Lac des Roches
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac des Roches clear sky chart from 2005-11-05 to 2017-10-31.

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%
14994
7%
47227
6%
14963
39%
14963
13%
36415

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
24%
771
3%
2707
3%
767
25%
767
6%
2367
January16th to endNight
32%
779
5%
2752
5%
779
33%
779
7%
2272
February1st to 15thNight
30%
699
5%
2384
5%
696
31%
696
7%
1963
February16th to endNight
43%
632
10%
2008
10%
632
45%
632
16%
1466
March1st to 15thNight
28%
720
7%
2139
4%
720
31%
720
11%
1709
March16th to endNight
32%
768
9%
2019
3%
768
35%
768
14%
1617
April1st to 15thNight
39%
719
7%
1799
3%
719
40%
719
16%
1423
April16th to endNight
35%
447
9%
1527
8%
447
39%
447
13%
1151
May1st to 15thNight
38%
359
9%
1440
13%
359
41%
359
13%
1025
May16th to endNight
44%
374
3%
1396
2%
374
45%
374
11%
1069
June1st to 15thNight
38%
360
0%
1080
0%
360
38%
360
13%
844
June16th to endNight
37%
360
0%
1080
0%
360
37%
360
13%
835
July1st to 15thNight
57%
340
1%
1106
0%
340
57%
340
23%
719
July16th to endNight
59%
376
7%
1329
8%
354
61%
354
23%
798
August1st to 15thNight
70%
360
13%
1432
20%
358
72%
358
27%
798
August16th to endNight
59%
589
17%
1735
16%
589
60%
589
28%
1092
September1st to 15thNight
57%
720
16%
1800
10%
720
57%
720
31%
1214
September16th to endNight
47%
716
16%
1955
10%
716
50%
716
23%
1361
October1st to 15thNight
43%
720
10%
2160
9%
720
45%
720
18%
1545
October16th to endNight
32%
768
8%
2463
6%
768
36%
768
12%
1903
November1st to 15thNight
24%
700
6%
2447
5%
700
27%
700
7%
2005
November16th to endNight
29%
810
5%
2610
3%
810
31%
810
8%
2206
December1st to 15thNight
29%
915
4%
2787
3%
915
31%
915
9%
2341
December16th to endNight
23%
992
3%
3072
2%
992
25%
992
6%
2692

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
12%12%48%7%35%5%5%6%27%
48551
Night
11%13%5%8%7%45%5%5%6%26%
47377
TransparencyDay
57%8%13%14%5%
48206
Night
57%8%13%13%5%
47227
SeeingDay
18%13%25%24%14%3
6629
Night
19%10%23%28%16%2
15001

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
11%16%6%12%9%45%6%6%7%12%
1241
16th to endDay
11%16%6%10%8%45%5%5%6%19%
1470
February1st to 15thDay
11%18%7%10%7%345%46%20%
1478
16th to endDay
7%13%7%11%8%45%5%5%7%21%
1466
March1st to 15thDay
7%19%6%11%8%46%6%5%6%16%
1821
16th to endDay
7%15%6%10%8%46%5%5%6%20%
2205
April1st to 15thDay
9%15%6%10%8%46%6%6%6%18%
2149
16th to endDay
11%15%5%9%9%45%5%6%6%19%
2430
May1st to 15thDay
14%13%5%7%6%35%5%6%6%25%
2511
16th to endDay
18%10%38%7%47%5%5%6%21%
2711
June1st to 15thDay
22%11%46%7%35%5%5%5%22%
2880
16th to endDay
16%10%47%8%46%5%5%6%23%
2880
July1st to 15thDay
10%6%25%5%35%5%5%7%40%
2784
16th to endDay
10%425%5%3446%7%44%
2748
August1st to 15thDay
8%5%25%6%35%6%5%8%42%
2520
16th to endDay
10%6%25%6%45%46%8%39%
2464
September1st to 15thDay
11%6%25%5%2445%5%46%
2160
16th to endDay
17%10%27%6%34447%31%
2004
October1st to 15thDay
12%14%36%6%3445%7%30%
1800
16th to endDay
18%13%46%5%345%5%6%26%
1759
November1st to 15thDay
18%18%6%9%7%35%445%18%
1410
16th to endDay
11%17%6%9%7%47%5%5%6%17%
1335
December1st to 15thDay
12%15%7%9%8%46%6%5%5%17%
1173
16th to endDay
8%17%8%11%9%46%6%5%7%14%
1152
January1st to 15thNight
14%19%8%12%7%35%5%45%13%
2707
16th to endNight
10%15%6%9%8%35%5%6%7%18%
2752
February1st to 15thNight
11%18%8%9%7%45%45%6%18%
2372
16th to endNight
7%12%5%8%7%35%5%5%7%30%
2008
March1st to 15thNight
7%15%7%10%7%36%5%5%7%22%
2139
16th to endNight
5%12%6%10%8%47%7%6%6%23%
2015
April1st to 15thNight
6%15%6%8%7%46%5%5%7%25%
1799
16th to endNight
8%13%6%9%7%5%6%45%7%26%
1527
May1st to 15thNight
13%12%47%6%45%446%28%
1439
16th to endNight
15%10%48%6%46%6%7%8%21%
1396
June1st to 15thNight
18%10%39%7%35%45%6%25%
1080
16th to endNight
13%11%48%7%45%5%5%7%26%
1080
July1st to 15thNight
10%424435%6%7%9%40%
1173
16th to endNight
9%426%6%36%6%5%9%39%
1421
August1st to 15thNight
7%415%435%5%6%7%47%
1440
16th to endNight
9%5%25%44446%10%41%
1735
September1st to 15thNight
10%7%25%5%24445%45%
1800
16th to endNight
13%8%35%6%3435%7%38%
1955
October1st to 15thNight
12%11%37%5%35%446%35%
2160
16th to endNight
15%13%47%6%4446%6%26%
2463
November1st to 15thNight
16%17%5%7%7%45%45%6%20%
2447
16th to endNight
11%19%7%8%7%5%6%5%5%5%17%
2610
December1st to 15thNight
10%16%6%11%8%46%5%5%5%18%
2787
16th to endNight
7%19%8%12%9%46%5%5%6%13%
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
68%13%11%41
1241
16th to endDay
65%11%12%7%21
1470
February1st to 15thDay
65%6%13%10%2
1478
16th to endDay
59%7%16%10%5%
1466
March1st to 15thDay
66%7%12%8%3
1821
16th to endDay
63%8%14%10%2
2205
April1st to 15thDay
64%7%12%11%3
2149
16th to endDay
63%8%13%10%3
2430
May1st to 15thDay
58%6%12%13%8%
2511
16th to endDay
62%8%13%12%3
2715
June1st to 15thDay
64%6%10%10%6%1
2880
16th to endDay
60%8%13%11%6%
2880
July1st to 15thDay
43%7%12%21%12%1
2623
16th to endDay
39%7%15%27%8%1
2577
August1st to 15thDay
38%8%17%24%9%
2503
16th to endDay
41%8%17%23%8%1
2464
September1st to 15thDay
38%7%14%26%10%1
2160
16th to endDay
53%7%12%18%7%1
2004
October1st to 15thDay
53%8%17%16%4
1800
16th to endDay
59%8%16%13%2
1759
November1st to 15thDay
68%8%10%8%3
1410
16th to endDay
66%9%10%9%2
1335
December1st to 15thDay
67%11%10%8%2
1173
16th to endDay
70%9%10%7%2
1152
January1st to 15thNight
72%8%9%6%1
2707
16th to endNight
66%9%12%7%21
2752
February1st to 15thNight
66%8%10%9%4
2384
16th to endNight
51%8%17%15%7%
2008
March1st to 15thNight
60%9%13%11%4
2139
16th to endNight
59%8%15%14%2
2019
April1st to 15thNight
56%8%15%15%4
1799
16th to endNight
58%6%13%16%5%
1527
May1st to 15thNight
55%5%10%17%10%
1440
16th to endNight
57%9%16%12%3
1396
June1st to 15thNight
60%6%9%16%6%
1080
16th to endNight
56%9%14%12%5%
1080
July1st to 15thNight
38%10%16%15%14%3
1106
16th to endNight
38%6%17%24%11%1
1329
August1st to 15thNight
31%8%17%27%12%2
1432
16th to endNight
37%7%17%27%7%2
1735
September1st to 15thNight
39%5%13%27%11%2
1800
16th to endNight
45%6%16%17%11%2
1955
October1st to 15thNight
49%7%15%21%5%
2160
16th to endNight
58%7%17%14%1
2463
November1st to 15thNight
65%8%11%9%31
2447
16th to endNight
69%8%10%8%3
2610
December1st to 15thNight
66%9%14%7%2
2787
16th to endNight
72%9%10%6%1
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
15%5%18%25%26%10%
60
16th to endDay
20%15%25%29%9%
64
February1st to 15thDay
21%15%26%26%10%
138
16th to endDay
11%18%31%26%9%1
219
March1st to 15thDay
25%26%30%14%3
270
16th to endDay
17%24%37%15%4
288
April1st to 15thDay
16%22%27%22%10%1
269
16th to endDay
17%22%34%18%5%1
270
May1st to 15thDay
20%18%22%25%11%1
288
16th to endDay
23%8%19%23%19%4
426
June1st to 15thDay
23%10%23%25%14%2
675
16th to endDay
20%10%22%27%15%3
675
July1st to 15thDay
14%8%25%27%21%3
557
16th to endDay
11%8%25%31%18%4
417
August1st to 15thDay
11%416%35%23%8%
315
16th to endDay
11%13%27%29%12%5%
332
September1st to 15thDay
17%10%28%21%17%3
315
16th to endDay
22%10%23%25%14%3
315
October1st to 15thDay
22%18%24%18%12%3
315
16th to endDay
30%11%22%20%14%
177
November1st to 15thDay
30%21%31%13%3
60
16th to endDay
18%13%16%28%11%11%
60
December1st to 15thDay
16%16%23%6%25%11%
60
16th to endDay
14%15%35%18%10%4
64
January1st to 15thNight
26%10%24%24%12%1
771
16th to endNight
19%10%27%27%12%1
779
February1st to 15thNight
22%8%23%27%15%1
704
16th to endNight
14%10%20%32%18%2
632
March1st to 15thNight
19%16%29%24%8%2
720
16th to endNight
13%15%28%25%15%1
768
April1st to 15thNight
15%10%23%29%18%3
719
16th to endNight
13%9%30%32%12%1
447
May1st to 15thNight
21%8%21%29%16%1
360
16th to endNight
20%420%28%23%2
375
June1st to 15thNight
22%7%18%31%17%1
360
16th to endNight
18%6%24%29%18%3
360
July1st to 15thNight
11%318%35%27%2
340
16th to endNight
11%315%32%32%3
376
August1st to 15thNight
8%29%29%40%9%
360
16th to endNight
14%415%33%28%3
589
September1st to 15thNight
14%5%16%27%30%7%
720
16th to endNight
20%9%16%25%24%3
716
October1st to 15thNight
19%8%20%29%18%3
720
16th to endNight
23%10%25%25%12%1
768
November1st to 15thNight
28%16%23%23%6%1
700
16th to endNight
24%12%24%26%9%2
810
December1st to 15thNight
19%12%25%29%11%
915
16th to endNight
19%14%29%26%8%
992
Page generated at 2017-11-01 14:23:37. Version ac04

Copyright 2017 A. Danko


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