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Mount Pinos
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mount Pinos clear sky chart from 2005-11-05 to 2017-09-10.

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
68%
15684
33%
46794
28%
15643
73%
15643
51%
22754

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
54%
716
25%
2443
22%
716
61%
716
36%
1286
January16th to endNight
52%
768
30%
2466
25%
768
61%
768
33%
1364
February1st to 15thNight
55%
700
29%
2110
27%
699
61%
699
39%
1153
February16th to endNight
52%
632
27%
1895
26%
632
57%
632
34%
1101
March1st to 15thNight
55%
720
23%
2144
21%
720
60%
720
37%
1190
March16th to endNight
58%
768
27%
1998
20%
768
63%
768
46%
1128
April1st to 15thNight
49%
719
27%
1799
13%
719
55%
719
45%
1041
April16th to endNight
59%
720
32%
1800
15%
720
65%
720
60%
907
May1st to 15thNight
66%
656
31%
1736
18%
656
69%
656
61%
850
May16th to endNight
61%
546
31%
1670
21%
546
68%
546
57%
725
June1st to 15thNight
80%
360
34%
1440
38%
360
85%
360
62%
496
June16th to endNight
93%
360
43%
1440
52%
360
95%
360
82%
418
July1st to 15thNight
92%
340
35%
1360
42%
340
92%
340
67%
449
July16th to endNight
92%
570
39%
1596
34%
534
93%
534
72%
654
August1st to 15thNight
92%
717
39%
1790
25%
713
93%
713
83%
787
August16th to endNight
94%
764
46%
1910
30%
764
94%
764
82%
856
September1st to 15thNight
92%
700
44%
1750
34%
700
93%
700
79%
803
September16th to endNight
87%
656
45%
1808
41%
656
91%
656
78%
756
October1st to 15thNight
73%
660
35%
1889
34%
660
79%
660
58%
888
October16th to endNight
71%
704
39%
2112
38%
704
79%
704
59%
958
November1st to 15thNight
69%
700
33%
2267
34%
700
73%
700
50%
1047
November16th to endNight
66%
720
32%
2340
31%
720
72%
720
46%
1138
December1st to 15thNight
58%
720
30%
2343
27%
720
65%
720
35%
1273
December16th to endNight
51%
768
27%
2688
27%
768
58%
768
29%
1486

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
2313323346%64%
47828
Night
2423323346%62%
46984
TransparencyDay
18%36%17%28%25%
47516
Night
19%37%18%28%23%
46797
SeeingDay
7%11%29%36%12%3
5927
Night
5%5%16%32%32%8%
15695

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
44245%35%447%52%
1493
16th to endDay
5%8%37%6%24235%49%
1755
February1st to 15thDay
47%34425%447%49%
1751
16th to endDay
6%7%35%5%23446%49%
1579
March1st to 15thDay
36%245%35%6%5%8%47%
1813
16th to endDay
36%234345%5%8%51%
2226
April1st to 15thDay
5%7%24413347%53%
2149
16th to endDay
321331345%8%62%
2160
May1st to 15thDay
321222345%7%65%
2214
16th to endDay
3412213336%66%
2441
June1st to 15thDay
113212336%72%
2520
16th to endDay
11113484%
2520
July1st to 15thDay
111222336%73%
2520
16th to endDay
2111112335%73%
2457
August1st to 15thDay
111111235%81%
2160
16th to endDay
11112245%79%
2292
September1st to 15thDay
11211235%79%
2097
16th to endDay
121223479%
1821
October1st to 15thDay
2412324445%65%
1738
16th to endDay
1213323335%68%
1760
November1st to 15thDay
25%13313347%64%
1592
16th to endDay
35%24434346%57%
1620
December1st to 15thDay
36%245%346%6%6%50%
1614
16th to endDay
7%7%34424445%49%
1536
January1st to 15thNight
35%36%6%3445%7%49%
2443
16th to endNight
47%345%345%5%5%48%
2466
February1st to 15thNight
38%35%5%2435%7%50%
2101
16th to endNight
5%6%25%6%35%45%6%47%
1895
March1st to 15thNight
26%37%5%26%5%5%7%46%
2144
16th to endNight
37%23426%5%48%50%
1998
April1st to 15thNight
38%346%25%446%51%
1799
16th to endNight
2313313348%63%
1800
May1st to 15thNight
3212213346%67%
1736
16th to endNight
3213312325%70%
1669
June1st to 15thNight
1212212245%74%
1440
16th to endNight
112388%
1440
July1st to 15thNight
11111223478%
1440
16th to endNight
11111223380%
1706
August1st to 15thNight
1112385%
1800
16th to endNight
11112286%
1910
September1st to 15thNight
1111122384%
1750
16th to endNight
1112225%81%
1808
October1st to 15thNight
2213324445%66%
1889
16th to endNight
2214313446%66%
2112
November1st to 15thNight
342432345%5%60%
2267
16th to endNight
25%1442346%9%55%
2340
December1st to 15thNight
35%25%6%35%5%5%8%49%
2343
16th to endNight
5%9%35%5%345%5%7%44%
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
28%37%18%25%17%
1493
16th to endDay
34%18%16%21%17%
1755
February1st to 15thDay
29%36%21%23%15%
1751
16th to endDay
32%47%22%25%7%
1579
March1st to 15thDay
26%5%12%22%19%12%
1813
16th to endDay
26%410%26%21%10%
2226
April1st to 15thDay
25%49%26%24%8%
2149
16th to endDay
17%410%26%29%11%
2160
May1st to 15thDay
16%37%22%35%14%
2214
16th to endDay
17%27%25%34%12%
2444
June1st to 15thDay
12%25%17%31%30%
2520
16th to endDay
5%127%29%52%
2520
July1st to 15thDay
12%237%22%52%
2371
16th to endDay
11%35%14%31%32%
2305
August1st to 15thDay
8%129%28%50%
2146
16th to endDay
9%228%37%39%
2292
September1st to 15thDay
8%249%32%43%
2097
16th to endDay
9%1210%38%36%
1821
October1st to 15thDay
19%2418%31%24%
1738
16th to endDay
15%35%14%32%28%
1760
November1st to 15thDay
19%25%20%31%20%
1592
16th to endDay
24%37%16%25%22%
1620
December1st to 15thDay
27%5%8%20%23%14%
1614
16th to endDay
33%38%22%17%14%
1536
January1st to 15thNight
28%47%18%24%17%
2443
16th to endNight
31%37%15%20%21%
2466
February1st to 15thNight
27%47%18%24%16%
2112
16th to endNight
32%47%22%25%8%
1895
March1st to 15thNight
27%5%9%22%19%14%
2144
16th to endNight
24%413%23%25%9%
1998
April1st to 15thNight
26%212%25%24%8%
1799
16th to endNight
13%311%29%32%9%
1800
May1st to 15thNight
14%210%26%35%10%
1737
16th to endNight
14%19%26%37%10%
1670
June1st to 15thNight
10%17%19%33%26%
1440
16th to endNight
429%29%53%
1440
July1st to 15thNight
9%1310%23%51%
1360
16th to endNight
9%25%18%28%36%
1596
August1st to 15thNight
5%1210%31%48%
1790
16th to endNight
6%119%43%37%
1910
September1st to 15thNight
7%2211%31%44%
1750
16th to endNight
6%2115%40%33%
1808
October1st to 15thNight
16%2420%30%25%
1889
16th to endNight
14%26%14%33%27%
2112
November1st to 15thNight
19%26%18%31%20%
2267
16th to endNight
22%28%15%27%22%
2340
December1st to 15thNight
29%47%16%25%16%
2343
16th to endNight
32%48%22%18%13%
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
14%21%42%15%4
121
16th to endDay
15%22%33%20%5%1
261
February1st to 15thDay
10%19%33%30%41
266
16th to endDay
13%21%35%24%5%
238
March1st to 15thDay
10%18%33%26%10%
270
16th to endDay
9%20%32%26%9%1
288
April1st to 15thDay
15%20%33%20%9%1
269
16th to endDay
5%24%37%25%5%1
270
May1st to 15thDay
13%12%34%27%9%3
288
16th to endDay
10%9%31%35%9%3
330
June1st to 15thDay
49%31%37%13%3
315
16th to endDay
1329%41%14%8%
315
July1st to 15thDay
219%45%22%9%
305
16th to endDay
2115%49%20%10%
327
August1st to 15thDay
2222%49%14%8%
315
16th to endDay
116%56%17%7%
332
September1st to 15thDay
2226%49%14%4
294
16th to endDay
2431%47%12%1
255
October1st to 15thDay
5%12%37%34%9%1
255
16th to endDay
5%12%33%40%9%
272
November1st to 15thDay
6%8%18%30%29%7%
98
16th to endDay
415%36%31%12%
90
December1st to 15thDay
10%8%23%41%15%
89
16th to endDay
15%21%25%28%9%
64
January1st to 15thNight
7%5%26%33%19%9%
720
16th to endNight
10%10%21%34%18%5%
768
February1st to 15thNight
5%7%22%34%20%8%
704
16th to endNight
9%9%21%32%19%6%
632
March1st to 15thNight
6%10%21%34%22%5%
720
16th to endNight
5%9%20%35%25%4
768
April1st to 15thNight
8%9%26%32%19%3
719
16th to endNight
48%23%33%25%4
720
May1st to 15thNight
5%421%35%29%4
657
16th to endNight
6%7%20%29%32%4
548
June1st to 15thNight
2310%42%37%3
360
16th to endNight
447%43%3
360
July1st to 15thNight
1122%63%10%
340
16th to endNight
117%62%17%
570
August1st to 15thNight
1327%57%10%
717
16th to endNight
1119%59%18%
764
September1st to 15thNight
1326%54%14%
700
16th to endNight
118%33%42%13%
656
October1st to 15thNight
3215%38%31%8%
660
16th to endNight
4217%29%34%11%
704
November1st to 15thNight
4416%35%29%10%
700
16th to endNight
5%419%36%25%9%
720
December1st to 15thNight
6%6%20%37%23%5%
720
16th to endNight
10%11%20%34%16%6%
768
Page generated at 2017-09-11 16:35:31. Version ac04

Copyright 2017 A. Danko


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