Poudre Canyon Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Poudre Canyon Observatory clear sky chart from 2005-11-05 to 2018-10-27.

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
44%
17469
28%
51264
14%
17425
57%
17425
39%
27353

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
28%
974
30%
2716
9%
970
46%
970
38%
1379
January16th to endNight
25%
896
34%
2768
12%
896
49%
896
35%
1383
February1st to 15thNight
21%
760
26%
2460
6%
758
44%
758
30%
1278
February16th to endNight
23%
684
32%
2050
8%
684
48%
684
34%
1125
March1st to 15thNight
32%
780
29%
2288
10%
780
48%
780
40%
1187
March16th to endNight
35%
739
26%
2195
11%
739
49%
739
35%
1220
April1st to 15thNight
34%
584
23%
1948
10%
584
53%
584
32%
1067
April16th to endNight
36%
579
22%
1929
14%
579
50%
579
28%
1121
May1st to 15thNight
44%
585
20%
1690
14%
585
51%
585
30%
1057
May16th to endNight
55%
611
18%
1626
11%
609
60%
609
38%
969
June1st to 15thNight
62%
585
21%
1560
16%
585
66%
585
46%
862
June16th to endNight
73%
585
27%
1560
21%
585
76%
585
57%
784
July1st to 15thNight
76%
555
21%
1480
17%
555
78%
555
46%
829
July16th to endNight
80%
612
26%
1554
23%
579
81%
579
48%
840
August1st to 15thNight
77%
575
23%
1754
23%
572
78%
572
44%
906
August16th to endNight
76%
621
30%
2070
33%
621
79%
621
43%
1029
September1st to 15thNight
70%
585
30%
1950
29%
585
76%
585
42%
983
September16th to endNight
67%
584
35%
2088
32%
584
76%
584
47%
943
October1st to 15thNight
47%
780
27%
2340
16%
780
56%
780
36%
1317
October16th to endNight
45%
855
35%
2487
16%
855
58%
855
43%
1278
November1st to 15thNight
41%
950
30%
2470
12%
950
51%
950
49%
1309
November16th to endNight
33%
975
35%
2639
12%
975
52%
975
47%
1344
December1st to 15thNight
23%
975
25%
2730
5%
975
41%
975
35%
1503
December16th to endNight
26%
1040
27%
2912
8%
1040
44%
1040
35%
1640

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%4244245%6%8%51%
52306
Night
5%41332335%7%58%
51437
TransparencyDay
29%413%26%19%6%
51981
Night
24%412%28%22%7%
51264
SeeingDay
11%9%32%27%13%3
7371
Night
8%10%31%32%14%2
17474

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
1415%423448%58%
1552
16th to endDay
423423348%61%
1820
February1st to 15thDay
5%25%32346%8%56%
1730
16th to endDay
17%25%423348%57%
1710
March1st to 15thDay
3425%32346%7%56%
2001
16th to endDay
5%7%243245%6%9%48%
2380
April1st to 15thDay
7%6%2442435%9%49%
2330
16th to endDay
12%7%24425%5%7%8%39%
2306
May1st to 15thDay
14%7%245%345%6%7%38%
2587
16th to endDay
11%5%245%35%6%7%9%38%
2840
June1st to 15thDay
6%313435%6%8%10%48%
2730
16th to endDay
3113425%5%7%9%55%
2730
July1st to 15thDay
7%314435%6%6%8%46%
2730
16th to endDay
32145%46%7%8%10%45%
2868
August1st to 15thDay
5%4146%46%7%9%10%40%
2447
16th to endDay
43145%36%6%6%6%50%
2484
September1st to 15thDay
8%3133245%6%7%53%
2340
16th to endDay
6%413323446%60%
2200
October1st to 15thDay
8%6%13323447%54%
1950
16th to endDay
431322235%7%62%
1980
November1st to 15thDay
2413314448%59%
1718
16th to endDay
141341247%7%61%
1649
December1st to 15thDay
15%2442345%8%56%
1560
16th to endDay
26%34424347%56%
1664
January1st to 15thNight
1314323347%63%
2716
16th to endNight
2423313346%64%
2768
February1st to 15thNight
16%24424347%58%
2450
16th to endNight
17%34423335%58%
2050
March1st to 15thNight
2423413447%60%
2288
16th to endNight
6%5%2322446%7%54%
2195
April1st to 15thNight
5%6%14423448%53%
1948
16th to endNight
14%6%13313446%49%
1929
May1st to 15thNight
15%424224348%45%
1689
16th to endNight
10%41332346%8%50%
1625
June1st to 15thNight
6%2232445%8%57%
1560
16th to endNight
42121335%7%67%
1560
July1st to 15thNight
6%2123235%7%10%53%
1560
16th to endNight
2213335%5%6%8%57%
1650
August1st to 15thNight
431242347%9%55%
1763
16th to endNight
431342445%8%57%
2070
September1st to 15thNight
8%313313446%59%
1950
16th to endNight
5%212313345%66%
2088
October1st to 15thNight
9%5%13322346%57%
2340
16th to endNight
45%12222336%63%
2487
November1st to 15thNight
2413312347%64%
2470
16th to endNight
232222335%7%64%
2639
December1st to 15thNight
25%25%422348%58%
2730
16th to endNight
36%24424348%55%
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
24%216%35%16%3
1553
16th to endDay
22%312%35%20%5%
1820
February1st to 15thDay
25%419%35%12%3
1731
16th to endDay
26%210%34%22%3
1710
March1st to 15thDay
25%313%30%22%4
2001
16th to endDay
31%415%29%15%3
2380
April1st to 15thDay
31%413%27%15%7%
2330
16th to endDay
39%5%12%24%14%3
2306
May1st to 15thDay
42%5%12%24%13%1
2587
16th to endDay
39%7%16%21%13%2
2844
June1st to 15thDay
27%6%17%21%18%8%
2730
16th to endDay
22%5%10%26%22%12%
2730
July1st to 15thDay
32%6%12%18%18%11%
2581
16th to endDay
29%6%14%26%16%7%
2701
August1st to 15thDay
33%7%14%18%14%10%
2432
16th to endDay
29%5%10%23%22%7%
2484
September1st to 15thDay
27%410%21%22%12%
2340
16th to endDay
24%37%25%32%6%
2200
October1st to 15thDay
29%411%22%25%6%
1950
16th to endDay
20%411%28%26%8%
1980
November1st to 15thDay
22%413%28%23%8%
1718
16th to endDay
20%210%33%28%5%
1649
December1st to 15thDay
24%415%36%16%2
1560
16th to endDay
27%414%29%19%3
1664
January1st to 15thNight
20%315%31%23%4
2716
16th to endNight
21%310%32%25%5%
2768
February1st to 15thNight
26%415%34%15%3
2460
16th to endNight
28%28%29%24%6%
2050
March1st to 15thNight
22%411%29%26%5%
2288
16th to endNight
27%5%12%31%19%3
2195
April1st to 15thNight
29%5%12%30%16%5%
1948
16th to endNight
35%410%28%18%2
1929
May1st to 15thNight
36%6%15%24%15%2
1690
16th to endNight
29%6%20%25%15%3
1626
June1st to 15thNight
23%5%18%23%17%11%
1560
16th to endNight
16%5%8%28%26%15%
1560
July1st to 15thNight
25%5%14%26%18%10%
1480
16th to endNight
22%5%15%30%16%10%
1554
August1st to 15thNight
22%6%17%24%18%10%
1754
16th to endNight
23%410%27%24%9%
2070
September1st to 15thNight
24%412%22%19%16%
1950
16th to endNight
21%27%31%29%8%
2088
October1st to 15thNight
28%5%11%20%25%8%
2340
16th to endNight
23%28%28%29%7%
2487
November1st to 15thNight
19%312%27%26%10%
2470
16th to endNight
19%310%32%26%7%
2639
December1st to 15thNight
25%415%30%18%5%
2730
16th to endNight
27%416%29%19%2
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
11%6%38%29%6%6%
135
16th to endDay
8%21%38%22%7%1
144
February1st to 15thDay
11%31%33%22%1
135
16th to endDay
6%17%47%24%4
120
March1st to 15thDay
14%14%41%24%4
186
16th to endDay
15%21%42%17%2
352
April1st to 15thDay
17%24%38%15%21
329
16th to endDay
26%18%33%15%41
318
May1st to 15thDay
21%8%32%24%9%3
507
16th to endDay
16%8%25%27%18%3
597
June1st to 15thDay
8%8%28%32%18%4
570
16th to endDay
6%435%28%20%5%
570
July1st to 15thDay
10%319%31%25%8%
550
16th to endDay
5%220%37%26%8%
583
August1st to 15thDay
9%434%36%14%1
359
16th to endDay
7%6%29%37%14%3
396
September1st to 15thDay
10%5%36%30%14%2
375
16th to endDay
11%5%34%31%14%2
238
October1st to 15thDay
17%7%33%26%10%4
180
16th to endDay
8%11%39%26%8%4
178
November1st to 15thDay
5%439%27%12%10%
135
16th to endDay
16%15%45%21%
135
December1st to 15thDay
11%21%46%18%1
135
16th to endDay
211%61%20%4
144
January1st to 15thNight
8%18%41%21%8%2
975
16th to endNight
9%20%41%22%6%
896
February1st to 15thNight
6%18%46%23%4
764
16th to endNight
8%15%46%26%3
684
March1st to 15thNight
5%14%43%28%7%1
780
16th to endNight
8%13%38%31%6%
739
April1st to 15thNight
12%9%39%30%6%
584
16th to endNight
19%10%29%29%10%1
579
May1st to 15thNight
19%5%24%31%15%2
585
16th to endNight
11%421%34%25%2
611
June1st to 15thNight
6%321%46%19%2
585
16th to endNight
5%214%50%24%2
585
July1st to 15thNight
8%17%40%38%4
555
16th to endNight
46%41%42%4
612
August1st to 15thNight
428%45%35%3
575
16th to endNight
5%17%44%34%6%
621
September1st to 15thNight
10%112%39%27%7%
585
16th to endNight
7%218%41%25%3
584
October1st to 15thNight
12%8%27%33%14%3
780
16th to endNight
9%9%31%34%12%2
855
November1st to 15thNight
8%9%37%32%9%2
950
16th to endNight
6%13%41%30%5%1
975
December1st to 15thNight
6%17%46%22%4
975
16th to endNight
8%13%45%25%6%
1040
Page generated at 2018-10-28 06:41:02. Version ac04

Copyright 2018 A. Danko


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