Lac Sacacomie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac Sacacomie clear sky chart from 2005-11-05 to 2017-04-07.

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
27%
14143
14%
45440
7%
14111
35%
14111
16%
32066

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
15%
720
11%
2506
3%
716
25%
716
11%
1898
January16th to endNight
20%
768
12%
2688
5%
768
29%
768
12%
1989
February1st to 15thNight
21%
704
11%
2343
3%
701
31%
701
13%
1733
February16th to endNight
20%
631
15%
1893
6%
631
33%
631
15%
1384
March1st to 15thNight
20%
720
14%
2159
8%
720
27%
720
14%
1608
March16th to endNight
27%
768
20%
2001
7%
768
36%
768
20%
1399
April1st to 15thNight
23%
686
17%
1716
5%
686
29%
686
18%
1292
April16th to endNight
25%
546
16%
1536
5%
546
34%
546
21%
1043
May1st to 15thNight
31%
358
16%
1348
13%
358
42%
358
18%
896
May16th to endNight
26%
343
12%
1369
10%
342
38%
342
17%
910
June1st to 15thNight
30%
330
7%
1320
4%
330
38%
330
13%
915
June16th to endNight
38%
330
6%
1320
7%
330
41%
330
16%
871
July1st to 15thNight
43%
310
10%
1240
14%
310
48%
310
23%
741
July16th to endNight
42%
348
10%
1306
10%
326
48%
326
22%
796
August1st to 15thNight
53%
332
13%
1313
15%
330
57%
330
20%
820
August16th to endNight
46%
660
17%
1710
9%
660
50%
660
32%
1097
September1st to 15thNight
40%
660
13%
1650
6%
660
43%
660
29%
1136
September16th to endNight
39%
657
20%
1815
11%
657
45%
657
30%
1149
October1st to 15thNight
27%
660
20%
1930
9%
660
39%
660
19%
1326
October16th to endNight
23%
704
12%
2278
6%
704
31%
704
16%
1637
November1st to 15thNight
28%
700
17%
2277
10%
700
38%
700
17%
1602
November16th to endNight
22%
720
14%
2514
8%
720
31%
720
11%
1846
December1st to 15thNight
19%
720
10%
2520
3%
720
27%
720
11%
1894
December16th to endNight
13%
768
12%
2688
3%
768
24%
768
9%
2084

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%
45797
Night
17%9%46%5%34446%33%
45610
TransparencyDay
53%5%11%18%9%1
45484
Night
51%5%12%20%9%1
45441
SeeingDay
22%12%29%22%9%3
4916
Night
23%11%30%25%8%
14143

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
16%14%5%8%8%3444424%
1432
16th to endDay
12%13%5%9%8%25%445%27%
1536
February1st to 15thDay
10%16%5%9%8%46%44425%
1515
16th to endDay
15%16%7%8%6%3434426%
1580
March1st to 15thDay
15%12%48%6%45%35%428%
1790
16th to endDay
15%10%45%6%34345%36%
2220
April1st to 15thDay
22%11%35%423346%31%
2048
16th to endDay
20%8%46%423345%36%
2093
May1st to 15thDay
22%8%36%5%34335%33%
2282
16th to endDay
23%7%36%6%3445%6%29%
2394
June1st to 15thDay
24%7%35%5%25%5%5%7%27%
2310
16th to endDay
21%7%36%7%36%5%5%7%25%
2310
July1st to 15thDay
15%6%37%6%46%5%6%7%30%
2310
16th to endDay
14%6%37%7%36%5%6%8%29%
2458
August1st to 15thDay
19%7%26%6%46%6%6%7%25%
2296
16th to endDay
12%5%25%5%36%6%6%8%36%
2138
September1st to 15thDay
18%5%26%6%3445%7%36%
1980
16th to endDay
18%6%25%424336%42%
1815
October1st to 15thDay
26%7%26%425%35%5%29%
1697
16th to endDay
24%13%46%5%34446%22%
1593
November1st to 15thDay
18%12%48%5%34346%29%
1581
16th to endDay
22%13%45%5%2333430%
1443
December1st to 15thDay
25%14%46%5%3433424%
1440
16th to endDay
22%15%47%6%34335%23%
1536
January1st to 15thNight
16%15%6%8%5%34445%25%
2506
16th to endNight
11%13%5%9%8%35%445%27%
2688
February1st to 15thNight
8%12%6%9%7%46%446%27%
2341
16th to endNight
15%12%48%6%34446%30%
1893
March1st to 15thNight
17%12%48%6%34345%28%
2147
16th to endNight
12%9%46%424435%39%
2001
April1st to 15thNight
22%8%5%5%5%2445%5%30%
1716
16th to endNight
19%6%25%42435%6%38%
1536
May1st to 15thNight
20%6%36%5%24436%37%
1348
16th to endNight
22%5%35%324347%36%
1367
June1st to 15thNight
23%7%36%5%2435%5%31%
1320
16th to endNight
18%5%35%5%35%5%5%7%34%
1320
July1st to 15thNight
12%425%4245%5%8%42%
1320
16th to endNight
14%425%425%45%7%43%
1402
August1st to 15thNight
13%5%25%435%5%5%7%40%
1323
16th to endNight
13%5%2442435%7%47%
1710
September1st to 15thNight
15%5%2442445%6%42%
1650
16th to endNight
19%413323345%48%
1815
October1st to 15thNight
20%7%25%424436%38%
1930
16th to endNight
25%7%25%423446%31%
2278
November1st to 15thNight
19%8%26%5%2445%5%33%
2277
16th to endNight
21%13%47%5%24335%28%
2514
December1st to 15thNight
21%14%47%434445%25%
2520
16th to endNight
21%15%6%7%6%34345%22%
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
62%5%8%15%7%
1433
16th to endDay
58%5%7%18%8%1
1536
February1st to 15thDay
60%49%17%6%
1517
16th to endDay
61%37%16%9%1
1580
March1st to 15thDay
58%49%15%11%1
1800
16th to endDay
49%5%8%18%13%4
2220
April1st to 15thDay
54%47%17%11%4
2048
16th to endDay
49%48%19%14%3
2093
May1st to 15thDay
51%5%8%18%12%2
2282
16th to endDay
54%6%10%17%10%1
2398
June1st to 15thDay
54%7%11%16%8%1
2310
16th to endDay
56%6%10%18%7%
2310
July1st to 15thDay
48%8%14%19%9%
2161
16th to endDay
50%8%15%18%7%
2291
August1st to 15thDay
52%9%15%17%4
2282
16th to endDay
40%9%17%23%9%
2138
September1st to 15thDay
45%6%16%22%9%
1980
16th to endDay
43%412%29%9%
1815
October1st to 15thDay
54%410%21%7%
1697
16th to endDay
60%5%11%16%5%
1593
November1st to 15thDay
55%5%11%17%8%
1581
16th to endDay
57%410%19%8%
1443
December1st to 15thDay
63%311%17%3
1440
16th to endDay
63%49%12%9%
1536
January1st to 15thNight
60%410%16%6%
2506
16th to endNight
58%49%16%8%1
2688
February1st to 15thNight
57%411%18%7%
2343
16th to endNight
55%39%17%11%1
1893
March1st to 15thNight
56%5%8%17%10%1
2160
16th to endNight
47%49%19%16%3
2001
April1st to 15thNight
54%46%19%13%2
1716
16th to endNight
46%49%20%15%3
1536
May1st to 15thNight
47%5%11%17%13%3
1348
16th to endNight
48%5%10%20%12%1
1369
June1st to 15thNight
52%6%14%17%8%
1320
16th to endNight
48%6%12%18%12%1
1320
July1st to 15thNight
38%6%18%24%11%
1240
16th to endNight
41%5%19%23%9%
1306
August1st to 15thNight
41%8%18%25%6%
1313
16th to endNight
36%5%18%27%10%
1710
September1st to 15thNight
41%6%15%25%10%
1650
16th to endNight
38%314%32%10%
1815
October1st to 15thNight
47%5%11%23%11%
1930
16th to endNight
53%413%20%7%
2278
November1st to 15thNight
50%5%12%19%9%1
2277
16th to endNight
59%310%18%7%
2514
December1st to 15thNight
60%5%12%17%4
2520
16th to endNight
64%48%14%7%
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
21%15%36%23%3
60
16th to endDay
21%14%39%17%43
64
February1st to 15thDay
24%24%34%15%1
82
16th to endDay
26%18%30%18%5%
239
March1st to 15thDay
24%15%32%21%4
270
16th to endDay
20%19%28%19%9%3
288
April1st to 15thDay
26%17%26%20%8%1
235
16th to endDay
22%15%31%16%10%4
210
May1st to 15thDay
25%14%26%22%7%3
228
16th to endDay
21%17%32%19%7%1
267
June1st to 15thDay
29%13%29%18%7%1
255
16th to endDay
20%9%34%27%7%1
255
July1st to 15thDay
14%9%34%27%10%4
245
16th to endDay
17%5%28%33%13%1
270
August1st to 15thDay
19%5%29%25%15%5%
253
16th to endDay
12%7%26%29%15%8%
268
September1st to 15thDay
20%7%27%20%16%8%
255
16th to endDay
18%11%30%18%14%7%
254
October1st to 15thDay
26%12%27%21%10%2
255
16th to endDay
31%12%26%20%9%
241
November1st to 15thDay
19%14%27%25%11%1
235
16th to endDay
31%20%23%17%6%
63
December1st to 15thDay
36%6%31%18%33
60
16th to endDay
37%17%34%10%
64
January1st to 15thNight
25%13%35%20%5%
720
16th to endNight
19%11%35%25%7%
768
February1st to 15thNight
16%13%37%25%7%
704
16th to endNight
22%14%34%23%5%
631
March1st to 15thNight
26%13%33%22%4
720
16th to endNight
18%17%30%23%8%1
768
April1st to 15thNight
28%13%28%24%4
686
16th to endNight
23%14%31%22%7%
546
May1st to 15thNight
23%9%31%26%8%
358
16th to endNight
24%7%36%23%7%
343
June1st to 15thNight
26%9%26%28%8%
330
16th to endNight
19%430%34%11%
330
July1st to 15thNight
13%331%31%18%1
310
16th to endNight
17%330%34%13%
348
August1st to 15thNight
15%320%40%19%1
332
16th to endNight
15%5%25%34%17%1
660
September1st to 15thNight
19%5%29%31%13%1
660
16th to endNight
21%8%28%24%15%1
657
October1st to 15thNight
21%12%30%25%8%
660
16th to endNight
31%10%29%20%7%
704
November1st to 15thNight
25%10%29%24%9%1
700
16th to endNight
25%18%25%22%6%2
720
December1st to 15thNight
30%11%31%21%4
720
16th to endNight
31%13%29%20%41
768
Page generated at 2017-04-08 05:35:13. Version ac04

Copyright 2017 A. Danko


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