MKWC archive forecast page
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Please select a year and month and links of all available forecasts for that period will be given in the 'Select Forecast' menu.
Selection: 2003
 11
 Nov 19 2003 (afternoon)


Mauna Kea Forecast Latest Forecast for Mauna Kea Observatories
5 PM HST Wednesday 19 November (0300 UTC Thursday 20 November) 2003

Warnings
None

Cloud Cover and Precipitation Forecast
The summit will remain free of fog and precipitation through the night. Cloud cover is expected to decrease to < 10% as the high clouds to the north of the summit move away and dissipate through the night.

Summary of Key Meteorological Variables
Summit temperatures will be near -1 C for the night. Precipitable water is expected to be near 2.5 to 3.5 mm tonight and 1 to 1.5 mm tomorrow morning. Winds will be from the NNW at 25 to 35 mph, with shear between 40 to 50 mph.

Discussion
The inversion is expected to quickly strengthen this evening, and it should be at full strength at 6-7 thousand feet by 8-9 pm tonight. It will likely remain very strong through Friday night. As a result, fog or precipitation is not expected during this time. Several weak bands of low-level moisture are slated to move in from the northeast on Saturday and Sunday night. Although they will hardly affect the strength of the inversion, it may bring a slight chance for fog on those days/nights. Daytime clouds will be very minimal on Thursday and Friday, but could pick up a bit this weekend.

The scattered high clouds to the north of the summit are expected to move away and dissipate over the next few hours. This will leave mostly clear skies for tonight. More scattered/isolated cirrus is expected to move in from the northwest later tomorrow and again on Friday night. More organized, but still scattered, cirrus is projected to move in from the north on Saturday and Sunday night. While most of these clouds are not expected to be directly over the summit during the next 4-5 nights, skies won't be totally clear.

Precipitable water is expected to start out near 3 mm for tonight, then quickly drop towards 1 mm during the second half of the night. It will eventually bottom out near 0.8 mm tomorrow night, then increase toward 1.2 mm on Friday and Saturday night. By Sunday night it could increase toward 1.5-2 mm. There is a chance that precipitable water could undergo some short-lived fluctuations over the weekend.

WARNING: Summit winds are slated to increase over the next 24-36 hours. It is expected to peak at 50 mph, with gusts near 60 mph, Friday afternoon/evening, then slowly subside over the following 2-3 days.

The low-level shearline has passed over the Big Island leaving very dry air at the summit. Skies are also gradually clearing as dry mid/upper-level air begins to move in from the north. Precipitable water is expected to respond to this as it rapidly declines over the next few hours. These dry and relatively cloud-free (actually isolated cirrus is possible along the northern skies from time to time) conditions are expected to persist through the next 3 nights. This can be attributed to the Kona low which has developed to the northeast of the state, and is digging our way. The summit will be situated on the dry stable side of the low, which will help maintain the dry conditions. However, the low will also increase summit level winds over the next 24-36 hours. These winds will likely peak at more than 50 mph late Friday afternoon then gradually subside during the weekend. Fortunately, winds will be from a fairly uniform direction through the depth of the troposphere. This will help keep turbulence in the free atmosphere to a minimum. However, I suspect seeing will likely fluctuate more than normal due to the local winds and the mesoscale pockets of mid/upper-level eddies produced by the low. At any rate, the low is slated to move over the islands as it gains reinforcement from the north on Sunday and into next week. IF this pans out, look for the atmosphere to become fairly moist.

Astronomical Observing Quality Guidance
Seeing/Cn2 Images are not available today. Sorry for the inconvenience.



5-day Forecast
Summary
Trends
08 pm HST
Wed 19 Nov
02 am HST
Thu 20 Nov
02 pm HST
Thu 20 Nov
08 pm HST
Thu 20 Nov
02 am HST
Fri 21 Nov
02 pm HST
Fri 21 Nov
02 am HST
Sat 22 Nov
02 pm HST
Sat 22 Nov
02 am HST
Sun 23 Nov
02 pm HST
Sun 23 Nov
02 am HST
Mon 24 Nov
02 pm HST
Mon 24 Nov
06 UTC
Thu 20 Nov
12 UTC
Thu 20 Nov
00 UTC
Fri 21 Nov
06 UTC
Fri 21 Nov
12 UTC
Fri 21 Nov
00 UTC
Sat 22 Nov
12 UTC
Sat 22 Nov
00 UTC
Sun 23 Nov
12 UTC
Sun 23 Nov
00 UTC
Mon 24 Nov
12 UTC
Mon 24 Nov
00 UTC
Tue 25 Nov
Cloud Cover (%) 5 to 15 0 to 10 0 to 5 5 to 15 0 to 10 0 to 10 0 to 10 0 to 10 5 to 15 5 to 15 10 to 20 10 to 20
Chance for Fog/Precip (%) 0/0 0/0 0/0 0/0 0/0 0/0 0/0 10/0 10/0 10/0 20/0 30/0
PW (mm, summit upward) 2.5 to 3.5 1 to 1.5 0.75 to 1.25 0.75 to 1.25 0.75 to 1.25 1 to 1.5 1 to 1.5 1 to 1.5 1 to 1.5 1.25 to 1.75 2 to 3 2.5 to 3.5
Summit Temp (oC) -1 -1 4.5 0 -1 4 -1 4.5 -0.5 5 0 5.5
Wind Dir/Speed (mph)
    Summit (615 hPa)
    19,000 ft (500 hPa)
    24,500 ft (400 hPa)
    31,000 ft (300 hPa)
    35,000 ft (250 hPa)
    40,000 ft (200 hPa)
    46,000 ft (150 hPa)
    54,000 ft (100 hPa)

NNW/25 to 35
NW/21
WNW/31
W/44
WNW/48
WNW/50
WNW/54
WNW/34
NNW/25 to 35
NNW/20
NW/29
NW/39
NW/49
NW/62
NW/55
WNW/36
N/25 to 40
NW/24
NW/34
NW/55
NNW/69
NW/72
WNW/62
NW/50
NNW/30 to 45
NW/32
NW/41
NW/57
NW/70
NW/70
WNW/62
NW/45
NW/30 to 45
NW/36
WNW/51
WNW/64
NW/78
NW/82
WNW/58
NW/48
NW/40 to 55
WNW/46
WNW/45
NW/65
NW/83
NW/87
NW/64
WNW/55
NW/40 to 55
WNW/49
NW/57
NW/81
NW/82
NW/88
NW/66
NW/55
NNW/35 to 50
NW/48
NW/54
NW/61
NW/69
NW/72
WNW/61
NW/54
NW/15 to 30
NW/26
NW/30
NW/41
NW/53
NW/62
NW/64
NW/37
W/15 to 30
W/26
WNW/33
WNW/39
NW/40
NW/45
NW/42
WNW/43
W/15 to 30
N/A
N/A
N/A
N/A
N/A
N/A
N/A
W/15 to 30
N/A
N/A
N/A
N/A
N/A
N/A
N/A


 Rise and Set times for the Sun and Moon
Night (HST)
Sun Set
Twilight End
Twilight Beg
Sun Rise
Moon Rise
Moon Set
Illum (%)
RA
Dec
Wed.Nov.19/Thu.Nov.20
17:51
18:58
5:17
6:24
3:02
N/A
17
12 39.2
-0 25
Thu.Nov.20/Fri.Nov.21
17:51
18:58
5:17
6:25
4:02
N/A
9
13 30.7
-6 54
Fri.Nov.21/Sat.Nov.22
17:51
18:58
5:18
6:25
5:05
16:17
3
14 24.8
-13 10
Sat.Nov.22/Sun.Nov.23
17:51
18:58
5:18
6:26
6:13
17:03
0
15 22.6
-18 46
Sun.Nov.23/Mon.Nov.24
17:51
18:58
5:19
6:26
7:22
17:54
0
16 24.2
-23 13


Forecast issued by: Ryan Lyman
rlyman@hawaii.edu
(808) 932-2323

Next update at 10 AM HST (2000 UTC) Thursday 20 November 2003.
Please call or email to be placed on the Mauna Kea Weather Bulletin email list.

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This page was last modified on: Wed, Apr 22 2009 - 2058 UTC
Send comments to: Ryan Lyman