Mookie Mountain Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mookie Mountain 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
48%
17805
21%
54002
15%
17763
55%
17763
26%
34269

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
25%
840
20%
2717
11%
836
38%
836
17%
1832
January16th to endNight
27%
896
23%
2884
12%
896
40%
896
20%
1867
February1st to 15thNight
29%
822
21%
2472
10%
820
40%
820
21%
1648
February16th to endNight
20%
735
20%
2205
7%
735
32%
735
16%
1544
March1st to 15thNight
27%
840
21%
2412
10%
840
36%
840
21%
1628
March16th to endNight
36%
896
18%
2464
11%
896
41%
896
26%
1628
April1st to 15thNight
41%
733
24%
2201
16%
733
51%
733
31%
1309
April16th to endNight
48%
624
24%
1947
17%
624
56%
624
31%
1171
May1st to 15thNight
54%
630
19%
1890
13%
630
58%
630
30%
1174
May16th to endNight
67%
657
18%
1971
13%
657
69%
657
31%
1211
June1st to 15thNight
70%
630
16%
1890
13%
630
72%
630
31%
1169
June16th to endNight
78%
597
15%
1791
14%
597
79%
597
35%
1061
July1st to 15thNight
76%
555
13%
1665
13%
555
76%
555
29%
1055
July16th to endNight
78%
612
15%
1739
14%
579
79%
579
31%
1092
August1st to 15thNight
75%
575
18%
1718
18%
572
75%
572
30%
1094
August16th to endNight
70%
621
18%
2070
20%
621
72%
621
26%
1300
September1st to 15thNight
63%
757
17%
2122
15%
757
64%
757
26%
1415
September16th to endNight
64%
777
25%
2145
22%
777
66%
777
33%
1334
October1st to 15thNight
56%
780
32%
2162
26%
780
62%
780
38%
1256
October16th to endNight
49%
832
32%
2499
24%
832
59%
832
34%
1433
November1st to 15thNight
49%
820
27%
2666
24%
820
58%
820
31%
1541
November16th to endNight
41%
840
26%
2730
18%
840
52%
840
26%
1615
December1st to 15thNight
34%
840
20%
2730
14%
840
43%
840
18%
1839
December16th to endNight
31%
896
18%
2912
12%
896
39%
896
16%
2053

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
11%6%36%6%35%5%5%7%37%
54714
Night
10%6%25%5%345%5%7%42%
54200
TransparencyDay
44%6%11%18%15%3
54415
Night
39%5%12%21%16%3
54003
SeeingDay
17%8%19%21%19%14%
7634
Night
15%9%19%28%22%4
17809

By Month

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
13%9%38%5%3445%5%38%
1881
16th to endDay
11%8%36%435%35%5%42%
2041
February1st to 15thDay
13%9%47%5%35%446%34%
2050
16th to endDay
15%7%47%5%3435%6%35%
1840
March1st to 15thDay
13%9%45%425%5%5%7%36%
2208
16th to endDay
11%9%35%5%35%45%7%38%
2463
April1st to 15thDay
10%7%35%5%35%5%5%7%40%
2418
16th to endDay
11%6%26%5%35%446%42%
2616
May1st to 15thDay
11%5%36%5%45%5%5%7%38%
2721
16th to endDay
9%5%36%8%46%5%6%8%35%
2847
June1st to 15thDay
7%6%27%6%47%8%7%9%32%
2730
16th to endDay
5%325%7%5%7%6%8%10%36%
2577
July1st to 15thDay
9%6%38%8%47%8%8%9%25%
2535
16th to endDay
7%5%27%8%6%9%9%8%8%26%
2673
August1st to 15thDay
7%5%26%7%5%8%7%8%11%28%
2481
16th to endDay
12%6%38%8%5%7%6%5%8%26%
2484
September1st to 15thDay
12%6%28%9%46%6%6%8%29%
2155
16th to endDay
13%5%15%5%35%5%5%8%38%
2145
October1st to 15thDay
10%314434445%52%
2126
16th to endDay
11%6%2331333355%
2075
November1st to 15thDay
13%5%24323435%51%
1852
16th to endDay
10%7%35%4235%5%6%45%
1890
December1st to 15thDay
14%8%47%5%35%5%46%34%
1890
16th to endDay
16%11%36%5%34446%33%
2016
January1st to 15thNight
13%8%37%5%35%445%37%
2717
16th to endNight
12%9%37%5%245%45%40%
2884
February1st to 15thNight
12%10%36%5%24346%39%
2463
16th to endNight
14%9%47%5%25%5%45%35%
2205
March1st to 15thNight
13%8%35%5%34446%39%
2412
16th to endNight
11%8%35%5%34346%43%
2464
April1st to 15thNight
10%5%2442445%7%48%
2201
16th to endNight
9%5%25%5%33448%47%
1947
May1st to 15thNight
9%5%24435%5%49%43%
1889
16th to endNight
6%3144347%7%11%43%
1970
June1st to 15thNight
5%3246%35%7%7%13%40%
1890
16th to endNight
22145%46%5%8%11%46%
1791
July1st to 15thNight
6%425%5%46%6%8%12%37%
1755
16th to endNight
43245%37%6%10%12%39%
1847
August1st to 15thNight
6%4245%45%6%7%11%41%
1729
16th to endNight
8%425%6%35%6%6%10%39%
2070
September1st to 15thNight
8%6%35%6%46%5%7%9%38%
2122
16th to endNight
8%5%25%425%45%8%47%
2145
October1st to 15thNight
9%323314446%55%
2162
16th to endNight
9%5%2342334455%
2499
November1st to 15thNight
12%5%14424336%50%
2666
16th to endNight
10%7%245%2345%6%47%
2730
December1st to 15thNight
14%7%36%5%34446%36%
2730
16th to endNight
14%11%46%6%34446%31%
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
47%46%19%19%3
1882
16th to endDay
42%38%21%18%5%
2041
February1st to 15thDay
50%36%18%17%2
2052
16th to endDay
48%38%18%17%3
1840
March1st to 15thDay
46%5%9%15%17%5%
2208
16th to endDay
44%5%13%20%14%2
2464
April1st to 15thDay
41%411%22%16%3
2418
16th to endDay
41%48%23%18%3
2616
May1st to 15thDay
42%5%12%22%13%2
2721
16th to endDay
44%7%13%19%13%1
2851
June1st to 15thDay
43%9%17%20%7%
2730
16th to endDay
38%8%16%21%12%2
2577
July1st to 15thDay
48%9%16%16%6%1
2396
16th to endDay
47%9%16%16%8%1
2518
August1st to 15thDay
43%11%15%18%8%1
2468
16th to endDay
52%8%14%15%8%1
2484
September1st to 15thDay
50%6%13%14%12%2
2155
16th to endDay
41%5%12%17%19%3
2145
October1st to 15thDay
33%5%9%20%25%6%
2126
16th to endDay
34%25%21%26%9%
2075
November1st to 15thDay
36%37%15%29%7%
1852
16th to endDay
38%36%18%25%6%
1890
December1st to 15thDay
49%47%18%16%4
1890
16th to endDay
52%310%16%14%3
2016
January1st to 15thNight
48%47%16%18%4
2717
16th to endNight
45%37%19%19%4
2884
February1st to 15thNight
46%38%19%17%4
2472
16th to endNight
50%5%7%19%15%2
2205
March1st to 15thNight
45%48%18%16%6%
2412
16th to endNight
42%312%24%15%1
2464
April1st to 15thNight
34%412%25%19%3
2201
16th to endNight
36%310%24%19%4
1947
May1st to 15thNight
37%5%16%24%13%1
1890
16th to endNight
30%10%18%25%11%2
1972
June1st to 15thNight
32%10%23%24%8%1
1890
16th to endNight
27%10%24%22%13%2
1791
July1st to 15thNight
34%10%23%20%9%1
1665
16th to endNight
30%12%23%21%9%1
1739
August1st to 15thNight
33%10%19%23%11%1
1718
16th to endNight
38%7%19%22%10%1
2070
September1st to 15thNight
39%9%17%17%13%2
2122
16th to endNight
34%6%12%23%19%2
2145
October1st to 15thNight
29%412%22%24%6%
2162
16th to endNight
33%3421%28%9%
2499
November1st to 15thNight
35%36%19%25%9%
2666
16th to endNight
37%37%21%22%7%
2730
December1st to 15thNight
48%49%16%16%5%
2730
16th to endNight
53%48%16%14%2
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
26%17%36%13%6%
180
16th to endDay
21%33%24%13%5%1
192
February1st to 15thDay
26%22%33%13%3
180
16th to endDay
36%20%31%10%
159
March1st to 15thDay
30%17%28%18%41
288
16th to endDay
19%18%25%23%11%1
416
April1st to 15thDay
19%14%26%23%13%2
390
16th to endDay
18%8%20%26%19%6%
379
May1st to 15thDay
15%8%26%19%19%11%
408
16th to endDay
12%5%16%27%19%18%
459
June1st to 15thDay
11%213%25%24%22%
435
16th to endDay
9%115%23%23%27%
388
July1st to 15thDay
13%18%21%24%31%
365
16th to endDay
8%16%18%27%36%
390
August1st to 15thDay
14%18%20%22%31%
358
16th to endDay
15%19%14%27%32%
396
September1st to 15thDay
12%412%15%34%21%
375
16th to endDay
15%28%26%33%14%
374
October1st to 15thDay
14%5%18%26%22%12%
375
16th to endDay
16%11%18%24%23%6%
395
November1st to 15thDay
27%12%25%23%8%1
180
16th to endDay
16%15%32%18%13%3
180
December1st to 15thDay
31%20%25%20%2
180
16th to endDay
32%18%33%13%2
192
January1st to 15thNight
23%17%29%22%6%
840
16th to endNight
19%19%29%27%4
896
February1st to 15thNight
23%16%27%27%4
824
16th to endNight
22%21%31%21%3
735
March1st to 15thNight
21%17%31%23%5%
840
16th to endNight
18%12%26%29%11%1
896
April1st to 15thNight
14%13%27%31%11%1
733
16th to endNight
12%7%24%34%19%
624
May1st to 15thNight
12%422%32%23%3
630
16th to endNight
9%112%33%33%9%
659
June1st to 15thNight
6%29%32%39%10%
630
16th to endNight
38%29%44%13%
597
July1st to 15thNight
8%1423%49%12%
555
16th to endNight
5%1419%52%17%
612
August1st to 15thNight
8%5%22%48%13%
575
16th to endNight
10%5%23%48%10%
621
September1st to 15thNight
11%29%26%41%9%
757
16th to endNight
11%112%32%35%4
777
October1st to 15thNight
11%6%20%29%26%6%
780
16th to endNight
13%9%21%30%22%2
832
November1st to 15thNight
16%8%20%33%18%3
820
16th to endNight
17%16%21%27%16%
840
December1st to 15thNight
22%13%24%28%10%
840
16th to endNight
24%15%25%29%6%
896
Page generated at 2019-06-20 08:02:28. Version ac04

Copyright 2019 A. Danko


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