Lost Silver Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lost Silver Observatory clear sky chart from 2005-11-05 to 2018-01-20.

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
77%
16107
37%
48455
33%
16069
81%
16069
55%
22742

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
76%
778
34%
2522
36%
776
80%
776
52%
1154
January16th to endNight
69%
788
36%
2561
36%
788
76%
788
42%
1286
February1st to 15thNight
74%
699
37%
2187
37%
699
81%
699
57%
977
February16th to endNight
67%
632
40%
1839
36%
632
74%
632
52%
906
March1st to 15thNight
69%
720
41%
1980
33%
720
76%
720
61%
945
March16th to endNight
75%
768
39%
2112
30%
768
82%
768
63%
991
April1st to 15thNight
68%
695
36%
1954
26%
695
76%
695
59%
924
April16th to endNight
72%
540
45%
1782
40%
540
82%
540
72%
655
May1st to 15thNight
72%
539
41%
1619
31%
539
80%
539
73%
642
May16th to endNight
77%
561
43%
1684
33%
561
84%
561
75%
658
June1st to 15thNight
85%
540
35%
1620
31%
540
86%
540
72%
661
June16th to endNight
87%
540
32%
1620
28%
540
88%
540
66%
699
July1st to 15thNight
83%
510
19%
1530
17%
510
83%
510
42%
827
July16th to endNight
82%
564
18%
1593
16%
531
81%
531
31%
979
August1st to 15thNight
86%
539
25%
1611
23%
536
86%
536
42%
868
August16th to endNight
83%
618
30%
1893
30%
618
83%
618
41%
1040
September1st to 15thNight
80%
720
29%
1980
26%
720
81%
720
43%
1158
September16th to endNight
86%
716
46%
1980
37%
716
89%
716
70%
900
October1st to 15thNight
80%
720
41%
2082
32%
720
86%
720
69%
902
October16th to endNight
87%
768
46%
2304
42%
768
90%
768
72%
958
November1st to 15thNight
82%
760
43%
2280
39%
760
85%
760
67%
971
November16th to endNight
73%
780
40%
2483
40%
780
77%
780
53%
1144
December1st to 15thNight
72%
780
38%
2535
38%
780
77%
780
51%
1149
December16th to endNight
68%
832
37%
2704
38%
832
73%
832
45%
1348

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
3213323446%64%
49067
Night
2212223346%67%
48651
TransparencyDay
19%35%10%25%35%
48762
Night
16%35%13%26%33%
48457
SeeingDay
5%6%18%31%26%11%
5830
Night
3211%37%37%7%
16117

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
221332445%5%63%
1746
16th to endDay
4413313346%62%
1766
February1st to 15thDay
5%312212236%67%
1673
16th to endDay
4323323445%63%
1633
March1st to 15thDay
2212213346%67%
1980
16th to endDay
211221223375%
2112
April1st to 15thDay
212212346%71%
1992
16th to endDay
11111112482%
2175
May1st to 15thDay
1111233478%
2331
16th to endDay
1111122383%
2429
June1st to 15thDay
21112235%78%
2340
16th to endDay
21221334472%
2340
July1st to 15thDay
4315%6%46%7%8%8%40%
2340
16th to endDay
6%5%27%9%5%8%7%7%11%27%
2467
August1st to 15thDay
6%425%6%47%7%7%8%39%
2340
16th to endDay
3315%6%45%5%7%9%46%
2305
September1st to 15thDay
6%4145%35%5%6%6%49%
1980
16th to endDay
31222234372%
1980
October1st to 15thDay
21121323476%
1878
16th to endDay
11121223478%
1920
November1st to 15thDay
112222335%74%
1909
16th to endDay
222213325%71%
1804
December1st to 15thDay
6%213323347%61%
1755
16th to endDay
5%31332345%7%61%
1872
January1st to 15thNight
4212223345%66%
2522
16th to endNight
431342445%5%59%
2561
February1st to 15thNight
3212313346%68%
2176
16th to endNight
2412223337%64%
1839
March1st to 15thNight
3112212345%70%
1980
16th to endNight
21121334473%
2112
April1st to 15thNight
2212213335%71%
1954
16th to endNight
1111111384%
1782
May1st to 15thNight
121246%78%
1619
16th to endNight
111221383%
1684
June1st to 15thNight
211222480%
1620
16th to endNight
212212236%74%
1620
July1st to 15thNight
22135%45%6%7%10%49%
1620
16th to endNight
3313447%8%10%16%34%
1701
August1st to 15thNight
22134246%8%10%53%
1620
16th to endNight
3323435%5%7%10%51%
1893
September1st to 15thNight
5%314425%46%8%53%
1980
16th to endNight
11121223477%
1980
October1st to 15thNight
11111222479%
2082
16th to endNight
11111222480%
2304
November1st to 15thNight
121212236%74%
2280
16th to endNight
4213322236%67%
2483
December1st to 15thNight
5%312212336%66%
2535
16th to endNight
4314323335%62%
2704

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
20%45%12%27%30%
1747
16th to endDay
22%3215%27%28%
1766
February1st to 15thDay
19%2212%28%35%
1673
16th to endDay
22%2313%29%28%
1633
March1st to 15thDay
17%226%32%39%
1980
16th to endDay
14%138%32%40%
2112
April1st to 15thDay
14%125%36%39%
1992
16th to endDay
9%116%26%55%
2175
May1st to 15thDay
9%126%22%57%
2331
16th to endDay
8%125%26%57%
2432
June1st to 15thDay
8%12321%62%
2340
16th to endDay
15%235%17%55%
2340
July1st to 15thDay
33%9%13%13%13%16%
2201
16th to endDay
46%10%16%17%6%2
2312
August1st to 15thDay
35%10%12%13%15%12%
2325
16th to endDay
31%7%12%18%16%14%
2305
September1st to 15thDay
31%6%8%16%18%18%
1980
16th to endDay
16%247%33%35%
1980
October1st to 15thDay
12%249%29%41%
1878
16th to endDay
9%139%26%49%
1920
November1st to 15thDay
11%2212%35%36%
1909
16th to endDay
15%139%29%39%
1804
December1st to 15thDay
22%2415%31%24%
1755
16th to endDay
21%45%16%31%19%
1872
January1st to 15thNight
18%25%13%29%29%
2522
16th to endNight
24%3413%30%22%
2561
February1st to 15thNight
16%25%15%25%34%
2187
16th to endNight
19%2313%34%26%
1839
March1st to 15thNight
15%2210%29%39%
1980
16th to endNight
13%2410%31%37%
2112
April1st to 15thNight
15%228%35%35%
1954
16th to endNight
8%117%26%54%
1782
May1st to 15thNight
8%127%27%52%
1620
16th to endNight
7%116%25%57%
1685
June1st to 15thNight
9%11421%61%
1620
16th to endNight
12%24419%57%
1620
July1st to 15thNight
23%7%18%16%16%17%
1530
16th to endNight
30%11%22%23%9%2
1593
August1st to 15thNight
21%9%13%23%18%13%
1611
16th to endNight
25%7%14%18%20%14%
1893
September1st to 15thNight
26%6%9%21%20%15%
1980
16th to endNight
10%2313%36%33%
1980
October1st to 15thNight
10%2414%26%41%
2082
16th to endNight
9%1310%26%47%
2304
November1st to 15thNight
12%1315%33%34%
2280
16th to endNight
18%238%27%38%
2483
December1st to 15thNight
19%2417%30%26%
2535
16th to endNight
23%36%16%28%21%
2704

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
6%5%14%34%33%4
135
16th to endDay
48%14%34%25%11%
109
February1st to 15thDay
5%11%15%37%25%4
188
16th to endDay
7%13%35%27%13%1
238
March1st to 15thDay
7%12%27%27%17%8%
270
16th to endDay
315%27%31%14%7%
288
April1st to 15thDay
312%34%24%15%7%
269
16th to endDay
118%31%30%11%6%
270
May1st to 15thDay
413%27%32%13%8%
288
16th to endDay
18%28%38%18%4
330
June1st to 15thDay
4223%41%20%6%
315
16th to endDay
49%42%28%13%
315
July1st to 15thDay
7%7%34%35%14%
305
16th to endDay
8%7%23%32%27%
327
August1st to 15thDay
7%7%23%41%19%
315
16th to endDay
415%21%42%24%
332
September1st to 15thDay
11%110%32%31%12%
315
16th to endDay
6%316%33%28%11%
315
October1st to 15thDay
25%19%29%29%13%
213
16th to endDay
37%24%45%19%
144
November1st to 15thDay
3314%30%40%6%
135
16th to endDay
15%16%30%36%9%
135
December1st to 15thDay
8%212%29%38%8%
135
16th to endDay
12%221%22%27%13%
144
January1st to 15thNight
5%210%45%30%5%
780
16th to endNight
6%213%43%28%4
788
February1st to 15thNight
3313%43%31%4
704
16th to endNight
5%5%19%46%20%2
632
March1st to 15thNight
2320%40%27%4
720
16th to endNight
2315%42%30%5%
768
April1st to 15thNight
3418%49%22%2
695
16th to endNight
2419%48%22%4
540
May1st to 15thNight
320%42%30%2
540
16th to endNight
1217%41%34%3
563
June1st to 15thNight
218%48%37%2
540
16th to endNight
1336%53%3
540
July1st to 15thNight
2424%58%8%
510
16th to endNight
5%115%59%18%
564
August1st to 15thNight
2115%61%18%
539
16th to endNight
4117%60%15%
618
September1st to 15thNight
5%322%53%14%
720
16th to endNight
27%35%44%9%
716
October1st to 15thNight
1113%36%38%7%
720
16th to endNight
17%34%43%11%
768
November1st to 15thNight
211%39%38%7%
760
16th to endNight
5%113%38%33%8%
780
December1st to 15thNight
6%311%41%30%6%
780
16th to endNight
6%314%42%26%6%
832
Page generated at 2018-01-21 10:19:21. Version ac04

Copyright 2018 A. Danko


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