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Smokey Jack Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Smokey Jack Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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
46%
24460
30%
74475
15%
24405
60%
24405
43%
37002

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 10thNight
38%
950
33%
2647
13%
946
57%
946
49%
1227
January11th to 20thNight
34%
797
37%
2462
17%
797
56%
797
47%
1076
January21st to endNight
36%
792
36%
2574
17%
792
60%
792
48%
1157
February1st to 10thNight
25%
720
31%
2340
10%
720
50%
720
43%
1086
February11th to 20thNight
26%
701
32%
2102
10%
700
48%
700
42%
1040
February21st to endNight
25%
592
40%
1776
8%
592
55%
592
44%
861
March1st to 10thNight
31%
720
32%
2142
10%
720
50%
720
46%
993
March11th to 20thNight
42%
720
30%
1980
14%
720
53%
720
47%
1048
March21st to endNight
33%
680
35%
2066
11%
680
57%
680
43%
1027
April1st to 10thNight
32%
540
30%
1800
12%
540
55%
540
42%
814
April11th to 20thNight
33%
533
27%
1777
14%
533
52%
533
33%
902
April21st to endNight
39%
540
27%
1800
13%
540
59%
540
34%
910
May1st to 10thNight
43%
540
26%
1769
17%
540
57%
540
35%
924
May11th to 20thNight
49%
531
18%
1463
10%
531
56%
531
33%
900
May21st to endNight
47%
583
23%
1552
10%
582
58%
582
41%
843
June1st to 10thNight
60%
540
26%
1440
15%
540
67%
540
45%
767
June11th to 20thNight
60%
540
29%
1440
19%
540
68%
540
55%
716
June21st to endNight
64%
540
23%
1440
16%
540
70%
540
44%
807
July1st to 10thNight
68%
525
17%
1400
14%
525
70%
525
31%
906
July11th to 20thNight
78%
522
22%
1392
18%
522
79%
522
45%
778
July21st to endNight
75%
591
12%
1641
12%
558
75%
558
25%
1071
August1st to 10thNight
71%
537
14%
1620
14%
534
71%
534
30%
967
August11th to 20thNight
72%
534
22%
1778
24%
534
75%
534
36%
973
August21st to endNight
72%
594
24%
1980
24%
594
75%
594
36%
1069
September1st to 10thNight
69%
540
28%
1800
26%
540
76%
540
38%
944
September11th to 20thNight
62%
540
36%
1804
29%
540
73%
540
44%
876
September21st to endNight
57%
540
33%
1980
25%
540
71%
540
45%
875
October1st to 10thNight
54%
720
31%
2160
17%
720
65%
720
47%
1091
October11th to 20thNight
52%
720
42%
2160
19%
720
70%
720
65%
885
October21st to endNight
48%
792
40%
2376
18%
792
64%
792
52%
1126
November1st to 10thNight
46%
908
39%
2388
15%
908
62%
908
62%
1111
November11th to 20thNight
41%
950
41%
2470
15%
950
58%
950
59%
1166
November21st to endNight
43%
950
36%
2513
15%
950
58%
950
52%
1257
December1st to 10thNight
37%
950
32%
2660
12%
950
52%
950
48%
1292
December11th to 20thNight
30%
950
32%
3111
11%
949
49%
949
42%
1468
December21st to endNight
25%
1038
21%
4672
8%
1026
45%
1026
28%
2049

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
34244345%6%8%56%
74775
Night
242332345%8%63%
75029
TransparencyDay
24%5%12%25%24%10%
74489
Night
20%5%13%27%26%9%
74838
SeeingDay
9%13%29%27%16%5%
14286
Night
6%10%33%33%16%3
24471

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 10thDay
131332345%8%68%
1518
11th to 20thDay
132432346%9%65%
1619
21st to endDay
434323348%65%
1782
February1st to 10thDay
436%32345%8%62%
1620
11th to 20thDay
132432345%8%66%
1744
21st to endDay
6%36%3235%5%9%59%
1480
March1st to 10thDay
1335%33445%9%61%
1813
11th to 20thDay
36%3443446%8%55%
1980
21st to endDay
27%24425%45%9%56%
2290
April1st to 10thDay
26%233245%6%9%58%
2160
11th to 20thDay
48%25%5%3446%8%51%
2131
21st to endDay
47%245%335%7%9%49%
2160
May1st to 10thDay
5%6%35%5%45%5%6%8%48%
2189
11th to 20thDay
7%6%35%5%35%5%8%9%43%
2428
21st to endDay
5%323435%6%7%9%53%
2724
June1st to 10thDay
4314435%6%8%12%51%
2520
11th to 20thDay
3213335%6%7%8%59%
2520
21st to endDay
33235%36%7%8%9%51%
2520
July1st to 10thDay
7%3245%36%6%7%9%47%
2520
11th to 20thDay
5%3245%5%8%7%8%10%44%
2520
21st to endDay
7%336%6%5%7%10%9%11%32%
2577
August1st to 10thDay
7%436%7%46%7%7%8%40%
2307
11th to 20thDay
6%3245%46%6%8%9%47%
2123
21st to endDay
6%325%5%35%6%6%9%49%
2376
September1st to 10thDay
6%324435%6%7%8%53%
2160
11th to 20thDay
5%21333446%8%63%
2156
21st to endDay
5%213323445%68%
1976
October1st to 10thDay
5%413335%5%5%6%60%
1800
11th to 20thDay
2312212336%74%
1800
21st to endDay
35%13323346%68%
1976
November1st to 10thDay
1312212348%73%
1673
11th to 20thDay
213213348%72%
1710
21st to endDay
1423323347%68%
1663
December1st to 10thDay
32231336%6%70%
1520
11th to 20thDay
132321346%9%65%
1926
21st to endDay
1335%42446%6%62%
2794
January1st to 10thNight
31232335%7%71%
2647
11th to 20thNight
1322223346%72%
2462
21st to endNight
32331345%7%70%
2574
February1st to 10thNight
434422346%68%
2340
11th to 20thNight
14243235%5%7%64%
2102
21st to endNight
425%423447%66%
1776
March1st to 10thNight
141322335%7%68%
2142
11th to 20thNight
25%2332445%8%62%
1980
21st to endNight
242332335%8%65%
2066
April1st to 10thNight
242332335%7%67%
1800
11th to 20thNight
47%2441345%7%59%
1777
21st to endNight
35%25%42445%7%58%
1800
May1st to 10thNight
45%26%42445%7%58%
1769
11th to 20thNight
7%8%244345%6%8%49%
1463
21st to endNight
6%5%1233345%8%60%
1552
June1st to 10thNight
4313335%45%8%62%
1440
11th to 20thNight
2213314339%69%
1440
21st to endNight
3323435%6%7%8%56%
1440
July1st to 10thNight
6%425%5%47%7%9%8%44%
1440
11th to 20thNight
5%324425%6%7%10%52%
1440
21st to endNight
4336%6%47%7%9%12%39%
1737
August1st to 10thNight
6%425%5%35%6%8%11%45%
1629
11th to 20thNight
5%4245%35%6%7%10%49%
1778
21st to endNight
5%324436%6%7%9%52%
1980
September1st to 10thNight
5%423435%5%6%9%54%
1800
11th to 20thNight
5%41232345%8%63%
1804
21st to endNight
431333345%6%67%
1980
October1st to 10thNight
5%31232345%7%66%
2160
11th to 20thNight
1112112346%79%
2160
21st to endNight
3423222345%70%
2376
November1st to 10thNight
131221225%6%75%
2388
11th to 20thNight
111221335%6%76%
2470
21st to endNight
15%2222325%8%69%
2513
December1st to 10thNight
1213324347%70%
2660
11th to 20thNight
132432346%9%64%
3271
21st to endNight
142442446%8%61%
4873

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 10thDay
15%314%36%26%5%
1519
11th to 20thDay
17%316%30%28%7%
1619
21st to endDay
20%39%35%24%9%
1782
February1st to 10thDay
20%414%31%22%9%
1620
11th to 20thDay
17%412%27%30%10%
1754
21st to endDay
24%38%25%27%13%
1480
March1st to 10thDay
20%311%26%30%10%
1813
11th to 20thDay
27%39%30%24%7%
1980
21st to endDay
26%5%10%30%24%6%
2290
April1st to 10thDay
23%5%12%25%23%12%
2160
11th to 20thDay
31%38%27%22%8%
2134
21st to endDay
30%6%10%27%22%5%
2160
May1st to 10thDay
32%5%11%24%21%6%
2189
11th to 20thDay
35%8%14%24%16%4
2432
21st to endDay
25%6%12%22%24%11%
2724
June1st to 10thDay
23%8%14%23%22%10%
2520
11th to 20thDay
20%6%9%17%26%22%
2520
21st to endDay
25%7%10%23%22%13%
2520
July1st to 10thDay
31%7%13%17%21%12%
2451
11th to 20thDay
31%7%14%28%14%6%
2445
21st to endDay
37%12%23%19%8%1
2434
August1st to 10thDay
37%8%18%15%15%6%
2292
11th to 20thDay
31%7%13%21%21%8%
2123
21st to endDay
28%6%14%24%22%5%
2376
September1st to 10thDay
27%6%11%21%22%13%
2160
11th to 20thDay
20%5%13%18%30%15%
2156
21st to endDay
19%47%26%34%11%
1976
October1st to 10thDay
23%6%9%23%29%10%
1800
11th to 20thDay
14%27%22%40%15%
1800
21st to endDay
20%27%28%33%11%
1976
November1st to 10thDay
12%39%24%39%14%
1673
11th to 20thDay
12%48%35%32%9%
1710
21st to endDay
19%36%25%32%14%
1663
December1st to 10thDay
14%416%32%26%8%
1520
11th to 20thDay
15%415%29%28%9%
1924
21st to endDay
19%7%11%24%25%13%
2794
January1st to 10thNight
14%315%34%28%6%
2647
11th to 20thNight
14%213%33%31%7%
2462
21st to endNight
15%5%10%36%27%8%
2574
February1st to 10thNight
20%213%33%22%10%
2340
11th to 20thNight
20%313%29%27%8%
2102
21st to endNight
19%38%28%32%11%
1776
March1st to 10thNight
16%312%29%31%9%
2142
11th to 20thNight
21%5%11%34%25%5%
1980
21st to endNight
19%5%11%31%29%4
2066
April1st to 10thNight
18%414%29%27%9%
1800
11th to 20thNight
26%411%28%26%6%
1777
21st to endNight
26%413%31%20%5%
1800
May1st to 10thNight
26%5%11%31%20%6%
1769
11th to 20thNight
32%7%17%21%17%5%
1464
21st to endNight
24%5%15%24%21%11%
1552
June1st to 10thNight
21%6%17%23%20%13%
1440
11th to 20thNight
16%5%11%23%25%21%
1440
21st to endNight
24%6%13%21%23%13%
1440
July1st to 10thNight
34%11%14%16%17%10%
1400
11th to 20thNight
24%7%23%28%13%7%
1392
21st to endNight
32%16%26%18%7%1
1641
August1st to 10thNight
31%11%21%18%12%7%
1620
11th to 20thNight
29%6%19%25%15%6%
1778
21st to endNight
26%8%18%24%19%5%
1980
September1st to 10thNight
26%6%15%24%21%8%
1800
11th to 20thNight
21%6%12%21%26%14%
1804
21st to endNight
19%410%25%34%9%
1980
October1st to 10thNight
20%5%11%24%27%12%
2160
11th to 20thNight
9%38%23%40%16%
2160
21st to endNight
18%37%31%30%12%
2376
November1st to 10thNight
11%39%28%35%14%
2388
11th to 20thNight
11%38%36%31%12%
2470
21st to endNight
17%39%24%34%13%
2513
December1st to 10thNight
16%416%31%25%9%
2660
11th to 20thNight
16%5%14%26%30%8%
3272
21st to endNight
19%7%12%25%25%12%
4873

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 10thDay
14%17%34%20%10%4
270
11th to 20thDay
13%18%37%26%6%1
254
21st to endDay
5%17%44%26%8%1
264
February1st to 10thDay
9%24%46%17%31
240
11th to 20thDay
12%29%39%16%41
240
21st to endDay
16%21%39%18%6%
198
March1st to 10thDay
13%21%40%20%6%1
253
11th to 20thDay
12%22%35%22%8%1
420
21st to endDay
15%26%39%16%3
462
April1st to 10thDay
15%25%34%20%6%1
420
11th to 20thDay
18%27%34%15%5%1
412
21st to endDay
16%24%37%15%7%1
420
May1st to 10thDay
12%19%37%21%9%2
452
11th to 20thDay
12%10%27%31%16%3
625
21st to endDay
8%13%30%28%16%5%
679
June1st to 10thDay
6%9%27%29%22%7%
630
11th to 20thDay
5%10%32%31%17%6%
630
21st to endDay
5%7%28%29%24%7%
630
July1st to 10thDay
8%216%36%28%10%
621
11th to 20thDay
4213%35%35%11%
618
21st to endDay
8%210%32%34%13%
519
August1st to 10thDay
7%316%36%26%12%
447
11th to 20thDay
5%222%36%25%9%
437
21st to endDay
9%319%36%25%8%
495
September1st to 10thDay
7%5%22%32%24%10%
450
11th to 20thDay
6%9%30%33%20%4
446
21st to endDay
7%7%23%28%28%8%
270
October1st to 10thDay
10%11%27%21%23%9%
270
11th to 20thDay
8%15%30%27%14%6%
270
21st to endDay
12%13%31%25%15%3
297
November1st to 10thDay
8%20%32%25%13%3
270
11th to 20thDay
5%19%41%22%9%4
270
21st to endDay
7%15%38%30%8%2
270
December1st to 10thDay
12%21%36%22%8%1
270
11th to 20thDay
9%22%39%18%10%2
270
21st to endDay
12%24%42%18%41
297
January1st to 10thNight
5%18%36%29%10%2
950
11th to 20thNight
5%19%39%27%9%2
797
21st to endNight
312%45%32%7%1
792
February1st to 10thNight
412%53%26%6%
720
11th to 20thNight
5%14%50%23%7%
704
21st to endNight
413%53%28%3
592
March1st to 10thNight
5%18%42%28%6%1
720
11th to 20thNight
6%8%39%34%12%1
720
21st to endNight
7%13%45%31%5%
680
April1st to 10thNight
7%13%44%30%6%
540
11th to 20thNight
10%14%37%31%7%1
533
21st to endNight
9%12%35%33%11%1
540
May1st to 10thNight
7%10%31%40%10%1
540
11th to 20thNight
12%6%25%36%18%2
531
21st to endNight
10%10%27%34%16%3
584
June1st to 10thNight
6%7%21%40%25%2
540
11th to 20thNight
37%26%45%17%2
540
21st to endNight
3418%39%32%3
540
July1st to 10thNight
8%28%37%40%6%
525
11th to 20thNight
6%15%37%42%10%
522
21st to endNight
5%2330%53%7%
591
August1st to 10thNight
7%26%35%40%10%
537
11th to 20thNight
7%110%41%35%6%
534
21st to endNight
5%211%40%36%6%
594
September1st to 10thNight
5%314%41%29%8%
540
11th to 20thNight
7%421%39%24%5%
540
21st to endNight
5%6%26%37%22%4
540
October1st to 10thNight
7%7%28%39%17%3
720
11th to 20thNight
37%34%38%16%3
720
21st to endNight
6%7%36%33%16%3
792
November1st to 10thNight
311%36%35%14%2
908
11th to 20thNight
412%40%30%11%2
950
21st to endNight
6%10%37%35%11%1
950
December1st to 10thNight
415%41%32%7%1
950
11th to 20thNight
5%15%45%26%8%1
950
21st to endNight
6%19%44%24%5%1
1045
Page generated at 2024-01-12 14:17:47. Version ac07

Copyright 2024 Attilla Danko


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