Copper Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Copper Mountain clear sky chart from 2005-11-05 to 2017-10-16.

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
41%
16035
21%
47213
12%
15989
49%
15989
30%
28312

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
29%
887
20%
2493
9%
882
39%
882
24%
1592
January16th to endNight
28%
768
24%
2496
14%
768
41%
768
25%
1524
February1st to 15thNight
23%
701
14%
2282
6%
698
33%
698
20%
1490
February16th to endNight
20%
632
21%
1894
6%
632
35%
632
23%
1215
March1st to 15thNight
30%
720
21%
2064
9%
720
41%
720
31%
1220
March16th to endNight
28%
711
20%
2055
9%
711
39%
711
27%
1273
April1st to 15thNight
30%
539
18%
1798
10%
539
41%
539
24%
1062
April16th to endNight
32%
540
19%
1800
12%
540
43%
540
23%
1108
May1st to 15thNight
35%
540
16%
1612
9%
540
44%
540
25%
1036
May16th to endNight
44%
563
17%
1498
9%
561
51%
561
32%
913
June1st to 15thNight
52%
540
24%
1440
13%
540
60%
540
49%
747
June16th to endNight
65%
540
28%
1440
21%
540
70%
540
53%
738
July1st to 15thNight
70%
510
16%
1360
13%
510
72%
510
32%
863
July16th to endNight
75%
564
15%
1503
15%
531
76%
531
31%
926
August1st to 15thNight
68%
539
15%
1632
14%
536
70%
536
32%
963
August16th to endNight
69%
573
23%
1910
23%
573
72%
573
32%
1091
September1st to 15thNight
67%
540
27%
1800
25%
540
74%
540
35%
990
September16th to endNight
61%
579
30%
1944
24%
579
71%
579
41%
991
October1st to 15thNight
41%
720
25%
2160
14%
720
50%
720
37%
1190
October16th to endNight
44%
708
30%
2124
15%
708
56%
708
37%
1162
November1st to 15thNight
37%
861
27%
2261
11%
861
47%
861
38%
1299
November16th to endNight
36%
900
27%
2439
13%
900
45%
900
35%
1409
December1st to 15thNight
21%
900
14%
2520
4%
900
30%
900
23%
1638
December16th to endNight
24%
960
17%
2688
8%
960
32%
960
19%
1872

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
5%8%48%7%35%446%41%
48216
Night
1437%6%3445%7%50%
47393
TransparencyDay
43%6%12%20%14%3
47898
Night
31%7%16%24%15%3
47213
SeeingDay
16%21%28%19%10%2
5912
Night
7%15%29%29%15%2
16038

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
35%14%8%46%346%43%
1456
16th to endDay
5%6%10%7%34346%46%
1728
February1st to 15thDay
5%6%16%9%45%336%38%
1580
16th to endDay
47%15%10%44336%39%
1580
March1st to 15thDay
8%5%11%8%34346%44%
1893
16th to endDay
29%7%11%6%34346%38%
2169
April1st to 15thDay
211%7%10%6%25%35%5%39%
2150
16th to endDay
316%8%11%7%35%346%30%
2160
May1st to 15thDay
5%16%6%8%6%345%5%6%31%
2336
16th to endDay
7%12%47%6%36%5%47%33%
2616
June1st to 15thDay
8%6%34425%45%8%45%
2520
16th to endDay
5%413425%45%6%54%
2520
July1st to 15thDay
12%6%36%6%35%5%5%6%37%
2520
16th to endDay
12%7%37%8%47%5%5%6%31%
2558
August1st to 15thDay
15%9%37%7%45%447%31%
2316
16th to endDay
10%7%38%7%45%5%5%6%34%
2292
September1st to 15thDay
12%7%35%5%3334447%
2160
16th to endDay
6%8%25%5%33335%51%
2016
October1st to 15thDay
5%9%45%5%24436%49%
1800
16th to endDay
37%47%413246%52%
1768
November1st to 15thDay
5%48%5%3235%6%54%
1584
16th to endDay
5%45%7%13236%57%
1518
December1st to 15thDay
5%5%12%9%6%5%45%7%38%
1440
16th to endDay
5%6%12%13%5%5%447%35%
1536
January1st to 15thNight
239%9%5%6%45%8%44%
2493
16th to endNight
349%9%46%435%48%
2496
February1st to 15thNight
3311%10%5%6%45%6%41%
2271
16th to endNight
35%11%10%44447%42%
1894
March1st to 15thNight
438%6%44347%52%
2064
16th to endNight
17%5%8%6%23346%49%
2055
April1st to 15thNight
6%47%6%245%6%8%47%
1798
16th to endNight
211%48%5%24346%47%
1800
May1st to 15thNight
49%46%5%2446%8%44%
1611
16th to endNight
27%3443436%9%49%
1497
June1st to 15thNight
231122346%8%63%
1440
16th to endNight
1223135%5%7%65%
1440
July1st to 15thNight
5%324426%6%6%10%46%
1440
16th to endNight
4324436%6%7%9%46%
1607
August1st to 15thNight
5%5%244345%8%8%48%
1641
16th to endNight
6%325%4245%6%8%48%
1910
September1st to 15thNight
5%324435%46%8%53%
1800
16th to endNight
241432345%6%61%
1944
October1st to 15thNight
25%24423447%57%
2160
16th to endNight
26%36%322245%59%
2124
November1st to 15thNight
336%5%14336%59%
2261
16th to endNight
338%5%23347%56%
2439
December1st to 15thNight
3310%8%45%5%5%7%44%
2520
16th to endNight
2310%11%5%6%5%5%7%39%
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
40%7%19%19%10%2
1457
16th to endDay
37%7%17%21%12%3
1728
February1st to 15thDay
47%7%15%18%8%2
1580
16th to endDay
43%6%13%22%12%2
1580
March1st to 15thDay
40%5%14%24%13%1
1893
16th to endDay
46%5%12%23%9%2
2169
April1st to 15thDay
46%5%14%19%11%3
2150
16th to endDay
54%5%11%20%7%1
2160
May1st to 15thDay
52%7%10%19%9%
2336
16th to endDay
48%7%12%18%9%2
2620
June1st to 15thDay
35%5%11%18%21%7%
2520
16th to endDay
29%38%22%26%9%
2520
July1st to 15thDay
46%6%11%13%14%7%
2371
16th to endDay
51%7%14%13%8%3
2399
August1st to 15thDay
53%7%9%11%12%4
2301
16th to endDay
48%6%10%18%13%3
2292
September1st to 15thDay
42%39%16%20%7%
2160
16th to endDay
36%310%24%22%2
2016
October1st to 15thDay
37%48%24%21%4
1800
16th to endDay
33%49%29%18%3
1768
November1st to 15thDay
28%6%15%21%22%5%
1584
16th to endDay
29%414%30%16%5%
1518
December1st to 15thDay
42%7%15%23%9%
1440
16th to endDay
48%8%11%17%10%3
1536
January1st to 15thNight
32%11%19%21%11%2
2493
16th to endNight
35%8%15%23%13%4
2496
February1st to 15thNight
39%9%16%21%10%1
2282
16th to endNight
38%5%14%22%14%2
1894
March1st to 15thNight
28%7%17%30%13%2
2064
16th to endNight
35%5%17%29%10%2
2055
April1st to 15thNight
33%7%16%25%14%2
1798
16th to endNight
37%7%17%26%11%
1800
May1st to 15thNight
37%8%16%25%11%
1612
16th to endNight
31%6%18%27%12%2
1498
June1st to 15thNight
17%6%17%25%24%7%
1440
16th to endNight
17%5%11%25%27%12%
1440
July1st to 15thNight
30%12%16%16%16%7%
1360
16th to endNight
29%12%23%18%11%4
1503
August1st to 15thNight
32%7%20%18%14%5%
1632
16th to endNight
30%7%18%22%17%3
1910
September1st to 15thNight
28%6%15%20%20%7%
1800
16th to endNight
22%6%15%32%20%2
1944
October1st to 15thNight
26%5%13%26%22%5%
2160
16th to endNight
25%5%12%31%20%3
2124
November1st to 15thNight
24%6%14%25%22%5%
2261
16th to endNight
28%414%29%18%4
2439
December1st to 15thNight
36%9%20%20%11%1
2520
16th to endNight
41%11%15%18%11%2
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
20%18%23%21%16%
90
16th to endDay
13%27%34%22%11
96
February1st to 15thDay
22%30%30%16%1
90
16th to endDay
20%24%24%25%21
81
March1st to 15thDay
20%35%26%14%3
183
16th to endDay
18%42%28%9%1
288
April1st to 15thDay
22%36%28%8%21
269
16th to endDay
23%42%24%7%1
270
May1st to 15thDay
17%25%33%16%6%1
371
16th to endDay
16%21%28%19%10%3
517
June1st to 15thDay
11%20%24%22%17%2
495
16th to endDay
7%14%30%24%21%3
495
July1st to 15thDay
15%7%23%24%21%6%
475
16th to endDay
15%9%24%25%18%7%
417
August1st to 15thDay
22%12%28%26%8%1
315
16th to endDay
16%7%36%25%11%2
332
September1st to 15thDay
20%18%32%20%6%2
315
16th to endDay
14%18%34%19%7%4
213
October1st to 15thDay
15%23%24%20%14%2
135
16th to endDay
15%20%28%24%10%2
99
November1st to 15thDay
12%21%20%24%16%5%
90
16th to endDay
22%26%34%14%2
90
December1st to 15thDay
18%35%33%10%2
90
16th to endDay
8%40%30%14%6%
96
January1st to 15thNight
10%24%29%22%9%2
887
16th to endNight
8%18%39%24%7%1
768
February1st to 15thNight
8%22%39%23%6%
704
16th to endNight
8%23%40%23%4
632
March1st to 15thNight
6%20%37%25%9%
720
16th to endNight
6%21%39%26%5%
711
April1st to 15thNight
6%22%36%27%6%
539
16th to endNight
10%19%33%28%6%1
540
May1st to 15thNight
9%11%37%28%12%
540
16th to endNight
7%10%30%30%18%2
563
June1st to 15thNight
5%6%31%36%19%1
540
16th to endNight
2422%40%29%1
540
July1st to 15thNight
6%111%38%39%2
510
16th to endNight
5%16%35%45%4
564
August1st to 15thNight
9%10%40%37%2
539
16th to endNight
7%212%36%35%6%
573
September1st to 15thNight
5%117%43%26%5%
540
16th to endNight
5%6%21%34%26%5%
579
October1st to 15thNight
7%14%33%26%13%4
720
16th to endNight
7%13%30%30%14%3
708
November1st to 15thNight
8%19%31%29%10%1
861
16th to endNight
7%21%31%28%8%1
900
December1st to 15thNight
8%28%38%18%5%
900
16th to endNight
10%24%32%23%7%
960
Page generated at 2017-10-17 14:35:28. Version ac04

Copyright 2017 A. Danko


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