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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 2020-10-22.

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%
19830
34%
59164
28%
19789
73%
19789
52%
28577

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
52%
896
26%
3058
23%
896
60%
896
36%
1601
January16th to endNight
52%
960
30%
3083
25%
960
63%
960
34%
1689
February1st to 15thNight
55%
880
30%
2650
28%
879
62%
879
41%
1408
February16th to endNight
51%
792
29%
2375
25%
792
60%
792
36%
1347
March1st to 15thNight
52%
900
21%
2681
19%
900
57%
900
32%
1575
March16th to endNight
57%
960
26%
2498
19%
960
62%
960
45%
1422
April1st to 15thNight
49%
899
27%
2249
14%
899
55%
899
44%
1313
April16th to endNight
60%
892
33%
2230
16%
892
66%
892
59%
1133
May1st to 15thNight
66%
820
31%
2170
19%
820
70%
820
62%
1057
May16th to endNight
60%
686
32%
2098
22%
686
67%
686
55%
932
June1st to 15thNight
79%
450
37%
1800
41%
450
85%
450
64%
606
June16th to endNight
92%
450
44%
1800
52%
450
95%
450
83%
518
July1st to 15thNight
93%
430
37%
1720
44%
430
93%
430
69%
562
July16th to endNight
92%
714
40%
2028
34%
678
93%
678
73%
823
August1st to 15thNight
93%
885
39%
2210
25%
881
93%
881
83%
975
August16th to endNight
94%
956
45%
2390
30%
956
95%
956
82%
1064
September1st to 15thNight
91%
900
46%
2250
36%
900
92%
900
82%
1013
September16th to endNight
87%
896
47%
2465
42%
896
92%
896
81%
1011
October1st to 15thNight
75%
900
37%
2576
35%
900
81%
900
63%
1164
October16th to endNight
73%
924
43%
2772
40%
924
82%
924
63%
1206
November1st to 15thNight
72%
880
35%
2848
36%
880
76%
880
52%
1290
November16th to endNight
64%
900
33%
2925
31%
900
71%
900
44%
1450
December1st to 15thNight
56%
900
29%
2928
26%
900
62%
900
34%
1615
December16th to endNight
51%
960
28%
3360
26%
960
59%
960
31%
1803

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%65%
60348
Night
2413323346%63%
59354
TransparencyDay
18%36%17%28%26%
60036
Night
18%36%17%28%24%
59167
SeeingDay
6%11%27%35%14%4
10104
Night
45%16%34%31%7%
19841

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
5%424435%45%8%50%
1868
16th to endDay
5%7%37%6%24347%48%
2193
February1st to 15thDay
47%35%424447%51%
2201
16th to endDay
5%7%35%5%23346%51%
1979
March1st to 15thDay
46%246%35%6%5%8%45%
2266
16th to endDay
36%245%345%5%8%49%
2782
April1st to 15thDay
5%7%245%23447%52%
2689
16th to endDay
3213323448%62%
2665
May1st to 15thDay
321221345%7%64%
2770
16th to endDay
3413313436%63%
3067
June1st to 15thDay
112212336%73%
3150
16th to endDay
1113485%
3150
July1st to 15thDay
111212335%75%
3150
16th to endDay
111112346%73%
3079
August1st to 15thDay
1111123481%
2653
16th to endDay
1112245%79%
2868
September1st to 15thDay
1111123481%
2700
16th to endDay
12223381%
2483
October1st to 15thDay
23121333471%
2370
16th to endDay
111222333472%
2302
November1st to 15thDay
2413213346%65%
2000
16th to endDay
35%3443435%7%54%
2025
December1st to 15thDay
35%245%345%5%7%50%
2018
16th to endDay
6%7%345%345%5%6%48%
1920
January1st to 15thNight
3435%6%3445%7%49%
3058
16th to endNight
46%35%5%345%5%6%49%
3083
February1st to 15thNight
37%25%5%2335%7%53%
2641
16th to endNight
47%25%6%35%445%50%
2375
March1st to 15thNight
37%37%5%36%5%6%8%42%
2681
16th to endNight
36%245%26%5%48%49%
2498
April1st to 15thNight
37%35%6%2445%7%49%
2249
16th to endNight
2313312347%63%
2230
May1st to 15thNight
3212213346%67%
2170
16th to endNight
2313312325%69%
2097
June1st to 15thNight
11212245%76%
1800
16th to endNight
12389%
1800
July1st to 15thNight
11111223480%
1800
16th to endNight
11111122381%
2138
August1st to 15thNight
112385%
2220
16th to endNight
11112386%
2390
September1st to 15thNight
111112385%
2250
16th to endNight
112222483%
2465
October1st to 15thNight
112224345%70%
2576
16th to endNight
1213212345%71%
2772
November1st to 15thNight
231332345%6%62%
2848
16th to endNight
25%2442445%8%54%
2925
December1st to 15thNight
36%25%6%35%5%5%8%48%
2928
16th to endNight
48%35%5%345%5%7%46%
3360

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
29%37%18%25%15%
1868
16th to endDay
32%29%16%22%15%
2193
February1st to 15thDay
29%25%19%26%16%
2201
16th to endDay
30%46%23%26%9%
1979
March1st to 15thDay
30%6%11%20%19%11%
2266
16th to endDay
28%410%26%19%9%
2782
April1st to 15thDay
27%410%25%23%8%
2689
16th to endDay
16%410%27%30%9%
2665
May1st to 15thDay
17%38%24%33%12%
2770
16th to endDay
19%28%26%32%11%
3070
June1st to 15thDay
11%25%17%33%28%
3150
16th to endDay
5%129%32%48%
3150
July1st to 15thDay
11%138%23%50%
3001
16th to endDay
11%35%15%28%36%
2927
August1st to 15thDay
8%128%27%51%
2639
16th to endDay
9%128%38%39%
2868
September1st to 15thDay
7%139%31%46%
2700
16th to endDay
8%1210%39%38%
2483
October1st to 15thDay
15%1416%27%35%
2370
16th to endDay
12%25%12%31%34%
2302
November1st to 15thDay
17%25%20%29%24%
2000
16th to endDay
26%38%16%25%20%
2025
December1st to 15thDay
27%5%8%19%22%16%
2018
16th to endDay
32%38%21%19%13%
1920
January1st to 15thNight
27%47%18%24%16%
3058
16th to endNight
30%47%16%22%19%
3083
February1st to 15thNight
25%47%17%26%19%
2652
16th to endNight
30%46%21%26%10%
2375
March1st to 15thNight
31%6%9%20%18%12%
2681
16th to endNight
25%413%23%25%8%
2498
April1st to 15thNight
27%313%24%23%8%
2249
16th to endNight
14%310%28%33%8%
2230
May1st to 15thNight
14%29%27%35%10%
2171
16th to endNight
15%29%27%35%9%
2098
June1st to 15thNight
9%17%20%35%25%
1800
16th to endNight
4210%32%49%
1800
July1st to 15thNight
8%1310%25%51%
1720
16th to endNight
8%25%17%26%39%
2028
August1st to 15thNight
5%129%30%50%
2210
16th to endNight
6%119%42%39%
2390
September1st to 15thNight
6%1210%31%48%
2250
16th to endNight
5%1214%39%37%
2465
October1st to 15thNight
13%2417%27%34%
2576
16th to endNight
12%25%12%31%35%
2772
November1st to 15thNight
17%36%17%30%24%
2848
16th to endNight
23%27%16%27%22%
2925
December1st to 15thNight
30%47%15%24%18%
2928
16th to endNight
30%48%22%20%13%
3360

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
13%20%33%23%9%
226
16th to endDay
12%20%33%23%8%1
411
February1st to 15thDay
10%20%28%27%8%3
446
16th to endDay
11%20%37%22%7%
398
March1st to 15thDay
13%22%33%24%7%
450
16th to endDay
11%20%32%25%8%
480
April1st to 15thDay
14%16%32%24%9%1
449
16th to endDay
6%20%32%28%9%3
438
May1st to 15thDay
10%10%31%30%11%4
468
16th to endDay
8%13%29%32%11%3
522
June1st to 15thDay
39%26%35%18%6%
495
16th to endDay
1327%40%19%8%
495
July1st to 15thDay
115%42%26%11%
485
16th to endDay
213%45%25%11%
519
August1st to 15thDay
1121%46%20%8%
479
16th to endDay
115%53%20%8%
524
September1st to 15thDay
1324%46%18%5%
495
16th to endDay
16%27%47%14%2
495
October1st to 15thDay
48%36%35%13%1
495
16th to endDay
39%31%38%13%3
490
November1st to 15thDay
2425%40%22%3
236
16th to endDay
7%18%28%27%15%3
225
December1st to 15thDay
8%13%30%30%15%
223
16th to endDay
10%18%27%28%10%3
160
January1st to 15thNight
7%6%27%32%18%7%
900
16th to endNight
9%9%22%35%18%5%
960
February1st to 15thNight
5%8%22%33%20%8%
884
16th to endNight
8%9%24%33%18%4
792
March1st to 15thNight
8%10%22%35%19%4
900
16th to endNight
5%9%21%36%23%3
960
April1st to 15thNight
8%9%26%32%20%3
899
16th to endNight
47%23%33%24%5%
892
May1st to 15thNight
4321%36%29%4
821
16th to endNight
5%7%21%30%31%3
688
June1st to 15thNight
1312%39%38%4
450
16th to endNight
5%45%44%4
450
July1st to 15thNight
1125%62%9%
430
16th to endNight
1123%58%15%
714
August1st to 15thNight
1331%52%10%
885
16th to endNight
1123%58%15%
956
September1st to 15thNight
5%31%51%12%
900
16th to endNight
18%38%40%10%
896
October1st to 15thNight
2215%44%29%6%
900
16th to endNight
3316%32%32%11%
924
November1st to 15thNight
3314%42%27%8%
880
16th to endNight
5%5%19%35%25%8%
900
December1st to 15thNight
7%8%21%35%22%4
900
16th to endNight
9%11%21%34%17%6%
960
Page generated at 2020-10-23 12:21:04. Version ac04

Copyright 2020 A. Danko


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