Black Canyon of the Gunnison
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Black Canyon of the Gunnison clear sky chart from 2005-11-05 to 2018-02-14.

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
60%
16505
24%
48850
21%
16468
63%
16468
34%
28929

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
57%
841
20%
2586
19%
840
60%
840
30%
1577
January16th to endNight
56%
832
25%
2704
27%
832
59%
832
28%
1644
February1st to 15thNight
52%
755
17%
2470
18%
755
54%
755
25%
1583
February16th to endNight
47%
632
24%
1932
19%
632
53%
632
28%
1227
March1st to 15thNight
56%
720
25%
1986
20%
720
60%
720
34%
1229
March16th to endNight
52%
762
23%
2106
18%
762
55%
762
30%
1372
April1st to 15thNight
48%
539
20%
1798
18%
539
53%
539
25%
1109
April16th to endNight
48%
540
23%
1800
19%
540
54%
540
26%
1095
May1st to 15thNight
49%
539
21%
1640
17%
539
53%
539
30%
994
May16th to endNight
56%
561
23%
1520
16%
561
61%
561
36%
912
June1st to 15thNight
64%
540
29%
1440
20%
540
70%
540
55%
740
June16th to endNight
74%
540
31%
1440
27%
540
77%
540
58%
720
July1st to 15thNight
76%
510
21%
1398
18%
510
77%
510
40%
811
July16th to endNight
80%
564
18%
1593
17%
531
81%
531
34%
948
August1st to 15thNight
77%
539
19%
1611
19%
536
77%
536
39%
887
August16th to endNight
75%
573
29%
1890
31%
573
77%
573
38%
1019
September1st to 15thNight
73%
540
28%
1800
29%
540
77%
540
37%
975
September16th to endNight
72%
659
37%
1978
31%
659
77%
659
49%
994
October1st to 15thNight
65%
720
31%
2160
24%
720
70%
720
44%
1142
October16th to endNight
69%
768
34%
2304
29%
768
72%
768
44%
1220
November1st to 15thNight
62%
841
30%
2361
23%
841
65%
841
41%
1344
November16th to endNight
61%
975
29%
2691
22%
975
64%
975
41%
1545
December1st to 15thNight
52%
975
15%
2730
12%
975
54%
975
29%
1764
December16th to endNight
43%
1040
18%
2912
13%
1040
46%
1040
21%
2078

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
6%7%2442445%6%49%
49225
Night
6%7%2432345%6%52%
49038
TransparencyDay
34%6%9%22%20%7%
48913
Night
32%5%10%23%20%7%
48851
SeeingDay
10%11%27%33%15%1
6157
Night
10%5%17%40%23%2
16517

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
7%10%3442445%7%45%
1692
16th to endDay
8%11%3332235%5%50%
1872
February1st to 15thDay
9%11%46%5%23346%41%
1693
16th to endDay
7%15%5%7%423345%39%
1541
March1st to 15thDay
5%10%46%323346%49%
1971
16th to endDay
5%10%45%425%45%6%44%
2118
April1st to 15thDay
8%11%45%424447%42%
2150
16th to endDay
7%9%35%43445%7%43%
2160
May1st to 15thDay
7%8%245%35%5%6%7%42%
2308
16th to endDay
5%5%244245%5%7%51%
2591
June1st to 15thDay
4313323347%60%
2520
16th to endDay
22221435%6%67%
2520
July1st to 15thDay
3315%436%6%6%9%49%
2476
16th to endDay
5%4246%37%7%8%8%38%
2467
August1st to 15thDay
6%425%6%45%8%7%8%40%
2340
16th to endDay
43245%25%7%7%8%48%
2312
September1st to 15thDay
6%314425%5%6%7%51%
2160
16th to endDay
6%313323335%62%
1978
October1st to 15thDay
8%313323445%58%
1800
16th to endDay
7%5%23322335%61%
1920
November1st to 15thDay
7%5%23223345%59%
1814
16th to endDay
5%7%2441224461%
1598
December1st to 15thDay
10%11%35%42233446%
1560
16th to endDay
10%16%46%5%2443436%
1664
January1st to 15thNight
7%11%34323335%50%
2586
16th to endNight
9%13%3421323451%
2704
February1st to 15thNight
8%12%37%5%22345%45%
2459
16th to endNight
6%16%3442345%445%
1932
March1st to 15thNight
5%8%45%323445%51%
1986
16th to endNight
8%11%35%33435%446%
2106
April1st to 15thNight
7%10%345%3345%6%44%
1798
16th to endNight
11%7%35%423345%47%
1800
May1st to 15thNight
9%5%25%4245%5%6%47%
1640
16th to endNight
8%41432445%6%54%
1519
June1st to 15thNight
22123135%46%66%
1440
16th to endNight
22132235%5%69%
1440
July1st to 15thNight
42124346%8%9%51%
1481
16th to endNight
11145%36%7%9%12%44%
1701
August1st to 15thNight
4313325%5%7%8%54%
1620
16th to endNight
43135%245%6%8%54%
1890
September1st to 15thNight
44144345%5%8%53%
1800
16th to endNight
6%21331233467%
1978
October1st to 15thNight
7%412313246%61%
2160
16th to endNight
7%412222235%63%
2304
November1st to 15thNight
7%6%12323345%59%
2361
16th to endNight
6%8%33212346%57%
2691
December1st to 15thNight
9%12%35%312245%47%
2730
16th to endNight
9%15%6%7%423335%38%
2912

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
38%6%18%23%12%
1693
16th to endDay
36%6%14%28%11%2
1872
February1st to 15thDay
45%5%15%22%8%2
1693
16th to endDay
47%5%6%26%13%1
1541
March1st to 15thDay
35%5%10%29%17%1
1971
16th to endDay
39%6%6%29%14%3
2118
April1st to 15thDay
41%5%8%21%17%5%
2150
16th to endDay
39%6%8%23%19%2
2160
May1st to 15thDay
38%7%7%23%20%2
2308
16th to endDay
31%7%8%21%25%6%
2594
June1st to 15thDay
23%4416%29%21%
2520
16th to endDay
17%4312%32%29%
2520
July1st to 15thDay
29%9%9%13%18%19%
2330
16th to endDay
36%9%14%19%12%7%
2312
August1st to 15thDay
36%10%10%16%15%10%
2325
16th to endDay
29%8%10%19%22%9%
2312
September1st to 15thDay
30%7%8%15%26%11%
2160
16th to endDay
24%5%6%20%34%8%
1978
October1st to 15thDay
28%46%26%28%5%
1800
16th to endDay
26%47%30%26%4
1920
November1st to 15thDay
28%48%25%27%5%
1814
16th to endDay
28%410%34%19%2
1598
December1st to 15thDay
42%414%25%12%1
1560
16th to endDay
53%5%12%18%9%
1664
January1st to 15thNight
36%5%16%26%14%1
2586
16th to endNight
37%5%12%28%13%2
2704
February1st to 15thNight
42%5%15%24%10%1
2470
16th to endNight
40%49%26%16%1
1932
March1st to 15thNight
34%5%8%30%18%2
1986
16th to endNight
40%5%5%25%20%2
2106
April1st to 15thNight
40%5%7%19%21%6%
1798
16th to endNight
38%5%7%22%21%4
1800
May1st to 15thNight
35%6%10%22%20%4
1641
16th to endNight
28%8%10%19%25%7%
1520
June1st to 15thNight
17%5%7%16%29%24%
1440
16th to endNight
15%4414%25%36%
1440
July1st to 15thNight
25%9%13%14%16%21%
1398
16th to endNight
27%11%20%18%11%10%
1593
August1st to 15thNight
25%8%18%19%14%14%
1611
16th to endNight
25%7%12%18%22%12%
1890
September1st to 15thNight
26%7%11%16%21%15%
1800
16th to endNight
20%45%22%36%10%
1978
October1st to 15thNight
24%47%25%27%9%
2160
16th to endNight
24%47%27%30%5%
2304
November1st to 15thNight
28%48%27%26%5%
2361
16th to endNight
28%49%30%23%3
2691
December1st to 15thNight
40%415%22%15%1
2730
16th to endNight
49%5%13%20%10%
2912

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
28%419%31%15%
135
16th to endDay
11%5%26%41%15%
144
February1st to 15thDay
23%6%25%33%10%
130
16th to endDay
12%14%19%40%8%3
81
March1st to 15thDay
12%19%25%28%12%1
261
16th to endDay
14%23%33%23%4
288
April1st to 15thDay
14%23%28%20%10%1
269
16th to endDay
20%24%32%18%4
270
May1st to 15thDay
12%21%31%23%11%
288
16th to endDay
8%14%26%30%17%2
492
June1st to 15thDay
7%11%29%29%20%1
495
16th to endDay
27%25%42%20%1
495
July1st to 15thDay
45%19%42%25%3
434
16th to endDay
7%419%41%24%2
327
August1st to 15thDay
7%7%26%40%15%1
315
16th to endDay
6%5%21%44%20%1
332
September1st to 15thDay
6%6%35%33%13%2
315
16th to endDay
8%11%31%34%13%1
258
October1st to 15thDay
7%12%26%31%20%2
135
16th to endDay
6%11%23%36%18%2
144
November1st to 15thDay
8%8%27%30%22%2
135
16th to endDay
16%9%27%35%9%1
135
December1st to 15thDay
16%7%32%36%7%
135
16th to endDay
14%6%29%36%12%
144
January1st to 15thNight
13%6%15%45%19%
845
16th to endNight
14%6%16%42%17%2
832
February1st to 15thNight
13%5%18%47%13%
760
16th to endNight
14%7%25%40%12%
632
March1st to 15thNight
8%7%22%43%18%
720
16th to endNight
14%6%21%38%18%
762
April1st to 15thNight
11%10%24%38%13%1
539
16th to endNight
16%6%21%35%18%1
540
May1st to 15thNight
11%5%25%38%17%1
540
16th to endNight
9%6%22%35%23%3
563
June1st to 15thNight
3423%39%27%1
540
16th to endNight
3215%44%31%3
540
July1st to 15thNight
49%41%41%2
510
16th to endNight
317%37%46%4
564
August1st to 15thNight
5%19%36%42%3
539
16th to endNight
5%19%34%44%5%
573
September1st to 15thNight
4311%42%35%2
540
16th to endNight
7%213%37%34%4
659
October1st to 15thNight
7%318%41%25%2
720
16th to endNight
9%213%40%29%4
768
November1st to 15thNight
10%5%18%40%23%2
841
16th to endNight
10%6%17%42%20%1
975
December1st to 15thNight
14%6%19%44%13%
975
16th to endNight
15%7%22%41%13%
1040
Page generated at 2018-02-15 08:58:50. Version ac04

Copyright 2018 A. Danko


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