Revelstoke
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Revelstoke clear sky chart from 2005-11-05 to 2017-09-19.

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
28%
14936
5%
46564
4%
14903
30%
14903
10%
38166

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
14%
822
2%
2639
1%
817
15%
817
3%
2475
January16th to endNight
11%
768
2%
2688
2%
768
12%
768
2%
2554
February1st to 15thNight
15%
700
3%
2440
2%
696
17%
696
4%
2215
February16th to endNight
19%
632
5%
1945
3%
632
22%
632
6%
1699
March1st to 15thNight
16%
720
2%
2160
1%
720
17%
720
5%
1953
March16th to endNight
21%
768
4%
2014
1%
768
22%
768
8%
1750
April1st to 15thNight
34%
719
5%
1799
2%
719
35%
719
12%
1511
April16th to endNight
36%
478
6%
1558
4%
478
38%
478
13%
1193
May1st to 15thNight
43%
359
9%
1440
10%
359
47%
359
17%
945
May16th to endNight
46%
374
5%
1361
3%
374
48%
374
16%
938
June1st to 15thNight
40%
360
0%
1183
0%
360
40%
360
16%
869
June16th to endNight
43%
360
0%
1080
0%
360
43%
360
16%
805
July1st to 15thNight
60%
340
2%
1071
0%
340
61%
340
29%
655
July16th to endNight
66%
376
9%
1416
12%
354
68%
354
30%
743
August1st to 15thNight
71%
360
13%
1432
18%
358
74%
358
31%
740
August16th to endNight
62%
585
19%
1731
17%
585
64%
585
34%
1021
September1st to 15thNight
55%
720
16%
1800
10%
720
57%
720
32%
1212
September16th to endNight
43%
671
14%
1837
10%
671
44%
671
22%
1304
October1st to 15thNight
34%
660
8%
1970
7%
660
36%
660
13%
1522
October16th to endNight
20%
704
3%
2288
3%
704
22%
704
6%
1976
November1st to 15thNight
11%
700
3%
2374
2%
700
11%
700
3%
2192
November16th to endNight
11%
889
2%
2689
0%
889
12%
889
3%
2525
December1st to 15thNight
12%
900
3%
2700
2%
900
13%
900
4%
2509
December16th to endNight
7%
971
1%
2949
0%
971
8%
971
2%
2860

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
16%14%5%9%7%45%445%21%
48270
Night
16%16%6%11%7%34445%19%
46714
TransparencyDay
64%6%11%12%4
47925
Night
67%6%10%11%4
46564
SeeingDay
20%11%27%26%10%3
6269
Night
24%6%27%27%13%
14942

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
22%25%7%12%6%332338%
1305
16th to endDay
13%22%10%16%10%5%23247%
1536
February1st to 15thDay
15%24%7%11%8%43335%12%
1424
16th to endDay
9%17%9%12%10%46%445%14%
1529
March1st to 15thDay
15%24%8%12%9%433349%
1800
16th to endDay
13%22%9%12%9%45%4449%
2209
April1st to 15thDay
14%19%6%11%8%5%5%45%5%12%
2149
16th to endDay
15%17%6%10%8%46%45%6%15%
2400
May1st to 15thDay
16%13%5%7%5%45%35%6%26%
2511
16th to endDay
17%13%48%7%35%45%6%21%
2748
June1st to 15thDay
24%10%5%8%9%45%445%18%
2774
16th to endDay
20%9%49%8%45%45%5%21%
2880
July1st to 15thDay
12%7%25%5%46%5%6%8%37%
2822
16th to endDay
9%6%25%6%45%5%6%7%41%
2657
August1st to 15thDay
9%5%25%5%45%5%7%8%39%
2520
16th to endDay
12%6%26%6%4446%7%38%
2467
September1st to 15thDay
13%8%38%6%24445%37%
2160
16th to endDay
23%10%37%7%3445%5%24%
1868
October1st to 15thDay
20%13%48%6%45%445%21%
1659
16th to endDay
25%19%6%9%6%2433413%
1584
November1st to 15thDay
27%21%7%11%8%343227%
1479
16th to endDay
16%22%9%14%7%36%3239%
1260
December1st to 15thDay
16%22%10%13%8%4442210%
1260
16th to endDay
14%26%10%16%9%35%3234
1269
January1st to 15thNight
23%26%8%11%6%35%3224
2639
16th to endNight
15%23%10%20%9%442223
2688
February1st to 15thNight
16%24%8%16%9%343237%
2428
16th to endNight
10%17%7%16%11%5%5%45%5%10%
1945
March1st to 15thNight
15%23%8%13%9%35%4339%
2160
16th to endNight
13%19%6%12%8%446%45%14%
2010
April1st to 15thNight
11%14%5%10%8%47%5%5%6%17%
1799
16th to endNight
12%13%5%7%6%45%5%6%7%25%
1558
May1st to 15thNight
13%9%36%4345%6%7%34%
1439
16th to endNight
13%7%37%6%46%6%6%8%29%
1361
June1st to 15thNight
22%7%36%6%24448%27%
1183
16th to endNight
18%6%46%6%36%46%7%27%
1080
July1st to 15thNight
8%4145%35%5%5%8%45%
1134
16th to endNight
9%31432446%8%51%
1512
August1st to 15thNight
6%313435%5%5%8%52%
1440
16th to endNight
7%424435%5%5%8%48%
1731
September1st to 15thNight
11%7%25%5%245%45%46%
1800
16th to endNight
18%8%25%5%25%44435%
1837
October1st to 15thNight
16%12%48%7%35%5%5%5%23%
1970
16th to endNight
23%17%6%11%7%2443412%
2288
November1st to 15thNight
28%24%7%11%5%233226%
2374
16th to endNight
18%23%10%15%8%444226%
2689
December1st to 15thNight
16%23%9%15%10%5%32335%
2700
16th to endNight
15%28%10%16%11%342222
2949

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
81%46%42
1305
16th to endDay
81%45%421
1536
February1st to 15thDay
76%5%8%7%2
1424
16th to endDay
72%6%11%6%3
1529
March1st to 15thDay
80%39%5%
1800
16th to endDay
77%6%10%3
2209
April1st to 15thDay
73%6%11%7%
2149
16th to endDay
69%7%13%7%1
2400
May1st to 15thDay
59%6%13%14%5%
2511
16th to endDay
62%8%13%13%2
2752
June1st to 15thDay
69%5%10%11%2
2774
16th to endDay
63%6%9%14%5%
2880
July1st to 15thDay
45%6%15%18%11%1
2657
16th to endDay
41%7%16%21%12%1
2490
August1st to 15thDay
40%6%18%23%9%1
2503
16th to endDay
43%6%15%23%9%
2467
September1st to 15thDay
47%5%13%23%9%
2160
16th to endDay
59%6%12%13%6%
1868
October1st to 15thDay
63%7%13%13%2
1659
16th to endDay
74%7%10%6%
1584
November1st to 15thDay
84%46%22
1479
16th to endDay
78%7%45%3
1260
December1st to 15thDay
81%446%2
1260
16th to endDay
86%5%421
1269
January1st to 15thNight
84%5%431
2639
16th to endNight
88%4311
2688
February1st to 15thNight
82%45%5%2
2440
16th to endNight
75%6%8%6%3
1945
March1st to 15thNight
80%5%6%5%1
2160
16th to endNight
71%7%11%7%1
2014
April1st to 15thNight
64%8%13%10%2
1799
16th to endNight
57%7%20%11%2
1558
May1st to 15thNight
47%6%20%19%6%
1440
16th to endNight
49%8%19%20%2
1361
June1st to 15thNight
54%6%15%19%3
1183
16th to endNight
53%8%15%16%41
1080
July1st to 15thNight
35%7%18%22%13%1
1071
16th to endNight
30%6%19%27%15%
1416
August1st to 15thNight
28%7%22%27%12%1
1432
16th to endNight
32%6%19%30%11%
1731
September1st to 15thNight
39%6%13%26%13%1
1800
16th to endNight
50%417%18%8%
1837
October1st to 15thNight
58%7%13%15%4
1970
16th to endNight
72%7%10%7%
2288
November1st to 15thNight
84%5%5%32
2374
16th to endNight
83%6%432
2689
December1st to 15thNight
85%326%1
2700
16th to endNight
91%3211
2949

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
8%20%41%20%10%
60
16th to endDay
15%9%31%32%46%
64
February1st to 15thDay
13%17%29%27%9%2
84
16th to endDay
17%12%32%24%10%1
229
March1st to 15thDay
29%26%30%11%2
270
16th to endDay
21%17%35%19%6%
288
April1st to 15thDay
20%17%30%25%5%
269
16th to endDay
22%15%31%20%7%2
270
May1st to 15thDay
21%14%27%24%7%3
288
16th to endDay
21%9%20%24%17%6%
463
June1st to 15thDay
26%10%23%25%11%2
569
16th to endDay
21%10%26%28%11%1
675
July1st to 15thDay
14%8%20%34%18%2
591
16th to endDay
12%11%30%31%10%3
327
August1st to 15thDay
12%6%25%33%14%7%
315
16th to endDay
12%12%29%30%8%6%
332
September1st to 15thDay
20%11%27%26%11%2
315
16th to endDay
26%12%25%25%8%1
268
October1st to 15thDay
26%10%30%23%8%1
239
16th to endDay
39%7%20%22%45%
96
November1st to 15thDay
32%6%36%19%4
73
16th to endDay
16%336%21%6%15%
60
December1st to 15thDay
13%10%25%21%21%8%
60
16th to endDay
10%140%31%14%1
64
January1st to 15thNight
37%9%27%18%6%1
822
16th to endNight
26%8%32%24%7%
768
February1st to 15thNight
29%8%27%22%11%
704
16th to endNight
18%5%32%26%15%
632
March1st to 15thNight
28%10%32%20%7%
720
16th to endNight
23%8%31%25%9%1
768
April1st to 15thNight
19%5%23%36%14%
719
16th to endNight
20%6%29%34%10%
478
May1st to 15thNight
17%426%34%17%
360
16th to endNight
15%6%24%34%18%
375
June1st to 15thNight
23%5%22%33%14%
360
16th to endNight
18%5%21%35%18%
360
July1st to 15thNight
12%317%37%27%
340
16th to endNight
11%114%42%29%
376
August1st to 15thNight
7%113%33%41%2
360
16th to endNight
10%317%40%27%
585
September1st to 15thNight
15%318%29%29%3
720
16th to endNight
23%322%31%18%
671
October1st to 15thNight
25%425%33%11%
660
16th to endNight
33%5%24%26%8%
704
November1st to 15thNight
41%10%27%16%4
700
16th to endNight
30%9%31%19%7%1
889
December1st to 15thNight
28%8%34%20%8%
900
16th to endNight
26%11%35%21%5%
971
Page generated at 2017-09-20 01:49:54. Version ac04

Copyright 2017 A. Danko


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