BuckSnort Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the BuckSnort Observatory clear sky chart from 2005-11-05 to 2019-06-19.

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%
17835
28%
54001
19%
17789
59%
17789
38%
29859

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
38%
1047
30%
2717
12%
1045
49%
1045
38%
1633
January16th to endNight
36%
1067
32%
2859
13%
1067
48%
1067
37%
1679
February1st to 15thNight
33%
824
28%
2465
13%
817
45%
817
31%
1442
February16th to endNight
24%
736
29%
2206
8%
736
40%
736
32%
1264
March1st to 15thNight
33%
662
29%
2342
15%
662
50%
662
28%
1326
March16th to endNight
35%
672
26%
2464
16%
672
49%
672
31%
1299
April1st to 15thNight
31%
629
26%
2307
13%
629
51%
629
30%
1245
April16th to endNight
32%
624
27%
1990
15%
624
50%
624
34%
1120
May1st to 15thNight
35%
629
25%
1890
16%
629
49%
629
34%
1096
May16th to endNight
49%
658
25%
1972
18%
657
62%
657
40%
1090
June1st to 15thNight
70%
630
25%
1890
26%
630
75%
630
54%
905
June16th to endNight
70%
597
24%
1791
27%
597
74%
597
44%
955
July1st to 15thNight
81%
555
24%
1665
27%
555
84%
555
49%
852
July16th to endNight
85%
612
30%
1738
36%
579
88%
579
54%
849
August1st to 15thNight
89%
575
35%
1744
41%
572
90%
572
60%
788
August16th to endNight
79%
621
23%
2125
30%
621
80%
621
37%
1132
September1st to 15thNight
74%
585
21%
2145
25%
585
75%
585
31%
1182
September16th to endNight
71%
582
28%
2145
29%
582
75%
582
33%
1147
October1st to 15thNight
70%
602
35%
2162
33%
602
75%
602
41%
1053
October16th to endNight
54%
832
35%
2496
21%
832
63%
832
45%
1289
November1st to 15thNight
50%
876
30%
2516
18%
876
57%
876
40%
1416
November16th to endNight
46%
1050
34%
2730
16%
1050
56%
1050
42%
1566
December1st to 15thNight
42%
1050
30%
2730
15%
1050
50%
1050
36%
1681
December16th to endNight
37%
1120
26%
2912
10%
1120
46%
1120
32%
1850

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%424424447%50%
54712
Night
9%413323347%56%
54204
Cloud CoverDay
10%42442445%6%51%
54710
Night
9%313323347%56%
54204
TransparencyDay
33%5%10%21%21%9%
54410
Night
28%410%21%22%12%
54009
SeeingDay
12%5%21%30%24%7%
7721
Night
11%6%27%36%16%1
17840

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
14%423313335%52%
1881
16th to endDay
12%323213445%55%
2082
February1st to 15thDay
13%5%14313235%53%
2050
16th to endDay
16%5%22313245%50%
1840
March1st to 15thDay
17%424423446%46%
2278
16th to endDay
13%5%24323346%51%
2464
April1st to 15thDay
11%5%24423347%49%
2301
16th to endDay
12%5%25%424335%50%
2571
May1st to 15thDay
14%6%245%3445%7%41%
2721
16th to endDay
11%5%25%5%25%5%6%8%41%
2846
June1st to 15thDay
4212425%46%9%54%
2730
16th to endDay
8%324435%5%6%8%47%
2577
July1st to 15thDay
6%2235%36%5%6%9%48%
2535
16th to endDay
5%213435%5%6%10%51%
2674
August1st to 15thDay
3133245%5%7%61%
2455
16th to endDay
8%4245%45%6%6%7%43%
2429
September1st to 15thDay
12%425%5%345%46%45%
2145
16th to endDay
9%425%5%3345%7%48%
2145
October1st to 15thDay
8%41432445%6%55%
2113
16th to endDay
9%312212235%65%
2080
November1st to 15thDay
11%425%223446%51%
1999
16th to endDay
11%322312225%60%
1890
December1st to 15thDay
15%5%23424236%50%
1890
16th to endDay
14%7%24413346%47%
2016
January1st to 15thNight
13%5%23212335%56%
2717
16th to endNight
13%324212335%56%
2859
February1st to 15thNight
12%5%2441322455%
2462
16th to endNight
15%42331225%5%52%
2206
March1st to 15thNight
14%42342335%6%50%
2342
16th to endNight
10%323324346%55%
2464
April1st to 15thNight
7%42442445%6%53%
2307
16th to endNight
10%413423347%53%
1990
May1st to 15thNight
9%41332435%9%50%
1889
16th to endNight
7%31342436%10%52%
1971
June1st to 15thNight
211231345%10%64%
1890
16th to endNight
5%31322345%9%58%
1791
July1st to 15thNight
411221346%10%59%
1755
16th to endNight
211222335%12%62%
1846
August1st to 15thNight
122213348%69%
1754
16th to endNight
6%31342346%10%53%
2125
September1st to 15thNight
9%42342446%8%49%
2145
16th to endNight
9%5%1422445%7%52%
2145
October1st to 15thNight
7%312213446%62%
2162
16th to endNight
9%31231223464%
2496
November1st to 15thNight
9%324323336%58%
2516
16th to endNight
10%423222235%60%
2730
December1st to 15thNight
13%424313246%51%
2730
16th to endNight
13%7%24322345%50%
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
14%5%23323235%53%
1881
16th to endDay
12%312313446%56%
2082
February1st to 15thDay
13%5%23323235%53%
2050
16th to endDay
16%5%23223436%50%
1840
March1st to 15thDay
16%424324446%46%
2278
16th to endDay
12%5%24313346%51%
2462
April1st to 15thDay
11%5%23424347%50%
2301
16th to endDay
11%5%24423345%50%
2571
May1st to 15thDay
14%5%25%42445%7%41%
2721
16th to endDay
11%5%25%5%345%6%8%41%
2846
June1st to 15thDay
42134345%6%9%55%
2730
16th to endDay
8%3246%345%6%8%47%
2577
July1st to 15thDay
6%214436%5%7%8%48%
2535
16th to endDay
6%2234245%6%10%51%
2674
August1st to 15thDay
311342446%7%61%
2455
16th to endDay
8%4145%45%6%6%7%44%
2429
September1st to 15thDay
12%425%5%345%5%6%45%
2145
16th to endDay
9%425%43445%7%49%
2145
October1st to 15thDay
9%31342345%6%55%
2113
16th to endDay
9%312212235%65%
2080
November1st to 15thDay
11%5%24314346%52%
1999
16th to endDay
11%412222225%61%
1890
December1st to 15thDay
15%6%24323245%50%
1890
16th to endDay
14%8%24322345%47%
2016
January1st to 15thNight
13%423212335%56%
2717
16th to endNight
13%313213345%57%
2859
February1st to 15thNight
12%5%2432322455%
2462
16th to endNight
15%413312245%53%
2206
March1st to 15thNight
14%414423347%49%
2342
16th to endNight
10%213323446%55%
2464
April1st to 15thNight
6%42443445%6%54%
2307
16th to endNight
9%41332335%6%54%
1990
May1st to 15thNight
9%41332445%8%50%
1889
16th to endNight
6%31332437%10%52%
1971
June1st to 15thNight
21231345%9%64%
1890
16th to endNight
5%22232236%8%59%
1791
July1st to 15thNight
411232346%10%60%
1755
16th to endNight
211222236%12%62%
1846
August1st to 15thNight
1112213348%70%
1754
16th to endNight
6%21342347%10%53%
2125
September1st to 15thNight
9%31342446%8%50%
2145
16th to endNight
9%5%2331335%8%52%
2145
October1st to 15thNight
7%33213445%62%
2162
16th to endNight
9%31221223465%
2496
November1st to 15thNight
9%414323345%58%
2516
16th to endNight
9%42232224460%
2730
December1st to 15thNight
13%5%24312346%51%
2730
16th to endNight
13%6%2432333451%
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
35%36%17%25%12%
1882
16th to endDay
29%37%16%27%15%
2082
February1st to 15thDay
34%36%16%21%16%
2051
16th to endDay
37%35%18%21%14%
1840
March1st to 15thDay
39%5%7%13%22%11%
2278
16th to endDay
34%49%19%22%9%
2464
April1st to 15thDay
35%37%19%20%13%
2301
16th to endDay
36%46%18%24%9%
2571
May1st to 15thDay
42%5%10%17%16%8%
2721
16th to endDay
39%6%10%21%18%3
2850
June1st to 15thDay
24%6%13%28%22%5%
2730
16th to endDay
33%6%13%23%18%4
2577
July1st to 15thDay
29%7%19%26%15%2
2396
16th to endDay
23%7%17%30%18%1
2519
August1st to 15thDay
20%6%14%33%22%2
2441
16th to endDay
36%7%14%24%13%3
2429
September1st to 15thDay
39%6%10%20%17%5%
2145
16th to endDay
35%5%9%19%21%8%
2145
October1st to 15thDay
28%5%10%22%18%14%
2113
16th to endDay
23%3417%30%20%
2080
November1st to 15thDay
34%49%21%21%10%
1999
16th to endDay
28%35%17%24%20%
1890
December1st to 15thDay
37%38%18%21%11%
1890
16th to endDay
38%37%16%23%9%
2016
January1st to 15thNight
31%25%18%23%17%
2717
16th to endNight
31%35%15%26%18%
2859
February1st to 15thNight
34%36%14%22%19%
2472
16th to endNight
33%27%17%21%17%
2206
March1st to 15thNight
35%38%14%23%14%
2342
16th to endNight
30%410%20%23%9%
2464
April1st to 15thNight
30%5%8%19%20%15%
2307
16th to endNight
30%5%10%19%22%10%
1990
May1st to 15thNight
31%5%13%22%18%8%
1890
16th to endNight
27%5%15%30%17%3
1973
June1st to 15thNight
16%5%16%31%24%5%
1890
16th to endNight
22%7%13%29%22%4
1791
July1st to 15thNight
18%7%20%33%18%1
1665
16th to endNight
15%6%20%34%21%2
1738
August1st to 15thNight
13%417%36%24%4
1744
16th to endNight
25%7%19%27%15%4
2125
September1st to 15thNight
31%6%13%23%17%6%
2145
16th to endNight
30%5%11%23%19%10%
2145
October1st to 15thNight
23%5%11%27%16%16%
2162
16th to endNight
24%35%15%27%23%
2496
November1st to 15thNight
29%37%24%22%13%
2516
16th to endNight
28%26%16%26%19%
2730
December1st to 15thNight
34%29%17%22%12%
2730
16th to endNight
36%46%15%24%12%
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
18%7%35%31%6%1
180
16th to endDay
15%11%36%22%10%2
192
February1st to 15thDay
17%14%40%21%6%
180
16th to endDay
23%14%36%22%3
159
March1st to 15thDay
24%15%35%19%4
180
16th to endDay
9%6%43%30%8%
192
April1st to 15thDay
15%9%46%21%7%
180
16th to endDay
12%13%41%20%9%1
463
May1st to 15thDay
16%8%34%29%10%1
618
16th to endDay
14%5%29%31%14%4
677
June1st to 15thDay
5%115%47%26%4
645
16th to endDay
6%29%41%32%8%
587
July1st to 15thDay
5%6%36%36%13%
550
16th to endDay
4329%45%17%
595
August1st to 15thDay
4331%46%13%
518
16th to endDay
11%5%27%36%17%
341
September1st to 15thDay
10%313%43%27%
180
16th to endDay
15%421%42%15%
180
October1st to 15thDay
6%110%27%42%10%
180
16th to endDay
19%5%19%24%27%3
192
November1st to 15thDay
22%5%24%29%15%2
180
16th to endDay
17%10%28%26%12%4
180
December1st to 15thDay
21%9%31%25%9%2
180
16th to endDay
26%10%34%22%5%
192
January1st to 15thNight
16%9%31%32%9%
1050
16th to endNight
15%8%35%31%7%
1067
February1st to 15thNight
15%12%34%31%5%
824
16th to endNight
18%10%44%22%3
736
March1st to 15thNight
16%10%35%32%4
662
16th to endNight
9%9%43%33%4
672
April1st to 15thNight
9%8%47%30%3
629
16th to endNight
10%9%43%27%8%
624
May1st to 15thNight
12%7%41%30%8%
630
16th to endNight
7%334%38%15%
659
June1st to 15thNight
2121%51%20%1
630
16th to endNight
4115%51%24%2
597
July1st to 15thNight
417%49%34%3
555
16th to endNight
2449%36%5%
612
August1st to 15thNight
1342%46%5%
575
16th to endNight
7%341%41%5%
621
September1st to 15thNight
10%16%35%40%6%
585
16th to endNight
12%17%38%35%4
582
October1st to 15thNight
8%16%43%27%2
602
16th to endNight
11%426%35%20%2
832
November1st to 15thNight
11%428%37%16%1
876
16th to endNight
13%8%28%33%14%
1050
December1st to 15thNight
16%7%29%36%9%
1050
16th to endNight
18%9%31%33%7%
1120
Page generated at 2019-06-20 07:02:29. Version ac04

Copyright 2019 A. Danko


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