Prairie Siding
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prairie Siding clear sky chart from 2005-11-05 to 2017-09-21.

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
37%
15362
14%
46812
10%
15325
42%
15325
20%
32802

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
15%
872
10%
2482
3%
871
21%
871
11%
1998
January16th to endNight
18%
768
9%
2496
4%
768
25%
768
9%
1994
February1st to 15thNight
20%
701
9%
2287
3%
701
27%
701
11%
1763
February16th to endNight
25%
631
12%
1903
6%
631
32%
631
13%
1437
March1st to 15thNight
26%
720
13%
2042
8%
720
31%
720
16%
1518
March16th to endNight
33%
768
18%
2112
11%
768
39%
768
23%
1474
April1st to 15thNight
30%
641
14%
1830
7%
641
37%
641
21%
1298
April16th to endNight
38%
540
20%
1620
8%
540
46%
540
25%
1065
May1st to 15thNight
41%
540
13%
1620
8%
540
46%
540
20%
1154
May16th to endNight
49%
534
16%
1657
12%
534
55%
534
28%
1039
June1st to 15thNight
54%
360
16%
1347
17%
360
60%
360
26%
798
June16th to endNight
59%
360
19%
1260
20%
360
65%
360
29%
719
July1st to 15thNight
65%
503
16%
1353
15%
503
66%
503
38%
807
July16th to endNight
67%
564
17%
1581
14%
531
69%
531
38%
899
August1st to 15thNight
70%
539
19%
1609
16%
536
72%
536
36%
962
August16th to endNight
67%
573
24%
1719
19%
573
71%
573
37%
992
September1st to 15thNight
59%
702
22%
1929
16%
702
62%
702
34%
1188
September16th to endNight
58%
681
23%
1881
17%
681
61%
681
33%
1166
October1st to 15thNight
46%
660
18%
1928
15%
660
50%
660
27%
1266
October16th to endNight
27%
704
13%
2159
7%
704
34%
704
15%
1574
November1st to 15thNight
34%
700
19%
2276
16%
700
40%
700
20%
1522
November16th to endNight
23%
720
11%
2471
9%
720
28%
720
12%
1834
December1st to 15thNight
17%
720
6%
2520
4%
720
21%
720
8%
2038
December16th to endNight
14%
861
6%
2730
1%
861
19%
861
7%
2297

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
13%7%36%5%35%5%5%7%34%
48026
Night
15%9%36%5%3445%6%34%
46994
Cloud CoverDay
14%7%36%5%35%5%5%7%34%
48036
Night
15%9%36%5%3445%6%34%
46998
TransparencyDay
47%7%13%20%10%1
47726
Night
48%6%12%20%11%1
46812
SeeingDay
16%7%25%26%17%7%
5728
Night
19%8%27%29%13%1
15371

By Month

Percentage Cloud Cover NE (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
18%14%8%9%7%45%345%17%
1451
16th to endDay
16%15%7%10%8%5%5%46%5%16%
1728
February1st to 15thDay
16%14%5%8%7%36%45%5%22%
1575
16th to endDay
13%12%6%8%7%45%446%24%
1569
March1st to 15thDay
19%9%47%6%44445%28%
1906
16th to endDay
17%8%47%6%34447%29%
2112
April1st to 15thDay
18%8%35%4245%5%7%32%
2127
16th to endDay
17%5%3443445%7%37%
2340
May1st to 15thDay
15%7%36%6%35%45%7%35%
2331
16th to endDay
11%425%5%345%6%9%42%
2455
June1st to 15thDay
9%6%25%435%5%7%9%40%
2610
16th to endDay
9%425%5%35%6%6%11%39%
2700
July1st to 15thDay
7%424435%6%6%9%47%
2524
16th to endDay
7%424426%47%10%42%
2479
August1st to 15thDay
7%425%5%25%5%7%10%42%
2340
16th to endDay
9%4144345%7%9%44%
2483
September1st to 15thDay
11%5%34435%5%6%8%40%
2016
16th to endDay
13%5%24425%5%48%42%
1872
October1st to 15thDay
12%6%26%5%3446%7%38%
1702
16th to endDay
22%7%25%5%345%4433%
1711
November1st to 15thDay
15%8%36%4245%46%38%
1582
16th to endDay
18%11%5%10%7%3445%7%23%
1488
December1st to 15thDay
18%13%5%10%8%45%446%17%
1440
16th to endDay
20%14%7%9%7%35%445%15%
1485
January1st to 15thNight
21%14%5%8%7%34345%22%
2482
16th to endNight
15%15%7%10%8%35%43421%
2496
February1st to 15thNight
16%13%6%9%6%35%435%26%
2285
16th to endNight
17%11%5%7%6%36%445%27%
1903
March1st to 15thNight
17%10%47%6%3345%7%28%
2030
16th to endNight
15%7%36%5%24446%37%
2112
April1st to 15thNight
17%8%46%434446%35%
1830
16th to endNight
14%6%16%4245%6%7%39%
1620
May1st to 15thNight
16%5%37%6%35%5%6%6%32%
1620
16th to endNight
11%426%5%2435%7%44%
1655
June1st to 15thNight
9%5%235%26%46%7%44%
1347
16th to endNight
8%423436%5%5%10%44%
1260
July1st to 15thNight
8%424323448%53%
1433
16th to endNight
6%3234245%6%10%49%
1688
August1st to 15thNight
5%325%5%35%46%9%48%
1620
16th to endNight
9%3245%13447%52%
1719
September1st to 15thNight
10%5%333345%6%6%48%
1929
16th to endNight
11%6%24424447%47%
1881
October1st to 15thNight
15%6%25%434346%43%
1928
16th to endNight
21%8%26%6%35%446%30%
2159
November1st to 15thNight
14%9%36%5%345%46%37%
2276
16th to endNight
23%12%36%5%2446%6%23%
2471
December1st to 15thNight
21%12%6%10%7%24435%19%
2520
16th to endNight
23%15%6%9%6%35%5%4416%
2730

Percentage Cloud Cover SE (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
18%15%7%9%7%36%345%18%
1451
16th to endDay
16%14%8%9%7%35%5%5%5%17%
1728
February1st to 15thDay
17%14%5%8%7%35%445%22%
1575
16th to endDay
13%12%5%9%7%46%346%24%
1569
March1st to 15thDay
19%10%5%8%5%34445%27%
1917
16th to endDay
18%8%47%6%3445%7%29%
2111
April1st to 15thDay
18%9%35%5%245%5%7%32%
2127
16th to endDay
17%5%35%435%45%7%37%
2340
May1st to 15thDay
16%7%36%5%35%447%34%
2331
16th to endDay
11%435%5%35%5%5%8%42%
2455
June1st to 15thDay
10%5%25%445%5%6%8%41%
2610
16th to endDay
9%325%5%35%7%6%10%39%
2700
July1st to 15thDay
8%3134246%5%9%47%
2524
16th to endDay
7%424425%5%7%10%43%
2479
August1st to 15thDay
7%425%5%35%5%7%10%42%
2340
16th to endDay
9%323425%5%6%9%44%
2483
September1st to 15thDay
11%5%25%425%5%6%7%41%
2016
16th to endDay
13%5%34425%45%8%41%
1872
October1st to 15thDay
12%6%36%5%245%5%7%38%
1702
16th to endDay
22%7%346%345%45%32%
1711
November1st to 15thDay
15%8%36%5%245%46%38%
1582
16th to endDay
18%10%49%6%35%45%7%23%
1488
December1st to 15thDay
18%13%6%9%7%45%5%46%17%
1440
16th to endDay
21%15%7%9%7%35%445%15%
1485
January1st to 15thNight
21%14%48%7%34345%22%
2482
16th to endNight
15%15%8%9%8%4443421%
2496
February1st to 15thNight
15%14%6%9%5%35%435%26%
2278
16th to endNight
17%12%47%6%35%435%27%
1903
March1st to 15thNight
18%10%47%6%3345%6%29%
2042
16th to endNight
16%7%35%5%25%45%6%37%
2112
April1st to 15thNight
18%9%46%434446%35%
1830
16th to endNight
13%6%26%4345%5%7%40%
1620
May1st to 15thNight
17%5%36%6%35%5%5%6%33%
1619
16th to endNight
11%426%6%2435%8%43%
1655
June1st to 15thNight
9%5%235%36%46%7%45%
1347
16th to endNight
8%5%23435%5%5%10%45%
1260
July1st to 15thNight
7%424423348%53%
1433
16th to endNight
6%323425%5%6%11%49%
1688
August1st to 15thNight
5%315%435%47%8%49%
1620
16th to endNight
9%42442335%7%52%
1719
September1st to 15thNight
10%5%333245%6%6%48%
1929
16th to endNight
11%6%2442445%6%47%
1881
October1st to 15thNight
15%6%35%434346%43%
1928
16th to endNight
21%8%26%6%35%45%6%30%
2159
November1st to 15thNight
14%8%35%5%345%5%5%38%
2276
16th to endNight
23%12%36%5%2445%6%24%
2471
December1st to 15thNight
21%12%6%9%7%34445%20%
2520
16th to endNight
23%15%5%9%6%35%44416%
2730

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
68%5%10%10%4
1452
16th to endDay
67%6%11%9%4
1728
February1st to 15thDay
63%6%9%13%5%
1577
16th to endDay
59%6%11%16%41
1569
March1st to 15thDay
58%6%11%15%6%
1917
16th to endDay
54%6%11%19%7%1
2112
April1st to 15thDay
50%7%12%18%11%
2127
16th to endDay
45%6%13%18%13%2
2340
May1st to 15thDay
47%7%11%20%10%2
2331
16th to endDay
38%7%14%23%14%1
2459
June1st to 15thDay
38%8%14%25%12%1
2610
16th to endDay
37%9%16%21%14%1
2700
July1st to 15thDay
31%7%12%26%19%3
2375
16th to endDay
32%9%17%22%15%2
2323
August1st to 15thDay
34%8%17%26%12%
2327
16th to endDay
32%8%15%26%14%2
2483
September1st to 15thDay
38%6%15%26%11%
2016
16th to endDay
39%6%13%27%13%
1872
October1st to 15thDay
42%7%14%21%11%1
1702
16th to endDay
51%7%16%17%6%
1711
November1st to 15thDay
45%7%14%19%11%1
1582
16th to endDay
60%6%14%15%3
1488
December1st to 15thDay
65%8%12%9%3
1440
16th to endDay
69%7%10%9%3
1485
January1st to 15thNight
64%5%9%13%6%
2482
16th to endNight
64%6%11%13%3
2496
February1st to 15thNight
60%6%11%15%5%
2287
16th to endNight
57%6%11%17%6%
1903
March1st to 15thNight
55%5%11%18%8%1
2042
16th to endNight
46%5%12%23%10%1
2112
April1st to 15thNight
50%412%19%12%1
1830
16th to endNight
41%7%11%18%16%4
1620
May1st to 15thNight
48%7%10%17%12%2
1620
16th to endNight
37%7%12%24%16%2
1657
June1st to 15thNight
36%7%11%28%15%
1347
16th to endNight
32%7%15%23%19%1
1260
July1st to 15thNight
29%6%10%28%22%2
1353
16th to endNight
27%7%16%25%19%3
1581
August1st to 15thNight
29%8%13%31%14%2
1609
16th to endNight
30%5%13%29%18%2
1719
September1st to 15thNight
33%6%14%25%17%2
1929
16th to endNight
35%5%12%29%16%1
1881
October1st to 15thNight
41%6%13%18%19%1
1928
16th to endNight
52%6%13%19%6%
2159
November1st to 15thNight
46%6%11%21%12%1
2276
16th to endNight
57%6%12%17%4
2471
December1st to 15thNight
65%7%10%12%4
2520
16th to endNight
70%6%9%9%3
2730

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
21%21%33%16%6%1
90
16th to endDay
32%13%32%19%2
96
February1st to 15thDay
25%17%37%17%1
90
16th to endDay
19%13%46%17%2
81
March1st to 15thDay
29%14%27%21%5%
207
16th to endDay
24%6%32%27%7%2
288
April1st to 15thDay
22%10%30%24%9%2
270
16th to endDay
20%9%31%18%12%8%
270
May1st to 15thDay
22%431%20%18%3
288
16th to endDay
14%7%25%28%15%8%
331
June1st to 15thDay
11%327%37%17%3
405
16th to endDay
12%5%31%30%15%4
495
July1st to 15thDay
9%225%31%22%8%
475
16th to endDay
9%219%27%27%13%
339
August1st to 15thDay
9%116%30%26%16%
313
16th to endDay
10%314%27%27%17%
332
September1st to 15thDay
11%318%23%28%13%
315
16th to endDay
16%312%25%26%14%
275
October1st to 15thDay
13%8%20%30%20%6%
255
16th to endDay
25%9%33%23%7%
223
November1st to 15thDay
13%12%24%33%13%3
90
16th to endDay
22%25%29%20%2
68
December1st to 15thDay
23%26%28%18%3
60
16th to endDay
23%33%33%9%
72
January1st to 15thNight
27%14%33%18%4
876
16th to endNight
22%13%33%24%6%
768
February1st to 15thNight
24%12%33%24%4
704
16th to endNight
21%12%30%29%5%
631
March1st to 15thNight
21%11%33%25%7%
720
16th to endNight
19%7%33%26%11%
768
April1st to 15thNight
21%11%30%31%5%
641
16th to endNight
16%7%34%30%10%1
540
May1st to 15thNight
18%328%35%13%1
540
16th to endNight
13%324%35%20%2
536
June1st to 15thNight
11%225%45%14%
360
16th to endNight
10%221%47%17%
360
July1st to 15thNight
10%114%41%27%3
503
16th to endNight
7%215%43%28%3
564
August1st to 15thNight
7%12%42%30%7%
539
16th to endNight
10%113%33%36%4
573
September1st to 15thNight
13%316%31%28%6%
702
16th to endNight
13%317%31%27%7%
681
October1st to 15thNight
17%7%21%28%21%3
660
16th to endNight
23%12%30%26%5%
704
November1st to 15thNight
17%10%30%26%12%1
700
16th to endNight
30%13%26%19%9%
720
December1st to 15thNight
28%14%32%18%5%
720
16th to endNight
29%13%35%18%3
861
Page generated at 2017-09-22 07:35:36. Version ac04

Copyright 2017 A. Danko


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