Colorado State Forest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Colorado State Forest clear sky chart from 2005-11-05 to 2017-09-14.

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
36%
15963
19%
46844
11%
15920
44%
15920
24%
29926

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
26%
900
15%
2506
8%
895
31%
895
17%
1815
January16th to endNight
24%
793
19%
2521
11%
793
34%
793
17%
1732
February1st to 15thNight
17%
697
9%
2288
5%
697
22%
697
11%
1716
February16th to endNight
14%
632
15%
1895
4%
632
26%
632
13%
1351
March1st to 15thNight
25%
720
16%
2079
6%
720
35%
720
21%
1343
March16th to endNight
22%
702
17%
2046
7%
702
32%
702
20%
1344
April1st to 15thNight
22%
539
14%
1798
6%
539
33%
539
16%
1198
April16th to endNight
28%
540
17%
1800
10%
540
38%
540
18%
1163
May1st to 15thNight
34%
540
15%
1560
6%
540
42%
540
22%
1055
May16th to endNight
46%
563
15%
1498
9%
561
52%
561
28%
968
June1st to 15thNight
47%
540
20%
1440
10%
540
54%
540
44%
763
June16th to endNight
61%
540
28%
1440
18%
540
67%
540
53%
725
July1st to 15thNight
71%
510
18%
1360
13%
510
75%
510
41%
783
July16th to endNight
74%
564
19%
1463
17%
531
74%
531
41%
824
August1st to 15thNight
71%
539
18%
1622
16%
536
72%
536
37%
896
August16th to endNight
71%
573
27%
1910
27%
573
76%
573
38%
1018
September1st to 15thNight
63%
537
27%
1790
21%
537
74%
537
39%
937
September16th to endNight
55%
525
30%
1780
25%
525
63%
525
40%
890
October1st to 15thNight
35%
660
24%
1980
13%
660
44%
660
27%
1199
October16th to endNight
33%
714
26%
2122
11%
714
45%
714
30%
1216
November1st to 15thNight
28%
875
23%
2275
9%
875
37%
875
27%
1434
November16th to endNight
26%
900
21%
2463
9%
900
36%
900
23%
1573
December1st to 15thNight
17%
900
8%
2520
2%
900
22%
900
13%
1904
December16th to endNight
19%
960
13%
2688
6%
960
25%
960
12%
2079

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%11%5%8%5%34446%40%
47881
Night
310%5%7%5%23346%46%
47020
TransparencyDay
47%411%20%12%3
47559
Night
40%414%23%13%3
46844
SeeingDay
17%23%27%17%10%2
5863
Night
14%17%25%24%14%2
15970

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
214%9%14%5%33325%35%
1432
16th to endDay
214%9%13%7%22215%38%
1713
February1st to 15thDay
318%9%15%7%22225%28%
1575
16th to endDay
115%12%14%8%23245%28%
1577
March1st to 15thDay
214%8%9%6%13335%39%
1878
16th to endDay
316%8%10%5%23347%32%
2176
April1st to 15thDay
5%17%7%8%424345%35%
2150
16th to endDay
7%20%7%8%6%2445%6%26%
2160
May1st to 15thDay
12%13%46%5%345%5%6%32%
2385
16th to endDay
12%11%37%5%35%5%5%8%30%
2616
June1st to 15thDay
7%5%245%345%6%7%46%
2520
16th to endDay
32124245%5%7%59%
2520
July1st to 15thDay
8%425%5%35%5%6%8%44%
2520
16th to endDay
7%435%6%37%6%7%7%38%
2603
August1st to 15thDay
11%6%36%6%46%6%5%7%35%
2328
16th to endDay
7%5%26%6%35%5%5%6%43%
2292
September1st to 15thDay
9%425%5%3434452%
2145
16th to endDay
11%6%2432223457%
1847
October1st to 15thDay
8%13%3332344448%
1650
16th to endDay
8%13%46%212245%47%
1738
November1st to 15thDay
314%5%7%323146%46%
1583
16th to endDay
114%5%9%5%11226%48%
1497
December1st to 15thDay
319%6%13%5%43235%30%
1440
16th to endDay
220%8%15%9%3332327%
1536
January1st to 15thNight
115%9%11%6%33235%36%
2506
16th to endNight
214%8%12%6%3222341%
2521
February1st to 15thNight
215%9%18%7%3323429%
2277
16th to endNight
113%9%14%8%22245%34%
1895
March1st to 15thNight
19%6%9%7%23236%46%
2079
16th to endNight
211%6%9%424346%44%
2046
April1st to 15thNight
313%6%7%5%34445%41%
1798
16th to endNight
5%15%5%6%5%24345%41%
1800
May1st to 15thNight
8%10%35%5%25%45%7%40%
1559
16th to endNight
6%7%235%35%5%5%7%46%
1497
June1st to 15thNight
33322345%8%61%
1440
16th to endNight
321231235%6%68%
1440
July1st to 15thNight
42123145%8%11%54%
1440
16th to endNight
3223425%5%5%6%58%
1563
August1st to 15thNight
43134346%7%9%51%
1631
16th to endNight
33134335%5%8%56%
1910
September1st to 15thNight
6%313323447%60%
1790
16th to endNight
6%5%13322335%63%
1780
October1st to 15thNight
7%11%23223345%51%
1980
16th to endNight
5%11%34212246%54%
2122
November1st to 15thNight
312%46%312336%51%
2275
16th to endNight
211%6%7%422337%48%
2463
December1st to 15thNight
318%6%11%7%45%235%31%
2520
16th to endNight
114%8%16%10%3322430%
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
54%417%14%7%1
1433
16th to endDay
52%215%18%8%1
1713
February1st to 15thDay
60%312%14%7%
1575
16th to endDay
59%311%16%7%1
1577
March1st to 15thDay
49%315%19%11%1
1878
16th to endDay
54%5%11%21%5%2
2176
April1st to 15thDay
53%412%17%10%2
2150
16th to endDay
61%39%18%5%
2160
May1st to 15thDay
54%411%20%8%
2385
16th to endDay
53%5%12%20%7%1
2620
June1st to 15thDay
37%6%12%20%18%5%
2520
16th to endDay
25%47%25%28%8%
2520
July1st to 15thDay
39%6%10%16%18%8%
2371
16th to endDay
43%6%11%20%12%5%
2440
August1st to 15thDay
49%5%11%13%14%5%
2313
16th to endDay
44%5%8%21%16%3
2292
September1st to 15thDay
37%38%19%21%9%
2145
16th to endDay
34%37%33%18%2
1847
October1st to 15thDay
40%410%28%13%2
1650
16th to endDay
40%211%31%11%1
1738
November1st to 15thDay
41%414%20%15%3
1583
16th to endDay
41%215%28%10%1
1497
December1st to 15thDay
57%319%14%5%
1440
16th to endDay
64%46%16%5%2
1536
January1st to 15thNight
52%413%18%8%2
2506
16th to endNight
51%210%21%11%2
2521
February1st to 15thNight
58%412%16%7%
2288
16th to endNight
53%311%19%10%2
1895
March1st to 15thNight
41%316%24%11%1
2079
16th to endNight
43%316%25%8%1
2046
April1st to 15thNight
46%5%13%21%12%1
1798
16th to endNight
46%214%26%9%
1800
May1st to 15thNight
44%6%15%26%7%
1560
16th to endNight
37%6%17%26%11%
1498
June1st to 15thNight
20%421%28%20%4
1440
16th to endNight
17%39%28%29%11%
1440
July1st to 15thNight
23%9%18%20%18%9%
1360
16th to endNight
26%6%20%20%19%6%
1463
August1st to 15thNight
27%6%20%18%18%8%
1622
16th to endNight
27%413%24%23%5%
1910
September1st to 15thNight
25%5%15%20%24%9%
1790
16th to endNight
24%312%35%21%2
1780
October1st to 15thNight
36%412%28%14%3
1980
16th to endNight
33%213%33%14%1
2122
November1st to 15thNight
35%414%23%17%4
2275
16th to endNight
38%414%28%12%2
2463
December1st to 15thNight
56%5%16%13%7%
2520
16th to endNight
59%5%9%18%5%1
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
24%22%26%15%10%1
90
16th to endDay
16%29%28%20%5%
96
February1st to 15thDay
34%33%18%12%1
90
16th to endDay
28%27%25%13%4
81
March1st to 15thDay
31%32%22%10%2
168
16th to endDay
23%46%21%7%
288
April1st to 15thDay
28%36%23%7%3
269
16th to endDay
31%36%24%5%2
270
May1st to 15thDay
23%25%27%14%7%2
402
16th to endDay
20%20%27%17%11%2
517
June1st to 15thDay
10%21%27%22%14%3
495
16th to endDay
420%30%24%16%3
495
July1st to 15thDay
11%12%23%25%21%5%
475
16th to endDay
8%11%24%29%19%6%
462
August1st to 15thDay
17%17%35%22%6%
315
16th to endDay
15%12%35%26%9%1
332
September1st to 15thDay
15%27%30%16%7%1
310
16th to endDay
16%19%33%12%14%4
156
October1st to 15thDay
8%24%38%10%14%3
90
16th to endDay
31%22%27%14%22
96
November1st to 15thDay
8%32%20%13%22%3
90
16th to endDay
30%37%24%7%
90
December1st to 15thDay
33%32%27%6%
90
16th to endDay
21%37%30%10%
96
January1st to 15thNight
24%19%25%20%7%2
900
16th to endNight
19%23%27%21%6%
793
February1st to 15thNight
19%26%29%18%5%
704
16th to endNight
20%26%31%17%3
632
March1st to 15thNight
15%25%29%19%9%
720
16th to endNight
13%24%35%20%5%
702
April1st to 15thNight
15%23%34%20%6%
539
16th to endNight
15%23%29%21%7%1
540
May1st to 15thNight
16%12%31%25%11%2
540
16th to endNight
13%10%24%29%20%1
563
June1st to 15thNight
5%13%29%32%18%1
540
16th to endNight
47%23%39%22%1
540
July1st to 15thNight
6%311%39%34%4
510
16th to endNight
428%37%40%5%
564
August1st to 15thNight
6%211%43%33%2
539
16th to endNight
4312%35%37%6%
573
September1st to 15thNight
7%5%21%36%24%4
537
16th to endNight
8%7%24%27%24%6%
525
October1st to 15thNight
17%15%28%21%14%3
660
16th to endNight
15%17%30%21%10%3
714
November1st to 15thNight
17%23%27%20%9%1
875
16th to endNight
18%27%25%20%6%1
900
December1st to 15thNight
23%27%27%16%5%
900
16th to endNight
21%24%28%18%6%
960
Page generated at 2017-09-15 08:29:59. Version ac04

Copyright 2017 A. Danko


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