Stone Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stone Creek 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
76%
15417
30%
46943
29%
15385
78%
15385
48%
23594

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
69%
716
21%
2491
24%
716
71%
716
33%
1373
January16th to endNight
66%
768
25%
2496
28%
768
67%
768
31%
1478
February1st to 15thNight
67%
697
25%
2175
27%
697
68%
697
33%
1269
February16th to endNight
63%
632
23%
1895
25%
632
65%
632
32%
1155
March1st to 15thNight
66%
720
19%
2121
21%
720
67%
720
36%
1235
March16th to endNight
68%
768
24%
2013
18%
768
71%
768
44%
1178
April1st to 15thNight
64%
719
25%
1799
15%
719
66%
719
42%
1085
April16th to endNight
69%
720
27%
1800
14%
720
72%
720
52%
985
May1st to 15thNight
74%
623
30%
1703
20%
623
76%
623
60%
825
May16th to endNight
74%
414
31%
1537
32%
414
78%
414
50%
642
June1st to 15thNight
84%
360
31%
1440
38%
360
87%
360
57%
524
June16th to endNight
93%
360
40%
1440
52%
360
95%
360
80%
422
July1st to 15thNight
93%
340
36%
1360
47%
340
93%
340
72%
423
July16th to endNight
90%
469
40%
1502
41%
440
91%
440
64%
590
August1st to 15thNight
90%
663
38%
1737
27%
660
90%
660
81%
749
August16th to endNight
94%
764
45%
1910
29%
764
94%
764
83%
848
September1st to 15thNight
93%
720
43%
1800
31%
720
93%
720
80%
809
September16th to endNight
88%
692
45%
1884
42%
692
90%
692
76%
812
October1st to 15thNight
82%
660
34%
1939
36%
660
84%
660
57%
912
October16th to endNight
83%
704
39%
2117
43%
704
85%
704
59%
971
November1st to 15thNight
80%
700
31%
2275
36%
700
82%
700
50%
1064
November16th to endNight
76%
720
29%
2340
32%
720
77%
720
41%
1213
December1st to 15thNight
68%
720
23%
2481
26%
720
69%
720
31%
1414
December16th to endNight
59%
768
23%
2688
24%
768
62%
768
26%
1618

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
8%312212335%65%
47986
Night
9%212212235%65%
47130
TransparencyDay
21%38%19%25%21%
47666
Night
22%39%20%24%18%
46951
SeeingDay
9%7%25%35%16%5%
5879
Night
9%17%34%38%9%
15430

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
15%413213346%53%
1447
16th to endDay
19%5%13323346%46%
1728
February1st to 15thDay
16%6%12323436%49%
1679
16th to endDay
20%5%15%32244444%
1579
March1st to 15thDay
15%5%2432445%8%42%
1836
16th to endDay
14%5%243236%5%5%47%
2210
April1st to 15thDay
14%5%24423336%51%
2149
16th to endDay
9%413323246%58%
2160
May1st to 15thDay
5%212212235%69%
2247
16th to endDay
5%213213446%63%
2574
June1st to 15thDay
2212212335%72%
2520
16th to endDay
111111287%
2520
July1st to 15thDay
111112483%
2520
16th to endDay
11111222380%
2561
August1st to 15thDay
111111386%
2211
16th to endDay
1111112383%
2292
September1st to 15thDay
111122283%
2160
16th to endDay
211123380%
1934
October1st to 15thDay
6%21221325%467%
1689
16th to endDay
6%212212245%69%
1752
November1st to 15thDay
10%312323245%61%
1584
16th to endDay
10%312323435%57%
1620
December1st to 15thDay
17%5%13322335%49%
1478
16th to endDay
18%5%34323336%45%
1536
January1st to 15thNight
13%412312347%54%
2491
16th to endNight
16%5%13323346%50%
2496
February1st to 15thNight
14%5%14213447%50%
2171
16th to endNight
20%413313346%49%
1895
March1st to 15thNight
14%313223346%53%
2121
16th to endNight
12%412212337%57%
2013
April1st to 15thNight
12%413222346%56%
1799
16th to endNight
7%312222325%68%
1800
May1st to 15thNight
4112111246%72%
1703
16th to endNight
5%22212235%71%
1536
June1st to 15thNight
211211225%75%
1440
16th to endNight
1111289%
1440
July1st to 15thNight
1111112384%
1440
16th to endNight
2212212379%
1605
August1st to 15thNight
111112285%
1746
16th to endNight
11121386%
1910
September1st to 15thNight
111121286%
1800
16th to endNight
211112383%
1884
October1st to 15thNight
5%22112237%69%
1939
16th to endNight
6%11112325%73%
2117
November1st to 15thNight
9%212111236%67%
2275
16th to endNight
8%313213346%60%
2340
December1st to 15thNight
14%413313346%51%
2481
16th to endNight
21%313413336%47%
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
32%413%20%20%7%
1447
16th to endDay
39%5%12%14%15%11%
1728
February1st to 15thDay
36%5%11%23%18%4
1679
16th to endDay
42%5%10%25%14%1
1579
March1st to 15thDay
36%7%13%18%16%6%
1836
16th to endDay
34%7%15%22%16%3
2210
April1st to 15thDay
34%411%26%17%5%
2149
16th to endDay
26%5%11%26%24%5%
2160
May1st to 15thDay
18%39%24%34%9%
2247
16th to endDay
19%410%29%28%7%
2578
June1st to 15thDay
14%49%19%28%23%
2520
16th to endDay
6%129%35%43%
2520
July1st to 15thDay
7%127%22%58%
2371
16th to endDay
9%3310%20%52%
2402
August1st to 15thDay
6%129%28%52%
2195
16th to endDay
7%1210%36%42%
2292
September1st to 15thDay
8%1312%31%42%
2160
16th to endDay
8%1323%37%24%
1934
October1st to 15thDay
19%37%21%28%19%
1689
16th to endDay
18%28%25%28%17%
1752
November1st to 15thDay
26%313%21%25%9%
1584
16th to endDay
29%312%21%26%6%
1620
December1st to 15thDay
38%5%10%20%20%4
1478
16th to endDay
40%6%13%19%15%5%
1536
January1st to 15thNight
31%411%23%21%7%
2491
16th to endNight
36%411%15%19%12%
2496
February1st to 15thNight
32%5%10%27%16%6%
2182
16th to endNight
36%414%26%15%2
1895
March1st to 15thNight
31%5%17%19%21%5%
2121
16th to endNight
27%5%16%26%19%4
2013
April1st to 15thNight
28%5%14%28%18%4
1799
16th to endNight
20%415%26%26%6%
1800
May1st to 15thNight
14%39%25%33%12%
1704
16th to endNight
16%48%29%31%9%
1537
June1st to 15thNight
13%211%21%27%24%
1440
16th to endNight
41310%32%48%
1440
July1st to 15thNight
6%216%25%58%
1360
16th to endNight
11%226%21%54%
1502
August1st to 15thNight
7%211%26%52%
1737
16th to endNight
6%138%34%46%
1910
September1st to 15thNight
7%1310%31%45%
1800
16th to endNight
9%1318%42%25%
1884
October1st to 15thNight
17%38%24%28%19%
1939
16th to endNight
15%36%25%29%19%
2117
November1st to 15thNight
20%313%24%26%11%
2275
16th to endNight
24%5%11%23%25%9%
2340
December1st to 15thNight
33%5%13%22%19%6%
2481
16th to endNight
39%413%19%15%6%
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
40%222%16%12%6%
75
16th to endDay
23%419%29%16%5%
256
February1st to 15thDay
22%424%23%18%7%
254
16th to endDay
23%10%25%25%14%1
238
March1st to 15thDay
14%13%24%25%17%4
270
16th to endDay
18%13%28%26%11%2
288
April1st to 15thDay
18%16%31%24%6%1
269
16th to endDay
12%16%32%26%9%1
270
May1st to 15thDay
8%12%35%31%7%4
288
16th to endDay
7%14%26%34%12%5%
330
June1st to 15thDay
312%31%34%14%3
315
16th to endDay
1325%42%18%9%
315
July1st to 15thDay
117%46%24%9%
305
16th to endDay
119%51%18%8%
327
August1st to 15thDay
3225%49%12%7%
315
16th to endDay
2119%49%18%9%
332
September1st to 15thDay
2124%47%18%5%
315
16th to endDay
45%26%42%18%2
288
October1st to 15thDay
48%30%38%16%2
255
16th to endDay
8%425%34%24%2
264
November1st to 15thDay
8%28%13%46%20%
90
16th to endDay
10%8%24%32%21%3
90
December1st to 15thDay
15%331%28%21%
66
16th to endDay
25%115%32%15%9%
64
January1st to 15thNight
14%18%35%27%11%
720
16th to endNight
18%27%35%26%9%
768
February1st to 15thNight
17%18%35%27%9%
704
16th to endNight
21%27%34%27%6%
632
March1st to 15thNight
14%29%36%29%7%
720
16th to endNight
13%211%35%32%4
768
April1st to 15thNight
11%414%37%27%3
719
16th to endNight
7%215%35%30%7%
720
May1st to 15thNight
4114%42%31%5%
624
16th to endNight
6%212%34%40%4
415
June1st to 15thNight
47%40%44%3
360
16th to endNight
1336%55%3
360
July1st to 15thNight
125%66%5%
340
16th to endNight
2118%62%14%
469
August1st to 15thNight
1427%57%9%
663
16th to endNight
1122%63%11%
764
September1st to 15thNight
327%53%14%
720
16th to endNight
2429%49%12%
692
October1st to 15thNight
6%5%36%39%10%
660
16th to endNight
7%5%31%37%17%
704
November1st to 15thNight
9%15%30%38%14%
700
16th to endNight
8%7%40%30%12%
720
December1st to 15thNight
15%16%42%26%7%
720
16th to endNight
22%110%39%22%5%
768
Page generated at 2017-09-25 06:02:22. Version ac04

Copyright 2017 A. Danko


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