 nights. There is a good chance that seeing will improve as the air mass dries/stabilizes over the next 2 nights, and could settle in around 0.4 arcseconds (or better) for Friday night.
No change since the morning forecast...Upper-level flow will begin to transition to a more zonal orientation over the course of the week, but not before a short-wave trough (SWT) passes through over the next 2-3 days. This SWT will prevent the ridge from restrengthening, and will help deepen the low-level cloud field over this period. This will likely erode the inversion, allow humidity to linger near 80% and could easily result in more fog/ice at the summit mainly over the next 2 nights. Precipitation is unlikely, mainly due to the lack of organized mid-level moisture in the area, but could happen should an isolated pocket of convection develop over/near the summit, mainly around tomorrow afternoon/evening. The atmosphere is set to stabilize as the short-wave trough shifts east of the Big Island around Wednesday afternoon/evening, which could allow the ridge building in from the west to expand. This will help augment the subsidence in the area and rebuild the inversion near 7-8 thousand feet by Thursday evening, ensuring dry/stable summit conditions probably through the remainder of the week. PW is expected to exceed 4 mm probably through Thursday evening, but should slip to 1 mm or less through Friday night. Seeing, on the other hand, will also not benefit from the residual moisture in the area and elevated inversion over the next 2 nights, but could improve as the atmosphere stabilizes for Wednesday and Thursday night. There is a resonable chance that seeing will slip to 0.3-0.4 arcseconds as very calm flow and stabilize skies prevail over the early part of the weekend.
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