Stony Plain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stony Plain clear sky chart from 2005-11-05 to 2017-12-01.

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%
15481
10%
47482
7%
15454
45%
15454
18%
34229

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
33%
895
7%
2685
4%
895
35%
895
13%
2098
January16th to endNight
31%
891
14%
2811
8%
891
38%
891
16%
2025
February1st to 15thNight
38%
699
8%
2451
7%
697
41%
697
14%
1767
February16th to endNight
46%
632
11%
2007
12%
632
49%
632
17%
1441
March1st to 15thNight
39%
720
14%
2124
10%
720
44%
720
18%
1544
March16th to endNight
40%
768
9%
2075
5%
767
42%
767
16%
1612
April1st to 15thNight
38%
608
10%
1688
6%
608
40%
608
16%
1284
April16th to endNight
40%
540
10%
1620
8%
540
43%
540
18%
1173
May1st to 15thNight
47%
362
7%
1299
6%
362
48%
362
17%
894
May16th to endNight
44%
374
0%
1309
0%
374
44%
374
15%
943
June1st to 15thNight
41%
360
0%
1230
0%
360
41%
360
12%
926
June16th to endNight
52%
360
0%
1080
0%
360
52%
360
18%
774
July1st to 15thNight
58%
340
0%
1114
0%
340
58%
340
22%
741
July16th to endNight
56%
376
3%
1239
1%
354
57%
354
20%
812
August1st to 15thNight
63%
360
6%
1400
7%
358
64%
358
21%
867
August16th to endNight
57%
571
12%
1717
11%
571
59%
571
26%
1106
September1st to 15thNight
59%
640
14%
1777
11%
640
60%
640
32%
1134
September16th to endNight
53%
716
19%
1980
12%
716
57%
716
33%
1250
October1st to 15thNight
43%
720
13%
2157
10%
720
47%
720
20%
1528
October16th to endNight
39%
768
15%
2496
11%
768
46%
768
19%
1734
November1st to 15thNight
33%
941
12%
2703
8%
941
37%
941
15%
2082
November16th to endNight
30%
975
10%
2925
5%
975
35%
975
14%
2251
December1st to 15thNight
32%
905
10%
2715
7%
905
34%
905
14%
2096
December16th to endNight
38%
960
12%
2880
7%
960
42%
960
17%
2147

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
11%9%47%6%35%5%6%8%31%
48985
Night
10%10%48%7%35%5%6%7%30%
47630
TransparencyDay
48%8%18%18%5%
48633
Night
50%7%15%18%6%
47487
SeeingDay
15%5%22%31%19%5%
6601
Night
15%425%35%17%2
15493

By Month

Percentage Cloud Cover NW (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
5%13%5%11%9%45%5%5%5%26%
1253
16th to endDay
7%13%5%9%7%445%5%7%28%
1425
February1st to 15thDay
10%11%48%7%36%5%6%8%25%
1411
16th to endDay
5%13%8%9%8%5%6%6%6%6%22%
1467
March1st to 15thDay
7%13%6%10%8%45%5%6%7%24%
1836
16th to endDay
12%11%5%8%6%36%6%7%8%21%
2144
April1st to 15thDay
12%10%46%6%35%6%6%7%29%
2260
16th to endDay
13%11%47%5%45%5%6%7%28%
2340
May1st to 15thDay
9%8%37%7%36%5%5%8%34%
2648
16th to endDay
19%6%26%5%25%5%6%7%31%
2802
June1st to 15thDay
17%8%37%6%46%5%5%7%25%
2728
16th to endDay
14%6%35%5%46%5%7%9%31%
2880
July1st to 15thDay
11%5%26%5%35%5%7%9%37%
2778
16th to endDay
10%4245%36%5%6%9%40%
2846
August1st to 15thDay
10%5%25%6%35%5%7%10%37%
2551
16th to endDay
8%5%25%5%45%5%7%9%40%
2486
September1st to 15thDay
13%6%26%424447%40%
2181
16th to endDay
11%5%15%5%3445%9%42%
1980
October1st to 15thDay
14%10%38%7%34336%34%
1803
16th to endDay
10%12%35%6%35%5%6%7%31%
1724
November1st to 15thDay
9%15%6%10%5%45%45%6%26%
1473
16th to endDay
6%11%6%11%7%44447%30%
1365
December1st to 15thDay
8%13%7%12%7%5%6%5%45%20%
1260
16th to endDay
7%11%5%11%10%5%7%5%47%23%
1344
January1st to 15thNight
8%12%6%9%9%47%45%6%23%
2685
16th to endNight
7%12%5%9%7%36%447%30%
2811
February1st to 15thNight
6%11%5%11%9%46%45%6%29%
2441
16th to endNight
8%12%5%6%7%45%5%5%8%29%
2007
March1st to 15thNight
8%9%49%8%37%5%7%7%28%
2124
16th to endNight
9%13%6%10%6%26%6%7%8%22%
2075
April1st to 15thNight
12%9%39%7%47%5%6%5%26%
1688
16th to endNight
14%10%47%5%445%5%7%29%
1620
May1st to 15thNight
10%7%47%6%5%6%5%7%6%32%
1298
16th to endNight
19%9%445%346%7%6%28%
1309
June1st to 15thNight
15%8%5%7%6%46%6%5%7%25%
1230
16th to endNight
12%5%37%6%45%7%8%10%27%
1080
July1st to 15thNight
11%426%5%26%5%7%9%38%
1182
16th to endNight
10%4247%36%6%7%10%35%
1323
August1st to 15thNight
9%416%5%25%6%6%9%40%
1407
16th to endNight
9%6%25%6%345%7%9%38%
1717
September1st to 15thNight
11%6%25%4235%5%7%45%
1777
16th to endNight
10%5%1443346%7%47%
1980
October1st to 15thNight
13%9%47%5%35%45%6%34%
2157
16th to endNight
9%9%37%6%35%5%6%8%33%
2496
November1st to 15thNight
12%13%5%10%6%4445%6%25%
2703
16th to endNight
8%12%6%11%8%46%446%27%
2925
December1st to 15thNight
9%15%6%10%7%3445%6%24%
2715
16th to endNight
5%13%7%10%8%36%45%8%26%
2880

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
58%8%13%13%5%
1253
16th to endDay
54%6%15%15%6%1
1425
February1st to 15thDay
54%8%16%14%5%
1411
16th to endDay
57%7%13%14%5%
1467
March1st to 15thDay
55%8%15%15%3
1836
16th to endDay
56%7%15%16%4
2145
April1st to 15thDay
51%7%16%17%5%
2260
16th to endDay
52%7%15%17%6%1
2340
May1st to 15thDay
46%8%13%21%9%
2648
16th to endDay
50%7%14%19%7%
2807
June1st to 15thDay
55%7%16%16%3
2728
16th to endDay
46%9%21%18%4
2880
July1st to 15thDay
41%9%21%23%3
2617
16th to endDay
37%11%28%20%1
2667
August1st to 15thDay
39%11%28%17%2
2533
16th to endDay
37%9%24%22%5%
2486
September1st to 15thDay
41%7%19%22%6%1
2181
16th to endDay
36%8%18%28%6%1
1980
October1st to 15thDay
50%6%15%20%6%
1803
16th to endDay
48%9%14%23%3
1724
November1st to 15thDay
56%6%14%16%4
1473
16th to endDay
52%8%16%15%5%
1365
December1st to 15thDay
64%7%10%15%2
1260
16th to endDay
58%6%12%16%6%
1344
January1st to 15thNight
59%7%15%12%31
2685
16th to endNight
51%7%14%17%7%1
2811
February1st to 15thNight
54%6%15%15%6%
2453
16th to endNight
51%7%14%16%8%
2007
March1st to 15thNight
50%8%14%19%6%
2124
16th to endNight
55%9%13%15%5%
2078
April1st to 15thNight
55%7%13%16%6%1
1688
16th to endNight
52%6%12%17%10%
1620
May1st to 15thNight
50%6%11%17%13%
1299
16th to endNight
53%7%14%14%8%2
1309
June1st to 15thNight
55%9%13%16%4
1230
16th to endNight
47%10%20%18%2
1080
July1st to 15thNight
39%12%22%21%5%
1114
16th to endNight
40%12%24%20%2
1239
August1st to 15thNight
37%11%28%20%2
1400
16th to endNight
38%8%21%23%6%
1717
September1st to 15thNight
36%6%19%25%9%1
1777
16th to endNight
33%8%16%27%11%2
1980
October1st to 15thNight
48%7%13%22%7%
2157
16th to endNight
45%9%17%22%5%
2496
November1st to 15thNight
57%6%10%18%5%
2703
16th to endNight
57%7%14%13%5%1
2925
December1st to 15thNight
58%6%14%14%4
2715
16th to endNight
55%5%16%16%5%
2880

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
6%5%25%33%25%5%
60
16th to endDay
6%315%43%23%7%
64
February1st to 15thDay
17%6%29%32%12%1
62
16th to endDay
15%422%30%21%5%
126
March1st to 15thDay
15%5%28%37%11%1
270
16th to endDay
18%329%31%17%1
288
April1st to 15thDay
17%8%26%36%9%1
269
16th to endDay
21%7%24%27%15%4
270
May1st to 15thDay
12%7%21%34%18%4
431
16th to endDay
19%5%18%30%18%7%
517
June1st to 15thDay
20%424%28%17%4
523
16th to endDay
16%5%20%29%22%6%
675
July1st to 15thDay
12%217%33%27%7%
551
16th to endDay
12%320%33%25%6%
515
August1st to 15thDay
12%211%32%26%15%
346
16th to endDay
11%324%33%22%4
332
September1st to 15thDay
20%5%23%25%19%5%
315
16th to endDay
13%11%23%26%18%6%
315
October1st to 15thDay
25%422%28%13%5%
192
16th to endDay
18%6%30%27%15%1
144
November1st to 15thDay
15%131%36%12%3
122
16th to endDay
15%430%33%8%7%
90
December1st to 15thDay
15%135%21%23%3
60
16th to endDay
7%7%14%39%21%9%
64
January1st to 15thNight
15%6%27%34%13%2
900
16th to endNight
13%8%31%31%12%1
891
February1st to 15thNight
11%7%22%39%17%1
704
16th to endNight
13%322%35%20%3
632
March1st to 15thNight
12%230%37%15%2
720
16th to endNight
15%424%37%15%3
768
April1st to 15thNight
15%5%29%31%16%1
608
16th to endNight
19%5%24%35%13%1
540
May1st to 15thNight
13%5%23%37%18%1
363
16th to endNight
21%5%18%36%16%2
375
June1st to 15thNight
16%8%22%34%14%3
360
16th to endNight
16%318%31%28%1
360
July1st to 15thNight
14%116%40%25%1
340
16th to endNight
12%219%38%25%1
376
August1st to 15thNight
11%212%32%34%6%
360
16th to endNight
13%117%40%25%
571
September1st to 15thNight
16%115%41%24%2
640
16th to endNight
14%324%37%18%2
716
October1st to 15thNight
18%325%34%16%2
720
16th to endNight
15%5%29%35%13%1
768
November1st to 15thNight
18%5%29%32%12%1
941
16th to endNight
13%6%33%32%11%2
975
December1st to 15thNight
17%7%26%29%15%2
905
16th to endNight
12%426%34%17%4
960
Page generated at 2017-12-02 07:14:18. Version ac04

Copyright 2017 A. Danko


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