Lac Connelly
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac Connelly clear sky chart from 2005-11-05 to 2017-09-23.

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%
14635
14%
46902
7%
14603
37%
14603
18%
32842

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
16%
720
10%
2506
3%
716
25%
716
10%
1917
January16th to endNight
20%
768
12%
2688
5%
768
30%
768
12%
1976
February1st to 15thNight
18%
704
10%
2311
3%
701
27%
701
12%
1744
February16th to endNight
21%
631
14%
1901
6%
631
32%
631
15%
1402
March1st to 15thNight
19%
720
14%
2160
8%
720
28%
720
14%
1617
March16th to endNight
30%
768
20%
1993
8%
768
37%
768
24%
1383
April1st to 15thNight
24%
718
17%
1796
5%
718
31%
718
21%
1331
April16th to endNight
26%
624
17%
1704
5%
624
35%
624
21%
1192
May1st to 15thNight
26%
378
15%
1458
10%
378
37%
378
15%
983
May16th to endNight
29%
375
13%
1497
11%
374
40%
374
17%
975
June1st to 15thNight
30%
360
7%
1440
5%
360
38%
360
14%
1008
June16th to endNight
39%
360
8%
1440
10%
360
43%
360
17%
938
July1st to 15thNight
48%
340
13%
1360
16%
340
55%
340
25%
768
July16th to endNight
51%
376
11%
1418
14%
354
55%
354
24%
831
August1st to 15thNight
52%
359
14%
1430
14%
357
58%
357
20%
894
August16th to endNight
51%
753
19%
1899
10%
753
55%
753
37%
1198
September1st to 15thNight
47%
720
14%
1800
6%
720
50%
720
31%
1217
September16th to endNight
47%
689
22%
1886
14%
689
52%
689
33%
1173
October1st to 15thNight
31%
660
20%
1952
10%
660
42%
660
22%
1311
October16th to endNight
25%
704
12%
2255
6%
704
34%
704
16%
1625
November1st to 15thNight
26%
700
18%
2280
10%
700
37%
700
16%
1591
November16th to endNight
22%
720
14%
2520
8%
720
31%
720
13%
1807
December1st to 15thNight
19%
720
10%
2520
4%
720
27%
720
11%
1895
December16th to endNight
14%
768
11%
2688
4%
768
24%
768
9%
2066

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
18%8%36%5%34446%32%
48015
Night
17%9%36%5%34446%34%
47071
Cloud CoverDay
18%8%36%5%3445%6%33%
48024
Night
17%8%36%5%34446%34%
47077
TransparencyDay
50%6%12%19%9%1
47702
Night
50%5%12%20%10%1
46902
SeeingDay
21%11%29%23%10%2
5575
Night
21%9%32%25%9%
14635

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%14%48%7%3444324%
1432
16th to endDay
11%15%6%8%6%35%44429%
1536
February1st to 15thDay
12%15%5%10%7%36%44426%
1548
16th to endDay
14%14%5%10%7%2443427%
1572
March1st to 15thDay
17%11%5%9%7%4433328%
1790
16th to endDay
15%10%35%433346%38%
2229
April1st to 15thDay
22%9%35%43334433%
2152
16th to endDay
20%7%25%5%34435%36%
2256
May1st to 15thDay
21%8%36%6%34446%30%
2505
16th to endDay
22%6%25%5%445%5%6%31%
2618
June1st to 15thDay
23%6%25%5%25%5%6%7%28%
2520
16th to endDay
19%7%26%6%46%5%6%7%27%
2520
July1st to 15thDay
14%5%35%5%46%6%5%8%35%
2520
16th to endDay
13%5%25%6%46%6%7%8%33%
2654
August1st to 15thDay
14%5%27%6%47%6%6%6%32%
2517
16th to endDay
10%425%5%3445%8%43%
2293
September1st to 15thDay
18%5%15%435%447%39%
2160
16th to endDay
15%434323346%48%
1910
October1st to 15thDay
22%7%35%5%24446%33%
1675
16th to endDay
24%9%37%6%34436%26%
1617
November1st to 15thDay
15%7%46%5%35%45%7%32%
1575
16th to endDay
22%10%36%5%24445%30%
1440
December1st to 15thDay
23%14%5%7%6%2343423%
1440
16th to endDay
22%16%5%8%5%2434424%
1536
January1st to 15thNight
15%14%5%8%7%34446%24%
2506
16th to endNight
10%12%6%8%7%46%5%45%28%
2688
February1st to 15thNight
10%12%5%9%8%35%5%5%426%
2309
16th to endNight
15%10%5%8%7%35%44430%
1901
March1st to 15thNight
17%10%5%6%6%36%445%29%
2147
16th to endNight
14%9%36%43344442%
1993
April1st to 15thNight
23%8%35%5%23335%34%
1796
16th to endNight
21%6%24423446%38%
1704
May1st to 15thNight
21%6%36%5%3444435%
1458
16th to endNight
22%5%2442435%7%37%
1495
June1st to 15thNight
23%7%45%42435%6%31%
1440
16th to endNight
17%6%25%5%3445%7%36%
1440
July1st to 15thNight
10%324425%5%5%10%43%
1440
16th to endNight
10%5%24435%5%5%7%44%
1514
August1st to 15thNight
10%5%26%5%35%5%6%8%40%
1440
16th to endNight
11%414424347%50%
1899
September1st to 15thNight
14%415%43445%7%42%
1800
16th to endNight
16%41332235%6%50%
1886
October1st to 15thNight
18%6%25%423446%39%
1952
16th to endNight
23%8%36%433445%33%
2255
November1st to 15thNight
18%7%36%5%34446%34%
2280
16th to endNight
20%11%47%5%23445%30%
2520
December1st to 15thNight
19%13%5%6%5%34445%26%
2520
16th to endNight
20%15%5%7%5%2343424%
2688

Percentage Cloud Cover SE (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%13%48%6%3445%5%24%
1432
16th to endDay
12%14%5%7%7%3445%430%
1536
February1st to 15thDay
14%13%5%7%7%46%5%45%25%
1548
16th to endDay
15%13%49%7%3434328%
1572
March1st to 15thDay
17%10%48%7%45%24428%
1800
16th to endDay
16%9%36%424346%38%
2228
April1st to 15thDay
23%9%34434445%33%
2152
16th to endDay
20%6%35%5%34345%37%
2256
May1st to 15thDay
22%7%36%6%33446%31%
2505
16th to endDay
22%6%25%435%5%5%7%32%
2618
June1st to 15thDay
22%6%25%5%3446%8%29%
2520
16th to endDay
18%6%36%6%36%6%7%6%28%
2520
July1st to 15thDay
13%425%5%46%5%6%8%35%
2520
16th to endDay
12%425%5%35%6%7%9%35%
2654
August1st to 15thDay
13%5%26%6%36%7%6%6%33%
2517
16th to endDay
10%4145%35%45%8%45%
2293
September1st to 15thDay
17%4145%245%5%8%39%
2160
16th to endDay
14%42342335%6%49%
1910
October1st to 15thDay
22%8%25%433446%34%
1675
16th to endDay
22%10%46%6%34346%27%
1617
November1st to 15thDay
15%9%25%5%35%5%5%7%33%
1575
16th to endDay
22%10%26%5%34337%31%
1440
December1st to 15thDay
23%13%6%6%5%3334424%
1440
16th to endDay
23%14%47%6%2434424%
1536
January1st to 15thNight
16%14%5%8%6%35%35%6%24%
2506
16th to endNight
11%11%6%8%7%45%45%5%28%
2688
February1st to 15thNight
11%11%5%9%8%45%5%5%5%26%
2302
16th to endNight
16%10%49%5%25%445%30%
1901
March1st to 15thNight
19%10%46%5%34445%29%
2160
16th to endNight
15%9%35%5%3443441%
1993
April1st to 15thNight
24%7%36%423435%34%
1796
16th to endNight
21%6%24334346%38%
1704
May1st to 15thNight
21%6%26%5%25%435%35%
1458
16th to endNight
22%5%25%42435%6%37%
1495
June1st to 15thNight
24%7%25%5%3335%6%31%
1440
16th to endNight
17%5%25%435%45%8%36%
1440
July1st to 15thNight
10%424425%5%6%9%43%
1440
16th to endNight
11%424425%46%8%43%
1514
August1st to 15thNight
12%327%5%25%5%6%8%40%
1440
16th to endNight
12%41432436%7%49%
1899
September1st to 15thNight
14%425%5%25%45%7%42%
1800
16th to endNight
16%41321335%5%50%
1886
October1st to 15thNight
19%5%25%424346%40%
1952
16th to endNight
23%8%36%424346%32%
2255
November1st to 15thNight
19%7%35%5%34446%34%
2280
16th to endNight
21%11%46%5%33345%31%
2520
December1st to 15thNight
21%12%5%5%5%34346%26%
2520
16th to endNight
22%15%6%7%42443424%
2688

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
61%5%10%15%6%
1433
16th to endDay
55%6%10%17%8%1
1536
February1st to 15thDay
60%410%17%5%
1550
16th to endDay
59%39%15%8%1
1572
March1st to 15thDay
59%311%14%9%1
1800
16th to endDay
46%310%19%15%4
2229
April1st to 15thDay
53%48%19%11%3
2152
16th to endDay
49%5%7%19%13%4
2256
May1st to 15thDay
53%5%8%18%12%2
2505
16th to endDay
50%7%11%18%11%1
2622
June1st to 15thDay
52%7%11%17%9%1
2520
16th to endDay
51%9%11%19%7%
2520
July1st to 15thDay
41%8%15%23%10%
2371
16th to endDay
42%9%17%20%8%
2487
August1st to 15thDay
47%9%16%19%6%
2503
16th to endDay
35%7%19%25%10%
2293
September1st to 15thDay
41%7%13%25%12%
2160
16th to endDay
36%414%31%11%
1910
October1st to 15thDay
50%5%10%21%10%
1675
16th to endDay
58%5%12%16%6%
1617
November1st to 15thDay
48%7%15%17%10%
1575
16th to endDay
54%6%13%18%7%
1440
December1st to 15thDay
63%5%12%14%4
1440
16th to endDay
64%5%9%12%8%
1536
January1st to 15thNight
60%6%10%16%5%
2506
16th to endNight
56%6%10%16%7%1
2688
February1st to 15thNight
59%5%11%17%6%
2311
16th to endNight
55%49%17%11%
1901
March1st to 15thNight
56%6%8%18%9%1
2160
16th to endNight
45%411%18%16%3
1993
April1st to 15thNight
51%46%21%14%1
1796
16th to endNight
47%5%8%18%16%3
1704
May1st to 15thNight
51%5%8%16%14%4
1458
16th to endNight
46%7%10%21%13%1
1497
June1st to 15thNight
52%6%11%18%10%
1440
16th to endNight
45%7%12%19%13%1
1440
July1st to 15thNight
33%7%16%27%13%
1360
16th to endNight
35%8%19%23%12%
1418
August1st to 15thNight
40%9%17%22%10%
1430
16th to endNight
33%6%17%30%12%
1899
September1st to 15thNight
39%6%15%25%13%
1800
16th to endNight
34%5%14%32%12%
1886
October1st to 15thNight
45%5%11%24%12%
1952
16th to endNight
53%5%13%19%7%
2255
November1st to 15thNight
50%5%13%19%8%2
2280
16th to endNight
56%411%20%6%
2520
December1st to 15thNight
59%5%13%17%3
2520
16th to endNight
63%410%13%7%1
2688

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%28%25%26%3
60
16th to endDay
23%17%35%17%41
64
February1st to 15thDay
28%23%37%9%1
85
16th to endDay
25%12%32%23%4
231
March1st to 15thDay
23%18%30%22%3
270
16th to endDay
23%11%33%18%9%2
288
April1st to 15thDay
26%16%32%14%8%1
270
16th to endDay
18%19%31%19%9%1
270
May1st to 15thDay
28%12%29%19%7%2
288
16th to endDay
22%14%32%21%7%1
331
June1st to 15thDay
25%12%32%21%8%
315
16th to endDay
23%7%29%29%8%1
315
July1st to 15thDay
14%8%35%25%12%4
305
16th to endDay
15%324%38%15%2
326
August1st to 15thDay
14%425%33%18%3
313
16th to endDay
12%5%25%29%17%10%
332
September1st to 15thDay
17%5%25%26%17%6%
315
16th to endDay
16%9%22%25%16%9%
283
October1st to 15thDay
24%10%28%21%13%1
255
16th to endDay
28%12%28%22%6%
246
November1st to 15thDay
19%15%34%19%10%1
229
16th to endDay
33%11%26%23%5%
60
December1st to 15thDay
25%15%36%18%5%
60
16th to endDay
37%23%34%4
64
January1st to 15thNight
21%16%35%21%4
720
16th to endNight
16%12%40%23%6%
768
February1st to 15thNight
17%11%42%22%5%
704
16th to endNight
22%11%38%23%4
631
March1st to 15thNight
23%13%37%21%3
720
16th to endNight
18%11%34%27%7%
768
April1st to 15thNight
26%12%31%24%4
718
16th to endNight
25%12%32%21%7%
624
May1st to 15thNight
23%7%35%24%6%1
378
16th to endNight
23%6%36%24%8%
375
June1st to 15thNight
29%7%28%25%8%
360
16th to endNight
21%430%30%13%
360
July1st to 15thNight
10%433%33%17%
340
16th to endNight
12%226%42%14%1
376
August1st to 15thNight
15%221%37%20%1
359
16th to endNight
14%325%32%20%2
753
September1st to 15thNight
17%5%26%36%13%1
720
16th to endNight
18%5%26%26%20%2
689
October1st to 15thNight
21%8%32%26%9%1
660
16th to endNight
29%9%30%23%6%
704
November1st to 15thNight
23%9%33%23%9%
700
16th to endNight
26%13%30%18%9%1
720
December1st to 15thNight
28%12%32%21%5%
720
16th to endNight
31%14%31%18%3
768
Page generated at 2017-09-24 09:15:56. Version ac04

Copyright 2017 A. Danko


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