Waning Moon II Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waning Moon II Observatory clear sky chart from 2005-11-05 to 2017-03-24.

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
59%
14414
23%
45185
19%
14371
64%
14371
30%
27025

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
43%
720
26%
2148
14%
716
54%
716
30%
1307
January16th to endNight
39%
768
26%
2304
15%
768
47%
768
27%
1455
February1st to 15thNight
42%
704
26%
2112
14%
701
52%
701
31%
1280
February16th to endNight
35%
631
23%
1893
12%
631
44%
631
27%
1209
March1st to 15thNight
42%
639
23%
2079
15%
639
50%
639
25%
1303
March16th to endNight
55%
555
24%
1956
21%
555
61%
555
31%
1067
April1st to 15thNight
49%
494
25%
1647
20%
494
58%
494
28%
974
April16th to endNight
57%
495
26%
1650
24%
495
64%
495
37%
874
May1st to 15thNight
66%
494
22%
1649
22%
494
70%
494
31%
949
May16th to endNight
74%
513
20%
1710
22%
513
76%
513
34%
960
June1st to 15thNight
81%
495
15%
1513
17%
495
82%
495
34%
893
June16th to endNight
77%
495
15%
1475
15%
495
77%
495
31%
928
July1st to 15thNight
82%
465
14%
1408
16%
465
82%
465
30%
879
July16th to endNight
77%
522
9%
1632
11%
489
76%
489
24%
1070
August1st to 15thNight
86%
494
13%
1638
17%
491
86%
491
32%
973
August16th to endNight
76%
525
13%
1750
16%
525
76%
525
24%
1119
September1st to 15thNight
72%
495
21%
1650
23%
495
73%
495
25%
1061
September16th to endNight
72%
638
27%
1796
24%
638
73%
638
34%
1103
October1st to 15thNight
74%
660
33%
1886
28%
660
76%
660
47%
986
October16th to endNight
60%
704
34%
2112
29%
704
66%
704
42%
1128
November1st to 15thNight
62%
700
33%
2123
29%
700
67%
700
38%
1184
November16th to endNight
52%
720
30%
2340
25%
720
61%
720
36%
1267
December1st to 15thNight
49%
720
24%
2340
19%
720
54%
720
26%
1442
December16th to endNight
38%
768
19%
2374
13%
768
44%
768
21%
1614

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
10%5%25%5%35%6%6%8%38%
45695
Night
10%42442446%8%47%
45398
TransparencyDay
39%8%12%17%15%6%
45411
Night
33%7%13%19%17%8%
45187
SeeingDay
11%213%23%30%18%
4489
Night
11%417%30%27%8%
14417

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%5%25%5%2436%5%43%
1790
16th to endDay
18%6%2442334444%
1920
February1st to 15thDay
13%6%25%41335%6%47%
1750
16th to endDay
16%5%36%5%33446%41%
1580
March1st to 15thDay
16%6%24424446%42%
1890
16th to endDay
10%6%35%425%46%8%43%
2108
April1st to 15thDay
13%5%25%5%35%5%6%8%37%
1971
16th to endDay
11%5%145%345%7%10%40%
1980
May1st to 15thDay
11%4245%46%6%6%9%37%
1971
16th to endDay
8%426%5%45%6%8%8%38%
2052
June1st to 15thDay
5%426%8%49%8%8%11%29%
2107
16th to endDay
45%36%7%5%9%8%10%12%26%
2138
July1st to 15thDay
7%6%38%8%5%9%8%7%9%24%
2129
16th to endDay
7%6%37%9%5%9%8%9%11%21%
2108
August1st to 15thDay
7%436%7%5%8%9%9%12%26%
1980
16th to endDay
9%7%28%8%5%6%8%8%10%25%
2100
September1st to 15thDay
11%6%26%6%37%7%8%8%29%
1980
16th to endDay
8%6%36%5%36%6%6%8%39%
1823
October1st to 15thDay
5%3244335%5%7%54%
1741
16th to endDay
7%314423447%56%
1760
November1st to 15thDay
8%42432445%7%53%
1732
16th to endDay
8%413424346%55%
1620
December1st to 15thDay
14%6%25%6%24446%42%
1620
16th to endDay
19%7%35%5%34446%34%
1845
January1st to 15thNight
14%5%24323347%47%
2148
16th to endNight
19%5%2332444445%
2304
February1st to 15thNight
13%5%24413446%48%
2103
16th to endNight
18%7%3331335%6%43%
1893
March1st to 15thNight
14%4245%25%35%7%42%
2079
16th to endNight
12%322324347%52%
1956
April1st to 15thNight
11%5%3442345%7%47%
1647
16th to endNight
8%31342346%8%52%
1650
May1st to 15thNight
7%425%425%5%5%10%46%
1649
16th to endNight
43334345%5%10%50%
1709
June1st to 15thNight
3314445%6%9%11%44%
1513
16th to endNight
4235%5%45%5%7%11%43%
1475
July1st to 15thNight
33245%25%7%8%14%42%
1499
16th to endNight
5%315%7%37%5%9%15%34%
1752
August1st to 15thNight
1214436%8%11%12%43%
1650
16th to endNight
7%325%6%35%6%9%13%37%
1750
September1st to 15thNight
7%5%15%5%36%5%7%10%40%
1650
16th to endNight
6%5%24435%46%8%47%
1796
October1st to 15thNight
4313224347%62%
1886
16th to endNight
9%313312245%60%
2112
November1st to 15thNight
8%5%24423336%55%
2123
16th to endNight
9%41442434457%
2340
December1st to 15thNight
12%5%25%424447%44%
2340
16th to endNight
18%8%345%2345%6%37%
2374

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
41%5%7%15%20%10%
1791
16th to endDay
42%46%16%20%9%
1920
February1st to 15thDay
36%5%9%16%21%10%
1752
16th to endDay
42%49%17%19%7%
1580
March1st to 15thDay
41%6%8%20%18%6%
1890
16th to endDay
37%5%10%18%21%5%
2110
April1st to 15thDay
40%8%9%17%16%8%
1971
16th to endDay
35%8%11%22%17%4
1980
May1st to 15thDay
37%9%12%21%11%6%
1971
16th to endDay
34%10%14%23%16%1
2056
June1st to 15thDay
40%12%14%20%10%1
2107
16th to endDay
40%13%18%18%8%
2138
July1st to 15thDay
46%14%17%15%41
1991
16th to endDay
46%15%20%14%2
1965
August1st to 15thDay
41%16%19%15%5%
1968
16th to endDay
47%13%16%12%7%1
2100
September1st to 15thDay
43%12%16%15%9%2
1980
16th to endDay
37%8%13%16%17%6%
1823
October1st to 15thDay
25%6%9%18%23%16%
1741
16th to endDay
25%46%15%28%18%
1760
November1st to 15thDay
29%48%18%30%8%
1732
16th to endDay
29%37%17%25%15%
1620
December1st to 15thDay
40%5%8%20%17%6%
1620
16th to endDay
49%5%8%16%15%4
1845
January1st to 15thNight
37%48%16%21%11%
2148
16th to endNight
42%27%14%22%11%
2304
February1st to 15thNight
36%48%18%20%11%
2112
16th to endNight
40%47%15%19%11%
1893
March1st to 15thNight
40%6%8%16%21%6%
2079
16th to endNight
31%5%12%19%23%7%
1956
April1st to 15thNight
35%6%11%22%15%9%
1647
16th to endNight
27%5%13%24%19%8%
1650
May1st to 15thNight
32%6%13%25%15%5%
1650
16th to endNight
27%9%16%27%16%2
1711
June1st to 15thNight
28%10%23%27%11%
1513
16th to endNight
31%11%22%22%11%
1475
July1st to 15thNight
29%13%29%21%5%
1408
16th to endNight
34%15%28%18%2
1632
August1st to 15thNight
23%16%31%21%6%
1638
16th to endNight
34%13%26%14%7%3
1750
September1st to 15thNight
35%12%18%16%12%4
1650
16th to endNight
32%7%15%19%17%7%
1796
October1st to 15thNight
21%5%10%21%23%17%
1886
16th to endNight
27%36%15%26%21%
2112
November1st to 15thNight
30%37%18%27%12%
2123
16th to endNight
29%47%17%22%19%
2340
December1st to 15thNight
38%5%9%20%18%6%
2340
16th to endNight
47%48%17%14%6%
2374

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
18%437%27%8%2
90
16th to endDay
21%15%34%25%3
96
February1st to 15thDay
7%14%32%34%10%1
90
16th to endDay
12%7%40%29%9%
81
March1st to 15thDay
24%440%30%1
90
16th to endDay
14%6%21%30%26%
152
April1st to 15thDay
19%5%23%29%20%1
210
16th to endDay
12%321%33%26%2
210
May1st to 15thDay
10%321%34%25%4
228
16th to endDay
10%19%24%32%22%
267
June1st to 15thDay
9%5%22%34%27%
255
16th to endDay
5%418%41%29%
392
July1st to 15thDay
7%218%41%29%
385
16th to endDay
9%28%37%41%
270
August1st to 15thDay
10%28%38%38%
253
16th to endDay
6%1414%37%35%
268
September1st to 15thDay
14%1219%38%24%
255
16th to endDay
12%6%23%40%17%
254
October1st to 15thDay
313%30%39%12%
181
16th to endDay
12%38%44%22%8%
96
November1st to 15thDay
22%15%37%20%4
90
16th to endDay
5%8%34%34%11%5%
90
December1st to 15thDay
26%427%28%10%2
90
16th to endDay
31%7%29%22%9%
96
January1st to 15thNight
16%7%28%38%8%
720
16th to endNight
21%8%27%33%9%
768
February1st to 15thNight
15%7%30%34%11%
704
16th to endNight
20%7%31%32%7%
631
March1st to 15thNight
17%6%28%34%12%
639
16th to endNight
14%5%20%36%22%1
555
April1st to 15thNight
12%5%25%37%18%
494
16th to endNight
10%323%40%21%1
495
May1st to 15thNight
8%115%45%27%1
495
16th to endNight
419%32%42%8%
515
June1st to 15thNight
4426%52%11%
495
16th to endNight
41320%45%25%
495
July1st to 15thNight
4212%52%28%
465
16th to endNight
4211%48%32%
522
August1st to 15thNight
329%49%35%
494
16th to endNight
9%114%44%28%
525
September1st to 15thNight
9%1215%44%25%
495
16th to endNight
10%15%30%45%7%
638
October1st to 15thNight
6%112%34%38%6%
660
16th to endNight
11%417%31%29%5%
704
November1st to 15thNight
10%417%39%23%4
700
16th to endNight
10%5%24%36%20%1
720
December1st to 15thNight
15%7%24%33%17%1
720
16th to endNight
23%6%25%31%12%
768
Page generated at 2017-03-25 11:39:47. Version ac04

Copyright 2017 A. Danko


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