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Wolf Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wolf Creek Observatory clear sky chart from 2005-11-05 to 2020-06-03.

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
50%
18794
23%
57886
16%
18751
57%
18751
28%
35761

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
28%
900
24%
2856
11%
896
43%
896
23%
1775
January16th to endNight
28%
960
27%
2880
12%
960
41%
960
23%
1864
February1st to 15thNight
31%
884
23%
2652
11%
881
42%
881
24%
1696
February16th to endNight
29%
791
24%
2373
11%
791
40%
791
24%
1532
March1st to 15thNight
29%
900
21%
2693
10%
900
38%
900
26%
1710
March16th to endNight
37%
883
24%
2563
12%
883
47%
883
30%
1553
April1st to 15thNight
41%
674
25%
2247
18%
674
51%
674
30%
1297
April16th to endNight
50%
669
28%
2228
21%
669
61%
669
36%
1194
May1st to 15thNight
56%
674
24%
2105
19%
674
63%
674
35%
1212
May16th to endNight
67%
705
21%
2114
17%
705
71%
705
31%
1318
June1st to 15thNight
72%
637
15%
1913
13%
637
73%
637
27%
1253
June16th to endNight
75%
630
15%
1890
14%
630
75%
630
30%
1198
July1st to 15thNight
76%
600
10%
1800
10%
600
76%
600
25%
1218
July16th to endNight
75%
660
14%
1993
15%
627
75%
627
27%
1282
August1st to 15thNight
75%
620
12%
2056
14%
617
75%
617
22%
1382
August16th to endNight
69%
669
16%
2230
19%
669
69%
669
21%
1505
September1st to 15thNight
66%
725
18%
2195
18%
725
67%
725
25%
1434
September16th to endNight
66%
837
27%
2310
21%
837
69%
837
33%
1446
October1st to 15thNight
62%
840
33%
2310
24%
840
69%
840
42%
1292
October16th to endNight
52%
896
33%
2647
26%
896
59%
896
35%
1520
November1st to 15thNight
52%
880
28%
2861
23%
880
61%
880
33%
1579
November16th to endNight
47%
900
31%
2925
22%
900
59%
900
33%
1600
December1st to 15thNight
39%
900
25%
2925
18%
900
50%
900
25%
1775
December16th to endNight
31%
960
19%
3120
12%
960
40%
960
18%
2126

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
11%5%25%5%35%5%5%7%41%
58506
Night
10%5%244345%5%8%45%
58094
TransparencyDay
39%7%11%17%17%6%
58216
Night
36%7%11%17%19%8%
57888
SeeingDay
14%7%20%23%21%11%
8687
Night
13%7%22%28%22%5%
18797

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
14%7%35%313346%44%
2068
16th to endDay
17%5%35%413445%45%
2400
February1st to 15thDay
16%6%26%5%2435%5%41%
2200
16th to endDay
17%7%25%5%34446%39%
1980
March1st to 15thDay
12%6%35%5%3445%7%41%
2255
16th to endDay
11%5%15%5%3445%7%44%
2727
April1st to 15thDay
11%5%245%25%45%7%44%
2691
16th to endDay
9%4135%345%5%6%50%
2667
May1st to 15thDay
9%4245%35%45%8%46%
2833
16th to endDay
7%426%5%35%6%6%9%41%
3055
June1st to 15thDay
7%5%27%8%46%7%6%10%33%
2756
16th to endDay
6%326%6%48%8%7%10%34%
2730
July1st to 15thDay
9%5%26%7%5%8%9%9%10%26%
2730
16th to endDay
7%5%26%9%5%7%7%8%10%27%
2759
August1st to 15thDay
8%5%25%7%5%8%7%8%12%28%
2475
16th to endDay
11%7%36%7%46%6%7%9%30%
2676
September1st to 15thDay
10%5%35%6%37%5%5%7%38%
2408
16th to endDay
9%4246%35%45%7%46%
2310
October1st to 15thDay
10%414423347%51%
2310
16th to endDay
12%413422346%53%
2279
November1st to 15thDay
12%5%24424335%52%
1987
16th to endDay
10%423423347%52%
2025
December1st to 15thDay
14%7%35%424336%44%
2025
16th to endDay
19%11%35%5%23345%35%
2160
January1st to 15thNight
14%7%35%423435%45%
2856
16th to endNight
18%7%25%323235%44%
2880
February1st to 15thNight
14%7%25%42335%6%43%
2643
16th to endNight
15%6%24433445%44%
2373
March1st to 15thNight
11%6%36%42335%7%44%
2693
16th to endNight
9%425%43345%6%49%
2563
April1st to 15thNight
9%4243245%6%7%47%
2247
16th to endNight
8%31332445%7%55%
2228
May1st to 15thNight
8%3244245%5%9%50%
2104
16th to endNight
6%415%6%35%5%6%11%43%
2114
June1st to 15thNight
5%415%6%46%7%8%13%35%
1913
16th to endNight
34346%45%7%8%12%39%
1890
July1st to 15thNight
4425%7%36%8%9%12%33%
1890
16th to endNight
5%325%5%37%7%7%12%38%
2109
August1st to 15thNight
6%325%5%5%6%9%9%13%32%
2068
16th to endNight
7%5%36%6%46%6%6%9%37%
2230
September1st to 15thNight
9%4246%36%6%7%8%40%
2195
16th to endNight
7%424435%6%6%8%46%
2310
October1st to 15thNight
7%413323347%57%
2310
16th to endNight
12%6%1331223456%
2647
November1st to 15thNight
12%413323446%54%
2861
16th to endNight
9%423323445%54%
2925
December1st to 15thNight
14%5%25%423446%46%
2925
16th to endNight
18%8%25%5%34446%36%
3120

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
40%47%15%25%7%
2069
16th to endDay
40%35%15%24%9%
2400
February1st to 15thDay
44%47%15%21%6%
2202
16th to endDay
46%45%14%20%8%
1980
March1st to 15thDay
40%5%9%15%21%8%
2255
16th to endDay
38%5%10%17%21%6%
2728
April1st to 15thDay
37%5%8%21%19%7%
2691
16th to endDay
31%6%9%21%25%6%
2667
May1st to 15thDay
34%7%9%17%24%5%
2833
16th to endDay
37%9%12%22%16%3
3059
June1st to 15thDay
42%10%13%21%10%1
2756
16th to endDay
40%11%17%17%10%1
2730
July1st to 15thDay
44%15%19%13%41
2591
16th to endDay
46%12%18%17%5%
2612
August1st to 15thDay
42%12%19%16%6%
2463
16th to endDay
48%10%14%13%9%2
2676
September1st to 15thDay
42%9%15%14%13%5%
2408
16th to endDay
36%7%11%19%21%4
2310
October1st to 15thDay
32%410%19%23%8%
2310
16th to endDay
32%36%14%26%16%
2279
November1st to 15thDay
35%37%17%25%11%
1987
16th to endDay
31%48%17%24%13%
2025
December1st to 15thDay
41%48%18%19%6%
2025
16th to endDay
51%36%19%12%6%
2160
January1st to 15thNight
41%35%17%23%8%
2856
16th to endNight
43%35%13%24%9%
2880
February1st to 15thNight
41%47%17%19%10%
2652
16th to endNight
41%5%6%14%20%11%
2373
March1st to 15thNight
39%49%15%21%9%
2693
16th to endNight
34%410%18%22%8%
2563
April1st to 15thNight
33%5%10%17%22%10%
2247
16th to endNight
27%5%9%24%22%9%
2228
May1st to 15thNight
30%6%11%19%24%8%
2105
16th to endNight
33%9%15%20%16%5%
2116
June1st to 15thNight
35%11%18%17%14%1
1913
16th to endNight
32%11%20%22%10%2
1890
July1st to 15thNight
35%15%27%14%5%1
1800
16th to endNight
33%13%22%22%6%
1993
August1st to 15thNight
35%16%20%18%5%2
2056
16th to endNight
40%11%16%13%14%3
2230
September1st to 15thNight
38%10%14%17%11%7%
2195
16th to endNight
32%8%10%20%20%6%
2310
October1st to 15thNight
27%411%20%23%12%
2310
16th to endNight
32%3412%28%18%
2647
November1st to 15thNight
30%46%17%26%13%
2861
16th to endNight
30%46%19%24%15%
2925
December1st to 15thNight
38%49%18%22%5%
2925
16th to endNight
48%5%6%17%15%5%
3120

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
21%18%32%18%5%3
225
16th to endDay
22%22%35%14%4
240
February1st to 15thDay
27%23%29%17%1
225
16th to endDay
19%19%41%17%
201
March1st to 15thDay
21%23%44%6%3
230
16th to endDay
16%13%32%27%9%1
480
April1st to 15thDay
17%13%32%20%14%
450
16th to endDay
14%10%26%26%16%5%
439
May1st to 15thDay
10%7%23%27%23%7%
468
16th to endDay
11%117%30%21%17%
523
June1st to 15thDay
9%112%30%27%18%
443
16th to endDay
7%210%22%30%26%
435
July1st to 15thDay
7%420%38%27%
425
16th to endDay
5%16%19%41%25%
454
August1st to 15thDay
10%15%20%34%27%
418
16th to endDay
12%6%20%34%24%
460
September1st to 15thDay
10%211%25%29%20%
435
16th to endDay
9%10%27%36%15%
434
October1st to 15thDay
12%219%27%30%7%
435
16th to endDay
19%8%25%21%20%4
352
November1st to 15thDay
24%9%31%25%8%1
225
16th to endDay
7%12%38%29%11%1
225
December1st to 15thDay
24%18%36%16%4
225
16th to endDay
28%18%29%19%5%
240
January1st to 15thNight
19%15%32%25%7%
900
16th to endNight
21%14%32%26%5%
960
February1st to 15thNight
19%12%33%29%5%
884
16th to endNight
18%15%32%28%4
791
March1st to 15thNight
14%15%37%25%7%
900
16th to endNight
12%12%34%27%12%
883
April1st to 15thNight
13%8%32%28%15%1
674
16th to endNight
9%8%27%34%19%
669
May1st to 15thNight
9%422%34%25%3
675
16th to endNight
7%115%34%35%6%
707
June1st to 15thNight
7%9%31%40%9%
637
16th to endNight
417%26%45%15%
630
July1st to 15thNight
6%5%23%44%19%
600
16th to endNight
6%1424%43%18%
660
August1st to 15thNight
8%323%45%19%
620
16th to endNight
8%16%25%42%15%
669
September1st to 15thNight
11%9%26%38%14%
725
16th to endNight
9%14%30%38%6%
837
October1st to 15thNight
10%120%34%28%3
840
16th to endNight
15%6%20%28%24%3
896
November1st to 15thNight
13%5%23%33%19%3
880
16th to endNight
12%11%26%34%14%1
900
December1st to 15thNight
17%10%27%31%11%1
900
16th to endNight
24%12%28%24%9%
960
Page generated at 2020-06-04 02:18:56. Version ac04

Copyright 2020 A. Danko


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