Mauna Kea Weather Center Forecast

Mauna Kea Observatories Forecast
5 PM HST Saturday 19 April (0300 UTC Sunday 20 April) 2014

Warning(s)
Increasing winds tomorrow

Cloud Cover and Fog/Precipitation Forecast
The summit will remain dry and stable, but broken mid/upper-level clouds will contribute to extensive cloud cover and/or periods of overcast skies through the night.

Summary of Key Meteorological Variables
Summit temperatures will be near 2.5 C this evening and 2 C tomorrow morning. Winds will be from the ENE at 10-20 mph, with seeing around 0.7 arcseconds, while precipitable water is expected to exceed 4 mm through the night.

Discussion
The tradewind inversion will continue to cap low-level moisture at or below 10 thousand feet and keep the mid/summit-level air mass predominately dry and stable through most of the next 5 nights. However, there is slight possibility that moderate/strong winds just below the summit will help push moisture beyond the inversion, perhaps allowing for short-lived fog on Sunday night; precipitation is not expected. Some minor afternoon clouds are possible for tomorrow, but will become minimal and short-lived thereafter.

Broken mid/upper-level clouds will continue to pass over the summit area contributing to extensive cloud cover or even periods of overcast skies through Monday afternoon. The high clouds are slated to shift eastward Monday evening, but there is a possibility for linger patches of mid-level clouds in the area through Tuesday night. Clear skies are likely for Wednesday night.

See table/graph for the seeing and precipitable water forecast, and there will be no MET discussion today.

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
HST	Cover (%)	Height (km)	Probability (%)	(Celcius)	(Dir/MPH)	(Arcseconds)	(mm)
Sat Apr 19 - 8 PM	80-100	7-10	0 / 0	2.5	E/10-20	0.5-0.9	4-6
Sun Apr 20 - 2 AM	80-100	6-10	0 / 0	2	ENE/10-20	0.5-0.9	4-6
2 PM	80-100	4-10	25 / 0	7	ENE/15-30	NaN	4-8
8 PM	80-100	6-10	30 / 0	1.5	ENE/20-35	0.7-1.3	4-6
Mon Apr 21 - 2 AM	80-100	6-10	30 / 0	1	ENE/20-35	0.7-1.3	4-6
2 PM	60-80	6-9	0 / 0	6	E/20-35	NaN	4-6
8 PM	50-70	6-8	0 / 0	2	ESE/20-35	0.6-1	3.5-4.5
Tue Apr 22 - 2 AM	40-60	6-8	0 / 0	2	ESE/15-30	0.5-0.8	3.5-4.5
2 PM	40-60	6-8	0 / 0	6.5	SE/5-15	NaN	3.5-4.5
Wed Apr 23 - 2 AM	20-40	6-7	0 / 0	1.5	ESE/5-15	0.5-0.9	3.5-4.5
2 PM	20-40	6-7	0 / 0	6.5	W/5-15	NaN	3-5
Thu Apr 24 - 2 AM	0-20	6-7	0 / 0	1	E/5-15	0.5-0.9	3-5
2 PM	0-20	Clear	0 / 0	6	E/5-15	NaN	3-5

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
Sun Apr 20 - Mon Apr 21	18:51	19:58	4:43	5:50	0:01	N/A	60	19 23.8	-17 14
Mon Apr 21 - Tue Apr 22	18:51	19:58	4:42	5:50	0:52	N/A	48	20 21.5	-14 33
Tue Apr 22 - Wed Apr 23	18:51	19:59	4:42	5:49	1:41	N/A	37	21 17.5	-11 03
Wed Apr 23 - Thu Apr 24	18:52	19:59	4:41	5:48	2:27	N/A	26	22 12.0	-6 58
Thu Apr 24 - Fri Apr 25	18:52	20:00	4:40	5:47	3:12	N/A	17	23 05.2	-2 33

Forecast Issued by: Ryan Lyman
Next update at 10 AM HST (2000 UTC) Monday 21 April 2014.

Additional Information
For public road conditions and snow report message please call (808) 935-6268.
This message is also available at the MKWC road conditions page.
NWS Hawaiian Islands Synoptic Discussion and Guidance
Honolulu National Weather Service Data and Products

Current Conditions
Temp		6.9 C
RH		16 %
Wind		ENE 0 mph
Road		Open