Strathcona Wilderness Centre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Strathcona Wilderness Centre clear sky chart from 2005-11-05 to 2017-09-17.

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%
15197
10%
46707
7%
15170
45%
15170
18%
33400

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
6%
2685
4%
895
35%
895
13%
2092
January16th to endNight
29%
915
14%
2835
7%
915
37%
915
17%
2047
February1st to 15thNight
41%
699
8%
2423
6%
697
45%
697
15%
1753
February16th to endNight
44%
632
11%
2031
11%
632
47%
632
18%
1446
March1st to 15thNight
38%
720
13%
2103
9%
720
43%
720
19%
1544
March16th to endNight
39%
768
10%
2102
6%
767
41%
767
16%
1637
April1st to 15thNight
42%
589
12%
1669
7%
589
45%
589
19%
1218
April16th to endNight
43%
540
11%
1620
10%
540
45%
540
19%
1145
May1st to 15thNight
48%
389
8%
1302
8%
389
50%
389
18%
891
May16th to endNight
41%
374
0%
1309
0%
374
41%
374
15%
946
June1st to 15thNight
41%
360
0%
1260
0%
360
41%
360
13%
927
June16th to endNight
51%
360
0%
1202
0%
360
51%
360
18%
830
July1st to 15thNight
59%
340
0%
1190
0%
340
59%
340
21%
761
July16th to endNight
59%
376
3%
1239
2%
354
60%
354
24%
763
August1st to 15thNight
64%
378
6%
1388
8%
376
65%
376
24%
834
August16th to endNight
56%
573
13%
1719
11%
573
58%
573
26%
1120
September1st to 15thNight
59%
612
15%
1768
11%
612
60%
612
31%
1095
September16th to endNight
52%
664
19%
1837
13%
664
57%
664
36%
1122
October1st to 15thNight
44%
660
15%
1969
10%
660
48%
660
22%
1362
October16th to endNight
39%
718
14%
2302
11%
718
45%
718
19%
1603
November1st to 15thNight
31%
875
14%
2474
9%
875
35%
875
17%
1861
November16th to endNight
31%
900
10%
2700
5%
900
35%
900
13%
2096
December1st to 15thNight
30%
900
8%
2700
4%
900
34%
900
12%
2151
December16th to endNight
37%
960
11%
2880
5%
960
42%
960
16%
2156

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
10%8%47%6%45%5%6%8%31%
48056
Night
9%9%48%7%45%5%6%7%31%
46863
TransparencyDay
48%8%17%18%5%
47706
Night
49%8%15%19%6%
46717
SeeingDay
14%5%23%31%19%6%
6133
Night
13%5%26%34%17%2
15209

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
412%6%10%8%5%8%5%6%7%22%
1253
16th to endDay
5%12%6%10%9%5%6%5%46%28%
1398
February1st to 15thDay
8%10%7%8%9%35%6%5%7%26%
1432
16th to endDay
5%12%7%12%8%37%6%5%6%23%
1441
March1st to 15thDay
6%12%6%9%8%47%5%6%9%23%
1856
16th to endDay
10%12%6%10%6%35%5%6%7%24%
2117
April1st to 15thDay
12%10%46%6%35%5%6%7%30%
2279
16th to endDay
14%11%45%6%45%47%7%29%
2340
May1st to 15thDay
9%8%37%7%35%6%5%7%34%
2647
16th to endDay
17%8%35%6%45%5%5%7%30%
2802
June1st to 15thDay
15%9%48%8%45%6%5%7%24%
2700
16th to endDay
14%6%37%7%35%5%7%9%29%
2719
July1st to 15thDay
11%426%6%35%5%6%9%37%
2700
16th to endDay
9%5%25%5%45%5%6%9%40%
2846
August1st to 15thDay
11%5%25%5%36%6%7%11%36%
2561
16th to endDay
8%425%5%45%5%6%9%41%
2483
September1st to 15thDay
12%6%25%4345%5%7%40%
2188
16th to endDay
10%5%245%3445%9%44%
1828
October1st to 15thDay
13%9%47%6%3445%6%33%
1659
16th to endDay
9%11%45%5%45%5%7%8%32%
1559
November1st to 15thDay
8%11%6%8%6%5%5%5%5%8%28%
1384
16th to endDay
6%11%6%12%8%25%45%6%30%
1260
December1st to 15thDay
5%13%8%10%11%5%8%6%5%7%17%
1260
16th to endDay
5%11%5%11%9%46%6%6%7%23%
1344
January1st to 15thNight
6%11%6%11%9%5%7%6%5%7%23%
2685
16th to endNight
6%10%6%9%7%45%46%7%31%
2835
February1st to 15thNight
5%8%5%11%9%47%5%48%28%
2421
16th to endNight
6%12%5%8%5%45%6%6%7%30%
2031
March1st to 15thNight
8%9%5%8%7%45%6%7%7%28%
2103
16th to endNight
10%11%6%10%8%45%5%7%9%21%
2100
April1st to 15thNight
10%9%47%7%5%5%5%6%6%30%
1669
16th to endNight
13%10%36%5%345%6%6%32%
1620
May1st to 15thNight
11%7%36%7%46%6%6%5%32%
1301
16th to endNight
20%7%37%5%35%5%5%5%29%
1309
June1st to 15thNight
15%8%47%8%45%6%5%6%26%
1260
16th to endNight
12%6%37%6%37%5%6%10%29%
1202
July1st to 15thNight
10%4246%36%6%7%10%37%
1260
16th to endNight
9%425%5%45%5%6%9%40%
1323
August1st to 15thNight
9%425%4345%7%9%42%
1395
16th to endNight
9%5%25%6%445%6%9%40%
1719
September1st to 15thNight
11%425%424347%47%
1768
16th to endNight
9%31442346%8%50%
1837
October1st to 15thNight
11%9%37%5%25%46%6%35%
1969
16th to endNight
9%8%37%7%35%6%6%7%32%
2302
November1st to 15thNight
11%13%5%8%6%35%5%5%6%28%
2474
16th to endNight
6%11%7%10%8%46%5%5%6%26%
2700
December1st to 15thNight
8%13%7%12%9%5%5%5%5%7%20%
2700
16th to endNight
410%5%10%8%5%7%7%6%9%25%
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
57%9%14%13%4
1253
16th to endDay
54%7%13%15%7%1
1398
February1st to 15thDay
55%6%18%14%5%
1432
16th to endDay
58%7%11%17%5%
1441
March1st to 15thDay
56%7%17%14%3
1856
16th to endDay
56%9%13%15%4
2118
April1st to 15thDay
50%7%16%17%6%
2279
16th to endDay
51%7%16%16%7%1
2340
May1st to 15thDay
46%7%13%22%9%
2647
16th to endDay
51%7%12%17%9%
2807
June1st to 15thDay
55%8%14%17%4
2700
16th to endDay
47%10%20%16%4
2719
July1st to 15thDay
41%10%22%23%3
2541
16th to endDay
38%11%28%20%1
2667
August1st to 15thDay
39%12%29%16%2
2543
16th to endDay
35%10%24%23%5%
2483
September1st to 15thDay
39%8%20%23%6%1
2188
16th to endDay
35%8%18%29%6%1
1828
October1st to 15thDay
49%7%15%21%5%
1659
16th to endDay
45%10%15%24%4
1559
November1st to 15thDay
51%7%17%18%4
1384
16th to endDay
54%7%17%15%4
1260
December1st to 15thDay
63%9%10%13%2
1260
16th to endDay
56%8%12%14%6%
1344
January1st to 15thNight
57%9%16%12%31
2685
16th to endNight
50%7%15%18%6%1
2835
February1st to 15thNight
53%7%16%16%6%
2432
16th to endNight
50%7%14%18%8%1
2031
March1st to 15thNight
50%8%15%18%6%
2103
16th to endNight
57%6%12%17%5%
2103
April1st to 15thNight
50%7%15%17%7%1
1669
16th to endNight
49%7%12%18%10%2
1620
May1st to 15thNight
47%8%9%20%12%1
1302
16th to endNight
54%6%10%18%8%1
1309
June1st to 15thNight
54%8%14%17%5%
1260
16th to endNight
47%8%21%17%4
1202
July1st to 15thNight
39%10%21%22%5%
1190
16th to endNight
37%9%24%25%3
1239
August1st to 15thNight
35%9%28%23%2
1388
16th to endNight
38%9%18%26%6%
1719
September1st to 15thNight
35%6%18%27%9%2
1768
16th to endNight
30%7%18%29%10%2
1837
October1st to 15thNight
45%7%15%24%7%
1969
16th to endNight
46%9%16%23%4
2302
November1st to 15thNight
53%8%11%20%5%1
2474
16th to endNight
57%8%13%13%5%
2700
December1st to 15thNight
61%7%13%12%4
2700
16th to endNight
53%8%16%15%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
11%326%40%13%5%
60
16th to endDay
4125%43%18%6%
64
February1st to 15thDay
13%327%36%15%4
66
16th to endDay
13%422%30%22%9%
100
March1st to 15thDay
11%437%34%9%2
270
16th to endDay
15%428%31%18%2
288
April1st to 15thDay
17%8%24%31%15%2
269
16th to endDay
24%8%18%30%13%5%
270
May1st to 15thDay
11%7%22%33%18%6%
456
16th to endDay
19%5%17%31%19%6%
517
June1st to 15thDay
17%5%24%30%15%6%
495
16th to endDay
15%5%21%29%20%7%
514
July1st to 15thDay
10%215%33%29%8%
475
16th to endDay
10%420%31%25%6%
515
August1st to 15thDay
13%115%27%26%14%
375
16th to endDay
9%5%27%26%26%3
332
September1st to 15thDay
16%425%29%18%5%
315
16th to endDay
13%12%27%29%12%4
260
October1st to 15thDay
26%5%25%26%10%5%
126
16th to endDay
18%325%32%15%5%
96
November1st to 15thDay
20%126%41%8%1
86
16th to endDay
10%8%28%28%13%11%
60
December1st to 15thDay
5%41%26%23%3
60
16th to endDay
6%128%29%25%9%
64
January1st to 15thNight
10%7%31%34%12%2
900
16th to endNight
11%8%35%31%11%1
915
February1st to 15thNight
9%6%25%37%19%2
704
16th to endNight
9%327%35%20%3
632
March1st to 15thNight
9%430%38%13%3
720
16th to endNight
13%426%34%17%2
768
April1st to 15thNight
12%6%28%31%18%2
589
16th to endNight
20%422%35%15%2
540
May1st to 15thNight
14%5%20%37%19%2
390
16th to endNight
22%5%19%27%22%2
375
June1st to 15thNight
20%420%34%16%3
360
16th to endNight
14%221%30%27%2
360
July1st to 15thNight
12%115%42%25%1
340
16th to endNight
11%317%41%23%3
376
August1st to 15thNight
11%215%32%32%6%
378
16th to endNight
11%219%39%26%1
573
September1st to 15thNight
13%218%37%27%1
612
16th to endNight
10%427%39%15%2
664
October1st to 15thNight
17%424%36%16%1
660
16th to endNight
15%430%36%12%
718
November1st to 15thNight
16%7%33%30%9%2
875
16th to endNight
12%7%32%33%11%3
900
December1st to 15thNight
14%8%31%29%14%2
900
16th to endNight
10%429%34%17%4
960
Page generated at 2017-09-18 06:38:20. Version ac04

Copyright 2017 A. Danko


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