Current Conditions
Temp11.4 C
RH15 %
WindSW 11 mph
RoadOpen (4x4)
Mauna Kea Observatories Forecast
09 AM HST (1900 UTC) Thursday 21 March 2019
Warning(s)
None
Cloud Cover and Fog/Precipitation Forecast
The summit will be clear, dry and stable through the night.
Summary of Key Meteorological Variables
Summit temperatures will be near 10.5 C this afternoon, 3.5 C this evening and 3 C tomorrow morning. Winds will be from the NNW at 5-15 mph. Seeing will be average (0.5-0.6) through the night. Precipitable water will range between 0.5 and 1 mm.
Discussion
The tradewind inversion will continue to ensure a dry and stable environment throughout most of this forecast period. Nevertheless the inversion is expected to weaken and lift, without vanishing altogether, from late Saturday and through the weekend, increasing moisture and the chances for some daytime clouds at the summit then. The models project the inversion to remain somewhat elevated and weakened as the front stalls north of the islands through the beginning of the coming week and before another upper level disturbance nears the island mid of next week.

Summit skies will be predominantly clear through the next two days. High clouds will be visible along the northern horizon from late Friday and will near during Saturday and Sunday but the bulk of them should remain North of the Big Island and summit skies will only be partially interested. Clearing will follow through the middle of the coming week.

Precipitable water will be in the 0.5 to 1 mm range tonight. It will linger close to 1 mm (0.8-1.2mm) on Friday night and 1.5 mmm on Saturday night, to then range between 1.75 and 2.25 mm on Sunday night and between 1 and 1.5 mm on Monday night.

Observing conditions will be average/good tonight as very dry, stable and calm conditions continue at the summit. The contributions from the free atmosphere might increase some even from tonight, but more so from tomorrow night and through the weekend as shear aloft gradually increases. A positive trend is expected on Monday night.

A dry and stable airmass remains in the area as the sub tropical ridge lays through the middle of the islands. As the upper level trough in the westerly moves eastward so does its associated front, which is expected to sweep by the islands through the weekend. Although it is projected to remain rather north and not affect much the summit weather, it will destabilize a bit the inversion, weakening and lifting it. As a result PW will increases a bit and some daytime clouds might appear through the weekend. High clouds might also be visible along the northern horizon and might only partially interest the summit on the weekend nights. Shear aloft though will gradually increases from today through the weekend, adding a contribution to the week ground layer turbulence and possibly variability, making the weekend nights less than optimal as seeing is concerned. The front is supposed to stall north of the State and slowly moves easterd pushed by yet another upper level trough/front which might interest the area during the middle of the coming week.
WRF Astronomical Observing Quality Guidance
Cloud Cover and Precipitable Water Analyses
MK CN² Profiles
5 Day Forecast Summary (Graphical Trend)
HST Cloud Fog/Precip Temp Wind Seeing PW
Cover (%) Height (km) Probability (%) (Celcius) (Dir/MPH) (Arcseconds) (mm)
Thu Mar 21 - 2 PM0-20Clear0 / 010.5WNW/0-10NaN0.9-1.3
8 PM0-10Clear0 / 03.5NW/5-150.45-0.750.5-1
Fri Mar 22 - 2 AM0-10Clear0 / 03NNW/5-150.4-0.70.5-1
2 PM0-20Clear0 / 08.5N/0-10NaN1-2
8 PM0-10Clear0 / 03.5NW/0-100.5-0.80.8-1.2
Sat Mar 23 - 2 AM0-10Clear0 / 03WNW/5-150.45-0.750.8-1.2
2 PM0-20Clear0 / 07NNE/0-10NaN1-2
8 PM10-207.5-80 / 02.5NE/0-100.45-0.851.25-1.75
Sun Mar 24 - 2 AM20-407-80 / 01.5NNE/0-100.5-0.91.5-2.5
2 PM30-507-80 / 05E/0-10NaN2-3
Mon Mar 25 - 2 AM30-506.5-80 / 00.5W/5-150.6-11.75-2.25
2 PM20-406.5-80 / 05WNW/5-15NaN1.5-2.5
Tue Mar 26 - 2 AM10-307.5-80 / 01NW/5-150.5-0.91-1.5
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
Thu Mar 21 - Fri Mar 22 18:42 19:46 5:11 6:15 19:31 N/A 97 13 23.7 -3 36
Fri Mar 22 - Sat Mar 23 18:42 19:47 5:10 6:15 20:31 N/A 92 14 18.5 -8 49
Sat Mar 23 - Sun Mar 24 18:43 19:47 5:09 6:14 21:30 N/A 85 15 12.9 -13 24
Sun Mar 24 - Mon Mar 25 18:43 19:47 5:08 6:13 22:28 N/A 76 16 07.0 -17 07
Mon Mar 25 - Tue Mar 26 18:43 19:48 5:07 6:12 23:24 N/A 67 17 01.0 -19 51
Forecast Issued by: Tiziana Cherubini
Next update at 5 PM HST Thursday 21 March (0300 UTC Friday 22 March) 2019.
Additional Information
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This message is also available at the MKWC road conditions page.
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