Eagle Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eagle Lake clear sky chart from 2005-11-05 to 2017-09-16.

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
61%
15033
24%
46862
21%
15004
65%
15004
37%
25775

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
56%
716
16%
2506
15%
716
60%
716
25%
1539
January16th to endNight
56%
768
21%
2532
22%
768
59%
768
27%
1530
February1st to 15thNight
51%
697
17%
2283
17%
696
55%
696
26%
1422
February16th to endNight
50%
632
20%
1895
17%
632
55%
632
27%
1189
March1st to 15thNight
48%
720
14%
2088
12%
720
51%
720
27%
1352
March16th to endNight
45%
768
17%
2040
11%
768
49%
768
28%
1317
April1st to 15thNight
45%
719
17%
1799
8%
719
49%
719
28%
1217
April16th to endNight
52%
720
21%
1800
10%
720
55%
720
41%
1066
May1st to 15thNight
55%
475
26%
1555
19%
475
62%
475
43%
772
May16th to endNight
56%
374
17%
1496
19%
374
61%
374
28%
784
June1st to 15thNight
63%
360
22%
1440
27%
360
70%
360
34%
686
June16th to endNight
77%
360
31%
1440
41%
360
83%
360
52%
552
July1st to 15thNight
87%
340
30%
1360
43%
340
89%
340
65%
460
July16th to endNight
88%
412
40%
1449
48%
387
90%
387
68%
502
August1st to 15thNight
87%
556
36%
1629
30%
553
88%
553
65%
721
August16th to endNight
84%
764
43%
1910
28%
764
85%
764
76%
888
September1st to 15thNight
84%
720
40%
1800
27%
720
85%
720
73%
848
September16th to endNight
73%
660
40%
1789
32%
660
79%
660
64%
833
October1st to 15thNight
65%
660
29%
1980
27%
660
72%
660
47%
991
October16th to endNight
66%
704
28%
2131
29%
704
70%
704
43%
1117
November1st to 15thNight
63%
700
21%
2275
21%
700
67%
700
32%
1306
November16th to endNight
53%
720
18%
2457
18%
720
58%
720
32%
1352
December1st to 15thNight
51%
720
17%
2520
16%
720
58%
720
24%
1574
December16th to endNight
43%
768
19%
2688
17%
768
49%
768
19%
1757

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
45%24424446%56%
47912
Night
45%2442445%7%55%
47038
TransparencyDay
28%410%20%21%15%
47587
Night
27%5%13%22%19%11%
46863
SeeingDay
11%15%26%26%16%4
5741
Night
8%8%17%34%26%5%
15046

By Month

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
38%37%7%36%5%5%8%39%
1432
16th to endDay
6%10%46%6%25%6%5%7%36%
1689
February1st to 15thDay
5%8%36%5%36%5%7%7%41%
1580
16th to endDay
411%5%7%6%35%45%7%39%
1579
March1st to 15thDay
7%9%47%5%35%5%5%8%35%
1869
16th to endDay
5%12%46%5%25%5%47%39%
2184
April1st to 15thDay
6%10%49%6%2445%6%38%
2149
16th to endDay
6%8%2442435%452%
2160
May1st to 15thDay
3424423348%59%
2391
16th to endDay
8%7%36%5%24446%46%
2615
June1st to 15thDay
6%5%24425%446%53%
2520
16th to endDay
221221222474%
2520
July1st to 15thDay
11221234475%
2520
16th to endDay
111111224378%
2618
August1st to 15thDay
11221234474%
2322
16th to endDay
111133383%
2292
September1st to 15thDay
11221332476%
2160
16th to endDay
3213211235%72%
1860
October1st to 15thDay
4324323235%62%
1650
16th to endDay
5%5%25%5%24446%55%
1741
November1st to 15thDay
7%6%244345%5%9%46%
1584
16th to endDay
47%35%5%26%45%6%45%
1501
December1st to 15thDay
6%8%48%5%35%47%8%38%
1440
16th to endDay
6%9%5%8%6%45%6%7%7%33%
1536
January1st to 15thNight
48%37%5%35%46%9%42%
2506
16th to endNight
5%9%35%5%35%46%8%44%
2532
February1st to 15thNight
5%9%36%5%35%5%6%8%40%
2271
16th to endNight
310%47%43445%7%43%
1895
March1st to 15thNight
5%10%35%5%2446%10%40%
2088
16th to endNight
5%9%36%4245%5%7%45%
2040
April1st to 15thNight
5%7%35%6%45%5%5%8%40%
1799
16th to endNight
5%5%23324447%56%
1800
May1st to 15thNight
5%313322445%62%
1555
16th to endNight
6%425%5%24347%52%
1496
June1st to 15thNight
441442345%6%58%
1440
16th to endNight
211231223375%
1440
July1st to 15thNight
1211122479%
1440
16th to endNight
1111222382%
1548
August1st to 15thNight
21111224475%
1638
16th to endNight
11111211383%
1910
September1st to 15thNight
211112225%79%
1800
16th to endNight
2112211235%76%
1789
October1st to 15thNight
5%313313325%65%
1980
16th to endNight
441432345%7%57%
2131
November1st to 15thNight
7%4234245%8%8%48%
2275
16th to endNight
35%35%5%35%46%9%49%
2457
December1st to 15thNight
6%7%37%5%345%6%8%40%
2520
16th to endNight
6%11%47%6%35%5%6%9%34%
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
40%10%16%22%9%
1432
16th to endDay
42%8%12%18%13%3
1689
February1st to 15thDay
38%8%16%23%12%
1580
16th to endDay
43%5%16%23%8%1
1579
March1st to 15thDay
43%7%13%20%12%2
1869
16th to endDay
42%5%20%17%9%3
2184
April1st to 15thDay
43%5%14%20%14%
2149
16th to endDay
33%414%27%17%3
2160
May1st to 15thDay
24%311%29%25%6%
2391
16th to endDay
38%49%24%19%4
2619
June1st to 15thDay
29%410%19%26%10%
2520
16th to endDay
15%15%16%38%22%
2520
July1st to 15thDay
12%2310%26%43%
2371
16th to endDay
10%2211%21%51%
2454
August1st to 15thDay
12%1413%24%42%
2306
16th to endDay
7%1312%33%41%
2292
September1st to 15thDay
11%1312%33%36%
2160
16th to endDay
15%15%24%31%19%
1860
October1st to 15thDay
25%37%26%29%8%
1650
16th to endDay
27%414%24%21%7%
1741
November1st to 15thDay
33%6%17%25%12%4
1584
16th to endDay
35%6%15%23%15%2
1501
December1st to 15thDay
42%7%15%23%11%
1440
16th to endDay
46%10%13%18%11%1
1536
January1st to 15thNight
36%8%18%23%11%1
2506
16th to endNight
36%6%14%21%14%7%
2532
February1st to 15thNight
38%6%16%21%13%3
2283
16th to endNight
38%5%16%26%10%2
1895
March1st to 15thNight
37%8%19%18%13%2
2088
16th to endNight
35%8%20%21%11%2
2040
April1st to 15thNight
37%8%17%23%11%1
1799
16th to endNight
25%6%18%28%16%3
1800
May1st to 15thNight
22%312%29%24%6%
1556
16th to endNight
31%5%16%26%15%5%
1496
June1st to 15thNight
25%5%13%22%24%8%
1440
16th to endNight
14%26%17%38%20%
1440
July1st to 15thNight
10%1316%28%40%
1360
16th to endNight
9%1211%25%50%
1449
August1st to 15thNight
12%3317%25%38%
1629
16th to endNight
8%1213%33%39%
1910
September1st to 15thNight
9%2412%31%38%
1800
16th to endNight
13%25%26%30%22%
1789
October1st to 15thNight
21%210%26%27%10%
1980
16th to endNight
23%5%14%26%22%7%
2131
November1st to 15thNight
29%8%18%24%14%4
2275
16th to endNight
29%6%18%26%15%4
2457
December1st to 15thNight
38%8%14%24%14%
2520
16th to endNight
42%8%13%19%14%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
23%16%36%21%1
60
16th to endDay
19%11%27%23%14%2
217
February1st to 15thDay
16%18%23%27%14%
237
16th to endDay
17%20%23%29%8%
238
March1st to 15thDay
22%20%27%17%11%1
270
16th to endDay
20%26%26%17%8%
288
April1st to 15thDay
18%25%24%19%9%2
269
16th to endDay
18%24%29%15%12%1
270
May1st to 15thDay
12%23%28%25%6%3
288
16th to endDay
16%16%23%21%17%4
330
June1st to 15thDay
12%19%26%22%14%4
315
16th to endDay
414%27%25%20%7%
315
July1st to 15thDay
15%25%38%22%6%
305
16th to endDay
18%24%38%18%8%
327
August1st to 15thDay
36%26%33%20%9%
315
16th to endDay
26%28%30%20%11%
332
September1st to 15thDay
35%24%33%27%5%
315
16th to endDay
5%13%23%29%25%3
258
October1st to 15thDay
12%13%27%26%16%3
255
16th to endDay
15%17%25%28%13%
253
November1st to 15thDay
12%6%20%25%30%5%
90
16th to endDay
11%24%31%22%7%2
70
December1st to 15thDay
25%20%31%20%3
60
16th to endDay
12%15%25%26%18%1
64
January1st to 15thNight
10%7%16%37%21%5%
720
16th to endNight
11%6%18%34%21%7%
768
February1st to 15thNight
11%9%19%34%21%3
704
16th to endNight
10%13%17%35%20%2
632
March1st to 15thNight
13%10%21%30%20%4
720
16th to endNight
10%18%21%29%16%2
768
April1st to 15thNight
10%15%21%34%17%1
719
16th to endNight
8%13%22%28%21%5%
720
May1st to 15thNight
6%8%26%32%22%3
476
16th to endNight
8%5%21%30%30%2
375
June1st to 15thNight
46%18%39%28%3
360
16th to endNight
3312%45%33%1
360
July1st to 15thNight
26%44%45%2
340
16th to endNight
16%43%44%3
412
August1st to 15thNight
3440%45%5%
556
16th to endNight
110%41%39%5%
764
September1st to 15thNight
29%33%44%9%
720
16th to endNight
4314%29%35%11%
660
October1st to 15thNight
7%6%16%34%27%7%
660
16th to endNight
7%7%13%32%27%10%
704
November1st to 15thNight
9%5%16%39%23%6%
700
16th to endNight
6%11%22%32%22%5%
720
December1st to 15thNight
10%10%19%34%20%5%
720
16th to endNight
14%14%20%31%17%1
768
Page generated at 2017-09-17 09:05:47. Version ac04

Copyright 2017 A. Danko


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