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 2017-09-23.

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%
15504
21%
47004
15%
15462
55%
15462
26%
29626

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
26%
720
20%
2327
11%
716
38%
716
17%
1558
January16th to endNight
26%
768
22%
2472
10%
768
39%
768
19%
1616
February1st to 15thNight
29%
702
22%
2112
10%
700
41%
700
22%
1370
February16th to endNight
21%
631
22%
1893
8%
631
34%
631
17%
1285
March1st to 15thNight
29%
720
21%
2067
12%
720
37%
720
22%
1377
March16th to endNight
37%
768
18%
2112
11%
768
42%
768
27%
1378
April1st to 15thNight
40%
628
24%
1886
15%
628
51%
628
31%
1115
April16th to endNight
48%
540
24%
1687
17%
540
56%
540
31%
1009
May1st to 15thNight
50%
540
18%
1620
11%
540
56%
540
28%
1024
May16th to endNight
67%
561
18%
1683
13%
561
69%
561
32%
1030
June1st to 15thNight
70%
540
15%
1620
12%
540
72%
540
31%
1000
June16th to endNight
80%
540
16%
1620
14%
540
80%
540
35%
960
July1st to 15thNight
76%
510
13%
1530
13%
510
76%
510
28%
968
July16th to endNight
79%
564
16%
1595
14%
531
79%
531
31%
996
August1st to 15thNight
75%
539
18%
1612
17%
536
76%
536
30%
1030
August16th to endNight
69%
573
19%
1910
21%
573
71%
573
26%
1201
September1st to 15thNight
63%
699
18%
1959
16%
699
64%
699
27%
1291
September16th to endNight
62%
689
26%
1903
22%
689
65%
689
33%
1190
October1st to 15thNight
55%
660
34%
1829
27%
660
61%
660
38%
1062
October16th to endNight
49%
704
32%
2115
24%
704
60%
704
34%
1212
November1st to 15thNight
51%
700
29%
2276
25%
700
60%
700
34%
1251
November16th to endNight
38%
720
25%
2340
17%
720
50%
720
25%
1399
December1st to 15thNight
35%
720
20%
2340
15%
720
44%
720
19%
1557
December16th to endNight
31%
768
19%
2496
13%
768
40%
768
17%
1747

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%
47898
Night
9%6%25%5%35%5%5%8%43%
47202
TransparencyDay
44%5%11%18%15%3
47599
Night
38%5%12%21%17%4
47005
SeeingDay
15%7%17%21%20%16%
5380
Night
14%9%20%28%22%4
15508

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%37%5%3345%438%
1611
16th to endDay
12%8%36%435%45%5%40%
1749
February1st to 15thDay
12%9%5%6%5%35%45%6%36%
1750
16th to endDay
13%7%47%5%3435%6%38%
1580
March1st to 15thDay
13%9%45%435%45%7%36%
1893
16th to endDay
12%8%35%5%35%447%38%
2111
April1st to 15thDay
9%7%35%5%35%5%5%7%42%
2072
16th to endDay
10%6%26%5%35%447%42%
2271
May1st to 15thDay
12%5%36%6%45%6%5%7%37%
2331
16th to endDay
9%5%36%7%46%6%6%8%35%
2431
June1st to 15thDay
7%6%27%6%5%7%8%7%9%30%
2340
16th to endDay
5%325%6%47%7%8%10%37%
2340
July1st to 15thDay
9%6%38%8%47%8%8%9%25%
2340
16th to endDay
7%5%37%8%6%9%8%8%7%26%
2465
August1st to 15thDay
7%426%7%5%7%7%8%11%28%
2334
16th to endDay
13%6%28%8%5%7%6%5%8%26%
2292
September1st to 15thDay
12%6%28%9%36%6%5%8%30%
1989
16th to endDay
13%5%16%5%345%5%8%39%
1894
October1st to 15thDay
10%413424445%54%
1799
16th to endDay
11%6%2341333356%
1756
November1st to 15thDay
10%424323345%54%
1582
16th to endDay
12%7%344235%5%6%45%
1620
December1st to 15thDay
12%8%47%5%35%5%5%7%35%
1620
16th to endDay
16%11%35%5%24446%34%
1728
January1st to 15thNight
13%7%37%5%35%445%37%
2327
16th to endNight
12%9%37%5%245%45%38%
2472
February1st to 15thNight
11%9%36%5%24445%42%
2103
16th to endNight
12%9%47%5%35%43438%
1893
March1st to 15thNight
12%9%34424446%40%
2067
16th to endNight
10%8%35%5%3435%6%44%
2112
April1st to 15thNight
9%42442445%7%49%
1886
16th to endNight
8%5%25%5%33448%47%
1687
May1st to 15thNight
10%5%24435%6%5%9%41%
1619
16th to endNight
6%3144347%7%12%43%
1682
June1st to 15thNight
5%3246%35%7%7%13%40%
1620
16th to endNight
32135%36%6%9%11%46%
1620
July1st to 15thNight
7%3245%46%7%7%12%37%
1620
16th to endNight
43245%37%6%10%12%39%
1703
August1st to 15thNight
5%4245%45%6%7%11%42%
1623
16th to endNight
8%5%25%6%35%6%6%10%38%
1910
September1st to 15thNight
8%6%25%6%36%5%6%8%39%
1959
16th to endNight
8%5%25%425%45%8%46%
1903
October1st to 15thNight
10%323313446%55%
1829
16th to endNight
9%42442343356%
2115
November1st to 15thNight
10%5%14324336%54%
2276
16th to endNight
11%7%25%5%23446%46%
2340
December1st to 15thNight
13%7%46%5%34446%37%
2340
16th to endNight
15%10%46%5%34446%32%
2496

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%18%19%4
1612
16th to endDay
44%38%21%18%4
1749
February1st to 15thDay
48%37%18%18%2
1752
16th to endDay
46%38%18%19%3
1580
March1st to 15thDay
45%5%9%16%18%5%
1893
16th to endDay
45%413%20%13%2
2112
April1st to 15thDay
40%411%23%17%3
2072
16th to endDay
41%48%23%18%3
2271
May1st to 15thDay
44%5%11%21%13%2
2331
16th to endDay
44%7%14%18%12%2
2435
June1st to 15thDay
44%9%17%21%6%
2340
16th to endDay
37%8%16%21%13%2
2340
July1st to 15thDay
48%9%16%16%6%1
2201
16th to endDay
47%9%17%15%8%1
2310
August1st to 15thDay
43%11%15%19%8%1
2321
16th to endDay
53%7%13%15%8%1
2292
September1st to 15thDay
49%6%12%15%13%3
1989
16th to endDay
41%5%11%17%20%3
1894
October1st to 15thDay
32%5%8%19%27%7%
1799
16th to endDay
34%2421%27%9%
1756
November1st to 15thDay
32%36%16%32%9%
1582
16th to endDay
39%26%19%25%6%
1620
December1st to 15thDay
48%48%17%17%4
1620
16th to endDay
50%310%15%15%3
1728
January1st to 15thNight
48%47%16%18%4
2327
16th to endNight
46%37%18%19%4
2472
February1st to 15thNight
44%28%20%19%4
2112
16th to endNight
48%46%21%17%2
1893
March1st to 15thNight
43%5%9%19%16%5%
2067
16th to endNight
41%313%25%13%1
2112
April1st to 15thNight
34%411%25%20%4
1886
16th to endNight
35%311%24%19%4
1687
May1st to 15thNight
38%6%16%22%15%1
1620
16th to endNight
29%11%20%25%10%2
1684
June1st to 15thNight
32%9%24%25%7%
1620
16th to endNight
28%9%23%21%14%2
1620
July1st to 15thNight
34%10%23%20%9%1
1530
16th to endNight
30%11%24%21%9%1
1595
August1st to 15thNight
33%11%19%24%11%1
1612
16th to endNight
39%6%19%22%11%1
1910
September1st to 15thNight
39%8%16%18%14%3
1959
16th to endNight
35%6%12%24%19%3
1903
October1st to 15thNight
29%411%21%26%6%
1829
16th to endNight
33%3420%29%9%
2115
November1st to 15thNight
32%25%20%28%10%
2276
16th to endNight
38%37%20%22%7%
2340
December1st to 15thNight
46%49%15%17%6%
2340
16th to endNight
52%47%16%15%3
2496

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
27%17%33%16%4
90
16th to endDay
20%36%29%8%5%
96
February1st to 15thDay
23%24%40%12%
90
16th to endDay
32%19%35%11%1
81
March1st to 15thDay
28%10%29%21%7%1
183
16th to endDay
16%15%26%25%13%2
288
April1st to 15thDay
18%13%24%23%17%3
270
16th to endDay
15%7%21%26%20%7%
270
May1st to 15thDay
16%7%28%15%17%14%
288
16th to endDay
12%5%16%27%19%19%
331
June1st to 15thDay
10%28%25%26%25%
315
16th to endDay
8%14%23%22%29%
315
July1st to 15thDay
14%110%22%21%30%
305
16th to endDay
8%1416%29%40%
326
August1st to 15thDay
12%18%20%23%32%
313
16th to endDay
15%28%14%27%31%
332
September1st to 15thDay
12%411%14%35%20%
315
16th to endDay
14%210%23%34%14%
283
October1st to 15thDay
15%6%17%27%22%10%
255
16th to endDay
14%10%16%25%26%6%
268
November1st to 15thDay
21%8%28%24%13%3
90
16th to endDay
20%15%30%21%10%3
90
December1st to 15thDay
25%24%25%20%31
90
16th to endDay
35%17%30%11%5%
96
January1st to 15thNight
23%17%29%23%6%
720
16th to endNight
19%19%30%27%3
768
February1st to 15thNight
22%16%28%28%3
704
16th to endNight
20%22%31%22%3
631
March1st to 15thNight
21%15%31%24%6%
720
16th to endNight
17%11%26%30%12%1
768
April1st to 15thNight
14%13%27%30%12%1
628
16th to endNight
11%7%25%34%18%
540
May1st to 15thNight
13%5%23%32%21%3
540
16th to endNight
9%212%35%31%8%
563
June1st to 15thNight
6%29%30%40%9%
540
16th to endNight
47%30%45%13%
540
July1st to 15thNight
8%1425%49%10%
510
16th to endNight
6%1418%52%17%
564
August1st to 15thNight
8%5%23%48%12%
539
16th to endNight
10%16%24%47%10%
573
September1st to 15thNight
12%29%26%40%8%
699
16th to endNight
12%213%33%33%4
689
October1st to 15thNight
12%6%20%30%24%5%
660
16th to endNight
12%8%22%29%23%2
704
November1st to 15thNight
13%8%21%32%19%4
700
16th to endNight
18%16%23%26%14%
720
December1st to 15thNight
20%13%24%29%11%1
720
16th to endNight
23%15%25%28%6%
768
Page generated at 2017-09-24 09:15:55. Version ac04

Copyright 2017 A. Danko


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