Bear Dance Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bear Dance Observatory clear sky chart from 2005-11-05 to 2018-10-08.

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
53%
17318
28%
51031
18%
17275
62%
17275
40%
27721

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
50%
973
31%
2716
20%
970
61%
970
48%
1393
January16th to endNight
49%
868
35%
2740
23%
868
63%
868
44%
1364
February1st to 15thNight
42%
762
25%
2421
17%
759
53%
759
38%
1285
February16th to endNight
38%
684
35%
2050
16%
684
57%
684
41%
1069
March1st to 15thNight
46%
780
28%
2298
15%
780
57%
780
41%
1235
March16th to endNight
43%
730
28%
2186
14%
730
56%
730
37%
1205
April1st to 15thNight
36%
584
24%
1948
12%
584
52%
584
32%
1053
April16th to endNight
41%
579
21%
1929
15%
579
52%
579
26%
1141
May1st to 15thNight
47%
584
20%
1771
16%
584
54%
584
27%
1136
May16th to endNight
48%
610
17%
1626
10%
609
55%
609
36%
975
June1st to 15thNight
61%
585
24%
1560
17%
585
66%
585
49%
828
June16th to endNight
67%
585
24%
1560
18%
585
71%
585
49%
836
July1st to 15thNight
64%
555
19%
1480
15%
555
67%
555
35%
903
July16th to endNight
72%
612
20%
1580
17%
579
73%
579
37%
948
August1st to 15thNight
66%
575
18%
1796
18%
572
69%
572
33%
1031
August16th to endNight
71%
621
24%
2070
25%
621
74%
621
36%
1127
September1st to 15thNight
67%
585
28%
1950
26%
585
74%
585
37%
1039
September16th to endNight
66%
582
32%
2100
30%
582
74%
582
43%
984
October1st to 15thNight
53%
726
30%
2230
19%
726
61%
726
40%
1192
October16th to endNight
63%
798
37%
2334
24%
798
71%
798
49%
1185
November1st to 15thNight
54%
950
33%
2470
19%
950
61%
950
50%
1318
November16th to endNight
52%
975
36%
2574
20%
975
61%
975
50%
1359
December1st to 15thNight
47%
975
26%
2730
13%
975
57%
975
44%
1453
December16th to endNight
42%
1040
29%
2912
15%
1040
53%
1040
37%
1662

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
5%5%2442446%8%51%
52116
Night
45%2332345%7%57%
51207
Cloud CoverDay
45%244245%6%8%51%
52114
Night
45%2432345%7%57%
51207
TransparencyDay
29%6%11%23%21%8%
51794
Night
25%412%26%22%7%
51031
SeeingDay
10%13%29%27%15%4
7242
Night
6%7%27%41%15%1
17324

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%24312447%62%
1552
16th to endDay
15%24213338%62%
1846
February1st to 15thDay
16%35%42335%7%55%
1770
16th to endDay
5%25%32345%7%58%
1710
March1st to 15thDay
45%2442435%7%55%
1989
16th to endDay
5%8%2442345%8%51%
2389
April1st to 15thDay
7%8%2432445%8%48%
2330
16th to endDay
9%9%245%2445%6%44%
2306
May1st to 15thDay
9%8%25%435%5%7%8%39%
2508
16th to endDay
8%423435%7%7%9%43%
2840
June1st to 15thDay
6%422425%5%7%9%49%
2730
16th to endDay
32133246%8%9%51%
2730
July1st to 15thDay
7%324435%6%7%10%43%
2730
16th to endDay
6%4245%36%6%7%10%41%
2838
August1st to 15thDay
6%4245%36%7%8%9%40%
2408
16th to endDay
6%314435%47%8%48%
2484
September1st to 15thDay
7%4134345%5%7%52%
2340
16th to endDay
5%313414345%62%
2189
October1st to 15thDay
6%41332335%6%59%
1896
16th to endDay
5%42222345%65%
1876
November1st to 15thDay
132331335%9%62%
1718
16th to endDay
1423222347%65%
1713
December1st to 15thDay
1425%5%22348%57%
1560
16th to endDay
25%26%424247%56%
1664
January1st to 15thNight
1314322347%64%
2716
16th to endNight
1425%323336%64%
2740
February1st to 15thNight
16%35%32335%8%56%
2411
16th to endNight
17%35%212345%61%
2050
March1st to 15thNight
34233135%5%7%57%
2298
16th to endNight
46%23323447%57%
2186
April1st to 15thNight
5%8%13323346%56%
1948
16th to endNight
11%10%13323336%49%
1929
May1st to 15thNight
11%7%2442346%8%43%
1770
16th to endNight
6%5%1342445%9%51%
1625
June1st to 15thNight
421122335%10%61%
1560
16th to endNight
31122245%6%9%59%
1560
July1st to 15thNight
5%3145%45%5%7%9%47%
1560
16th to endNight
7%213326%5%8%10%47%
1679
August1st to 15thNight
5%413425%5%6%10%48%
1805
16th to endNight
4423425%47%8%52%
2070
September1st to 15thNight
7%3134245%7%8%52%
1950
16th to endNight
4412322346%64%
2100
October1st to 15thNight
6%423222445%60%
2230
16th to endNight
45%12312347%64%
2334
November1st to 15thNight
1324322337%64%
2470
16th to endNight
1423313246%65%
2574
December1st to 15thNight
1425%322347%61%
2730
16th to endNight
26%35%423447%56%
2912

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
15%24312348%61%
1552
16th to endDay
15%24223248%62%
1846
February1st to 15thDay
16%36%43335%7%55%
1770
16th to endDay
5%2432345%7%58%
1710
March1st to 15thDay
45%25%32435%8%54%
1989
16th to endDay
48%24423449%50%
2387
April1st to 15thDay
6%8%2442445%7%48%
2330
16th to endDay
9%8%24425%45%6%44%
2306
May1st to 15thDay
8%7%35%5%26%5%6%8%38%
2508
16th to endDay
7%424436%7%7%9%42%
2840
June1st to 15thDay
6%312435%6%7%9%49%
2730
16th to endDay
3213425%6%7%10%51%
2730
July1st to 15thDay
6%324425%6%8%9%43%
2730
16th to endDay
5%424437%6%7%11%41%
2838
August1st to 15thDay
5%425%5%45%7%8%9%40%
2408
16th to endDay
5%314446%5%6%8%48%
2484
September1st to 15thDay
7%413425%5%5%7%52%
2340
16th to endDay
5%313423445%62%
2189
October1st to 15thDay
5%31342335%5%60%
1896
16th to endDay
5%422212346%65%
1876
November1st to 15thDay
132232335%9%62%
1718
16th to endDay
2423212447%64%
1713
December1st to 15thDay
1435%5%23348%57%
1560
16th to endDay
25%25%433347%56%
1664
January1st to 15thNight
324322347%64%
2716
16th to endNight
15%25%313337%63%
2740
February1st to 15thNight
16%25%42335%7%56%
2411
16th to endNight
17%35%222245%61%
2050
March1st to 15thNight
34243235%6%6%57%
2298
16th to endNight
46%24323347%57%
2186
April1st to 15thNight
5%8%13323446%56%
1948
16th to endNight
11%9%23323336%49%
1929
May1st to 15thNight
12%7%2442346%8%43%
1770
16th to endNight
5%5%2342346%9%51%
1625
June1st to 15thNight
421222335%11%61%
1560
16th to endNight
31123146%6%8%59%
1560
July1st to 15thNight
5%3146%35%5%7%9%47%
1560
16th to endNight
5%213335%6%8%10%47%
1679
August1st to 15thNight
5%424425%6%6%10%48%
1805
16th to endNight
44234245%7%8%52%
2070
September1st to 15thNight
6%3133245%7%8%52%
1950
16th to endNight
4312313446%64%
2100
October1st to 15thNight
6%5%23223446%59%
2230
16th to endNight
35%12312347%63%
2334
November1st to 15thNight
2324313347%64%
2470
16th to endNight
25%23313346%64%
2574
December1st to 15thNight
142432335%8%60%
2730
16th to endNight
26%35%423447%56%
2912

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
22%413%31%22%6%
1553
16th to endDay
22%311%30%23%8%
1846
February1st to 15thDay
28%314%32%15%4
1771
16th to endDay
24%5%7%27%27%8%
1710
March1st to 15thDay
28%49%25%22%8%
1989
16th to endDay
32%5%10%25%20%5%
2389
April1st to 15thDay
34%5%11%24%17%7%
2330
16th to endDay
40%6%10%21%16%4
2306
May1st to 15thDay
42%7%11%22%14%1
2508
16th to endDay
34%8%14%20%15%6%
2844
June1st to 15thDay
29%7%11%19%18%13%
2730
16th to endDay
25%6%10%20%24%11%
2730
July1st to 15thDay
33%9%11%18%16%9%
2581
16th to endDay
35%8%15%23%13%4
2674
August1st to 15thDay
36%10%13%18%13%7%
2393
16th to endDay
32%6%12%22%21%4
2484
September1st to 15thDay
30%5%10%20%20%12%
2340
16th to endDay
23%48%22%32%8%
2189
October1st to 15thDay
25%5%10%21%28%8%
1896
16th to endDay
21%38%25%30%11%
1876
November1st to 15thDay
20%311%25%26%13%
1718
16th to endDay
20%37%24%33%10%
1713
December1st to 15thDay
25%314%27%22%6%
1560
16th to endDay
28%414%23%22%6%
1664
January1st to 15thNight
20%312%31%25%6%
2716
16th to endNight
21%49%29%26%8%
2740
February1st to 15thNight
27%315%32%16%4
2421
16th to endNight
24%26%31%25%9%
2050
March1st to 15thNight
24%410%26%27%6%
2298
16th to endNight
27%411%27%23%4
2186
April1st to 15thNight
29%412%26%19%6%
1948
16th to endNight
37%411%26%17%3
1929
May1st to 15thNight
38%7%12%23%14%3
1771
16th to endNight
30%6%20%23%14%5%
1626
June1st to 15thNight
19%6%17%26%14%14%
1560
16th to endNight
19%6%13%23%25%11%
1560
July1st to 15thNight
32%7%15%22%14%7%
1480
16th to endNight
29%7%20%26%13%2
1580
August1st to 15thNight
30%7%17%24%13%6%
1796
16th to endNight
27%6%14%28%17%4
2070
September1st to 15thNight
27%5%13%24%18%11%
1950
16th to endNight
21%411%26%29%7%
2100
October1st to 15thNight
26%411%22%25%10%
2230
16th to endNight
21%38%26%30%9%
2334
November1st to 15thNight
20%29%24%27%14%
2470
16th to endNight
21%28%26%31%9%
2574
December1st to 15thNight
23%415%29%20%7%
2730
16th to endNight
28%5%13%24%23%4
2912

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
11%8%27%36%15%1
135
16th to endDay
212%33%38%13%
144
February1st to 15thDay
8%18%47%22%2
135
16th to endDay
421%41%24%8%
120
March1st to 15thDay
8%22%33%28%5%1
174
16th to endDay
15%31%31%15%4
352
April1st to 15thDay
14%29%34%15%4
329
16th to endDay
25%23%30%13%5%1
318
May1st to 15thDay
13%12%32%28%11%1
491
16th to endDay
14%13%26%27%14%4
597
June1st to 15thDay
8%12%26%27%18%5%
570
16th to endDay
6%7%31%25%24%4
570
July1st to 15thDay
8%420%29%27%9%
550
16th to endDay
9%417%31%28%8%
553
August1st to 15thDay
11%5%28%33%15%5%
359
16th to endDay
10%7%31%31%15%4
396
September1st to 15thDay
9%10%32%27%14%4
375
16th to endDay
9%10%37%25%14%3
224
October1st to 15thDay
5%17%29%27%13%5%
157
16th to endDay
8%13%27%26%19%4
144
November1st to 15thDay
5%12%28%28%20%4
135
16th to endDay
7%15%35%35%5%
135
December1st to 15thDay
5%22%37%26%5%1
135
16th to endDay
216%36%36%7%
144
January1st to 15thNight
28%33%44%9%1
975
16th to endNight
27%34%45%8%1
868
February1st to 15thNight
48%38%43%5%
764
16th to endNight
5%10%40%37%5%
684
March1st to 15thNight
49%33%41%10%
780
16th to endNight
8%11%34%39%6%
730
April1st to 15thNight
10%12%38%31%6%
584
16th to endNight
18%10%27%33%10%
579
May1st to 15thNight
16%5%22%39%14%1
585
16th to endNight
8%6%28%38%16%1
611
June1st to 15thNight
5%5%24%42%20%2
585
16th to endNight
4320%45%25%
585
July1st to 15thNight
7%214%37%34%4
555
16th to endNight
7%211%38%36%4
612
August1st to 15thNight
9%112%39%32%4
575
16th to endNight
7%113%42%30%4
621
September1st to 15thNight
8%214%38%31%4
585
16th to endNight
6%417%44%24%3
582
October1st to 15thNight
8%6%27%39%14%3
726
16th to endNight
6%5%20%45%18%3
798
November1st to 15thNight
39%27%43%14%1
950
16th to endNight
47%31%44%9%1
975
December1st to 15thNight
49%33%43%8%
975
16th to endNight
410%37%37%9%
1040
Page generated at 2018-10-09 08:39:15. Version ac04

Copyright 2018 A. Danko


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