Lac des Piles
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac des Piles clear sky chart from 2005-11-05 to 2018-01-12.

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
29%
15054
14%
48501
8%
15022
37%
15022
17%
34304

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
19%
765
11%
2662
4%
761
27%
761
10%
2042
January16th to endNight
25%
768
12%
2688
6%
768
33%
768
12%
2009
February1st to 15thNight
22%
704
11%
2351
3%
701
31%
701
13%
1743
February16th to endNight
23%
631
14%
1893
7%
631
33%
631
15%
1421
March1st to 15thNight
21%
720
14%
2159
8%
720
30%
720
15%
1598
March16th to endNight
29%
768
20%
2007
7%
768
38%
768
22%
1399
April1st to 15thNight
25%
718
17%
1796
6%
718
30%
718
19%
1342
April16th to endNight
25%
582
16%
1662
4%
582
34%
582
20%
1145
May1st to 15thNight
29%
403
15%
1483
12%
403
39%
403
17%
997
May16th to endNight
29%
375
12%
1497
10%
374
41%
374
15%
1012
June1st to 15thNight
33%
360
7%
1440
6%
360
40%
360
15%
979
June16th to endNight
41%
360
7%
1440
7%
360
44%
360
16%
963
July1st to 15thNight
47%
340
9%
1360
14%
340
50%
340
22%
831
July16th to endNight
46%
376
11%
1418
12%
354
51%
354
21%
859
August1st to 15thNight
54%
371
12%
1442
14%
369
57%
369
20%
890
August16th to endNight
46%
702
19%
1848
11%
702
50%
702
32%
1195
September1st to 15thNight
44%
720
14%
1811
7%
720
47%
720
31%
1213
September16th to endNight
44%
717
21%
1980
13%
717
50%
717
31%
1259
October1st to 15thNight
32%
720
19%
2094
9%
720
43%
720
23%
1425
October16th to endNight
25%
768
13%
2496
7%
768
33%
768
17%
1794
November1st to 15thNight
28%
760
16%
2472
9%
760
38%
760
16%
1729
November16th to endNight
24%
780
14%
2711
8%
780
33%
780
12%
2000
December1st to 15thNight
20%
813
9%
2873
3%
813
28%
813
11%
2186
December16th to endNight
15%
833
12%
2918
4%
833
25%
833
9%
2273

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
19%9%36%6%35%446%30%
48825
Night
19%9%36%5%34445%32%
48671
TransparencyDay
53%412%19%9%1
48512
Night
53%411%20%9%1
48502
SeeingDay
24%10%27%22%11%3
5902
Night
24%8%28%27%9%
15054

By Month

Percentage Cloud Cover NE (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
19%15%5%8%8%3334322%
1520
16th to endDay
13%13%7%7%7%46%445%26%
1536
February1st to 15thDay
11%14%6%10%8%45%33425%
1510
16th to endDay
16%14%6%8%6%35%33426%
1580
March1st to 15thDay
17%12%5%7%6%34435%29%
1790
16th to endDay
14%10%46%6%44445%36%
2214
April1st to 15thDay
24%9%35%43333432%
2152
16th to endDay
20%8%35%5%24445%35%
2298
May1st to 15thDay
24%7%35%5%34445%31%
2478
16th to endDay
23%7%36%6%34446%28%
2618
June1st to 15thDay
21%6%36%5%36%5%5%7%27%
2520
16th to endDay
21%8%36%6%45%5%5%6%26%
2520
July1st to 15thDay
16%6%26%6%36%5%6%8%30%
2520
16th to endDay
16%6%36%6%45%5%7%7%31%
2654
August1st to 15thDay
17%7%26%6%35%6%7%8%27%
2494
16th to endDay
12%5%25%5%35%5%6%9%38%
2351
September1st to 15thDay
19%6%25%42435%6%39%
2148
16th to endDay
18%425%423347%43%
1980
October1st to 15thDay
24%8%25%5%34446%31%
1863
16th to endDay
24%9%36%5%35%5%46%24%
1728
November1st to 15thDay
19%9%47%6%35%335%30%
1716
16th to endDay
23%12%45%5%23335%30%
1576
December1st to 15thDay
24%14%47%5%3333424%
1411
16th to endDay
23%13%47%5%3433424%
1648
January1st to 15thNight
19%17%5%7%5%24345%24%
2662
16th to endNight
14%13%5%8%7%35%445%26%
2688
February1st to 15thNight
10%12%5%11%8%45%445%27%
2349
16th to endNight
16%11%5%9%6%35%44329%
1893
March1st to 15thNight
18%12%37%6%2445%429%
2147
16th to endNight
13%10%45%5%35%34439%
2007
April1st to 15thNight
24%9%45%433335%32%
1796
16th to endNight
22%6%25%42434438%
1662
May1st to 15thNight
21%7%35%424345%35%
1483
16th to endNight
23%5%35%5%34447%32%
1495
June1st to 15thNight
23%7%35%5%25%45%6%31%
1440
16th to endNight
19%6%36%6%35%5%5%7%30%
1440
July1st to 15thNight
15%5%25%5%3446%8%38%
1440
16th to endNight
14%6%25%5%245%5%7%40%
1514
August1st to 15thNight
14%5%15%5%35%47%8%37%
1452
16th to endNight
13%5%24425%446%45%
1848
September1st to 15thNight
16%5%24433446%43%
1811
16th to endNight
17%5%23324346%48%
1980
October1st to 15thNight
18%7%25%5%24445%39%
2094
16th to endNight
27%7%35%423346%31%
2496
November1st to 15thNight
21%7%26%6%3445%5%32%
2472
16th to endNight
23%12%36%5%2433429%
2711
December1st to 15thNight
23%13%47%6%33445%24%
2873
16th to endNight
20%16%6%9%5%2343423%
2918

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
66%47%15%6%
1521
16th to endDay
60%38%19%7%1
1536
February1st to 15thDay
62%211%16%6%
1512
16th to endDay
61%29%15%9%1
1580
March1st to 15thDay
57%210%14%12%1
1800
16th to endDay
49%5%8%19%14%3
2214
April1st to 15thDay
54%38%17%12%3
2152
16th to endDay
50%39%18%14%3
2298
May1st to 15thDay
54%38%18%12%1
2478
16th to endDay
55%310%17%11%1
2622
June1st to 15thDay
54%5%11%17%9%1
2520
16th to endDay
56%411%18%8%
2520
July1st to 15thDay
47%5%16%22%8%
2371
16th to endDay
50%6%15%19%7%
2487
August1st to 15thDay
50%6%18%19%5%
2480
16th to endDay
39%420%26%9%
2351
September1st to 15thDay
43%316%23%11%
2148
16th to endDay
41%314%30%9%
1980
October1st to 15thDay
54%311%22%7%
1863
16th to endDay
58%413%18%4
1728
November1st to 15thDay
56%411%18%8%
1716
16th to endDay
57%410%19%7%
1576
December1st to 15thDay
64%211%18%4
1411
16th to endDay
64%38%14%9%
1648
January1st to 15thNight
63%49%17%6%
2662
16th to endNight
60%38%16%8%
2688
February1st to 15thNight
60%310%17%7%
2351
16th to endNight
58%38%16%11%
1893
March1st to 15thNight
58%39%17%10%1
2160
16th to endNight
47%49%19%16%3
2007
April1st to 15thNight
55%35%20%14%2
1796
16th to endNight
47%49%19%15%3
1662
May1st to 15thNight
51%310%17%14%3
1483
16th to endNight
52%310%19%11%2
1497
June1st to 15thNight
52%412%19%9%1
1440
16th to endNight
50%5%12%18%12%1
1440
July1st to 15thNight
41%5%17%22%11%
1360
16th to endNight
43%417%24%10%
1418
August1st to 15thNight
42%6%18%25%6%
1442
16th to endNight
38%416%31%8%
1848
September1st to 15thNight
41%415%27%10%
1811
16th to endNight
38%313%32%10%
1980
October1st to 15thNight
46%411%25%11%
2094
16th to endNight
53%5%12%21%6%
2496
November1st to 15thNight
52%412%19%9%1
2472
16th to endNight
59%39%19%6%
2711
December1st to 15thNight
63%211%16%4
2873
16th to endNight
65%38%13%8%
2918

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
29%9%29%23%8%
82
16th to endDay
28%7%34%21%6%1
64
February1st to 15thDay
25%20%27%23%21
91
16th to endDay
26%12%32%21%5%
239
March1st to 15thDay
26%15%28%22%6%
270
16th to endDay
20%15%27%20%12%3
288
April1st to 15thDay
31%12%24%22%7%2
270
16th to endDay
24%13%33%16%7%4
270
May1st to 15thDay
32%9%26%21%7%2
288
16th to endDay
26%13%30%19%9%1
331
June1st to 15thDay
26%8%32%21%7%2
315
16th to endDay
25%8%31%23%10%1
315
July1st to 15thDay
18%6%29%27%12%4
305
16th to endDay
18%7%21%33%17%1
326
August1st to 15thDay
18%422%30%18%4
313
16th to endDay
13%6%25%25%21%7%
332
September1st to 15thDay
21%7%22%24%15%8%
315
16th to endDay
17%9%27%20%15%9%
314
October1st to 15thDay
27%11%25%20%13%2
314
16th to endDay
31%12%24%22%10%
288
November1st to 15thDay
26%10%29%21%11%1
280
16th to endDay
34%15%24%20%21
106
December1st to 15thDay
40%5%33%15%32
90
16th to endDay
31%14%37%13%3
96
January1st to 15thNight
29%8%31%24%5%
765
16th to endNight
22%9%31%28%7%
768
February1st to 15thNight
16%10%37%26%7%
704
16th to endNight
24%10%30%26%8%
631
March1st to 15thNight
27%9%33%25%3
720
16th to endNight
20%13%30%26%8%1
768
April1st to 15thNight
32%9%25%25%6%
718
16th to endNight
26%12%31%24%6%
582
May1st to 15thNight
26%7%28%28%7%
403
16th to endNight
26%6%31%26%8%
375
June1st to 15thNight
26%424%35%7%
360
16th to endNight
21%423%37%12%
360
July1st to 15thNight
14%226%34%20%1
340
16th to endNight
17%423%38%15%
376
August1st to 15thNight
15%216%41%21%1
371
16th to endNight
15%425%33%19%
702
September1st to 15thNight
20%425%32%15%1
720
16th to endNight
20%5%25%28%17%1
717
October1st to 15thNight
21%7%30%28%10%
720
16th to endNight
33%7%29%22%7%
768
November1st to 15thNight
27%8%27%24%10%1
760
16th to endNight
31%10%25%23%8%1
780
December1st to 15thNight
32%8%28%23%6%
813
16th to endNight
31%8%30%21%6%1
833
Page generated at 2018-01-12 22:01:35. Version ac04

Copyright 2018 A. Danko


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