Bruneau Dunes Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bruneau Dunes Observatory clear sky chart from 2005-11-05 to 2017-08-12.

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
57%
14711
21%
46449
18%
14687
62%
14687
32%
27291

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
46%
716
11%
2506
11%
716
48%
716
16%
1793
January16th to endNight
49%
768
11%
2688
11%
768
51%
768
19%
1831
February1st to 15thNight
50%
697
11%
2216
10%
697
53%
697
22%
1487
February16th to endNight
47%
632
17%
1895
14%
632
53%
632
25%
1248
March1st to 15thNight
45%
720
14%
2137
10%
720
51%
720
23%
1448
March16th to endNight
46%
768
18%
2067
11%
768
50%
768
28%
1376
April1st to 15thNight
48%
719
21%
1799
10%
719
53%
719
33%
1162
April16th to endNight
51%
564
26%
1644
16%
564
56%
564
36%
942
May1st to 15thNight
56%
539
27%
1619
19%
539
63%
539
42%
859
May16th to endNight
63%
428
20%
1552
23%
428
67%
428
32%
820
June1st to 15thNight
59%
360
18%
1440
23%
360
65%
360
28%
762
June16th to endNight
71%
360
29%
1440
36%
360
82%
360
56%
525
July1st to 15thNight
77%
340
25%
1360
34%
340
83%
340
52%
516
July16th to endNight
78%
376
35%
1416
43%
354
84%
354
56%
515
August1st to 15thNight
76%
509
32%
1558
27%
507
79%
507
56%
716
August16th to endNight
79%
627
38%
1677
25%
627
82%
627
69%
761
September1st to 15thNight
80%
660
37%
1711
25%
660
83%
660
64%
840
September16th to endNight
72%
656
37%
1815
30%
656
76%
656
52%
930
October1st to 15thNight
65%
660
30%
1831
24%
660
71%
660
43%
1024
October16th to endNight
60%
704
27%
2288
23%
704
67%
704
36%
1235
November1st to 15thNight
55%
700
24%
2275
22%
700
60%
700
28%
1372
November16th to endNight
51%
720
18%
2340
13%
720
58%
720
26%
1485
December1st to 15thNight
48%
720
9%
2487
8%
720
52%
720
18%
1723
December16th to endNight
37%
768
13%
2688
11%
768
43%
768
16%
1921

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
6%42442445%7%54%
47535
Night
8%5%2442445%6%50%
46621
TransparencyDay
29%5%12%21%19%11%
47206
Night
33%5%12%21%16%9%
46450
SeeingDay
8%7%23%30%21%7%
5233
Night
10%420%38%22%3
14724

By Month

Percentage Cloud Cover SW (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
12%8%47%6%346%5%7%34%
1432
16th to endDay
11%9%27%6%5%5%449%33%
1536
February1st to 15thDay
9%8%25%6%245%6%8%40%
1643
16th to endDay
8%9%35%5%35%5%6%7%39%
1579
March1st to 15thDay
8%7%46%6%345%6%8%38%
1821
16th to endDay
8%7%35%5%35%5%6%8%39%
2154
April1st to 15thDay
6%5%25%435%5%7%9%44%
2149
16th to endDay
6%5%2343445%7%53%
2316
May1st to 15thDay
331343445%7%58%
2331
16th to endDay
6%414425%46%8%50%
2559
June1st to 15thDay
6%4243345%5%8%52%
2520
16th to endDay
222112235%74%
2520
July1st to 15thDay
2112313346%70%
2520
16th to endDay
21221222476%
2657
August1st to 15thDay
322223345%68%
2305
16th to endDay
112212235%77%
2171
September1st to 15thDay
221211335%74%
1918
16th to endDay
5%31322233468%
1815
October1st to 15thDay
5%414323347%59%
1795
16th to endDay
5%31432445%7%54%
1584
November1st to 15thDay
9%5%25%424448%46%
1584
16th to endDay
10%8%25%5%35%45%8%39%
1620
December1st to 15thDay
15%6%36%5%2445%6%38%
1470
16th to endDay
15%11%5%8%5%34447%28%
1536
January1st to 15thNight
11%9%48%6%35%5%5%7%32%
2506
16th to endNight
13%8%47%43435%6%38%
2688
February1st to 15thNight
12%7%25%5%245%5%6%40%
2205
16th to endNight
9%8%35%5%35%5%6%8%39%
1895
March1st to 15thNight
8%7%26%6%35%5%6%6%39%
2137
16th to endNight
10%7%35%5%25%5%47%43%
2067
April1st to 15thNight
8%5%25%445%5%7%6%46%
1799
16th to endNight
7%42342445%7%52%
1644
May1st to 15thNight
5%314322446%59%
1619
16th to endNight
5%5%2343346%9%50%
1551
June1st to 15thNight
5%415%435%5%5%7%50%
1440
16th to endNight
211212245%74%
1440
July1st to 15thNight
1122445%7%70%
1440
16th to endNight
211121322474%
1512
August1st to 15thNight
2112212446%68%
1566
16th to endNight
111113236%75%
1677
September1st to 15thNight
21121333474%
1711
16th to endNight
5%21332333467%
1815
October1st to 15thNight
6%313334445%58%
1831
16th to endNight
7%31442335%7%55%
2288
November1st to 15thNight
11%5%25%424446%48%
2275
16th to endNight
10%6%35%5%35%447%44%
2340
December1st to 15thNight
13%9%36%5%245%6%6%36%
2487
16th to endNight
18%10%37%5%25%446%32%
2688

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
49%11%18%18%2
1432
16th to endDay
50%10%20%16%2
1536
February1st to 15thDay
41%8%21%22%5%
1643
16th to endDay
43%7%17%24%6%
1579
March1st to 15thDay
42%8%15%24%6%2
1821
16th to endDay
42%6%15%22%10%1
2154
April1st to 15thDay
34%5%16%25%15%1
2149
16th to endDay
30%5%12%27%21%3
2316
May1st to 15thDay
23%5%9%27%27%7%
2331
16th to endDay
30%6%13%25%18%6%
2563
June1st to 15thDay
29%6%10%22%24%7%
2520
16th to endDay
12%25%18%39%21%
2520
July1st to 15thDay
14%2414%30%32%
2371
16th to endDay
12%137%24%50%
2490
August1st to 15thDay
17%25%12%27%34%
2288
16th to endDay
11%1416%35%30%
2171
September1st to 15thDay
13%25%16%34%26%
1918
16th to endDay
21%26%23%32%13%
1815
October1st to 15thDay
26%5%11%30%21%5%
1795
16th to endDay
28%7%12%31%18%1
1584
November1st to 15thDay
36%7%16%27%10%1
1584
16th to endDay
42%7%19%24%5%
1620
December1st to 15thDay
46%8%23%17%4
1470
16th to endDay
55%7%18%16%1
1536
January1st to 15thNight
50%9%18%17%3
2506
16th to endNight
48%6%18%22%4
2688
February1st to 15thNight
43%8%21%20%5%
2216
16th to endNight
40%8%18%25%6%
1895
March1st to 15thNight
43%8%13%23%9%2
2137
16th to endNight
40%5%15%26%11%1
2067
April1st to 15thNight
36%5%13%26%16%2
1799
16th to endNight
30%410%28%22%2
1644
May1st to 15thNight
24%48%23%33%5%
1620
16th to endNight
28%6%10%26%20%7%
1552
June1st to 15thNight
32%410%20%25%6%
1440
16th to endNight
11%36%19%32%26%
1440
July1st to 15thNight
14%35%12%28%36%
1360
16th to endNight
13%127%22%51%
1416
August1st to 15thNight
16%35%13%21%39%
1558
16th to endNight
11%15%13%28%39%
1677
September1st to 15thNight
13%3412%34%31%
1711
16th to endNight
20%3420%31%19%
1815
October1st to 15thNight
26%48%26%26%7%
1831
16th to endNight
28%5%12%29%21%2
2288
November1st to 15thNight
36%5%12%27%16%2
2275
16th to endNight
40%5%15%29%7%
2340
December1st to 15thNight
47%8%21%17%4
2487
16th to endNight
53%6%16%20%3
2688

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
15%121%35%15%11%
60
16th to endDay
25%320%25%25%1
64
February1st to 15thDay
16%7%22%19%28%5%
173
16th to endDay
14%13%26%31%11%3
238
March1st to 15thDay
11%13%32%25%14%2
270
16th to endDay
13%14%34%30%6%
288
April1st to 15thDay
9%15%26%24%15%7%
269
16th to endDay
9%15%30%26%14%4
270
May1st to 15thDay
5%10%31%28%17%6%
288
16th to endDay
8%8%13%35%23%10%
330
June1st to 15thDay
7%8%27%29%19%6%
315
16th to endDay
2426%32%23%10%
315
July1st to 15thDay
1220%30%30%12%
305
16th to endDay
2219%38%27%8%
327
August1st to 15thDay
5%321%33%28%8%
300
16th to endDay
1217%37%27%13%
268
September1st to 15thDay
4420%28%30%11%
255
16th to endDay
8%5%15%29%27%14%
255
October1st to 15thDay
8%7%23%26%25%8%
238
16th to endDay
14%5%23%31%19%5%
96
November1st to 15thDay
12%210%40%35%
90
16th to endDay
20%11%34%25%8%
90
December1st to 15thDay
35%6%13%33%9%1
65
16th to endDay
20%6%25%28%10%9%
64
January1st to 15thNight
14%321%38%19%2
720
16th to endNight
16%317%34%25%3
768
February1st to 15thNight
15%319%41%19%
704
16th to endNight
11%5%30%34%16%
632
March1st to 15thNight
11%5%28%36%16%1
720
16th to endNight
14%7%25%38%13%1
768
April1st to 15thNight
10%7%26%36%17%2
719
16th to endNight
7%7%29%35%17%3
564
May1st to 15thNight
6%7%25%37%19%3
540
16th to endNight
6%5%18%34%31%3
429
June1st to 15thNight
7%6%18%39%26%2
360
16th to endNight
2321%40%30%1
360
July1st to 15thNight
1115%47%32%1
340
16th to endNight
3212%46%33%1
376
August1st to 15thNight
3212%50%30%
509
16th to endNight
2211%45%34%3
627
September1st to 15thNight
2210%42%34%7%
660
16th to endNight
7%312%32%33%10%
656
October1st to 15thNight
8%417%39%26%5%
660
16th to endNight
9%318%37%24%6%
704
November1st to 15thNight
13%5%17%38%22%2
700
16th to endNight
13%423%37%17%3
720
December1st to 15thNight
17%418%39%17%2
720
16th to endNight
24%5%23%33%11%1
768
Page generated at 2017-08-13 12:16:30. Version ac04

Copyright 2017 A. Danko


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