Tumbler Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tumbler Ridge clear sky chart from 2005-11-05 to 2017-08-12.

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
30%
14827
9%
46361
5%
14795
34%
14795
14%
33522

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
22%
923
8%
2858
5%
918
25%
918
10%
2194
January16th to endNight
20%
800
11%
2880
6%
800
27%
800
9%
2101
February1st to 15thNight
25%
699
8%
2444
5%
698
30%
698
10%
1803
February16th to endNight
29%
632
9%
2047
7%
632
34%
632
13%
1516
March1st to 15thNight
22%
720
12%
2140
6%
720
28%
720
13%
1594
March16th to endNight
35%
768
10%
2015
4%
767
38%
767
19%
1501
April1st to 15thNight
34%
695
12%
1775
4%
695
40%
695
18%
1321
April16th to endNight
33%
375
9%
1455
8%
375
39%
375
11%
1051
May1st to 15thNight
39%
359
4%
1428
3%
359
41%
359
18%
920
May16th to endNight
39%
375
0%
1122
0%
374
39%
374
15%
842
June1st to 15thNight
40%
360
0%
1080
0%
360
40%
360
18%
769
June16th to endNight
41%
360
0%
1080
0%
360
41%
360
19%
751
July1st to 15thNight
42%
340
0%
1020
0%
340
42%
340
23%
666
July16th to endNight
51%
376
0%
1169
0%
354
52%
354
28%
707
August1st to 15thNight
55%
352
6%
1371
7%
350
56%
350
23%
807
August16th to endNight
42%
449
9%
1499
9%
449
46%
449
16%
1020
September1st to 15thNight
43%
660
12%
1650
7%
660
44%
660
28%
1129
September16th to endNight
29%
656
13%
1799
5%
656
34%
656
18%
1286
October1st to 15thNight
28%
660
10%
1980
4%
660
35%
660
14%
1441
October16th to endNight
20%
704
8%
2345
3%
704
28%
704
11%
1748
November1st to 15thNight
20%
730
13%
2480
7%
730
29%
730
11%
1740
November16th to endNight
22%
912
10%
2772
4%
912
27%
912
12%
2101
December1st to 15thNight
21%
930
10%
2880
5%
930
26%
930
11%
2229
December16th to endNight
23%
992
12%
3072
4%
992
31%
992
11%
2285

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%9%48%7%46%6%6%7%29%
47663
Night
7%10%47%6%45%5%6%8%32%
46497
TransparencyDay
52%9%16%16%4
47300
Night
49%9%16%18%5%
46366
SeeingDay
20%16%29%20%10%2
6793
Night
16%16%28%24%12%1
14834

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
310%5%10%7%46%5%7%9%27%
1092
16th to endDay
411%410%7%35%5%6%9%31%
1344
February1st to 15thDay
410%5%11%7%5%6%5%47%30%
1419
16th to endDay
412%6%11%7%37%6%5%7%27%
1427
March1st to 15thDay
311%6%11%8%47%5%7%6%26%
1818
16th to endDay
5%14%6%9%7%37%6%7%8%22%
2205
April1st to 15thDay
7%14%5%9%8%46%5%6%7%25%
2173
16th to endDay
11%12%5%10%6%46%5%5%7%24%
2505
May1st to 15thDay
9%10%5%7%7%36%5%6%7%30%
2517
16th to endDay
17%10%48%7%36%6%5%7%22%
2991
June1st to 15thDay
16%9%37%7%46%6%5%7%26%
2880
16th to endDay
13%7%47%7%36%5%7%7%29%
2880
July1st to 15thDay
15%5%25%5%46%6%5%8%34%
2880
16th to endDay
9%4246%47%7%7%9%35%
2917
August1st to 15thDay
10%5%25%6%36%6%7%8%36%
2496
16th to endDay
12%6%36%7%46%6%6%8%32%
2349
September1st to 15thDay
13%7%35%5%45%5%47%37%
1980
16th to endDay
11%8%25%436%5%6%9%35%
1831
October1st to 15thDay
11%13%38%7%35%5%5%6%29%
1650
16th to endDay
9%12%48%6%346%7%9%26%
1526
November1st to 15thDay
7%12%6%7%5%36%6%5%8%31%
1365
16th to endDay
310%7%11%9%35%6%7%5%28%
1186
December1st to 15thDay
7%10%7%10%6%35%6%49%27%
1080
16th to endDay
211%49%9%6%7%5%6%7%29%
1152
January1st to 15thNight
311%6%10%8%35%6%6%9%27%
2858
16th to endNight
5%11%5%7%7%46%6%6%8%30%
2880
February1st to 15thNight
5%11%5%10%6%5%6%6%7%7%27%
2432
16th to endNight
39%7%11%8%47%6%6%8%26%
2047
March1st to 15thNight
29%6%11%9%46%5%6%9%29%
2140
16th to endNight
5%13%6%6%6%35%5%8%7%30%
2015
April1st to 15thNight
7%8%5%6%7%37%5%6%7%34%
1775
16th to endNight
10%11%48%5%35%5%6%7%29%
1455
May1st to 15thNight
9%8%35%5%26%6%8%8%36%
1428
16th to endNight
18%9%35%6%36%5%5%9%26%
1122
June1st to 15thNight
12%6%48%5%35%5%46%35%
1080
16th to endNight
11%8%35%6%25%5%7%7%35%
1080
July1st to 15thNight
13%425%435%5%6%8%40%
1080
16th to endNight
6%423437%7%6%8%46%
1250
August1st to 15thNight
9%3246%345%6%7%47%
1378
16th to endNight
9%5%26%6%46%7%8%9%33%
1499
September1st to 15thNight
9%7%145%3445%6%45%
1650
16th to endNight
10%7%25%5%35%5%7%10%35%
1799
October1st to 15thNight
11%11%37%5%3446%7%33%
1980
16th to endNight
9%11%6%7%5%45%5%6%7%30%
2345
November1st to 15thNight
7%10%37%5%45%5%7%7%35%
2480
16th to endNight
5%13%5%9%6%46%5%5%8%28%
2772
December1st to 15thNight
412%5%9%8%46%6%6%6%28%
2880
16th to endNight
312%5%8%8%45%5%6%7%32%
3072

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
52%13%18%12%21
1092
16th to endDay
49%10%18%14%6%1
1344
February1st to 15thDay
53%10%14%14%7%
1419
16th to endDay
55%6%16%15%41
1427
March1st to 15thDay
56%7%14%15%4
1818
16th to endDay
57%9%17%12%4
2205
April1st to 15thDay
58%7%14%15%4
2173
16th to endDay
59%8%13%13%4
2505
May1st to 15thDay
53%7%15%14%8%
2517
16th to endDay
61%7%12%16%3
2996
June1st to 15thDay
57%7%12%18%4
2880
16th to endDay
53%8%14%17%5%
2880
July1st to 15thDay
47%8%15%21%5%1
2711
16th to endDay
42%11%23%18%3
2736
August1st to 15thDay
42%12%20%20%4
2478
16th to endDay
47%10%21%16%3
2349
September1st to 15thDay
46%8%23%16%5%
1980
16th to endDay
45%11%19%19%4
1831
October1st to 15thDay
54%9%20%14%1
1650
16th to endDay
52%11%20%14%1
1526
November1st to 15thDay
52%9%17%16%31
1365
16th to endDay
54%10%16%12%5%
1186
December1st to 15thDay
54%11%13%16%3
1080
16th to endDay
53%9%15%15%5%
1152
January1st to 15thNight
53%12%17%13%21
2858
16th to endNight
51%11%15%13%6%1
2880
February1st to 15thNight
53%10%16%13%6%
2444
16th to endNight
53%8%15%16%41
2047
March1st to 15thNight
52%8%13%18%5%
2140
16th to endNight
49%8%18%18%4
2019
April1st to 15thNight
48%9%13%23%5%
1775
16th to endNight
53%9%14%15%6%
1455
May1st to 15thNight
42%9%16%20%10%
1429
16th to endNight
54%7%15%16%5%
1122
June1st to 15thNight
49%6%14%23%5%
1080
16th to endNight
47%7%14%23%6%
1080
July1st to 15thNight
40%7%18%25%7%
1020
16th to endNight
31%10%29%24%4
1169
August1st to 15thNight
35%9%22%28%4
1371
16th to endNight
42%13%20%19%4
1499
September1st to 15thNight
39%8%24%21%6%
1650
16th to endNight
42%12%18%19%6%
1799
October1st to 15thNight
49%9%19%17%3
1980
16th to endNight
53%9%18%16%2
2345
November1st to 15thNight
47%10%17%19%5%
2480
16th to endNight
54%10%14%14%41
2772
December1st to 15thNight
55%10%13%16%3
2880
16th to endNight
51%10%14%19%4
3072

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
16%8%25%25%11%13%
60
16th to endDay
18%23%25%20%12%
64
February1st to 15thDay
20%23%30%16%8%
84
16th to endDay
15%18%34%20%9%
213
March1st to 15thDay
17%30%32%14%4
270
16th to endDay
19%20%33%21%5%
288
April1st to 15thDay
30%21%24%16%41
269
16th to endDay
22%22%32%15%4
270
May1st to 15thDay
20%22%29%18%7%1
294
16th to endDay
22%10%26%21%14%3
705
June1st to 15thDay
22%14%25%21%12%3
675
16th to endDay
19%12%29%22%12%3
675
July1st to 15thDay
18%13%26%23%14%2
645
16th to endDay
12%13%34%27%10%1
585
August1st to 15thDay
13%10%27%28%17%2
329
16th to endDay
24%20%32%17%4
268
September1st to 15thDay
25%16%34%15%5%2
255
16th to endDay
23%26%31%12%5%
255
October1st to 15thDay
35%17%27%14%5%
255
16th to endDay
24%14%23%18%15%3
90
November1st to 15thDay
28%31%26%10%3
60
16th to endDay
15%18%28%21%13%3
60
December1st to 15thDay
8%13%20%33%20%5%
60
16th to endDay
17%14%28%23%14%3
64
January1st to 15thNight
17%19%29%24%7%1
923
16th to endNight
20%24%27%22%31
800
February1st to 15thNight
17%21%25%21%12%2
705
16th to endNight
8%14%31%29%13%1
632
March1st to 15thNight
12%20%36%24%5%1
720
16th to endNight
14%12%27%26%17%1
768
April1st to 15thNight
13%13%28%29%13%2
695
16th to endNight
18%14%26%23%16%1
375
May1st to 15thNight
14%10%27%26%18%3
360
16th to endNight
22%9%18%26%20%3
375
June1st to 15thNight
15%8%25%28%20%1
360
16th to endNight
15%10%23%27%21%1
360
July1st to 15thNight
16%7%27%30%17%1
340
16th to endNight
8%9%26%32%19%3
376
August1st to 15thNight
11%321%26%32%4
352
16th to endNight
14%8%27%25%22%1
449
September1st to 15thNight
15%8%26%27%19%1
660
16th to endNight
18%19%28%20%11%1
656
October1st to 15thNight
24%15%25%24%9%
660
16th to endNight
22%19%29%21%7%
704
November1st to 15thNight
21%24%26%18%7%
730
16th to endNight
17%20%32%22%7%
912
December1st to 15thNight
17%18%32%21%8%1
930
16th to endNight
17%18%29%23%10%1
992
Page generated at 2017-08-13 11:16:56. Version ac04

Copyright 2017 A. Danko


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