Maunakea Observatories Forecast
5 PM HST Monday 13 May (0300 UTC Tuesday 14 May) 2024
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Warning(s)
Fog, ice and high humidity
Chance for flurries and convection
Cloud Cover and Fog/Precipitation Forecast
There is a high risk for more fog, ice and flurries throughout the night; shallow convection may also develop along the eastern skies this afternoon/evening. Patches of mid/low-level clouds will continue to linger and/or develop in the area through the night.
Summary of Key Meteorological Variables
Summit temperatures will be near -2 C this evening and -2.5 C tomorrow morning. Winds will be from the SSW at 10-20 mph for the first half of the night, switching to a more WSW direction for the second half. Seeing and PW are expected to exceed 1 arcsecond and 4 mm, respectively, throughout the night.
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Discussion
The atmosphere below 18 thousand feet will remain fairly saturated with an elevated/indistinct inversion, contributing to a high risk for fog, ice, high humidity and/or flurries at the summit probably through the next 5 nights. There is also a possibility for isolated convection developing in the area mainly for this evening and again on Wednesday. Extensive daytime clouds are expected throughout the forecast period.
Patchy clouds mainly up to 18 thousand feet will continue to linger in the area for this evening, but should push further off toward the NE skies for Tuesday night. However, there is a chance that deeper clouds will return to the area and/or develop along the NW skies for Wednesday and Thursday night. Thick clouds are also set to quickly build in from the south, likely contributing to extensive cloud cover through Friday night.
Precipitable water is expected to exceed 4 mm throughout the forecast period.
A mixture of boundary layer turbulence, instability and/or moisture will contribute to poor/bad seeing through the next 5 nights.
No change since the morning forecast...Although the mid/upper-level low to the NE will continue to dissipate and shift off toward the NE, a very distinct tropical upper-tropospheric trough (TUTT) will persist over the state, while another embedded low develops to the NW later in the week. This will allow mostly widespread instability to prevail in the area, and combined with lots of residual mid/low-level moisture, will prohibit/limit the inversion from restrengthening probably until late in the weekend, at the earliest. As a result, there is high risk for extensive fog, ice, high humidity and periods of light flurries at the summit over the next 5 nights. Isolated convection may also develop in the area, particularly along the eastern skies for this afternoon/evening, but should slip further off toward the NE as the night progresses and for tomorrow. The aformentioned new low digging in from the NW could introduce fresh instability to the area, which could allow for more convection to develop in the area, particularly along the NW to northern skies for over the remainder of the forecast period. Eventually, even deeper moisture/clouds is expected to build in from the south, which may saturated most of the air mass and perhaps contribute to overcast skies for Friday night.
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5 Day Forecast Summary (Graphical Trend)
| HST |
Cloud |
Fog/Precip |
Temp |
Wind |
Seeing |
PW |
| Cover (%) |
Height (km) |
Probability (%) |
(Celsius) |
(Dir/MPH) |
(Arcseconds) |
(mm) |
| Mon May 13 - 8 PM | 40-60 | 4-6 | 95 / 65 | -2 | SSW/10-20 | 0.8-1.6 | 6-10 |
| Tue May 14 - 2 AM | 20-40 | 4-5 | 90 / 40 | -2.5 | WSW/10-20 | 0.8-1.6 | 4-8 |
| 2 PM | 60-80 | 4-6 | 90 / 50 | 1 | W/15-30 | NaN | 6-10 |
| 8 PM | 0-20 | 4-5 | 75 / 25 | -2 | W/15-30 | 0.7-1.3 | 4-6 |
| Wed May 15 - 2 AM | 0-20 | 4-4.5 | 75 / 20 | -2.5 | WSW/20-35 | 0.8-1.6 | 4-6 |
| 2 PM | 70-90 | 4-7 | 95 / 60 | 1 | WSW/20-35 | NaN | 6-10 |
| 8 PM | 10-30 | 4-5 | 85 / 40 | -2 | WSW/20-35 | 0.8-1.6 | 4-8 |
| Thu May 16 - 2 AM | 10-30 | 4-5 | 85 / 40 | -2.5 | WSW/20-35 | 0.8-1.6 | 4-8 |
| 2 PM | 70-90 | 4-7 | 95 / 65 | 1 | WSW/15-30 | NaN | 6-10 |
| Fri May 17 - 2 AM | 10-30 | 4-5 | 80 / 40 | -2.5 | SW/15-30 | 0.7-1.5 | 4-8 |
| 2 PM | 60-80 | 4-6 | 90 / 50 | 2 | WSW/10-20 | NaN | 6-10 |
| Sat May 18 - 2 AM | 80-100 | 4-10 | 75 / 25 | -1 | WSW/10-20 | 0.7-1.3 | 6-10 |
| 2 PM | 80-100 | 4-10 | 90 / 60 | 3 | E/5-15 | NaN | 8-12 |
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Rise and Set times for the Sun and Moon
| Night (HST) |
Sun Set |
Twilight End |
Twilight Beg |
Sun Rise |
Moon Rise |
Moon Set |
Illumination (%) |
RA |
DEC |
| Mon May 13 - Tue May 14 |
19:00 |
20:10 |
4:26 |
5:37 |
N/A |
0:38 |
39 |
9 00.1 |
21 18 |
| Tue May 14 - Wed May 15 |
19:00 |
20:11 |
4:26 |
5:36 |
N/A |
1:16 |
49 |
9 48.2 |
16 58 |
| Wed May 15 - Thu May 16 |
19:00 |
20:11 |
4:25 |
5:36 |
N/A |
1:49 |
58 |
10 33.4 |
12 01 |
| Thu May 16 - Fri May 17 |
19:01 |
20:12 |
4:25 |
5:36 |
N/A |
2:21 |
67 |
11 16.6 |
6 39 |
| Fri May 17 - Sat May 18 |
19:01 |
20:12 |
4:24 |
5:35 |
N/A |
2:51 |
76 |
11 58.8 |
1 01 |
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Forecast Issued by: Ryan Lyman
Next update at 10 AM HST (2000 UTC) Tuesday 14 May 2024.
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Additional Information
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