SGPalisadeCO Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the SGPalisadeCO Observatory clear sky chart from 2005-11-05 to 2017-08-12.

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
65%
15755
25%
46560
22%
15718
68%
15718
37%
26568

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
67%
761
22%
2372
22%
761
70%
761
36%
1347
January16th to endNight
63%
768
25%
2496
26%
768
65%
768
31%
1454
February1st to 15thNight
62%
699
18%
2288
19%
699
65%
699
30%
1367
February16th to endNight
53%
632
24%
1944
20%
632
59%
632
29%
1189
March1st to 15thNight
62%
720
27%
1980
21%
720
66%
720
39%
1159
March16th to endNight
56%
768
23%
2112
18%
768
60%
768
33%
1336
April1st to 15thNight
51%
550
21%
1809
19%
550
55%
550
28%
1085
April16th to endNight
52%
540
23%
1776
20%
540
59%
540
29%
1036
May1st to 15thNight
57%
540
22%
1620
17%
540
61%
540
34%
942
May16th to endNight
62%
562
25%
1541
18%
561
66%
561
37%
898
June1st to 15thNight
68%
540
27%
1440
22%
540
71%
540
54%
745
June16th to endNight
79%
540
33%
1440
28%
540
82%
540
62%
709
July1st to 15thNight
81%
510
20%
1415
18%
510
83%
510
46%
772
July16th to endNight
82%
564
23%
1593
21%
531
83%
531
43%
848
August1st to 15thNight
78%
527
23%
1575
21%
524
79%
524
44%
847
August16th to endNight
80%
525
29%
1704
31%
525
82%
525
43%
875
September1st to 15thNight
75%
495
33%
1650
35%
495
79%
495
44%
827
September16th to endNight
74%
634
36%
1826
30%
634
78%
634
53%
909
October1st to 15thNight
66%
660
32%
1980
25%
660
70%
660
46%
1024
October16th to endNight
69%
704
34%
2112
26%
704
74%
704
47%
1073
November1st to 15thNight
65%
756
30%
2159
24%
756
69%
756
40%
1209
November16th to endNight
62%
900
27%
2520
22%
900
65%
900
43%
1400
December1st to 15thNight
58%
900
15%
2520
12%
900
60%
900
31%
1621
December16th to endNight
53%
960
15%
2688
12%
960
55%
960
22%
1896

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
442442445%7%53%
47412
Night
5%5%2442445%7%54%
46749
TransparencyDay
28%5%11%22%20%11%
47102
Night
29%5%12%22%19%10%
46560
SeeingDay
7%10%25%32%19%4
5561
Night
7%416%38%28%4
15765

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
46%15%5%345%6%7%50%
1576
16th to endDay
6%7%24324345%54%
1728
February1st to 15thDay
47%36%5%3446%9%43%
1575
16th to endDay
6%9%47%5%35%346%43%
1527
March1st to 15thDay
46%25%4245%5%7%51%
1980
16th to endDay
37%35%5%25%447%48%
2112
April1st to 15thDay
7%6%25%43346%7%47%
2138
16th to endDay
46%25%425%5%6%7%48%
2181
May1st to 15thDay
5%5%245%35%6%6%7%46%
2331
16th to endDay
43233246%5%9%53%
2573
June1st to 15thDay
3213324446%63%
2520
16th to endDay
1122325%5%72%
2520
July1st to 15thDay
2213436%6%7%9%50%
2457
16th to endDay
3314436%6%9%11%44%
2467
August1st to 15thDay
43245%46%6%6%6%48%
2290
16th to endDay
323425%5%7%8%55%
2146
September1st to 15thDay
5%2135%245%5%5%58%
1980
16th to endDay
3113313345%67%
1801
October1st to 15thDay
6%21231345%7%59%
1650
16th to endDay
431321245%6%63%
1760
November1st to 15thDay
5%413323346%61%
1684
16th to endDay
45%24313247%60%
1440
December1st to 15thDay
7%8%47%42345%6%45%
1440
16th to endDay
7%11%35%5%25%5%6%7%38%
1536
January1st to 15thNight
46%25%42435%6%53%
2372
16th to endNight
6%9%3432335%6%51%
2496
February1st to 15thNight
37%25%435%5%5%8%47%
2277
16th to endNight
5%9%35%5%246%5%6%45%
1944
March1st to 15thNight
45%25%3335%5%6%54%
1980
16th to endNight
5%6%36%5%345%5%6%48%
2112
April1st to 15thNight
5%7%27%5%25%5%46%46%
1809
16th to endNight
8%6%35%424446%49%
1776
May1st to 15thNight
7%424325%5%6%8%49%
1619
16th to endNight
7%4134245%6%7%53%
1540
June1st to 15thNight
2213313447%67%
1440
16th to endNight
212213447%69%
1440
July1st to 15thNight
2212335%6%7%10%55%
1500
16th to endNight
1113426%6%7%12%49%
1701
August1st to 15thNight
32143145%6%9%55%
1584
16th to endNight
31124245%7%10%55%
1704
September1st to 15thNight
332332445%7%59%
1650
16th to endNight
421222234469%
1826
October1st to 15thNight
5%323323345%63%
1980
16th to endNight
6%313322337%62%
2112
November1st to 15thNight
5%424324445%58%
2159
16th to endNight
6%5%23323337%59%
2520
December1st to 15thNight
8%8%35%423446%47%
2520
16th to endNight
7%12%47%5%36%45%6%37%
2688

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
31%8%25%28%6%
1577
16th to endDay
32%6%19%27%12%2
1728
February1st to 15thDay
36%8%18%23%10%1
1575
16th to endDay
42%5%9%28%12%1
1527
March1st to 15thDay
31%414%29%17%3
1980
16th to endDay
33%5%9%30%16%4
2112
April1st to 15thDay
35%5%9%21%21%6%
2138
16th to endDay
32%7%10%22%21%6%
2181
May1st to 15thDay
34%6%7%21%23%6%
2331
16th to endDay
25%6%10%21%27%8%
2576
June1st to 15thDay
21%45%13%26%27%
2520
16th to endDay
13%2310%27%42%
2520
July1st to 15thDay
26%7%10%13%16%25%
2313
16th to endDay
27%7%14%19%16%14%
2312
August1st to 15thDay
34%6%10%15%15%17%
2275
16th to endDay
23%6%10%20%23%15%
2146
September1st to 15thDay
25%5%7%15%25%20%
1980
16th to endDay
19%47%18%38%11%
1801
October1st to 15thDay
24%48%27%28%6%
1650
16th to endDay
21%49%30%30%3
1760
November1st to 15thDay
25%310%27%27%6%
1684
16th to endDay
26%414%34%19%1
1440
December1st to 15thDay
38%6%19%27%7%
1440
16th to endDay
45%8%20%20%5%
1536
January1st to 15thNight
28%7%21%30%11%
2372
16th to endNight
34%5%16%28%14%2
2496
February1st to 15thNight
33%7%19%25%12%1
2288
16th to endNight
35%6%11%26%16%1
1944
March1st to 15thNight
29%5%11%30%19%3
1980
16th to endNight
35%5%8%23%22%4
2112
April1st to 15thNight
37%5%7%20%19%10%
1809
16th to endNight
33%6%8%22%21%6%
1776
May1st to 15thNight
31%6%12%17%26%5%
1620
16th to endNight
28%6%9%20%25%10%
1541
June1st to 15thNight
17%46%14%27%28%
1440
16th to endNight
15%2311%21%45%
1440
July1st to 15thNight
22%6%11%14%14%29%
1415
16th to endNight
23%6%16%18%18%16%
1593
August1st to 15thNight
24%5%13%21%16%18%
1575
16th to endNight
22%6%10%17%22%19%
1704
September1st to 15thNight
23%410%16%18%26%
1650
16th to endNight
18%36%19%31%20%
1826
October1st to 15thNight
23%39%22%29%11%
1980
16th to endNight
22%38%26%32%6%
2112
November1st to 15thNight
28%48%25%26%6%
2159
16th to endNight
27%310%30%23%3
2520
December1st to 15thNight
37%6%17%24%14%
2520
16th to endNight
45%8%17%21%5%
2688

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
25%7%12%22%22%10%
90
16th to endDay
16%216%41%17%5%
96
February1st to 15thDay
12%321%44%17%1
90
16th to endDay
13%14%19%33%14%4
96
March1st to 15thDay
7%22%27%25%15%1
270
16th to endDay
10%26%36%21%4
288
April1st to 15thDay
11%23%32%17%10%3
269
16th to endDay
15%20%35%20%7%
270
May1st to 15thDay
9%17%36%24%11%1
288
16th to endDay
8%12%25%29%19%5%
474
June1st to 15thDay
311%26%30%23%4
495
16th to endDay
25%20%36%29%5%
495
July1st to 15thDay
2218%34%32%8%
417
16th to endDay
3317%48%24%3
327
August1st to 15thDay
7%224%41%20%5%
300
16th to endDay
5%420%42%23%4
268
September1st to 15thDay
5%6%35%36%12%2
255
16th to endDay
7%7%21%37%21%4
221
October1st to 15thDay
26%18%33%23%15%
90
16th to endDay
8%9%20%33%22%5%
96
November1st to 15thDay
18%22%32%31%4
90
16th to endDay
15%13%25%36%5%3
90
December1st to 15thDay
13%6%31%38%10%
90
16th to endDay
11%7%23%41%13%2
96
January1st to 15thNight
7%413%44%26%3
765
16th to endNight
11%412%43%22%4
768
February1st to 15thNight
7%219%46%20%3
704
16th to endNight
9%5%24%44%14%1
632
March1st to 15thNight
5%7%19%43%23%1
720
16th to endNight
7%7%22%41%19%1
768
April1st to 15thNight
7%9%24%40%14%2
550
16th to endNight
12%8%22%34%17%4
540
May1st to 15thNight
9%5%21%40%19%3
540
16th to endNight
9%7%17%31%29%5%
563
June1st to 15thNight
3420%40%27%4
540
16th to endNight
3113%42%35%4
540
July1st to 15thNight
36%29%52%6%
510
16th to endNight
2428%55%8%
564
August1st to 15thNight
5%17%29%50%5%
527
16th to endNight
37%31%46%9%
525
September1st to 15thNight
4112%38%38%4
495
16th to endNight
5%312%24%42%11%
634
October1st to 15thNight
6%319%35%28%6%
660
16th to endNight
7%415%34%32%6%
704
November1st to 15thNight
7%5%16%37%30%3
756
16th to endNight
7%7%17%40%22%4
900
December1st to 15thNight
11%418%46%17%1
900
16th to endNight
11%6%20%41%18%1
960
Page generated at 2017-08-13 12:16:26. Version ac04

Copyright 2017 A. Danko


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