Quail Run Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quail Run Observatory clear sky chart from 2005-11-05 to 2017-04-01.

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
78%
15108
37%
45330
34%
15070
82%
15070
57%
21100

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
77%
718
34%
2327
37%
716
81%
716
51%
1088
January16th to endNight
69%
768
37%
2496
36%
768
76%
768
46%
1218
February1st to 15thNight
73%
700
37%
2177
37%
700
80%
700
55%
1002
February16th to endNight
68%
632
36%
1874
36%
632
72%
632
48%
952
March1st to 15thNight
71%
720
41%
1980
34%
720
78%
720
61%
947
March16th to endNight
77%
768
40%
2112
31%
768
84%
768
66%
969
April1st to 15thNight
69%
653
36%
1814
25%
653
76%
653
59%
887
April16th to endNight
73%
495
44%
1576
37%
495
81%
495
75%
587
May1st to 15thNight
75%
494
42%
1484
33%
494
83%
494
73%
599
May16th to endNight
77%
513
38%
1540
30%
513
82%
513
72%
623
June1st to 15thNight
86%
495
37%
1485
32%
495
87%
495
73%
602
June16th to endNight
90%
495
33%
1485
29%
495
90%
495
72%
606
July1st to 15thNight
81%
465
25%
1395
21%
465
82%
465
49%
709
July16th to endNight
84%
522
27%
1467
23%
489
84%
489
42%
814
August1st to 15thNight
84%
494
31%
1476
28%
491
84%
491
45%
768
August16th to endNight
82%
588
32%
1722
30%
588
82%
588
43%
939
September1st to 15thNight
80%
660
34%
1815
29%
660
82%
660
50%
975
September16th to endNight
84%
656
43%
1815
36%
656
87%
656
70%
808
October1st to 15thNight
82%
660
42%
1893
35%
660
86%
660
65%
853
October16th to endNight
86%
704
45%
2112
39%
704
90%
704
70%
880
November1st to 15thNight
83%
700
42%
2109
40%
700
86%
700
68%
890
November16th to endNight
77%
720
40%
2340
38%
720
82%
720
56%
1026
December1st to 15thNight
75%
720
38%
2340
41%
720
79%
720
50%
1100
December16th to endNight
72%
768
37%
2496
38%
768
75%
768
43%
1258

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
3212213345%69%
45767
Night
3212212346%69%
45527
TransparencyDay
16%2411%24%40%
45462
Night
16%2411%23%41%
45333
SeeingDay
4415%31%34%10%
4790
Night
4110%42%36%4
15117

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
5%313223335%65%
1611
16th to endDay
6%212223335%65%
1728
February1st to 15thDay
3313312335%68%
1682
16th to endDay
6%313224345%64%
1600
March1st to 15thDay
5%112212335%70%
1980
16th to endDay
2212212335%71%
2112
April1st to 15thDay
212212336%73%
1817
16th to endDay
2111111482%
2051
May1st to 15thDay
1111223480%
2136
16th to endDay
2111121383%
2221
June1st to 15thDay
21111212382%
2145
16th to endDay
11111122381%
2145
July1st to 15thDay
3322425%5%7%8%55%
2145
16th to endDay
4425%5%35%7%8%11%43%
2285
August1st to 15thDay
421342445%10%54%
2145
16th to endDay
32123245%6%8%57%
2124
September1st to 15thDay
421332345%6%60%
1815
16th to endDay
21221222378%
1815
October1st to 15thDay
21121223476%
1735
16th to endDay
1111123380%
1760
November1st to 15thDay
111112246%76%
1747
16th to endDay
42321212474%
1620
December1st to 15thDay
6%313223346%64%
1620
16th to endDay
7%212313446%62%
1728
January1st to 15thNight
5%213322345%66%
2327
16th to endNight
8%21232324463%
2496
February1st to 15thNight
4312212227%68%
2167
16th to endNight
5%213323436%61%
1874
March1st to 15thNight
4212112235%71%
1980
16th to endNight
311212236%74%
2112
April1st to 15thNight
4212213235%70%
1814
16th to endNight
1111111385%
1576
May1st to 15thNight
1112337%77%
1484
16th to endNight
2111112284%
1540
June1st to 15thNight
1111222381%
1485
16th to endNight
1211222382%
1485
July1st to 15thNight
22133245%6%12%54%
1485
16th to endNight
32135%35%6%9%14%45%
1575
August1st to 15thNight
2114435%5%6%9%55%
1485
16th to endNight
21145%45%5%5%8%56%
1722
September1st to 15thNight
2113425%45%7%59%
1815
16th to endNight
11211233477%
1815
October1st to 15thNight
211221223475%
1893
16th to endNight
12111122380%
2112
November1st to 15thNight
31121212477%
2109
16th to endNight
32231223472%
2340
December1st to 15thNight
7%212212245%66%
2340
16th to endNight
7%313322336%61%
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
21%25%14%27%29%
1612
16th to endDay
21%3314%27%29%
1728
February1st to 15thDay
18%2414%28%30%
1682
16th to endDay
22%2313%31%27%
1600
March1st to 15thDay
17%136%29%41%
1980
16th to endDay
16%237%29%41%
2112
April1st to 15thDay
13%126%33%42%
1817
16th to endDay
9%26%22%59%
2051
May1st to 15thDay
8%137%21%58%
2136
16th to endDay
8%12420%61%
2224
June1st to 15thDay
9%11213%71%
2145
16th to endDay
10%12411%70%
2145
July1st to 15thDay
23%5%9%14%18%28%
2006
16th to endDay
29%8%11%22%19%8%
2130
August1st to 15thDay
25%5%9%17%17%25%
2130
16th to endDay
21%6%8%19%24%20%
2124
September1st to 15thDay
22%5%7%13%23%28%
1815
16th to endDay
12%125%25%52%
1815
October1st to 15thDay
11%239%25%47%
1735
16th to endDay
9%238%25%51%
1760
November1st to 15thDay
10%1210%33%42%
1747
16th to endDay
16%128%28%42%
1620
December1st to 15thDay
21%2415%30%24%
1620
16th to endDay
22%35%20%31%15%
1728
January1st to 15thNight
20%25%12%26%32%
2327
16th to endNight
23%2412%26%30%
2496
February1st to 15thNight
18%15%14%24%35%
2178
16th to endNight
22%3412%26%30%
1874
March1st to 15thNight
16%128%23%47%
1980
16th to endNight
13%138%28%43%
2112
April1st to 15thNight
17%126%30%40%
1814
16th to endNight
7%25%21%62%
1576
May1st to 15thNight
8%236%22%58%
1485
16th to endNight
9%12417%65%
1541
June1st to 15thNight
9%11312%71%
1485
16th to endNight
9%2238%74%
1485
July1st to 15thNight
21%412%17%14%29%
1395
16th to endNight
23%8%13%21%22%10%
1467
August1st to 15thNight
23%5%10%18%15%26%
1476
16th to endNight
24%6%8%16%23%20%
1722
September1st to 15thNight
21%48%16%21%26%
1815
16th to endNight
11%136%24%53%
1815
October1st to 15thNight
13%2211%21%49%
1893
16th to endNight
10%128%19%57%
2112
November1st to 15thNight
12%139%27%47%
2109
16th to endNight
17%138%23%45%
2340
December1st to 15thNight
20%2313%28%30%
2340
16th to endNight
25%25%16%28%21%
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
16%111%46%22%2
90
16th to endDay
6%5%10%35%27%15%
96
February1st to 15thDay
5%414%34%37%3
197
16th to endDay
6%8%23%34%23%4
238
March1st to 15thDay
47%23%29%22%11%
270
16th to endDay
212%20%28%25%11%
288
April1st to 15thDay
6%9%29%30%18%5%
211
16th to endDay
310%34%31%16%2
210
May1st to 15thDay
18%32%32%21%4
228
16th to endDay
2421%35%29%6%
266
June1st to 15thDay
3318%39%27%7%
255
16th to endDay
317%40%36%10%
255
July1st to 15thDay
218%31%45%10%
245
16th to endDay
4420%52%18%
271
August1st to 15thDay
3223%50%19%
255
16th to endDay
320%53%22%
268
September1st to 15thDay
9%19%30%38%10%
255
16th to endDay
6%112%33%36%8%
255
October1st to 15thDay
2314%32%32%14%
175
16th to endDay
4222%51%19%
96
November1st to 15thDay
1121%24%37%14%
90
16th to endDay
3314%41%32%5%
90
December1st to 15thDay
46%26%53%8%
90
16th to endDay
16%414%35%27%2
96
January1st to 15thNight
5%110%53%25%2
720
16th to endNight
9%14%44%27%2
768
February1st to 15thNight
5%112%48%28%2
704
16th to endNight
6%217%49%22%1
632
March1st to 15thNight
5%118%42%28%3
720
16th to endNight
2213%45%31%4
768
April1st to 15thNight
5%118%49%23%1
653
16th to endNight
2219%47%24%2
495
May1st to 15thNight
1218%46%28%2
495
16th to endNight
2214%43%35%1
515
June1st to 15thNight
18%53%33%1
495
16th to endNight
1440%51%1
495
July1st to 15thNight
46%30%51%7%
465
16th to endNight
3217%65%9%
522
August1st to 15thNight
2221%62%10%
494
16th to endNight
2321%59%11%
588
September1st to 15thNight
27%30%51%6%
660
16th to endNight
217%38%44%6%
656
October1st to 15thNight
219%44%39%3
660
16th to endNight
26%42%41%6%
704
November1st to 15thNight
39%45%37%3
700
16th to endNight
4111%46%33%2
720
December1st to 15thNight
8%19%45%33%2
720
16th to endNight
9%29%50%25%2
768
Page generated at 2017-04-02 04:39:09. Version ac04

Copyright 2017 A. Danko


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