Long Lake Conservation Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Long Lake Conservation Center clear sky chart from 2005-11-05 to 2017-12-20.

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
36%
16602
14%
47880
8%
16555
41%
16555
22%
33291

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
29%
900
10%
2632
6%
895
33%
895
16%
1964
January16th to endNight
23%
960
13%
2583
4%
960
30%
960
16%
2002
February1st to 15thNight
32%
879
15%
2285
4%
875
38%
875
22%
1645
February16th to endNight
30%
771
14%
2033
5%
771
36%
771
20%
1494
March1st to 15thNight
32%
588
13%
2028
10%
588
37%
588
19%
1375
March16th to endNight
33%
576
15%
2096
11%
576
41%
576
16%
1440
April1st to 15thNight
32%
539
15%
1797
12%
539
39%
539
19%
1227
April16th to endNight
31%
540
16%
1638
10%
540
39%
540
18%
1194
May1st to 15thNight
31%
540
14%
1467
6%
540
37%
540
21%
1051
May16th to endNight
40%
563
11%
1498
4%
561
44%
561
27%
1017
June1st to 15thNight
45%
540
10%
1341
4%
540
48%
540
31%
901
June16th to endNight
50%
540
12%
1260
6%
540
51%
540
34%
841
July1st to 15thNight
58%
510
15%
1190
7%
510
60%
510
44%
745
July16th to endNight
60%
564
18%
1417
9%
531
63%
531
43%
821
August1st to 15thNight
64%
539
19%
1587
15%
536
67%
536
37%
918
August16th to endNight
53%
573
22%
1770
20%
573
60%
573
35%
1022
September1st to 15thNight
58%
540
19%
1800
19%
540
64%
540
35%
993
September16th to endNight
43%
579
18%
1982
15%
579
49%
579
26%
1200
October1st to 15thNight
37%
720
19%
2160
12%
720
43%
720
27%
1371
October16th to endNight
27%
768
14%
2340
6%
768
34%
768
17%
1692
November1st to 15thNight
29%
939
15%
2650
7%
939
36%
939
21%
1890
November16th to endNight
29%
975
15%
2730
9%
975
35%
975
19%
1985
December1st to 15thNight
24%
975
8%
2730
3%
975
29%
975
13%
2167
December16th to endNight
18%
984
9%
2866
3%
984
26%
984
11%
2336

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
14%8%36%5%3445%7%34%
48968
Night
13%8%47%5%3445%6%36%
48041
Cloud CoverDay
14%8%36%6%3445%7%34%
48979
Night
12%8%47%5%3445%6%36%
48045
Cloud CoverDay
14%8%36%6%3445%7%34%
48977
Night
12%8%47%5%3445%6%36%
48045
TransparencyDay
49%6%12%22%8%
48644
Night
47%5%12%23%9%1
47883
SeeingDay
18%6%28%26%15%4
6469
Night
17%6%31%30%12%1
16603

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
10%11%7%9%7%5%6%5%6%7%21%
1303
16th to endDay
10%12%8%11%7%46%5%5%6%19%
1638
February1st to 15thDay
6%12%5%9%6%36%45%7%30%
1575
16th to endDay
11%11%5%9%8%4445%6%27%
1439
March1st to 15thDay
15%8%5%7%6%45%446%32%
1933
16th to endDay
19%9%45%6%34346%31%
2127
April1st to 15thDay
15%10%35%5%3445%6%35%
2151
16th to endDay
22%9%35%6%34435%30%
2320
May1st to 15thDay
20%8%46%5%3435%6%30%
2484
16th to endDay
16%6%246%335%6%7%36%
2617
June1st to 15thDay
16%6%35%425%45%8%36%
2616
16th to endDay
14%5%25%5%35%46%8%37%
2700
July1st to 15thDay
9%42443446%8%47%
2697
16th to endDay
8%425%425%5%6%10%45%
2655
August1st to 15thDay
9%4245%35%5%6%8%43%
2363
16th to endDay
14%5%2442345%7%45%
2432
September1st to 15thDay
9%415%5%3445%8%45%
2160
16th to endDay
17%5%25%4245%46%41%
1964
October1st to 15thDay
17%8%345%33446%37%
1800
16th to endDay
22%10%35%5%34445%31%
1884
November1st to 15thDay
16%12%5%5%5%34435%33%
1536
16th to endDay
16%10%5%9%6%445%5%7%24%
1560
December1st to 15thDay
13%14%7%11%8%5%5%45%420%
1560
16th to endDay
15%17%7%12%8%3433318%
1454
January1st to 15thNight
10%9%6%9%8%36%5%6%7%26%
2632
16th to endNight
11%12%6%10%7%35%46%6%25%
2583
February1st to 15thNight
7%11%5%8%5%36%35%5%36%
2285
16th to endNight
10%9%48%8%45%5%6%7%30%
2033
March1st to 15thNight
10%10%5%7%5%35%445%37%
2016
16th to endNight
16%10%36%5%25%346%34%
2096
April1st to 15thNight
17%8%45%5%33435%37%
1797
16th to endNight
20%8%5%6%5%23446%31%
1638
May1st to 15thNight
19%7%45%43435%6%36%
1467
16th to endNight
13%5%25%5%25%5%6%7%39%
1496
June1st to 15thNight
14%424435%5%48%43%
1341
16th to endNight
11%2245%345%5%8%45%
1260
July1st to 15thNight
6%3133245%49%54%
1260
16th to endNight
5%31342435%9%55%
1513
August1st to 15thNight
8%41442445%6%53%
1596
16th to endNight
10%313424336%54%
1770
September1st to 15thNight
7%3243235%5%7%54%
1800
16th to endNight
13%5%24433347%47%
1982
October1st to 15thNight
14%7%23423346%45%
2160
16th to endNight
20%10%36%5%34446%32%
2340
November1st to 15thNight
14%11%5%6%434445%35%
2650
16th to endNight
15%8%47%5%3446%8%30%
2730
December1st to 15thNight
13%12%6%11%7%45%5%5%6%21%
2730
16th to endNight
14%16%7%12%7%34345%19%
2866

Percentage Cloud Cover SW (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
10%11%7%9%7%5%6%6%5%7%21%
1303
16th to endDay
10%12%7%12%8%46%5%5%6%19%
1638
February1st to 15thDay
7%12%5%9%6%46%45%6%31%
1575
16th to endDay
11%12%5%10%8%4445%6%27%
1439
March1st to 15thDay
14%8%48%7%35%446%32%
1944
16th to endDay
19%9%35%6%34346%31%
2127
April1st to 15thDay
15%10%36%6%2445%6%35%
2151
16th to endDay
22%10%35%6%35%43430%
2320
May1st to 15thDay
20%8%46%5%3435%6%30%
2484
16th to endDay
16%6%346%3446%7%36%
2617
June1st to 15thDay
15%6%25%425%45%8%36%
2616
16th to endDay
14%5%25%5%35%5%6%9%37%
2700
July1st to 15thDay
9%42443446%8%47%
2697
16th to endDay
7%42442446%10%45%
2655
August1st to 15thDay
9%425%5%35%5%5%8%43%
2363
16th to endDay
13%5%2442345%7%45%
2432
September1st to 15thDay
9%5%15%5%34449%45%
2160
16th to endDay
16%6%25%424446%41%
1964
October1st to 15thDay
17%9%245%33446%37%
1800
16th to endDay
22%9%35%5%34436%30%
1884
November1st to 15thDay
15%13%6%5%5%34335%33%
1536
16th to endDay
16%10%6%8%6%45%5%5%6%24%
1560
December1st to 15thDay
13%14%6%11%9%5%445%419%
1560
16th to endDay
15%17%7%12%9%3433318%
1454
January1st to 15thNight
10%9%6%10%7%46%5%6%6%26%
2632
16th to endNight
11%12%6%10%7%35%46%6%24%
2583
February1st to 15thNight
6%11%5%8%6%35%35%5%35%
2278
16th to endNight
10%9%48%8%45%5%6%7%29%
2033
March1st to 15thNight
10%9%5%7%5%35%446%36%
2028
16th to endNight
16%10%47%5%25%345%34%
2096
April1st to 15thNight
17%9%45%5%33435%37%
1797
16th to endNight
20%9%45%5%23446%31%
1638
May1st to 15thNight
19%7%45%424346%35%
1466
16th to endNight
12%5%345%346%6%8%39%
1496
June1st to 15thNight
14%4233445%48%43%
1341
16th to endNight
11%3245%345%5%8%45%
1260
July1st to 15thNight
6%3134245%48%54%
1260
16th to endNight
5%31342335%10%55%
1513
August1st to 15thNight
8%41432445%6%53%
1596
16th to endNight
10%314323337%54%
1770
September1st to 15thNight
7%32432345%7%54%
1800
16th to endNight
13%5%25%433347%46%
1982
October1st to 15thNight
14%7%23423346%45%
2160
16th to endNight
20%10%36%5%24346%32%
2340
November1st to 15thNight
14%11%46%5%24445%35%
2650
16th to endNight
15%8%47%6%3446%7%30%
2730
December1st to 15thNight
13%12%6%11%7%5%5%5%5%6%20%
2730
16th to endNight
14%16%7%11%8%34445%19%
2866

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
10%11%6%10%7%5%6%6%5%7%21%
1303
16th to endDay
10%12%7%12%8%46%6%5%7%18%
1638
February1st to 15thDay
7%11%5%9%6%36%45%6%31%
1575
16th to endDay
11%11%5%9%9%3445%6%27%
1439
March1st to 15thDay
14%8%5%7%6%35%446%32%
1944
16th to endDay
19%9%36%6%34346%31%
2125
April1st to 15thDay
14%10%36%6%3445%6%35%
2151
16th to endDay
21%10%35%6%35%43430%
2320
May1st to 15thDay
20%8%37%5%34346%30%
2484
16th to endDay
15%6%35%6%3446%7%35%
2617
June1st to 15thDay
15%6%25%435%5%5%8%35%
2616
16th to endDay
13%5%25%5%35%5%6%9%36%
2700
July1st to 15thDay
9%42443446%8%47%
2697
16th to endDay
7%425%4245%6%10%45%
2655
August1st to 15thDay
8%425%5%35%5%5%9%42%
2363
16th to endDay
13%5%2442345%7%45%
2432
September1st to 15thDay
9%5%16%5%345%49%44%
2160
16th to endDay
16%6%25%4345%46%40%
1964
October1st to 15thDay
17%9%25%5%23446%37%
1800
16th to endDay
21%10%36%5%34436%30%
1884
November1st to 15thDay
16%12%6%6%5%34435%32%
1536
16th to endDay
16%10%5%8%6%45%5%6%6%24%
1560
December1st to 15thDay
13%14%7%10%9%5%445%5%19%
1560
16th to endDay
15%17%7%12%9%3433317%
1454
January1st to 15thNight
10%9%6%9%8%46%46%6%26%
2632
16th to endNight
11%13%5%10%7%35%5%5%6%24%
2583
February1st to 15thNight
6%11%5%8%6%35%35%5%35%
2278
16th to endNight
10%8%5%8%8%45%5%6%7%29%
2033
March1st to 15thNight
10%9%5%7%5%44446%36%
2028
16th to endNight
16%9%47%5%35%345%34%
2096
April1st to 15thNight
17%9%46%5%24435%36%
1797
16th to endNight
19%9%46%5%24446%31%
1638
May1st to 15thNight
18%8%35%5%24346%35%
1466
16th to endNight
12%5%35%5%35%6%6%8%38%
1496
June1st to 15thNight
13%424435%5%5%9%42%
1341
16th to endNight
10%3245%345%5%9%45%
1260
July1st to 15thNight
6%3134245%5%8%54%
1260
16th to endNight
5%31442436%9%54%
1513
August1st to 15thNight
7%41442436%6%53%
1596
16th to endNight
10%424323337%54%
1770
September1st to 15thNight
7%3243235%47%54%
1800
16th to endNight
13%5%25%5%34347%45%
1982
October1st to 15thNight
14%8%23433446%45%
2160
16th to endNight
19%10%46%5%24446%32%
2340
November1st to 15thNight
14%11%46%5%2445%5%35%
2650
16th to endNight
15%8%47%6%3446%7%30%
2730
December1st to 15thNight
13%12%6%11%8%45%5%5%6%20%
2730
16th to endNight
14%16%7%11%8%34445%19%
2866

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
60%410%16%7%
1304
16th to endDay
64%6%9%15%3
1638
February1st to 15thDay
53%5%12%18%9%
1576
16th to endDay
57%412%18%6%
1439
March1st to 15thDay
53%5%14%18%7%
1944
16th to endDay
55%5%12%21%4
2127
April1st to 15thDay
50%412%18%13%1
2151
16th to endDay
57%49%17%10%
2320
May1st to 15thDay
55%6%10%20%6%
2484
16th to endDay
46%7%11%22%10%
2621
June1st to 15thDay
45%6%16%23%7%
2616
16th to endDay
42%7%15%24%9%
2700
July1st to 15thDay
33%7%12%29%15%
2538
16th to endDay
34%8%16%25%13%1
2488
August1st to 15thDay
37%7%12%30%9%1
2348
16th to endDay
37%5%16%26%12%
2432
September1st to 15thDay
37%5%14%33%7%
2160
16th to endDay
43%5%15%30%4
1964
October1st to 15thDay
47%414%22%10%
1800
16th to endDay
56%5%12%19%7%
1884
November1st to 15thDay
54%5%11%18%9%
1536
16th to endDay
59%6%12%13%6%1
1560
December1st to 15thDay
66%5%10%14%3
1560
16th to endDay
72%46%10%5%
1454
January1st to 15thNight
56%5%10%20%6%
2632
16th to endNight
58%5%11%17%6%
2583
February1st to 15thNight
49%411%24%9%
2288
16th to endNight
52%5%11%22%8%
2033
March1st to 15thNight
48%415%19%10%
2028
16th to endNight
52%413%21%8%
2096
April1st to 15thNight
50%39%21%13%1
1797
16th to endNight
54%47%19%12%1
1638
May1st to 15thNight
49%5%10%23%10%
1467
16th to endNight
42%6%13%21%14%1
1498
June1st to 15thNight
39%5%16%24%12%1
1341
16th to endNight
36%7%15%25%13%1
1260
July1st to 15thNight
28%6%15%32%15%2
1190
16th to endNight
24%7%16%32%16%2
1417
August1st to 15thNight
29%6%13%33%13%3
1587
16th to endNight
31%5%13%30%16%2
1770
September1st to 15thNight
28%6%15%37%12%
1800
16th to endNight
38%414%33%8%
1982
October1st to 15thNight
41%312%28%12%1
2160
16th to endNight
53%5%11%19%9%
2340
November1st to 15thNight
50%5%11%22%9%1
2650
16th to endNight
51%6%17%17%6%1
2730
December1st to 15thNight
62%5%13%14%3
2730
16th to endNight
66%411%12%4
2866

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
20%8%28%23%18%
90
16th to endDay
21%6%32%28%11%
96
February1st to 15thDay
16%14%46%18%3
90
16th to endDay
20%7%43%19%7%1
81
March1st to 15thDay
21%430%31%12%1
90
16th to endDay
27%10%25%20%14%
111
April1st to 15thDay
16%8%35%27%9%2
270
16th to endDay
31%6%29%22%8%2
430
May1st to 15thDay
25%12%26%23%8%3
468
16th to endDay
20%8%27%26%12%4
517
June1st to 15thDay
18%7%30%26%12%4
495
16th to endDay
16%7%32%23%15%4
495
July1st to 15thDay
10%5%27%25%22%9%
475
16th to endDay
9%328%27%23%7%
515
August1st to 15thDay
10%221%32%28%4
493
16th to endDay
16%222%33%19%5%
472
September1st to 15thDay
7%421%38%23%4
315
16th to endDay
20%8%32%23%10%4
174
October1st to 15thDay
20%434%21%12%5%
135
16th to endDay
29%6%34%18%10%
144
November1st to 15thDay
20%9%33%25%8%1
135
16th to endDay
34%8%34%18%3
135
December1st to 15thDay
24%8%31%30%31
135
16th to endDay
31%9%36%17%5%
108
January1st to 15thNight
16%8%33%28%10%2
900
16th to endNight
18%8%38%27%7%
960
February1st to 15thNight
13%7%35%31%11%1
880
16th to endNight
13%7%36%27%12%1
771
March1st to 15thNight
14%7%37%29%9%1
588
16th to endNight
21%7%29%27%10%3
576
April1st to 15thNight
21%6%33%30%8%
539
16th to endNight
25%430%29%8%
540
May1st to 15thNight
22%8%33%26%8%1
540
16th to endNight
14%433%31%13%1
563
June1st to 15thNight
15%429%37%11%
540
16th to endNight
12%327%40%16%
540
July1st to 15thNight
9%227%37%22%1
510
16th to endNight
9%223%41%21%2
564
August1st to 15thNight
10%17%44%24%1
539
16th to endNight
11%325%37%20%1
573
September1st to 15thNight
9%224%37%22%2
540
16th to endNight
15%433%27%15%3
579
October1st to 15thNight
20%8%29%30%10%
720
16th to endNight
26%6%32%27%6%
768
November1st to 15thNight
21%8%32%27%9%
939
16th to endNight
20%10%33%26%8%
975
December1st to 15thNight
19%8%35%26%9%
975
16th to endNight
23%7%33%25%8%2
984
Page generated at 2017-12-21 06:04:42. Version ac04

Copyright 2017 A. Danko


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