High Lonesome Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the High Lonesome Observatory clear sky chart from 2005-11-05 to 2017-09-24.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
48%
15689
25%
47164
17%
15641
56%
15641
32%
27770

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
31%
900
29%
2327
11%
895
44%
895
30%
1442
January16th to endNight
29%
960
29%
2496
10%
960
41%
960
31%
1552
February1st to 15thNight
27%
880
21%
2287
6%
875
36%
875
28%
1490
February16th to endNight
26%
582
27%
1844
10%
582
40%
582
27%
1067
March1st to 15thNight
32%
540
22%
1980
15%
540
42%
540
20%
1215
March16th to endNight
36%
576
19%
2112
16%
576
43%
576
22%
1303
April1st to 15thNight
35%
539
24%
1830
13%
539
51%
539
28%
1043
April16th to endNight
36%
540
23%
1800
16%
540
49%
540
28%
1034
May1st to 15thNight
47%
539
19%
1696
16%
539
55%
539
26%
1056
May16th to endNight
53%
563
21%
1685
18%
561
59%
561
31%
1028
June1st to 15thNight
74%
540
23%
1620
22%
540
78%
540
45%
850
June16th to endNight
74%
540
25%
1620
25%
540
77%
540
44%
856
July1st to 15thNight
74%
510
18%
1530
18%
510
76%
510
35%
887
July16th to endNight
81%
564
25%
1594
28%
531
83%
531
43%
859
August1st to 15thNight
76%
539
24%
1617
27%
536
78%
536
41%
881
August16th to endNight
76%
573
23%
1910
29%
573
76%
573
34%
1084
September1st to 15thNight
69%
540
26%
1800
28%
540
72%
540
33%
1017
September16th to endNight
69%
545
33%
1934
32%
545
73%
545
35%
1011
October1st to 15thNight
56%
660
30%
1980
23%
660
61%
660
37%
1129
October16th to endNight
50%
704
35%
2112
22%
704
61%
704
41%
1119
November1st to 15thNight
50%
700
31%
2100
21%
700
59%
700
36%
1162
November16th to endNight
37%
795
29%
2292
16%
795
48%
795
30%
1399
December1st to 15thNight
35%
900
22%
2502
10%
900
43%
900
28%
1603
December16th to endNight
31%
960
24%
2496
10%
960
40%
960
25%
1683

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
12%5%25%5%3445%6%44%
47748
Night
11%424323347%51%
47360
TransparencyDay
38%6%10%21%17%4
47448
Night
33%5%10%23%21%6%
47165
SeeingDay
12%6%21%27%24%7%
5737
Night
14%9%24%31%18%2
15690

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
17%5%2331333450%
1611
16th to endDay
13%6%2442323450%
1728
February1st to 15thDay
16%7%23423335%48%
1575
16th to endDay
15%7%35%5%2333443%
1638
March1st to 15thDay
17%6%24433335%44%
1980
16th to endDay
16%8%35%5%24445%39%
2110
April1st to 15thDay
13%6%25%433446%46%
2118
16th to endDay
15%5%25%43445%6%40%
2160
May1st to 15thDay
16%6%36%5%34445%39%
2253
16th to endDay
10%5%35%7%35%6%6%7%37%
2430
June1st to 15thDay
7%425%6%46%5%7%7%42%
2340
16th to endDay
5%4246%45%6%7%9%42%
2340
July1st to 15thDay
8%5%27%7%37%7%7%9%34%
2340
16th to endDay
5%425%6%46%6%7%11%39%
2466
August1st to 15thDay
7%4245%37%6%8%10%39%
2331
16th to endDay
8%5%15%6%35%6%6%9%39%
2292
September1st to 15thDay
14%414435%46%6%44%
2160
16th to endDay
9%31343435%7%52%
1869
October1st to 15thDay
14%424313445%51%
1650
16th to endDay
13%31231333458%
1760
November1st to 15thDay
9%424323336%57%
1758
16th to endDay
14%5%24323335%50%
1659
December1st to 15thDay
16%5%2431235%6%46%
1452
16th to endDay
16%6%45%42423345%
1728
January1st to 15thNight
15%5%13322235%53%
2327
16th to endNight
13%42332333454%
2496
February1st to 15thNight
15%6%25%412245%48%
2278
16th to endNight
12%6%13423336%51%
1844
March1st to 15thNight
17%6%25%423346%44%
1980
16th to endNight
15%6%35%424346%44%
2112
April1st to 15thNight
10%424324347%52%
1830
16th to endNight
11%424423446%51%
1800
May1st to 15thNight
12%325%325%5%5%6%46%
1695
16th to endNight
7%326%43446%9%47%
1683
June1st to 15thNight
42133233410%59%
1620
16th to endNight
421322245%10%58%
1620
July1st to 15thNight
2325%5%36%6%7%11%45%
1620
16th to endNight
321343447%11%54%
1702
August1st to 15thNight
43134345%7%10%51%
1627
16th to endNight
5%3135%25%5%7%10%46%
1910
September1st to 15thNight
10%42332445%7%52%
1800
16th to endNight
6%4234235%5%6%56%
1934
October1st to 15thNight
10%314413336%56%
1980
16th to endNight
12%3231222463%
2112
November1st to 15thNight
8%423324346%56%
2100
16th to endNight
14%5%2332334452%
2292
December1st to 15thNight
15%6%24323345%47%
2502
16th to endNight
16%7%25%42333446%
2496

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
38%37%25%19%5%
1612
16th to endDay
38%38%23%22%4
1728
February1st to 15thDay
40%49%23%16%5%
1576
16th to endDay
45%37%21%16%5%
1638
March1st to 15thDay
43%49%18%16%7%
1980
16th to endDay
47%5%9%22%14%1
2112
April1st to 15thDay
39%5%9%21%19%4
2118
16th to endDay
43%6%8%18%18%3
2160
May1st to 15thDay
47%6%9%15%17%3
2253
16th to endDay
43%8%12%21%12%1
2434
June1st to 15thDay
37%8%13%22%16%
2340
16th to endDay
34%8%13%23%17%2
2340
July1st to 15thDay
41%9%14%24%9%1
2201
16th to endDay
34%10%16%25%13%1
2311
August1st to 15thDay
35%9%15%23%15%2
2317
16th to endDay
38%9%15%19%13%3
2292
September1st to 15thDay
38%7%10%20%15%7%
2160
16th to endDay
30%6%11%21%23%6%
1869
October1st to 15thDay
34%5%7%20%23%8%
1650
16th to endDay
29%36%23%26%10%
1760
November1st to 15thDay
29%48%26%22%7%
1758
16th to endDay
37%37%20%25%5%
1659
December1st to 15thDay
39%411%22%18%4
1452
16th to endDay
44%37%21%17%4
1728
January1st to 15thNight
35%37%21%27%5%
2327
16th to endNight
34%36%24%23%6%
2496
February1st to 15thNight
39%48%23%18%5%
2288
16th to endNight
35%39%26%18%7%
1844
March1st to 15thNight
42%49%16%19%6%
1980
16th to endNight
42%49%21%17%3
2112
April1st to 15thNight
32%5%10%21%20%9%
1830
16th to endNight
34%5%10%22%23%3
1800
May1st to 15thNight
37%7%11%20%17%6%
1696
16th to endNight
32%8%17%24%14%1
1685
June1st to 15thNight
21%6%13%32%23%2
1620
16th to endNight
22%6%12%28%25%4
1620
July1st to 15thNight
28%8%18%25%16%2
1530
16th to endNight
22%8%16%32%18%1
1594
August1st to 15thNight
24%7%17%28%19%2
1617
16th to endNight
28%8%17%24%18%3
1910
September1st to 15thNight
30%6%9%23%21%8%
1800
16th to endNight
27%5%9%22%26%7%
1934
October1st to 15thNight
30%410%18%23%12%
1980
16th to endNight
27%25%22%30%12%
2112
November1st to 15thNight
29%38%24%23%10%
2100
16th to endNight
36%46%18%27%6%
2292
December1st to 15thNight
39%49%21%19%6%
2502
16th to endNight
42%48%20%17%5%
2496

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
22%15%34%23%4
90
16th to endDay
19%28%31%13%7%
96
February1st to 15thDay
20%13%46%16%21
90
16th to endDay
19%20%33%20%31
81
March1st to 15thDay
23%24%41%10%1
90
16th to endDay
18%21%30%23%5%
96
April1st to 15thDay
19%15%33%18%11%
237
16th to endDay
22%10%31%22%10%2
270
May1st to 15thDay
18%12%31%21%14%1
390
16th to endDay
11%7%35%25%14%5%
517
June1st to 15thDay
9%215%33%30%7%
495
16th to endDay
6%221%35%26%8%
495
July1st to 15thDay
5%218%35%29%8%
475
16th to endDay
46%28%41%19%
515
August1st to 15thDay
8%110%32%33%13%
484
16th to endDay
12%6%29%37%14%
332
September1st to 15thDay
11%10%22%43%11%
315
16th to endDay
6%11%37%31%11%
117
October1st to 15thDay
6%5%28%33%20%5%
90
16th to endDay
16%7%23%32%17%2
96
November1st to 15thDay
8%10%30%25%23%2
90
16th to endDay
31%22%18%17%10%
90
December1st to 15thDay
18%12%33%23%8%3
90
16th to endDay
17%21%38%18%3
96
January1st to 15thNight
21%16%27%27%6%
900
16th to endNight
16%15%36%27%3
960
February1st to 15thNight
20%15%33%26%3
880
16th to endNight
18%18%35%25%2
582
March1st to 15thNight
21%11%31%31%4
540
16th to endNight
18%11%31%29%7%
576
April1st to 15thNight
13%13%35%28%8%
539
16th to endNight
13%12%33%29%10%
540
May1st to 15thNight
13%7%28%35%14%1
540
16th to endNight
8%5%25%35%21%3
563
June1st to 15thNight
4112%42%35%3
540
16th to endNight
4112%39%37%4
540
July1st to 15thNight
2112%38%39%5%
510
16th to endNight
45%31%47%11%
564
August1st to 15thNight
6%7%35%40%10%
539
16th to endNight
7%8%32%43%7%
573
September1st to 15thNight
13%10%29%42%4
540
16th to endNight
8%113%33%36%6%
545
October1st to 15thNight
13%322%30%27%3
660
16th to endNight
13%8%25%31%19%1
704
November1st to 15thNight
10%9%25%36%17%
700
16th to endNight
19%13%28%26%12%
795
December1st to 15thNight
20%12%29%30%8%
900
16th to endNight
21%14%28%29%5%
960
Page generated at 2017-09-25 08:02:30. Version ac04

Copyright 2017 A. Danko


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