Echo Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Echo Park clear sky chart from 2005-11-05 to 2017-09-19.

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
63%
15937
22%
46937
19%
15899
66%
15899
34%
27751

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
61%
781
17%
2392
16%
781
63%
781
30%
1491
January16th to endNight
60%
768
20%
2496
21%
768
62%
768
27%
1529
February1st to 15thNight
60%
697
15%
2288
17%
696
62%
696
27%
1421
February16th to endNight
53%
632
18%
1968
15%
632
60%
632
28%
1224
March1st to 15thNight
62%
720
20%
1980
17%
720
64%
720
36%
1198
March16th to endNight
54%
768
19%
2112
14%
768
58%
768
30%
1354
April1st to 15thNight
47%
563
15%
1822
12%
563
50%
563
23%
1148
April16th to endNight
48%
540
19%
1716
15%
540
52%
540
25%
1066
May1st to 15thNight
54%
540
20%
1620
16%
540
56%
540
29%
993
May16th to endNight
60%
562
20%
1524
15%
561
63%
561
33%
942
June1st to 15thNight
65%
540
22%
1440
18%
540
67%
540
42%
831
June16th to endNight
76%
540
30%
1440
27%
540
79%
540
60%
720
July1st to 15thNight
77%
510
19%
1391
17%
510
78%
510
44%
795
July16th to endNight
83%
564
23%
1593
23%
531
82%
531
46%
826
August1st to 15thNight
77%
539
22%
1611
21%
536
78%
536
43%
847
August16th to endNight
80%
573
34%
1821
34%
573
82%
573
45%
904
September1st to 15thNight
76%
543
30%
1803
31%
543
79%
543
42%
904
September16th to endNight
74%
671
35%
1875
29%
671
77%
671
51%
971
October1st to 15thNight
67%
660
28%
1980
23%
660
71%
660
42%
1088
October16th to endNight
66%
704
29%
2112
23%
704
70%
704
39%
1154
November1st to 15thNight
62%
762
25%
2225
20%
762
65%
762
35%
1306
November16th to endNight
64%
900
24%
2520
19%
900
66%
900
41%
1425
December1st to 15thNight
57%
900
13%
2520
10%
900
58%
900
29%
1647
December16th to endNight
49%
960
11%
2688
9%
960
51%
960
20%
1967

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
35%25%5%35%5%6%8%48%
47879
Night
35%25%5%35%5%5%8%49%
47123
TransparencyDay
30%7%14%21%17%8%
47567
Night
31%6%14%23%16%6%
46937
SeeingDay
7%10%26%32%18%3
5780
Night
6%417%43%24%3
15950

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
17%27%6%45%6%8%9%39%
1555
16th to endDay
29%5%7%5%45%46%6%43%
1728
February1st to 15thDay
36%38%7%36%6%7%10%35%
1575
16th to endDay
28%47%6%26%5%6%8%39%
1503
March1st to 15thDay
27%45%4345%6%8%47%
1980
16th to endDay
28%36%5%36%6%7%9%38%
2112
April1st to 15thDay
39%36%5%445%6%7%42%
2126
16th to endDay
5%9%48%5%46%5%6%7%36%
2241
May1st to 15thDay
6%6%36%5%35%5%6%9%41%
2331
16th to endDay
5%5%25%6%45%5%6%8%45%
2588
June1st to 15thDay
4313425%45%9%56%
2520
16th to endDay
11222335%7%69%
2520
July1st to 15thDay
23135%35%6%7%9%49%
2484
16th to endDay
2324436%5%7%9%49%
2467
August1st to 15thDay
33134346%8%10%49%
2340
16th to endDay
22123245%6%9%58%
2381
September1st to 15thDay
321442345%7%61%
2154
16th to endDay
4213222236%67%
1830
October1st to 15thDay
6%5%1342335%8%54%
1650
16th to endDay
442442446%8%53%
1760
November1st to 15thDay
2425%5%34447%56%
1618
16th to endDay
1425%5%35%6%7%8%49%
1440
December1st to 15thDay
39%47%6%46%6%6%8%36%
1440
16th to endDay
38%5%9%8%5%6%6%6%10%29%
1536
January1st to 15thNight
38%35%5%35%5%6%8%46%
2392
16th to endNight
29%47%424447%46%
2496
February1st to 15thNight
25%37%5%35%6%5%9%44%
2277
16th to endNight
18%47%6%25%45%8%43%
1968
March1st to 15thNight
36%35%43447%8%48%
1980
16th to endNight
46%36%6%36%5%5%7%42%
2112
April1st to 15thNight
5%8%35%5%37%46%7%41%
1822
16th to endNight
6%7%35%5%36%5%6%7%42%
1716
May1st to 15thNight
7%5%25%435%45%8%45%
1619
16th to endNight
6%5%34435%6%6%8%44%
1523
June1st to 15thNight
3313435%6%6%9%53%
1440
16th to endNight
121222345%6%67%
1440
July1st to 15thNight
22145%35%6%6%8%52%
1473
16th to endNight
12245%36%5%7%10%51%
1701
August1st to 15thNight
2315%4245%6%9%54%
1620
16th to endNight
2213335%5%5%9%58%
1821
September1st to 15thNight
4314325%45%8%57%
1803
16th to endNight
5%23322346%65%
1875
October1st to 15thNight
5%424433448%55%
1980
16th to endNight
45%234245%46%55%
2112
November1st to 15thNight
45%25%42446%7%52%
2225
16th to endNight
24245%2446%9%53%
2520
December1st to 15thNight
37%47%6%2445%8%43%
2520
16th to endNight
49%5%10%8%45%5%6%7%32%
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
38%11%26%18%4
1556
16th to endDay
39%9%21%20%8%1
1728
February1st to 15thDay
38%12%23%17%6%
1575
16th to endDay
40%7%18%25%7%
1503
March1st to 15thDay
32%7%19%25%12%1
1980
16th to endDay
37%9%15%27%8%2
2112
April1st to 15thDay
37%7%14%20%16%3
2126
16th to endDay
40%6%13%21%14%2
2241
May1st to 15thDay
35%7%12%20%21%2
2331
16th to endDay
32%6%12%25%19%3
2591
June1st to 15thDay
23%6%9%19%28%13%
2520
16th to endDay
13%36%11%31%34%
2520
July1st to 15thDay
25%5%12%15%17%23%
2338
16th to endDay
26%6%11%17%19%18%
2312
August1st to 15thDay
25%6%13%18%16%18%
2325
16th to endDay
19%5%9%23%26%14%
2381
September1st to 15thDay
21%310%19%25%18%
2154
16th to endDay
18%37%28%33%8%
1830
October1st to 15thDay
26%5%13%31%20%2
1650
16th to endDay
26%5%15%33%17%1
1760
November1st to 15thDay
28%5%14%31%17%2
1618
16th to endDay
28%8%22%27%12%
1440
December1st to 15thDay
42%11%26%15%3
1440
16th to endDay
48%11%19%15%3
1536
January1st to 15thNight
34%8%23%24%7%
2392
16th to endNight
37%7%19%23%10%2
2496
February1st to 15thNight
35%9%21%23%9%
2288
16th to endNight
37%6%19%24%11%
1968
March1st to 15thNight
31%6%19%28%11%2
1980
16th to endNight
38%6%15%27%9%3
2112
April1st to 15thNight
38%7%13%18%18%3
1822
16th to endNight
37%7%13%21%17%2
1716
May1st to 15thNight
35%6%11%21%20%3
1620
16th to endNight
33%6%12%23%20%2
1524
June1st to 15thNight
25%7%9%17%25%15%
1440
16th to endNight
16%25%11%26%36%
1440
July1st to 15thNight
25%6%8%18%16%24%
1391
16th to endNight
22%5%12%20%18%20%
1593
August1st to 15thNight
24%414%19%18%17%
1611
16th to endNight
22%48%19%29%15%
1821
September1st to 15thNight
24%49%18%24%19%
1803
16th to endNight
20%47%23%30%13%
1875
October1st to 15thNight
27%311%29%22%5%
1980
16th to endNight
27%5%11%29%24%2
2112
November1st to 15thNight
29%7%13%26%20%2
2225
16th to endNight
25%6%17%33%15%1
2520
December1st to 15thNight
36%9%22%24%6%
2520
16th to endNight
48%8%19%17%4
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
8%7%22%38%20%2
90
16th to endDay
9%412%50%21%2
96
February1st to 15thDay
13%221%38%20%4
90
16th to endDay
7%5%29%37%18%
108
March1st to 15thDay
6%12%33%32%12%1
270
16th to endDay
12%18%38%24%4
288
April1st to 15thDay
8%23%36%21%7%2
269
16th to endDay
14%29%27%21%8%
270
May1st to 15thDay
11%19%34%21%11%1
288
16th to endDay
11%11%25%25%20%6%
489
June1st to 15thDay
7%10%24%29%24%3
495
16th to endDay
37%23%33%28%4
495
July1st to 15thDay
45%23%29%30%7%
442
16th to endDay
4423%45%17%3
327
August1st to 15thDay
7%5%34%35%13%3
315
16th to endDay
3320%42%26%3
332
September1st to 15thDay
311%28%30%20%5%
315
16th to endDay
8%8%24%30%23%5%
249
October1st to 15thDay
35%23%35%27%4
90
16th to endDay
11%7%30%32%16%2
96
November1st to 15thDay
36%16%38%24%10%
90
16th to endDay
8%14%28%38%8%
90
December1st to 15thDay
5%6%30%52%41
90
16th to endDay
10%5%20%51%11%1
96
January1st to 15thNight
7%218%49%19%3
786
16th to endNight
8%219%48%17%2
768
February1st to 15thNight
4220%55%15%1
704
16th to endNight
46%24%50%13%
632
March1st to 15thNight
5%418%49%19%2
720
16th to endNight
7%6%24%42%17%1
768
April1st to 15thNight
11%9%25%36%14%1
563
16th to endNight
10%12%24%31%17%2
540
May1st to 15thNight
10%7%22%35%20%4
540
16th to endNight
9%5%18%36%24%5%
563
June1st to 15thNight
5%5%18%43%24%2
540
16th to endNight
2215%45%30%3
540
July1st to 15thNight
419%35%45%4
510
16th to endNight
15%36%49%6%
564
August1st to 15thNight
317%41%41%4
539
16th to endNight
316%35%42%9%
573
September1st to 15thNight
6%19%40%34%6%
543
16th to endNight
6%212%31%36%11%
671
October1st to 15thNight
9%215%41%25%5%
660
16th to endNight
7%414%39%27%5%
704
November1st to 15thNight
6%5%16%41%27%3
762
16th to endNight
47%17%47%19%3
900
December1st to 15thNight
8%320%53%13%1
900
16th to endNight
9%6%20%46%13%2
960
Page generated at 2017-09-20 02:49:46. Version ac04

Copyright 2017 A. Danko


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