Las Cienegas
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Las Cienegas clear sky chart from 2005-11-05 to 2017-12-04.

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
71%
15863
35%
47828
29%
15824
78%
15824
51%
23103

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
70%
718
32%
2327
32%
716
75%
716
50%
1092
January16th to endNight
62%
768
34%
2496
31%
768
71%
768
40%
1271
February1st to 15thNight
67%
697
36%
2202
33%
696
77%
696
52%
1004
February16th to endNight
60%
632
39%
1817
32%
632
70%
632
49%
911
March1st to 15thNight
61%
720
40%
1980
29%
720
71%
720
56%
961
March16th to endNight
67%
768
38%
2112
26%
768
78%
768
56%
1028
April1st to 15thNight
60%
677
35%
1936
22%
677
71%
677
54%
930
April16th to endNight
63%
540
44%
1800
33%
540
78%
540
64%
685
May1st to 15thNight
66%
539
39%
1637
27%
539
78%
539
68%
658
May16th to endNight
73%
561
43%
1684
33%
561
80%
561
71%
673
June1st to 15thNight
79%
540
35%
1620
29%
540
81%
540
67%
676
June16th to endNight
82%
540
29%
1620
25%
540
83%
540
55%
759
July1st to 15thNight
80%
510
16%
1530
14%
510
80%
510
36%
877
July16th to endNight
78%
564
13%
1593
11%
531
78%
531
25%
1051
August1st to 15thNight
84%
539
22%
1611
21%
536
84%
536
35%
932
August16th to endNight
80%
582
27%
1880
28%
582
81%
582
35%
1068
September1st to 15thNight
74%
720
26%
1980
22%
720
75%
720
39%
1187
September16th to endNight
82%
716
43%
1980
32%
716
88%
716
66%
914
October1st to 15thNight
78%
720
39%
2100
30%
720
84%
720
65%
922
October16th to endNight
81%
768
44%
2304
37%
768
87%
768
67%
982
November1st to 15thNight
76%
760
42%
2280
33%
760
83%
760
63%
978
November16th to endNight
68%
780
40%
2451
35%
780
75%
780
51%
1151
December1st to 15thNight
68%
736
36%
2392
36%
736
73%
736
47%
1132
December16th to endNight
62%
768
35%
2496
33%
768
68%
768
41%
1261

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
3213324446%62%
48655
Night
2213323346%65%
48033
TransparencyDay
22%46%12%27%27%
48350
Night
18%37%14%28%26%
47839
SeeingDay
7%11%23%31%19%5%
5647
Night
4414%34%34%7%
15875

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
321432435%6%61%
1611
16th to endDay
442331345%6%59%
1728
February1st to 15thDay
4413322236%67%
1649
16th to endDay
3413312345%63%
1657
March1st to 15thDay
2214223345%65%
1980
16th to endDay
2212113335%71%
2112
April1st to 15thDay
2112213345%70%
2012
16th to endDay
111111112481%
2160
May1st to 15thDay
112212335%76%
2310
16th to endDay
11121222481%
2429
June1st to 15thDay
111112235%76%
2340
16th to endDay
221222345%5%66%
2340
July1st to 15thDay
4325%7%47%8%9%10%36%
2340
16th to endDay
8%6%48%7%6%7%7%8%9%24%
2467
August1st to 15thDay
6%437%7%5%8%7%7%7%33%
2340
16th to endDay
4325%6%47%7%6%8%42%
2318
September1st to 15thDay
6%425%5%46%6%6%7%44%
1980
16th to endDay
3223235%46%65%
1980
October1st to 15thDay
212223345%71%
1860
16th to endDay
1111212236%75%
1920
November1st to 15thDay
111212346%73%
1909
16th to endDay
321221223471%
1836
December1st to 15thDay
4323323447%60%
1649
16th to endDay
442331245%7%60%
1728
January1st to 15thNight
3323213345%65%
2327
16th to endNight
5%324425%45%6%56%
2496
February1st to 15thNight
2213313337%67%
2200
16th to endNight
1313424446%63%
1817
March1st to 15thNight
2213312246%68%
1980
16th to endNight
121231333471%
2112
April1st to 15thNight
1312313325%69%
1936
16th to endNight
11111112481%
1800
May1st to 15thNight
1112246%77%
1637
16th to endNight
111212383%
1684
June1st to 15thNight
21111113478%
1620
16th to endNight
312313435%68%
1620
July1st to 15thNight
22245%37%6%8%11%45%
1620
16th to endNight
3235%6%5%7%8%11%14%31%
1701
August1st to 15thNight
22135%35%6%8%9%50%
1620
16th to endNight
4324435%5%7%9%48%
1880
September1st to 15thNight
6%42442446%9%50%
1980
16th to endNight
1111112346%74%
1980
October1st to 15thNight
111212235%77%
2100
16th to endNight
11211225%77%
2304
November1st to 15thNight
112212346%73%
2280
16th to endNight
3313312235%68%
2451
December1st to 15thNight
4313213347%63%
2392
16th to endNight
4324423446%59%
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
22%35%13%30%24%
1612
16th to endDay
23%2417%28%23%
1728
February1st to 15thDay
20%1412%31%29%
1649
16th to endDay
22%2314%30%25%
1657
March1st to 15thDay
19%237%36%29%
1980
16th to endDay
16%2310%38%29%
2112
April1st to 15thDay
15%137%41%30%
2012
16th to endDay
10%128%30%47%
2160
May1st to 15thDay
11%138%29%45%
2310
16th to endDay
9%127%31%46%
2432
June1st to 15thDay
11%125%25%53%
2340
16th to endDay
19%35%7%22%41%
2340
July1st to 15thDay
35%13%13%13%13%10%
2201
16th to endDay
50%13%18%12%5%
2312
August1st to 15thDay
44%10%10%14%15%3
2325
16th to endDay
36%9%13%16%15%9%
2318
September1st to 15thDay
36%7%10%16%18%10%
1980
16th to endDay
20%27%13%33%23%
1980
October1st to 15thDay
14%45%11%31%32%
1860
16th to endDay
12%2411%32%37%
1920
November1st to 15thDay
13%2314%38%28%
1909
16th to endDay
18%2311%30%33%
1836
December1st to 15thDay
22%25%16%33%19%
1649
16th to endDay
22%27%20%31%15%
1728
January1st to 15thNight
20%25%12%31%26%
2327
16th to endNight
25%36%17%28%19%
2496
February1st to 15thNight
17%25%15%27%31%
2211
16th to endNight
20%35%14%33%23%
1817
March1st to 15thNight
17%1312%31%32%
1980
16th to endNight
17%1411%36%29%
2112
April1st to 15thNight
17%239%40%26%
1936
16th to endNight
10%128%30%46%
1800
May1st to 15thNight
8%239%33%42%
1638
16th to endNight
7%228%34%44%
1685
June1st to 15thNight
11%12426%53%
1620
16th to endNight
15%45%8%22%43%
1620
July1st to 15thNight
25%10%20%17%14%10%
1530
16th to endNight
34%14%27%17%41
1593
August1st to 15thNight
24%12%15%21%20%5%
1611
16th to endNight
28%7%16%17%19%9%
1880
September1st to 15thNight
28%7%13%19%21%8%
1980
16th to endNight
11%36%16%38%23%
1980
October1st to 15thNight
11%26%17%30%30%
2100
16th to endNight
11%2412%30%38%
2304
November1st to 15thNight
12%1419%33%28%
2280
16th to endNight
20%1311%29%32%
2451
December1st to 15thNight
21%25%17%32%20%
2392
16th to endNight
23%47%18%28%17%
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
12%16%24%35%11%
90
16th to endDay
6%11%26%33%17%5%
96
February1st to 15thDay
7%14%26%30%17%2
164
16th to endDay
9%31%28%21%8%
238
March1st to 15thDay
6%21%34%20%13%4
270
16th to endDay
5%26%29%22%10%5%
288
April1st to 15thDay
7%18%37%25%8%3
269
16th to endDay
5%24%37%21%9%2
270
May1st to 15thDay
5%20%35%24%11%3
288
16th to endDay
315%37%31%8%3
330
June1st to 15thDay
46%34%36%14%3
315
16th to endDay
5%120%45%20%6%
315
July1st to 15thDay
6%12%46%28%5%
305
16th to endDay
15%19%31%28%13%
327
August1st to 15thDay
13%6%30%35%13%
315
16th to endDay
6%18%35%35%12%
332
September1st to 15thDay
9%113%40%26%6%
315
16th to endDay
7%7%22%34%21%6%
315
October1st to 15thDay
37%27%31%20%10%
195
16th to endDay
2320%32%34%6%
144
November1st to 15thDay
5%14%17%40%20%2
135
16th to endDay
5%15%21%29%25%2
135
December1st to 15thDay
6%8%23%32%30%1
100
16th to endDay
11%19%23%32%11%1
96
January1st to 15thNight
5%316%41%28%4
720
16th to endNight
7%5%17%38%27%4
768
February1st to 15thNight
25%19%38%28%5%
704
16th to endNight
39%22%42%20%2
632
March1st to 15thNight
48%22%34%26%3
720
16th to endNight
27%18%38%28%4
768
April1st to 15thNight
38%23%42%20%1
677
16th to endNight
28%24%40%20%4
540
May1st to 15thNight
15%25%36%29%2
540
16th to endNight
419%40%31%2
563
June1st to 15thNight
3211%45%34%2
540
16th to endNight
37%34%48%5%
540
July1st to 15thNight
4424%56%10%
510
16th to endNight
3416%54%19%
564
August1st to 15thNight
3115%56%22%
539
16th to endNight
6%315%53%20%
582
September1st to 15thNight
7%17%19%50%15%
720
16th to endNight
2110%34%40%10%
716
October1st to 15thNight
2213%35%37%7%
720
16th to endNight
2110%33%41%10%
768
November1st to 15thNight
3412%36%36%7%
760
16th to endNight
6%5%15%33%31%7%
780
December1st to 15thNight
7%6%13%39%26%6%
736
16th to endNight
5%7%17%40%22%6%
768
Page generated at 2017-12-05 08:18:57. Version ac04

Copyright 2017 A. Danko


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