Gold Ridge observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gold Ridge observatory clear sky chart from 2005-11-05 to 2017-10-31.

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
48%
15566
23%
47453
16%
15523
57%
15523
28%
29081

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
25%
720
24%
2327
10%
716
42%
716
21%
1436
January16th to endNight
25%
768
24%
2379
11%
768
39%
768
20%
1549
February1st to 15thNight
28%
704
25%
2112
9%
701
44%
701
25%
1323
February16th to endNight
24%
631
23%
1893
8%
631
37%
631
23%
1200
March1st to 15thNight
29%
720
22%
2103
11%
720
39%
720
25%
1317
March16th to endNight
38%
768
23%
2112
12%
768
47%
768
29%
1316
April1st to 15thNight
41%
569
25%
1827
16%
569
53%
569
30%
1047
April16th to endNight
49%
540
26%
1758
18%
540
59%
540
32%
994
May1st to 15thNight
51%
540
23%
1620
13%
540
59%
540
32%
978
May16th to endNight
64%
561
22%
1682
17%
561
67%
561
34%
1007
June1st to 15thNight
73%
540
16%
1620
14%
540
74%
540
32%
1015
June16th to endNight
78%
540
18%
1620
16%
540
78%
540
35%
963
July1st to 15thNight
75%
510
15%
1530
14%
510
77%
510
29%
981
July16th to endNight
71%
564
15%
1595
14%
531
73%
531
28%
1048
August1st to 15thNight
74%
539
18%
1730
21%
536
75%
536
28%
1101
August16th to endNight
68%
573
18%
1910
21%
573
69%
573
23%
1256
September1st to 15thNight
67%
666
20%
1926
19%
666
68%
666
29%
1240
September16th to endNight
63%
717
27%
1980
20%
717
67%
717
35%
1214
October1st to 15thNight
57%
720
33%
1980
25%
720
64%
720
42%
1127
October16th to endNight
49%
768
35%
2297
26%
768
61%
768
37%
1272
November1st to 15thNight
50%
700
30%
2276
24%
700
61%
700
36%
1207
November16th to endNight
38%
720
26%
2340
17%
720
51%
720
27%
1371
December1st to 15thNight
35%
720
23%
2340
15%
720
46%
720
24%
1449
December16th to endNight
32%
768
19%
2496
14%
768
40%
768
19%
1670

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
12%5%25%5%35%5%5%7%40%
48287
Night
11%5%2442445%7%46%
47652
TransparencyDay
41%7%11%17%17%4
47988
Night
35%6%11%19%19%6%
47455
SeeingDay
15%6%19%23%21%13%
5461
Night
14%8%22%27%22%4
15568

By Month

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
17%7%34323346%43%
1611
16th to endDay
16%6%24423345%44%
1842
February1st to 15thDay
15%7%245%24445%43%
1750
16th to endDay
18%6%24434335%43%
1580
March1st to 15thDay
16%7%35%6%23346%40%
1854
16th to endDay
16%5%25%42345%8%41%
2111
April1st to 15thDay
13%6%245%34347%44%
2131
16th to endDay
10%5%25%435%46%6%47%
2199
May1st to 15thDay
10%5%25%5%35%45%7%42%
2331
16th to endDay
7%5%346%36%6%5%8%41%
2431
June1st to 15thDay
9%5%26%6%47%7%7%10%30%
2340
16th to endDay
5%2246%46%7%9%10%39%
2340
July1st to 15thDay
9%5%37%7%48%7%8%10%27%
2340
16th to endDay
7%5%26%7%49%7%8%10%28%
2465
August1st to 15thDay
7%5%26%6%6%8%8%8%11%28%
2216
16th to endDay
14%6%37%7%46%6%6%9%28%
2292
September1st to 15thDay
13%6%26%6%45%5%7%7%34%
2021
16th to endDay
14%5%25%5%335%46%43%
1980
October1st to 15thDay
13%5%24323447%49%
1980
16th to endDay
11%41442333457%
1923
November1st to 15thDay
12%5%24323335%53%
1582
16th to endDay
14%6%1341335%6%49%
1620
December1st to 15thDay
16%7%25%424446%39%
1620
16th to endDay
23%8%35%5%2323435%
1728
January1st to 15thNight
16%6%25%324336%43%
2327
16th to endNight
17%7%35%424445%41%
2379
February1st to 15thNight
14%5%235%2435%5%45%
2103
16th to endNight
16%5%24424345%45%
1893
March1st to 15thNight
14%5%2442435%8%44%
2103
16th to endNight
11%5%145%2445%8%46%
2112
April1st to 15thNight
12%41332445%8%49%
1827
16th to endNight
9%42342445%6%52%
1758
May1st to 15thNight
9%3145%35%6%6%8%47%
1619
16th to endNight
6%425%4336%5%8%49%
1682
June1st to 15thNight
3325%5%46%6%9%12%40%
1620
16th to endNight
3324435%6%8%12%45%
1620
July1st to 15thNight
5%225%5%36%8%8%12%39%
1620
16th to endNight
5%325%6%37%7%8%11%37%
1703
August1st to 15thNight
4425%5%47%6%7%10%40%
1741
16th to endNight
11%5%25%6%35%6%6%10%36%
1910
September1st to 15thNight
8%425%5%45%5%6%9%42%
1926
16th to endNight
10%415%42345%6%50%
1980
October1st to 15thNight
10%413323336%57%
1980
16th to endNight
9%41442334359%
2297
November1st to 15thNight
10%5%13323235%58%
2276
16th to endNight
11%6%25%424435%50%
2340
December1st to 15thNight
14%7%35%424346%45%
2340
16th to endNight
20%7%35%423346%36%
2496

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
43%37%14%25%4
1612
16th to endDay
41%37%18%21%8%
1842
February1st to 15thDay
42%47%19%23%3
1752
16th to endDay
44%36%16%22%6%
1580
March1st to 15thDay
45%48%15%19%6%
1854
16th to endDay
40%6%11%19%17%3
2112
April1st to 15thDay
40%49%20%18%7%
2131
16th to endDay
35%5%9%20%24%4
2199
May1st to 15thDay
39%6%12%17%19%4
2331
16th to endDay
38%8%12%23%13%2
2435
June1st to 15thDay
44%10%14%19%9%
2340
16th to endDay
33%11%17%21%13%2
2340
July1st to 15thDay
45%12%18%15%6%1
2201
16th to endDay
45%12%16%16%8%
2310
August1st to 15thDay
44%12%16%17%7%1
2203
16th to endDay
50%9%14%14%9%1
2292
September1st to 15thDay
45%9%12%15%12%4
2021
16th to endDay
40%6%11%17%21%2
1980
October1st to 15thDay
34%5%8%17%25%8%
1980
16th to endDay
30%3416%31%12%
1923
November1st to 15thDay
34%26%15%29%11%
1582
16th to endDay
35%46%16%26%9%
1620
December1st to 15thDay
43%5%9%18%16%7%
1620
16th to endDay
52%36%17%14%5%
1728
January1st to 15thNight
41%36%18%24%5%
2327
16th to endNight
44%45%17%19%8%
2379
February1st to 15thNight
40%36%19%20%10%
2112
16th to endNight
40%36%17%24%6%
1893
March1st to 15thNight
38%5%10%20%18%7%
2103
16th to endNight
35%5%9%23%21%4
2112
April1st to 15thNight
33%49%22%20%9%
1827
16th to endNight
31%5%10%23%21%7%
1758
May1st to 15thNight
32%7%13%18%24%3
1620
16th to endNight
30%8%14%27%15%4
1684
June1st to 15thNight
30%11%20%23%12%
1620
16th to endNight
28%9%20%21%16%2
1620
July1st to 15thNight
31%13%20%22%10%1
1530
16th to endNight
34%11%22%18%11%1
1595
August1st to 15thNight
34%11%16%23%12%2
1730
16th to endNight
40%10%17%17%12%2
1910
September1st to 15thNight
35%9%16%19%14%4
1926
16th to endNight
32%6%11%22%19%6%
1980
October1st to 15thNight
28%39%24%24%9%
1980
16th to endNight
28%4413%33%14%
2297
November1st to 15thNight
29%26%17%29%14%
2276
16th to endNight
36%37%15%24%12%
2340
December1st to 15thNight
40%39%19%19%7%
2340
16th to endNight
48%38%16%17%5%
2496

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
25%17%33%16%42
90
16th to endDay
23%28%38%5%31
96
February1st to 15thDay
23%24%38%11%2
90
16th to endDay
29%8%49%12%
81
March1st to 15thDay
21%19%38%14%32
144
16th to endDay
20%11%29%23%12%1
288
April1st to 15thDay
20%13%27%18%17%1
270
16th to endDay
14%6%28%28%16%5%
270
May1st to 15thDay
16%10%23%21%16%11%
288
16th to endDay
13%314%30%22%16%
331
June1st to 15thDay
13%13%24%23%24%
315
16th to endDay
7%13%24%26%26%
315
July1st to 15thDay
6%17%26%30%27%
305
16th to endDay
8%18%19%31%30%
326
August1st to 15thDay
11%6%26%35%18%
313
16th to endDay
15%7%26%30%18%
332
September1st to 15thDay
14%37%21%34%17%
315
16th to endDay
15%114%28%29%9%
314
October1st to 15thDay
16%124%28%21%6%
315
16th to endDay
13%8%21%26%23%6%
297
November1st to 15thDay
24%20%15%31%7%1
90
16th to endDay
12%14%42%17%12%1
90
December1st to 15thDay
22%23%38%7%6%1
90
16th to endDay
35%12%29%16%5%1
96
January1st to 15thNight
23%15%32%22%5%
720
16th to endNight
21%16%33%23%4
768
February1st to 15thNight
19%13%33%28%4
704
16th to endNight
20%18%33%24%3
631
March1st to 15thNight
17%15%33%25%6%
720
16th to endNight
14%13%30%27%14%
768
April1st to 15thNight
15%9%31%26%15%1
569
16th to endNight
11%7%27%35%15%1
540
May1st to 15thNight
10%5%26%28%24%4
540
16th to endNight
10%15%33%34%5%
563
June1st to 15thNight
5%110%35%36%11%
540
16th to endNight
46%30%44%14%
540
July1st to 15thNight
5%7%21%48%15%
510
16th to endNight
7%16%22%45%17%
564
August1st to 15thNight
6%6%24%47%14%
539
16th to endNight
13%15%26%40%12%
573
September1st to 15thNight
11%11%25%40%10%
666
16th to endNight
12%114%32%33%5%
717
October1st to 15thNight
12%322%31%24%5%
720
16th to endNight
12%9%23%28%22%3
768
November1st to 15thNight
13%7%25%29%21%3
700
16th to endNight
16%14%27%28%12%
720
December1st to 15thNight
20%10%29%29%9%
720
16th to endNight
25%12%27%26%7%
768
Page generated at 2017-11-01 16:23:32. Version ac04

Copyright 2017 A. Danko


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