Missouri Gulch Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Missouri Gulch Observatory clear sky chart from 2005-11-06 to 2024-01-13.

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
35%
24572
26%
74467
11%
24517
50%
24517
34%
39449

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
21%
950
29%
2647
8%
946
42%
946
32%
1400
January11th to 20thNight
19%
857
31%
2495
8%
857
42%
857
28%
1254
January21st to endNight
15%
792
29%
2574
6%
792
41%
792
29%
1300
February1st to 10thNight
12%
720
25%
2340
4%
720
36%
720
27%
1175
February11th to 20thNight
16%
701
26%
2147
4%
700
39%
700
27%
1126
February21st to endNight
14%
592
33%
1776
4%
592
44%
592
29%
945
March1st to 10thNight
21%
720
28%
2155
6%
720
43%
720
33%
1137
March11th to 20thNight
29%
720
27%
1980
11%
720
42%
720
34%
1131
March21st to endNight
23%
677
25%
2063
5%
677
43%
677
28%
1146
April1st to 10thNight
22%
540
26%
1800
7%
540
45%
540
29%
946
April11th to 20thNight
26%
533
22%
1777
10%
533
42%
533
26%
989
April21st to endNight
27%
540
21%
1800
9%
540
45%
540
26%
1034
May1st to 10thNight
32%
540
19%
1679
9%
540
45%
540
26%
1057
May11th to 20thNight
45%
531
15%
1418
10%
531
48%
531
26%
922
May21st to endNight
47%
584
19%
1552
10%
582
56%
582
37%
901
June1st to 10thNight
62%
540
24%
1440
17%
540
66%
540
48%
774
June11th to 20thNight
52%
540
26%
1440
15%
540
60%
540
48%
768
June21st to endNight
67%
540
25%
1440
19%
540
71%
540
52%
757
July1st to 10thNight
70%
525
21%
1400
17%
525
73%
525
39%
828
July11th to 20thNight
75%
522
27%
1392
22%
522
77%
522
48%
750
July21st to endNight
71%
591
21%
1557
18%
558
74%
558
36%
905
August1st to 10thNight
67%
537
17%
1602
16%
534
69%
534
36%
907
August11th to 20thNight
71%
534
27%
1748
26%
534
76%
534
42%
885
August21st to endNight
68%
594
29%
1980
30%
594
73%
594
39%
1042
September1st to 10thNight
65%
540
31%
1800
28%
540
74%
540
40%
922
September11th to 20thNight
58%
540
36%
1800
29%
540
70%
540
45%
855
September21st to endNight
51%
554
31%
1994
22%
554
65%
554
40%
955
October1st to 10thNight
42%
720
28%
2160
14%
720
55%
720
38%
1171
October11th to 20thNight
37%
720
34%
2160
12%
720
54%
720
48%
1015
October21st to endNight
27%
816
31%
2400
9%
816
44%
816
34%
1301
November1st to 10thNight
26%
925
32%
2405
7%
925
43%
925
46%
1241
November11th to 20thNight
20%
950
34%
2470
7%
950
39%
950
39%
1303
November21st to endNight
24%
950
28%
2598
6%
950
43%
950
38%
1399
December1st to 10thNight
19%
950
27%
2660
6%
950
38%
950
32%
1405
December11th to 20thNight
14%
949
26%
3129
4%
949
34%
949
27%
1593
December21st to endNight
16%
1038
17%
4689
4%
1026
35%
1026
20%
2210

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
46%36%5%35%5%6%8%49%
74763
Night
35%2442445%8%59%
74981
TransparencyDay
30%8%13%21%20%7%
74472
Night
23%7%15%24%23%8%
74794
SeeingDay
10%19%34%23%11%3
14419
Night
8%16%36%26%12%2
24583

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
236%4325%5%10%59%
1518
11th to 20thDay
15%36%5%25%36%7%58%
1524
21st to endDay
448%5%36%45%8%53%
1782
February1st to 10thDay
439%6%3335%10%55%
1620
11th to 20thDay
425%5%25%45%9%58%
1700
21st to endDay
15%5%7%6%3345%7%55%
1480
March1st to 10thDay
17%36%4345%7%9%51%
1803
11th to 20thDay
310%5%6%43445%9%46%
1980
21st to endDay
311%5%6%435%5%6%10%43%
2291
April1st to 10thDay
37%45%5%345%7%8%49%
2160
11th to 20thDay
6%12%46%6%35%5%5%7%40%
2131
21st to endDay
6%10%46%5%46%6%8%7%38%
2160
May1st to 10thDay
9%11%36%5%36%6%5%9%36%
2274
11th to 20thDay
12%11%35%5%35%5%7%8%34%
2478
21st to endDay
9%7%36%5%46%6%7%9%38%
2724
June1st to 10thDay
5%425%6%46%7%7%9%45%
2520
11th to 20thDay
6%5%25%5%36%5%6%9%48%
2520
21st to endDay
5%425%6%47%6%8%9%45%
2520
July1st to 10thDay
8%5%35%5%46%7%8%10%40%
2520
11th to 20thDay
6%435%6%47%6%7%9%45%
2520
21st to endDay
8%5%35%7%47%8%8%9%36%
2666
August1st to 10thDay
8%6%36%7%46%7%7%11%36%
2328
11th to 20thDay
6%6%345%35%6%6%7%47%
2150
21st to endDay
6%5%26%5%46%7%7%8%43%
2376
September1st to 10thDay
5%6%245%345%5%7%54%
2160
11th to 20thDay
7%4145%345%5%7%55%
2160
21st to endDay
7%424323347%60%
1962
October1st to 10thDay
5%6%36%5%3445%7%53%
1800
11th to 20thDay
331442445%6%65%
1800
21st to endDay
46%2432435%8%59%
1936
November1st to 10thDay
1314324348%67%
1673
11th to 20thDay
132442335%9%65%
1710
21st to endDay
438%32346%8%59%
1577
December1st to 10thDay
436%5%35%449%59%
1520
11th to 20thDay
142442447%10%57%
1926
21st to endDay
1437%6%2446%8%54%
2794
January1st to 10thNight
325%42445%8%63%
2647
11th to 20thNight
324424448%65%
2495
21st to endNight
14345%3445%8%60%
2574
February1st to 10thNight
335%334449%63%
2340
11th to 20thNight
325%5%2245%8%62%
2147
21st to endNight
1437%5%34448%59%
1776
March1st to 10thNight
143333347%10%59%
2155
11th to 20thNight
27%25%433447%58%
1980
21st to endNight
27%36%424449%56%
2063
April1st to 10thNight
26%244235%5%7%60%
1800
11th to 20thNight
48%36%32436%7%53%
1777
21st to endNight
6%10%245%2345%9%49%
1800
May1st to 10thNight
8%8%25%5%345%6%8%46%
1679
11th to 20thNight
11%9%2442446%8%45%
1417
21st to endNight
5%6%2443435%9%56%
1552
June1st to 10thNight
431232445%10%60%
1440
11th to 20thNight
431432346%9%61%
1440
21st to endNight
321332448%8%61%
1440
July1st to 10thNight
5%423435%5%7%8%53%
1440
11th to 20thNight
2213435%6%6%11%58%
1440
21st to endNight
5%424435%6%7%11%48%
1649
August1st to 10thNight
4425%5%345%6%9%53%
1611
11th to 20thNight
5%423335%5%6%8%57%
1748
21st to endNight
44235%346%5%8%55%
1980
September1st to 10thNight
6%32342445%7%59%
1800
11th to 20thNight
6%41322345%7%64%
1800
21st to endNight
6%41332345%5%63%
1994
October1st to 10thNight
46%14434446%61%
2160
11th to 20thNight
2413322245%73%
2160
21st to endNight
37%35%42335%8%57%
2400
November1st to 10thNight
121333325%6%70%
2405
11th to 20thNight
141432335%8%66%
2470
21st to endNight
1426%41346%7%62%
2598
December1st to 10thNight
142432335%9%64%
2660
11th to 20thNight
1436%5%3346%10%56%
3271
21st to endNight
15%25%5%345%7%8%55%
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
20%8%18%27%22%5%
1519
11th to 20thDay
26%5%17%24%20%7%
1524
21st to endDay
29%6%18%25%17%6%
1782
February1st to 10thDay
28%7%20%22%17%7%
1620
11th to 20thDay
24%7%16%24%23%6%
1710
21st to endDay
30%5%14%23%20%8%
1480
March1st to 10thDay
27%8%13%26%22%4
1803
11th to 20thDay
33%6%14%24%19%4
1980
21st to endDay
35%7%15%23%15%4
2291
April1st to 10thDay
31%8%12%23%18%8%
2160
11th to 20thDay
40%8%13%18%16%5%
2134
21st to endDay
40%10%12%22%15%2
2160
May1st to 10thDay
44%10%11%19%14%2
2274
11th to 20thDay
45%12%12%21%9%2
2482
21st to endDay
40%10%13%19%14%5%
2724
June1st to 10thDay
30%12%15%20%17%7%
2520
11th to 20thDay
30%10%11%15%22%12%
2520
21st to endDay
29%10%12%18%21%9%
2520
July1st to 10thDay
35%11%13%16%19%8%
2451
11th to 20thDay
31%11%12%20%17%9%
2445
21st to endDay
37%13%16%18%11%4
2518
August1st to 10thDay
39%12%15%17%12%5%
2313
11th to 20thDay
32%8%14%17%21%8%
2150
21st to endDay
33%9%11%19%21%6%
2376
September1st to 10thDay
27%7%11%18%23%15%
2160
11th to 20thDay
26%8%12%19%26%10%
2160
21st to endDay
25%5%8%21%33%8%
1962
October1st to 10thDay
29%8%10%19%27%8%
1800
11th to 20thDay
20%5%11%25%29%10%
1800
21st to endDay
24%6%12%25%23%10%
1936
November1st to 10thDay
16%7%13%22%32%11%
1673
11th to 20thDay
18%6%14%27%28%7%
1710
21st to endDay
24%413%24%23%12%
1577
December1st to 10thDay
23%8%17%26%19%7%
1520
11th to 20thDay
19%7%17%29%24%4
1924
21st to endDay
26%7%14%22%24%7%
2794
January1st to 10thNight
19%8%16%28%23%6%
2647
11th to 20thNight
19%6%18%24%26%7%
2495
21st to endNight
23%6%18%26%21%6%
2574
February1st to 10thNight
20%7%19%28%20%6%
2340
11th to 20thNight
21%7%15%25%25%6%
2147
21st to endNight
24%5%13%26%23%9%
1776
March1st to 10thNight
21%7%12%28%26%5%
2155
11th to 20thNight
26%6%12%27%24%5%
1980
21st to endNight
27%6%15%27%20%4
2063
April1st to 10thNight
23%9%12%26%23%7%
1800
11th to 20thNight
30%7%14%24%20%5%
1777
21st to endNight
31%8%13%26%19%3
1800
May1st to 10thNight
34%11%12%24%15%4
1679
11th to 20thNight
37%10%18%22%12%1
1418
21st to endNight
26%8%18%23%19%6%
1552
June1st to 10thNight
20%8%20%28%16%8%
1440
11th to 20thNight
20%7%13%17%25%18%
1440
21st to endNight
18%7%13%22%28%12%
1440
July1st to 10thNight
27%9%14%22%20%8%
1400
11th to 20thNight
19%9%14%26%22%11%
1392
21st to endNight
27%10%20%25%14%5%
1557
August1st to 10thNight
26%10%20%23%15%6%
1602
11th to 20thNight
23%6%15%22%24%10%
1748
21st to endNight
25%7%12%23%26%7%
1980
September1st to 10thNight
24%6%9%21%24%15%
1800
11th to 20thNight
20%6%12%23%25%15%
1800
21st to endNight
22%5%9%24%30%9%
1994
October1st to 10thNight
24%6%11%22%27%9%
2160
11th to 20thNight
16%413%23%31%14%
2160
21st to endNight
26%413%23%26%8%
2400
November1st to 10thNight
15%6%13%23%31%12%
2405
11th to 20thNight
18%5%14%28%27%8%
2470
21st to endNight
22%6%11%24%27%10%
2598
December1st to 10thNight
19%8%17%25%23%8%
2660
11th to 20thNight
20%7%18%25%25%5%
3272
21st to endNight
23%8%17%22%23%8%
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
11%20%43%15%8%2
270
11th to 20thDay
7%37%37%15%21
246
21st to endDay
441%39%14%2
264
February1st to 10thDay
10%46%35%6%11
240
11th to 20thDay
12%35%41%9%3
240
21st to endDay
8%37%44%9%2
198
March1st to 10thDay
8%35%40%14%3
243
11th to 20thDay
15%28%35%20%2
420
21st to endDay
14%32%40%12%2
462
April1st to 10thDay
15%32%36%13%3
420
11th to 20thDay
18%35%33%12%2
412
21st to endDay
19%25%37%15%41
420
May1st to 10thDay
15%21%38%18%6%1
510
11th to 20thDay
19%11%34%24%10%2
625
21st to endDay
14%14%29%29%12%2
679
June1st to 10thDay
8%10%29%31%16%5%
630
11th to 20thDay
8%12%37%29%11%3
630
21st to endDay
5%9%36%29%15%6%
630
July1st to 10thDay
8%324%35%24%5%
621
11th to 20thDay
6%426%36%21%7%
618
21st to endDay
8%424%34%24%6%
608
August1st to 10thDay
13%6%31%32%15%4
447
11th to 20thDay
8%6%32%32%17%4
437
21st to endDay
9%7%31%32%18%3
495
September1st to 10thDay
10%8%32%32%15%4
450
11th to 20thDay
8%10%35%34%12%1
450
21st to endDay
7%16%36%21%16%4
270
October1st to 10thDay
8%19%30%24%15%4
270
11th to 20thDay
6%25%40%20%7%2
270
21st to endDay
9%28%38%19%5%1
297
November1st to 10thDay
6%24%45%14%10%1
270
11th to 20thDay
11%26%42%16%41
270
21st to endDay
8%30%40%19%3
270
December1st to 10thDay
10%31%39%15%31
270
11th to 20thDay
7%35%46%10%3
270
21st to endDay
10%37%37%12%3
297
January1st to 10thNight
10%24%40%17%7%2
950
11th to 20thNight
11%30%35%16%6%1
857
21st to endNight
8%26%47%14%41
792
February1st to 10thNight
9%28%46%12%4
720
11th to 20thNight
9%27%44%15%4
704
21st to endNight
6%28%47%17%2
592
March1st to 10thNight
6%24%46%18%7%
720
11th to 20thNight
7%19%41%25%7%1
720
21st to endNight
8%25%41%22%41
677
April1st to 10thNight
10%16%48%22%4
540
11th to 20thNight
10%21%40%21%8%1
533
21st to endNight
13%17%39%21%8%1
540
May1st to 10thNight
12%9%42%26%10%1
540
11th to 20thNight
19%5%26%36%12%2
531
21st to endNight
9%8%30%34%17%2
584
June1st to 10thNight
5%324%41%23%3
540
11th to 20thNight
7%432%42%14%1
540
21st to endNight
5%220%44%26%3
540
July1st to 10thNight
7%213%38%37%4
525
11th to 20thNight
2114%40%36%5%
522
21st to endNight
6%111%37%38%6%
591
August1st to 10thNight
6%314%40%34%3
537
11th to 20thNight
7%114%45%27%5%
534
21st to endNight
6%215%41%29%7%
594
September1st to 10thNight
5%220%42%24%6%
540
11th to 20thNight
9%326%37%20%5%
540
21st to endNight
8%7%29%35%16%5%
554
October1st to 10thNight
7%12%34%30%13%4
720
11th to 20thNight
6%16%39%27%10%2
720
21st to endNight
11%18%41%21%9%1
816
November1st to 10thNight
5%19%47%20%8%1
925
11th to 20thNight
9%25%44%17%41
950
21st to endNight
5%20%46%24%4
950
December1st to 10thNight
11%22%46%18%3
950
11th to 20thNight
7%26%48%14%5%1
950
21st to endNight
8%28%42%17%5%1
1045
Page generated at 2024-01-09 23:25:03. Version ac07

Copyright 2024 Attilla Danko


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