Quail Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quail Creek clear sky chart from 2005-11-05 to 2017-09-24.

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
76%
15614
35%
46979
31%
15576
81%
15576
53%
22432

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
75%
718
33%
2327
34%
716
80%
716
53%
1069
January16th to endNight
67%
768
34%
2496
33%
768
75%
768
41%
1279
February1st to 15thNight
73%
698
36%
2190
34%
698
81%
698
55%
997
February16th to endNight
66%
632
39%
1831
34%
632
73%
632
50%
923
March1st to 15thNight
67%
720
40%
1980
32%
720
75%
720
59%
960
March16th to endNight
74%
768
38%
2112
28%
768
81%
768
61%
1008
April1st to 15thNight
68%
689
35%
1948
25%
689
76%
689
57%
938
April16th to endNight
71%
540
44%
1794
38%
540
82%
540
70%
671
May1st to 15thNight
71%
539
40%
1619
30%
539
80%
539
73%
646
May16th to endNight
78%
561
43%
1684
34%
561
84%
561
76%
653
June1st to 15thNight
85%
540
35%
1620
30%
540
86%
540
71%
661
June16th to endNight
87%
540
30%
1620
26%
540
88%
540
62%
718
July1st to 15thNight
84%
510
18%
1530
16%
510
84%
510
37%
857
July16th to endNight
82%
564
16%
1593
13%
531
81%
531
27%
1027
August1st to 15thNight
87%
539
23%
1611
22%
536
87%
536
39%
896
August16th to endNight
84%
604
28%
1888
29%
604
84%
604
38%
1057
September1st to 15thNight
80%
720
28%
1980
24%
720
81%
720
41%
1164
September16th to endNight
85%
692
44%
1914
34%
692
89%
692
67%
886
October1st to 15thNight
79%
660
41%
1914
31%
660
86%
660
67%
843
October16th to endNight
85%
704
43%
2112
38%
704
90%
704
68%
896
November1st to 15thNight
81%
700
43%
2100
38%
700
85%
700
69%
880
November16th to endNight
71%
720
39%
2280
36%
720
75%
720
52%
1063
December1st to 15thNight
72%
720
38%
2340
38%
720
77%
720
51%
1071
December16th to endNight
67%
768
34%
2496
34%
768
72%
768
42%
1269

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
3213324446%64%
47939
Night
2212223346%68%
47181
TransparencyDay
21%46%11%25%31%
47634
Night
17%37%13%27%30%
46987
SeeingDay
5%8%20%32%24%8%
5446
Night
3213%36%36%7%
15625

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
2213314347%64%
1611
16th to endDay
4312323347%62%
1728
February1st to 15thDay
4313213335%68%
1664
16th to endDay
4312313346%64%
1642
March1st to 15thDay
2111223346%68%
1980
16th to endDay
22221223475%
2112
April1st to 15thDay
212222346%72%
2000
16th to endDay
11211112383%
2163
May1st to 15thDay
111223480%
2331
16th to endDay
111212383%
2429
June1st to 15thDay
11111235%79%
2340
16th to endDay
213223335%71%
2340
July1st to 15thDay
3325%7%5%8%7%8%9%39%
2340
16th to endDay
7%5%37%9%5%8%8%7%10%28%
2467
August1st to 15thDay
5%4246%48%8%8%9%37%
2340
16th to endDay
32246%37%6%6%9%46%
2310
September1st to 15thDay
6%315%6%45%6%5%7%47%
1980
16th to endDay
312223445%69%
1904
October1st to 15thDay
111222335%74%
1714
16th to endDay
11212235%78%
1760
November1st to 15thDay
111112245%77%
1759
16th to endDay
211221333472%
1677
December1st to 15thDay
5%213212446%64%
1620
16th to endDay
5%21221346%6%62%
1728
January1st to 15thNight
3212222345%68%
2327
16th to endNight
4214424446%60%
2496
February1st to 15thNight
2212223346%69%
2185
16th to endNight
2313223347%65%
1831
March1st to 15thNight
2112212246%71%
1980
16th to endNight
2111212345%73%
2112
April1st to 15thNight
121232224472%
1948
16th to endNight
211111384%
1794
May1st to 15thNight
112235%80%
1619
16th to endNight
11112384%
1684
June1st to 15thNight
21111125%80%
1620
16th to endNight
1112222336%72%
1620
July1st to 15thNight
1214425%7%9%12%49%
1620
16th to endNight
33145%45%8%12%17%33%
1701
August1st to 15thNight
2213325%5%7%11%53%
1620
16th to endNight
32133345%7%11%50%
1888
September1st to 15thNight
43244245%6%8%53%
1980
16th to endNight
12212236%75%
1914
October1st to 15thNight
11121223478%
1914
16th to endNight
1111223480%
2112
November1st to 15thNight
11212235%77%
2100
16th to endNight
333322225%69%
2280
December1st to 15thNight
4212213247%68%
2340
16th to endNight
5%313333346%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%36%12%27%28%
1612
16th to endDay
23%3416%26%26%
1728
February1st to 15thDay
20%1312%28%33%
1664
16th to endDay
23%3413%29%26%
1642
March1st to 15thDay
18%137%32%35%
1980
16th to endDay
16%229%34%35%
2112
April1st to 15thDay
14%136%39%34%
2000
16th to endDay
10%127%28%50%
2163
May1st to 15thDay
10%138%25%51%
2331
16th to endDay
8%136%29%51%
2432
June1st to 15thDay
9%13424%57%
2340
16th to endDay
16%35%6%18%49%
2340
July1st to 15thDay
36%9%13%13%14%12%
2201
16th to endDay
47%14%16%14%6%
2312
August1st to 15thDay
39%11%10%14%16%6%
2325
16th to endDay
33%9%12%18%15%11%
2310
September1st to 15thDay
35%5%10%15%18%15%
1980
16th to endDay
18%37%9%33%27%
1904
October1st to 15thDay
14%26%10%30%35%
1714
16th to endDay
10%249%30%42%
1760
November1st to 15thDay
11%2310%36%35%
1759
16th to endDay
18%1410%28%36%
1677
December1st to 15thDay
21%3415%33%21%
1620
16th to endDay
22%38%17%31%17%
1728
January1st to 15thNight
19%27%12%29%29%
2327
16th to endNight
25%45%14%28%21%
2496
February1st to 15thNight
17%25%15%25%33%
2196
16th to endNight
20%3412%34%24%
1831
March1st to 15thNight
16%2310%30%36%
1980
16th to endNight
15%1411%33%32%
2112
April1st to 15thNight
17%239%36%30%
1948
16th to endNight
9%118%28%50%
1794
May1st to 15thNight
7%238%28%48%
1620
16th to endNight
7%127%29%51%
1685
June1st to 15thNight
10%13421%58%
1620
16th to endNight
14%16%5%20%51%
1620
July1st to 15thNight
23%10%18%17%15%14%
1530
16th to endNight
30%15%23%20%7%1
1593
August1st to 15thNight
23%9%15%21%20%9%
1611
16th to endNight
25%8%15%17%20%11%
1888
September1st to 15thNight
27%7%11%20%20%12%
1980
16th to endNight
12%25%14%37%27%
1914
October1st to 15thNight
11%36%15%28%35%
1914
16th to endNight
10%2412%26%44%
2112
November1st to 15thNight
11%1316%33%33%
2100
16th to endNight
20%149%27%36%
2280
December1st to 15thNight
18%25%16%32%23%
2340
16th to endNight
24%37%17%27%19%
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
8%10%21%47%11%1
90
16th to endDay
6%7%20%33%25%7%
96
February1st to 15thDay
5%12%17%39%22%3
179
16th to endDay
8%20%31%24%12%2
238
March1st to 15thDay
6%17%26%27%14%8%
270
16th to endDay
318%29%27%15%5%
288
April1st to 15thDay
415%35%24%14%5%
269
16th to endDay
220%34%26%10%4
270
May1st to 15thDay
217%34%27%13%5%
288
16th to endDay
28%32%38%14%3
330
June1st to 15thDay
3427%40%16%6%
315
16th to endDay
313%45%27%9%
315
July1st to 15thDay
319%40%34%11%
305
16th to endDay
11%7%26%33%19%
327
August1st to 15thDay
6%7%26%40%17%
315
16th to endDay
5%1329%41%18%
332
September1st to 15thDay
13%11%34%30%8%
315
16th to endDay
45%19%36%25%9%
288
October1st to 15thDay
17%24%31%23%11%
154
16th to endDay
412%27%43%12%
96
November1st to 15thDay
113%16%33%30%5%
90
16th to endDay
411%26%31%25%1
90
December1st to 15thDay
3417%27%43%3
90
16th to endDay
10%6%31%34%17%
96
January1st to 15thNight
4214%43%31%4
720
16th to endNight
6%316%42%27%3
768
February1st to 15thNight
3315%41%29%5%
704
16th to endNight
46%21%45%20%2
632
March1st to 15thNight
3421%39%28%3
720
16th to endNight
2415%41%29%5%
768
April1st to 15thNight
2420%47%23%1
689
16th to endNight
2421%43%24%3
540
May1st to 15thNight
323%38%32%2
540
16th to endNight
217%42%33%3
563
June1st to 15thNight
217%46%38%2
540
16th to endNight
1435%52%5%
540
July1st to 15thNight
11325%58%9%
510
16th to endNight
4114%62%15%
564
August1st to 15thNight
2116%59%19%
539
16th to endNight
5%217%56%18%
604
September1st to 15thNight
5%325%51%13%
720
16th to endNight
210%33%43%10%
692
October1st to 15thNight
1114%38%35%8%
660
16th to endNight
19%35%42%10%
704
November1st to 15thNight
1113%40%35%7%
700
16th to endNight
5%217%37%30%6%
720
December1st to 15thNight
5%5%14%40%28%5%
720
16th to endNight
7%416%42%23%6%
768
Page generated at 2017-09-25 06:02:23. Version ac04

Copyright 2017 A. Danko


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