Mano Prieto Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mano Prieto Observatory clear sky chart from 2005-11-05 to 2017-03-15.

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
62%
14832
31%
45254
23%
14791
71%
14791
44%
23397

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
53%
716
34%
2148
21%
716
66%
716
43%
1130
January16th to endNight
52%
768
38%
2304
24%
768
66%
768
45%
1171
February1st to 15thNight
56%
701
36%
2107
22%
696
70%
696
49%
1022
February16th to endNight
45%
632
35%
1894
18%
632
60%
632
49%
921
March1st to 15thNight
52%
720
34%
2139
19%
720
64%
720
46%
1073
March16th to endNight
48%
596
35%
1828
20%
596
63%
596
46%
901
April1st to 15thNight
45%
494
36%
1648
22%
494
64%
494
41%
792
April16th to endNight
50%
495
34%
1650
24%
495
67%
495
48%
741
May1st to 15thNight
50%
494
29%
1649
22%
494
65%
494
42%
817
May16th to endNight
63%
513
25%
1615
24%
513
69%
513
38%
873
June1st to 15thNight
75%
495
26%
1485
24%
495
80%
495
50%
746
June16th to endNight
75%
495
21%
1485
22%
495
77%
495
39%
831
July1st to 15thNight
81%
465
20%
1544
24%
465
81%
465
37%
849
July16th to endNight
82%
522
21%
1631
23%
489
84%
489
34%
909
August1st to 15thNight
86%
494
25%
1639
33%
491
86%
491
41%
846
August16th to endNight
78%
525
20%
1750
23%
525
78%
525
29%
1050
September1st to 15thNight
77%
495
20%
1659
22%
495
77%
495
29%
988
September16th to endNight
77%
492
25%
1815
28%
492
78%
492
29%
1028
October1st to 15thNight
73%
511
33%
1831
33%
511
76%
511
43%
876
October16th to endNight
71%
704
37%
2112
26%
704
77%
704
55%
998
November1st to 15thNight
68%
781
38%
2181
24%
781
74%
781
60%
1035
November16th to endNight
63%
900
38%
2340
21%
900
71%
900
56%
1202
December1st to 15thNight
56%
900
37%
2340
21%
900
64%
900
48%
1292
December16th to endNight
49%
924
38%
2460
19%
924
61%
924
47%
1306

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
431342445%7%56%
45438
Night
321332445%7%59%
45479
Cloud CoverDay
431332445%7%56%
45436
Night
321332445%7%59%
45479
TransparencyDay
24%5%9%17%24%18%
45158
Night
22%5%9%18%24%19%
45261
SeeingDay
6%6%21%30%25%8%
4459
Night
5%422%39%25%2
14842

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
45%14322346%60%
1790
16th to endDay
3423213346%63%
1920
February1st to 15thDay
22121145%46%67%
1750
16th to endDay
1212312347%69%
1580
March1st to 15thDay
132343445%7%59%
1815
16th to endDay
2313324347%64%
2043
April1st to 15thDay
2212314447%63%
1970
16th to endDay
1212212336%71%
1980
May1st to 15thDay
321232345%7%62%
1971
16th to endDay
321232445%8%61%
2144
June1st to 15thDay
1123245%7%8%63%
2145
16th to endDay
4313426%6%8%10%46%
2145
July1st to 15thDay
7%4245%47%7%7%11%36%
1980
16th to endDay
6%325%7%48%8%8%9%35%
2109
August1st to 15thDay
5%3146%38%8%9%11%37%
1980
16th to endDay
7%5%36%6%5%7%8%8%8%32%
2100
September1st to 15thDay
11%5%25%6%37%7%6%7%34%
1969
16th to endDay
7%5%25%5%3445%7%47%
1815
October1st to 15thDay
4412323446%61%
1796
16th to endDay
32321233471%
1760
November1st to 15thDay
3312212245%69%
1663
16th to endDay
4212212235%70%
1620
December1st to 15thDay
3323313347%63%
1620
16th to endDay
332322345%6%62%
1773
January1st to 15thNight
4324433445%59%
2148
16th to endNight
5%21332345%7%60%
2304
February1st to 15thNight
121232435%6%65%
2102
16th to endNight
222233446%66%
1894
March1st to 15thNight
331242335%7%61%
2139
16th to endNight
3313423346%64%
1828
April1st to 15thNight
4313313446%63%
1648
16th to endNight
221222424469%
1650
May1st to 15thNight
321342445%6%60%
1649
16th to endNight
4214425%5%6%7%55%
1614
June1st to 15thNight
212235%6%9%10%55%
1485
16th to endNight
4213335%6%9%11%48%
1485
July1st to 15thNight
3214426%5%8%11%48%
1644
16th to endNight
4314335%6%7%13%46%
1751
August1st to 15thNight
3112435%5%8%17%45%
1650
16th to endNight
43146%46%7%8%12%41%
1750
September1st to 15thNight
7%4244346%7%10%44%
1659
16th to endNight
5%424435%5%6%9%47%
1815
October1st to 15thNight
4213413447%61%
1831
16th to endNight
2312313335%70%
2112
November1st to 15thNight
2212212346%71%
2181
16th to endNight
3212323335%70%
2340
December1st to 15thNight
4213423347%61%
2340
16th to endNight
341332333466%
2460

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
5%5%23323336%60%
1790
16th to endDay
4413223346%63%
1920
February1st to 15thDay
22121145%5%5%67%
1750
16th to endDay
122212347%69%
1580
March1st to 15thDay
13135%2435%7%59%
1815
16th to endDay
2312324446%64%
2041
April1st to 15thDay
221231445%6%64%
1970
16th to endDay
222212346%71%
1980
May1st to 15thDay
321332435%6%63%
1971
16th to endDay
322224449%61%
2144
June1st to 15thDay
1113245%6%8%63%
2145
16th to endDay
4313436%6%8%10%46%
2145
July1st to 15thDay
7%425%5%46%7%8%10%37%
1980
16th to endDay
6%425%7%47%8%7%9%35%
2109
August1st to 15thDay
6%2145%47%7%10%11%37%
1980
16th to endDay
8%5%35%6%5%7%7%8%8%32%
2100
September1st to 15thDay
12%5%26%5%46%7%7%8%33%
1969
16th to endDay
8%5%25%5%345%5%7%46%
1815
October1st to 15thDay
5%312324446%61%
1796
16th to endDay
32231233471%
1760
November1st to 15thDay
3312212335%69%
1663
16th to endDay
4212212136%70%
1620
December1st to 15thDay
3324223347%63%
1620
16th to endDay
3322223447%62%
1773
January1st to 15thNight
4424424345%60%
2148
16th to endNight
5%212413447%60%
2304
February1st to 15thNight
132324346%65%
2102
16th to endNight
222224347%65%
1894
March1st to 15thNight
331332335%7%61%
2139
16th to endNight
3213423345%64%
1828
April1st to 15thNight
4313313446%63%
1648
16th to endNight
2212324345%69%
1650
May1st to 15thNight
422342445%5%60%
1649
16th to endNight
4214325%5%6%8%55%
1614
June1st to 15thNight
212335%7%8%9%55%
1485
16th to endNight
4213335%7%9%10%48%
1485
July1st to 15thNight
3214426%6%7%11%49%
1644
16th to endNight
4314435%6%7%13%46%
1751
August1st to 15thNight
3212435%6%8%16%46%
1650
16th to endNight
43136%45%6%8%11%42%
1750
September1st to 15thNight
7%424435%6%7%11%43%
1659
16th to endNight
6%424435%6%6%9%47%
1815
October1st to 15thNight
5%214322447%61%
1831
16th to endNight
231231234471%
2112
November1st to 15thNight
3212112345%72%
2181
16th to endNight
321232323470%
2340
December1st to 15thNight
4313324346%61%
2340
16th to endNight
341332333466%
2460

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
25%3417%30%17%
1791
16th to endDay
21%36%14%33%20%
1920
February1st to 15thDay
16%46%14%26%31%
1751
16th to endDay
15%2416%35%26%
1580
March1st to 15thDay
22%36%16%26%24%
1815
16th to endDay
19%36%13%28%29%
2043
April1st to 15thDay
19%47%9%29%30%
1970
16th to endDay
14%25%8%32%36%
1980
May1st to 15thDay
20%37%13%24%31%
1971
16th to endDay
19%49%17%24%24%
2147
June1st to 15thDay
14%5%10%20%27%21%
2145
16th to endDay
27%8%12%21%19%10%
2145
July1st to 15thDay
36%10%13%22%14%2
1851
16th to endDay
37%9%17%25%9%1
1966
August1st to 15thDay
33%9%17%26%12%1
1967
16th to endDay
42%10%15%18%11%1
2100
September1st to 15thDay
43%9%14%19%9%3
1969
16th to endDay
34%6%11%19%20%7%
1815
October1st to 15thDay
21%5%10%23%21%17%
1796
16th to endDay
17%15%16%28%29%
1760
November1st to 15thDay
17%37%19%29%23%
1663
16th to endDay
18%16%15%32%26%
1620
December1st to 15thDay
21%36%18%32%18%
1620
16th to endDay
20%36%21%32%15%
1773
January1st to 15thNight
25%36%14%29%20%
2148
16th to endNight
22%35%15%33%19%
2304
February1st to 15thNight
18%45%11%26%33%
2112
16th to endNight
19%35%9%32%29%
1894
March1st to 15thNight
21%35%15%27%26%
2139
16th to endNight
21%35%13%26%28%
1828
April1st to 15thNight
21%46%12%26%28%
1648
16th to endNight
17%36%11%24%36%
1650
May1st to 15thNight
22%5%6%15%19%29%
1650
16th to endNight
25%7%9%18%18%21%
1616
June1st to 15thNight
17%7%14%23%23%13%
1485
16th to endNight
25%8%16%20%18%11%
1485
July1st to 15thNight
25%8%18%29%15%2
1544
16th to endNight
25%11%19%29%12%1
1631
August1st to 15thNight
20%9%21%29%17%
1639
16th to endNight
31%10%15%26%13%2
1750
September1st to 15thNight
30%11%20%23%10%3
1659
16th to endNight
30%9%13%20%18%7%
1815
October1st to 15thNight
22%412%23%19%17%
1831
16th to endNight
17%35%13%28%31%
2112
November1st to 15thNight
15%36%18%34%22%
2181
16th to endNight
18%25%13%30%30%
2340
December1st to 15thNight
23%4420%28%19%
2340
16th to endNight
22%25%18%34%16%
2460

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
10%14%35%25%14%
90
16th to endDay
8%25%28%23%9%5%
96
February1st to 15thDay
310%23%23%37%2
90
16th to endDay
11%14%28%28%14%2
81
March1st to 15thDay
5%43%30%14%3
107
16th to endDay
215%50%24%6%
224
April1st to 15thDay
417%48%22%7%
209
16th to endDay
122%43%26%4
210
May1st to 15thDay
316%45%27%7%
228
16th to endDay
35%29%42%18%1
359
June1st to 15thDay
1113%43%33%6%
420
16th to endDay
6%7%35%43%7%
420
July1st to 15thDay
8%434%35%15%
245
16th to endDay
5%1428%42%17%
271
August1st to 15thDay
8%5%19%43%22%
255
16th to endDay
13%1431%35%14%
268
September1st to 15thDay
10%210%27%34%15%
244
16th to endDay
10%111%28%34%14%
90
October1st to 15thDay
18%115%22%30%12%
90
16th to endDay
5%420%23%25%20%
96
November1st to 15thDay
16%8%25%21%18%8%
90
16th to endDay
13%14%24%32%11%4
90
December1st to 15thDay
10%8%23%41%15%1
90
16th to endDay
8%16%36%27%11%
96
January1st to 15thNight
6%430%38%17%2
720
16th to endNight
6%7%29%39%15%1
768
February1st to 15thNight
36%31%36%19%1
704
16th to endNight
48%39%37%9%
632
March1st to 15thNight
48%31%36%16%1
720
16th to endNight
37%35%38%13%1
596
April1st to 15thNight
6%9%35%39%9%
494
16th to endNight
37%34%43%9%
495
May1st to 15thNight
5%434%42%11%
495
16th to endNight
3325%46%19%
515
June1st to 15thNight
117%54%25%
495
16th to endNight
419%52%31%1
495
July1st to 15thNight
45%43%43%2
465
16th to endNight
4241%47%3
522
August1st to 15thNight
3123%64%7%
494
16th to endNight
5%228%58%3
525
September1st to 15thNight
8%1428%50%6%
495
16th to endNight
7%7%40%38%5%
492
October1st to 15thNight
7%112%44%31%3
511
16th to endNight
5%217%35%30%8%
704
November1st to 15thNight
4222%36%28%5%
781
16th to endNight
45%21%39%25%3
900
December1st to 15thNight
6%427%40%18%2
900
16th to endNight
5%9%30%37%13%2
924
Page generated at 2017-03-16 10:05:31. Version ac04

Copyright 2017 A. Danko


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