Gopherville Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gopherville Observatory clear sky chart from 2005-11-05 to 2017-12-02.

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
78%
16299
40%
47868
33%
16257
84%
16257
65%
20828

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
72%
720
34%
2327
32%
716
80%
716
52%
1051
January16th to endNight
66%
768
42%
2406
35%
768
78%
768
52%
1111
February1st to 15thNight
73%
700
41%
2110
36%
699
83%
699
61%
930
February16th to endNight
66%
632
36%
1895
35%
632
73%
632
47%
954
March1st to 15thNight
70%
720
39%
2070
33%
720
80%
720
64%
925
March16th to endNight
72%
768
40%
2112
31%
768
81%
768
66%
952
April1st to 15thNight
65%
719
39%
1887
23%
719
75%
719
70%
860
April16th to endNight
70%
658
46%
1738
26%
658
81%
658
80%
728
May1st to 15thNight
73%
539
43%
1619
31%
539
80%
539
75%
627
May16th to endNight
77%
562
43%
1684
30%
561
84%
561
81%
630
June1st to 15thNight
82%
540
38%
1620
30%
540
85%
540
81%
612
June16th to endNight
90%
540
38%
1620
33%
540
91%
540
79%
625
July1st to 15thNight
89%
510
31%
1530
26%
510
90%
510
68%
652
July16th to endNight
88%
564
36%
1593
29%
531
89%
531
61%
715
August1st to 15thNight
91%
635
36%
1708
26%
632
92%
632
70%
779
August16th to endNight
89%
764
42%
1910
30%
764
90%
764
67%
953
September1st to 15thNight
88%
720
37%
1962
31%
720
90%
720
66%
910
September16th to endNight
86%
716
50%
1980
43%
716
90%
716
81%
807
October1st to 15thNight
78%
720
43%
1980
35%
720
84%
720
71%
876
October16th to endNight
84%
768
47%
2271
42%
768
90%
768
73%
926
November1st to 15thNight
81%
760
39%
2449
37%
760
88%
760
65%
1006
November16th to endNight
78%
780
44%
2535
44%
780
84%
780
62%
1045
December1st to 15thNight
73%
728
39%
2366
37%
728
81%
728
56%
1036
December16th to endNight
69%
768
40%
2496
37%
768
78%
768
53%
1118

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
111212235%75%
48574
Night
111212235%75%
48066
TransparencyDay
11%2411%24%45%
48269
Night
12%2311%23%46%
47872
SeeingDay
2313%31%36%12%
5982
Night
2213%40%36%5%
16305

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
2213313335%69%
1611
16th to endDay
321223335%69%
1815
February1st to 15thDay
2211212237%72%
1751
16th to endDay
21232445%6%64%
1579
March1st to 15thDay
212212246%73%
1888
16th to endDay
121112236%76%
2112
April1st to 15thDay
11112246%76%
2059
16th to endDay
12486%
2220
May1st to 15thDay
11223482%
2331
16th to endDay
1111287%
2429
June1st to 15thDay
11112486%
2340
16th to endDay
11111286%
2340
July1st to 15thDay
111213346%70%
2340
16th to endDay
311342346%8%60%
2467
August1st to 15thDay
11231236%7%68%
2240
16th to endDay
212212346%71%
2292
September1st to 15thDay
22211335%6%69%
1998
16th to endDay
111112287%
1980
October1st to 15thDay
111113384%
1980
16th to endDay
11123481%
1952
November1st to 15thDay
11221232477%
1737
16th to endDay
212212236%75%
1755
December1st to 15thDay
222413347%66%
1630
16th to endDay
2112313348%67%
1728
January1st to 15thNight
222322445%68%
2327
16th to endNight
4313212335%69%
2406
February1st to 15thNight
1212213245%73%
2101
16th to endNight
4213234445%62%
1895
March1st to 15thNight
211112247%73%
2070
16th to endNight
111212235%75%
2112
April1st to 15thNight
111211135%78%
1887
16th to endNight
1111487%
1738
May1st to 15thNight
11124482%
1619
16th to endNight
1111288%
1684
June1st to 15thNight
1111486%
1620
16th to endNight
111111386%
1620
July1st to 15thNight
11222338%72%
1620
16th to endNight
11122124410%66%
1701
August1st to 15thNight
1213247%73%
1717
16th to endNight
211112347%71%
1910
September1st to 15thNight
112213335%75%
1962
16th to endNight
11111287%
1980
October1st to 15thNight
11111122480%
1980
16th to endNight
111223480%
2271
November1st to 15thNight
111122335%75%
2449
16th to endNight
1112211235%74%
2535
December1st to 15thNight
223312246%69%
2366
16th to endNight
321221235%6%68%
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
17%25%11%27%35%
1612
16th to endDay
17%25%16%25%32%
1815
February1st to 15thDay
14%1413%28%38%
1751
16th to endDay
18%36%15%28%28%
1579
March1st to 15thDay
13%129%26%46%
1888
16th to endDay
11%139%29%43%
2112
April1st to 15thDay
9%139%30%44%
2059
16th to endDay
5%117%26%58%
2220
May1st to 15thDay
7%28%21%59%
2331
16th to endDay
6%15%25%60%
2432
June1st to 15thDay
6%11418%68%
2340
16th to endDay
7%12310%75%
2340
July1st to 15thDay
12%46%12%21%41%
2201
16th to endDay
19%5%8%21%25%18%
2312
August1st to 15thDay
13%37%18%23%32%
2225
16th to endDay
13%45%15%31%29%
2292
September1st to 15thDay
15%45%13%24%37%
1998
16th to endDay
6%25%20%63%
1980
October1st to 15thDay
7%1310%25%53%
1980
16th to endDay
8%139%18%57%
1952
November1st to 15thDay
11%1212%27%43%
1737
16th to endDay
12%1312%24%46%
1755
December1st to 15thDay
18%25%15%28%30%
1630
16th to endDay
15%38%18%30%22%
1728
January1st to 15thNight
17%25%9%24%40%
2327
16th to endNight
19%2313%21%39%
2406
February1st to 15thNight
14%1315%21%43%
2112
16th to endNight
22%2412%22%35%
1895
March1st to 15thNight
12%139%24%47%
2070
16th to endNight
12%1410%25%45%
2112
April1st to 15thNight
10%1210%31%43%
1887
16th to endNight
5%18%24%57%
1738
May1st to 15thNight
6%127%24%57%
1620
16th to endNight
5%16%24%62%
1685
June1st to 15thNight
6%1417%69%
1620
16th to endNight
6%128%79%
1620
July1st to 15thNight
10%35%12%24%44%
1530
16th to endNight
13%48%23%31%20%
1593
August1st to 15thNight
10%27%17%25%36%
1708
16th to endNight
12%36%14%29%32%
1910
September1st to 15thNight
13%2413%28%37%
1962
16th to endNight
6%16%23%61%
1980
October1st to 15thNight
10%139%21%53%
1980
16th to endNight
9%138%16%60%
2271
November1st to 15thNight
12%1310%24%46%
2449
16th to endNight
13%1211%23%48%
2535
December1st to 15thNight
16%2414%25%36%
2366
16th to endNight
16%35%17%29%27%
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
6%222%43%25%
90
16th to endDay
6%5%25%31%26%5%
183
February1st to 15thDay
35%18%39%26%6%
266
16th to endDay
47%21%31%28%5%
238
March1st to 15thDay
45%20%24%34%10%
270
16th to endDay
27%24%24%26%15%
288
April1st to 15thDay
38%18%30%26%11%
269
16th to endDay
10%24%37%20%7%
270
May1st to 15thDay
35%19%32%26%12%
288
16th to endDay
1317%34%36%5%
330
June1st to 15thDay
211%42%37%6%
315
16th to endDay
8%29%44%16%
315
July1st to 15thDay
6%30%44%17%
305
16th to endDay
2329%47%17%
327
August1st to 15thDay
2332%42%18%
315
16th to endDay
1125%47%24%
332
September1st to 15thDay
7%7%27%42%14%
315
16th to endDay
213%24%42%16%
315
October1st to 15thDay
113%30%43%9%
315
16th to endDay
217%19%47%21%
176
November1st to 15thDay
2212%38%31%12%
135
16th to endDay
6%5%17%31%22%14%
135
December1st to 15thDay
26%12%27%43%7%
94
16th to endDay
7%121%47%20%1
96
January1st to 15thNight
3217%47%25%3
720
16th to endNight
6%218%42%27%2
768
February1st to 15thNight
1217%43%31%3
704
16th to endNight
4320%49%18%3
632
March1st to 15thNight
3321%36%29%5%
720
16th to endNight
2416%39%31%5%
768
April1st to 15thNight
25%23%40%25%3
719
16th to endNight
15%21%40%28%3
658
May1st to 15thNight
420%38%33%3
540
16th to endNight
1317%41%34%2
563
June1st to 15thNight
14%50%32%1
540
16th to endNight
15%43%46%2
540
July1st to 15thNight
15%38%48%6%
510
16th to endNight
2432%56%3
564
August1st to 15thNight
1331%57%5%
635
16th to endNight
4229%52%10%
764
September1st to 15thNight
2430%51%10%
720
16th to endNight
19%35%45%8%
716
October1st to 15thNight
2114%38%38%4
720
16th to endNight
1110%35%42%9%
768
November1st to 15thNight
113%42%35%6%
760
16th to endNight
3111%39%35%9%
780
December1st to 15thNight
2215%46%30%2
728
16th to endNight
4217%48%22%4
768
Page generated at 2017-12-03 09:16:37. Version ac04

Copyright 2017 A. Danko


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