Current Conditions
Temp1.1 C
RH96 %
WindSSE 9 mph
RoadOpen
Mauna Kea Observatories Forecast
5 PM HST Monday 21 July (0300 UTC Tuesday 22 July) 2014
Warning(s)
chances for fog/high humidity
Cloud Cover and Fog/Precipitation Forecast
Cloud cover will continue to be extensive through this evening and tonight as more mid/high clouds will continue to fill in from the SSW. Precipitation is unlikely but possible.
Summary of Key Meteorological Variables
Summit temperature will be near 4 C this evening and 2.5 C tonight and tomorrow morning. Precipitable water will exceed 4 mm throughout the night. Winds will be from the ESE at 10 to 20 mph. Observing conditions will remain poor.
Discussion
The latest Hilo sounding shows signs of slowly rebuilding tradewind inversion and signs of drying airmasses. Nevertheless the low level moisture supply will continue to linger around through at least tomorrow before slowly starting drying out. Therefore expect episodes of high relative humidity and possible fog tonight and Tuesday night. Conditions should continue to slowly improve over the following days as more stable and dry air masses settle in. Another bout of tropical moisture might interest the State by late this coming weekend and into the beginning of next week.

Mid/high clouds will continue to fill in from the SSW resulting in extensive cloud cover throughout tomorrow night. Cloud cover should start decreasing afterward and clearer skies are likely at least until the end of this week.

Precipitable water will exceed the 4 mm threshold through Tuesday night. It is projected to linger in the 3 to 4 mm on Wednesday and Thusday night. It might increase some and range between 3 and 5 mm on Friday night.

Overall observing conditions will remain poor/unoperable at least through tomorrow night. Lingering moisture and instability might still make it less than average for the rest of the forecast period but with more of a chance for operations then.

Not much is changed since this morning forecast... An upper level trough NW of the State will continue to move westward while weakening. While its influence on the State's weather is diminishing, it is still responsible for the advection of the large supply of low level moisture in the area and mid high clouds over the southern part of the State particularly and the Big Island. As a result the air masses over the Big Island are moist and somewhat unstable still. Episodes of fog and high humidity are therefore quite likely tonight and tomorrow, decreasing in time. The overall weather conditions will improve afterward with the air masses stabilizing slowly and clouds slowly clearing from the area. The global model project another area of tropical moisture reaching the State by the coming weekend and into the beginning of the next 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)
Mon Jul 21 - 8 PM60-805-1060 / 104E/5-150.7-1.14-12
Tue Jul 22 - 2 AM70-806-1040 / 52.5ESE/10-200.6-14-8
2 PM50-706-1060 / 207SE/5-15NaN4-10
8 PM60-805-1070 / 302.5E/5-150.55-0.954-10
Wed Jul 23 - 2 AM60-805-1050 / 101.5ENE/5-150.7-1.14-8
2 PM30-507-1030 / 09ENE/10-20NaN3-5
8 PM30-508-910 / 04.5ENE/15-250.45-0.853-4
Thu Jul 24 - 2 AM10-308-90 / 03ENE/10-200.4-0.83-4
2 PM10-308-930 / 012NE/10-20NaN3-5
Fri Jul 25 - 2 AM0-20Clear0 / 05ENE/10-200.4-0.83-4
2 PM0-20Clear20 / 011ENE/5-15NaN3-5
Sat Jul 26 - 2 AM10-308-90 / 03.5ENE/5-150.5-0.93-5
2 PM20-407-960 / 108NE/5-15NaN4-6
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 Jul 21 - Tue Jul 22 19:12 20:24 4:33 5:44 2:22 N/A 18 4 34.4 17 47
Tue Jul 22 - Wed Jul 23 19:12 20:24 4:33 5:45 3:10 N/A 11 5 25.7 18 24
Wed Jul 23 - Thu Jul 24 19:12 20:23 4:34 5:45 4:00 N/A 6 6 16.3 18 08
Thu Jul 24 - Fri Jul 25 19:11 20:23 4:34 5:46 4:49 17:39 2 7 06.0 17 04
Fri Jul 25 - Sat Jul 26 19:11 20:22 4:35 5:46 5:39 18:23 0 7 54.5 15 14
Forecast Issued by: Tiziana Cherubini
Next update at 10 AM HST (2000 UTC) Tuesday 22 July 2014.
Additional Information
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