Stoneman Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stoneman Lake clear sky chart from 2005-11-05 to 2017-12-02.

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
52%
15882
33%
47825
20%
15838
65%
15838
43%
24005

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
41%
720
30%
2327
18%
716
57%
716
35%
1189
January16th to endNight
40%
768
34%
2496
20%
768
59%
768
33%
1334
February1st to 15thNight
45%
703
31%
2226
19%
700
62%
700
40%
1090
February16th to endNight
33%
632
34%
1879
19%
632
52%
632
36%
989
March1st to 15thNight
42%
720
36%
1980
18%
720
59%
720
43%
1041
March16th to endNight
45%
768
34%
2112
16%
768
61%
768
47%
1072
April1st to 15thNight
37%
683
28%
1942
11%
683
52%
683
39%
1005
April16th to endNight
42%
540
40%
1695
19%
540
64%
540
49%
712
May1st to 15thNight
45%
540
34%
1619
19%
539
58%
539
50%
739
May16th to endNight
48%
561
34%
1684
19%
561
60%
561
52%
746
June1st to 15thNight
51%
540
32%
1620
21%
540
60%
540
63%
691
June16th to endNight
68%
540
33%
1620
28%
540
72%
540
66%
682
July1st to 15thNight
73%
510
19%
1530
15%
510
76%
510
38%
866
July16th to endNight
73%
564
16%
1593
14%
531
73%
531
31%
970
August1st to 15thNight
77%
539
25%
1611
21%
536
78%
536
37%
897
August16th to endNight
80%
594
30%
1821
28%
594
82%
594
41%
984
September1st to 15thNight
73%
720
28%
1980
20%
720
77%
720
46%
1117
September16th to endNight
69%
716
43%
1980
27%
716
79%
716
63%
903
October1st to 15thNight
53%
720
37%
2082
21%
720
67%
720
54%
968
October16th to endNight
59%
768
42%
2304
28%
768
72%
768
52%
1050
November1st to 15thNight
50%
760
34%
2327
19%
760
66%
760
46%
1123
November16th to endNight
48%
780
39%
2535
26%
780
65%
780
44%
1163
December1st to 15thNight
46%
728
31%
2366
20%
728
62%
728
35%
1234
December16th to endNight
36%
768
29%
2496
19%
768
50%
768
27%
1440

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
4424424446%58%
48620
Night
3413323446%63%
48021
TransparencyDay
25%47%17%28%17%
48315
Night
21%37%18%28%19%
47827
SeeingDay
9%18%30%28%10%2
5641
Night
5%11%24%30%22%4
15885

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
46%1332324462%
1611
16th to endDay
7%8%22313337%56%
1728
February1st to 15thDay
28%34213346%57%
1634
16th to endDay
38%24423347%54%
1594
March1st to 15thDay
36%2332345%5%60%
1980
16th to endDay
45%23232346%62%
2112
April1st to 15thDay
3414324446%60%
2006
16th to endDay
3413322336%66%
2262
May1st to 15thDay
3313313346%65%
2331
16th to endDay
4213313335%66%
2429
June1st to 15thDay
11111223478%
2340
16th to endDay
111222433473%
2340
July1st to 15thDay
5%325%5%47%6%7%7%43%
2340
16th to endDay
9%5%37%7%5%7%8%8%9%28%
2467
August1st to 15thDay
7%5%36%7%46%5%7%6%39%
2340
16th to endDay
6%425%5%36%6%7%8%42%
2378
September1st to 15thDay
7%425%7%35%5%5%6%46%
1980
16th to endDay
323323235%69%
1980
October1st to 15thDay
221332332469%
1875
16th to endDay
2313212235%70%
1920
November1st to 15thDay
231321345%5%66%
1860
16th to endDay
441221224468%
1755
December1st to 15thDay
5%9%23322346%56%
1630
16th to endDay
6%9%35%42343450%
1728
January1st to 15thNight
36%34313445%59%
2327
16th to endNight
5%8%24222345%57%
2496
February1st to 15thNight
27%23213345%63%
2215
16th to endNight
47%2232345%7%58%
1879
March1st to 15thNight
35%1231235%6%63%
1980
16th to endNight
3212223446%66%
2112
April1st to 15thNight
3423323345%62%
1942
16th to endNight
111221223475%
1695
May1st to 15thNight
2112223335%71%
1619
16th to endNight
221121323473%
1684
June1st to 15thNight
21111124477%
1620
16th to endNight
111221232378%
1620
July1st to 15thNight
3314425%7%7%9%49%
1620
16th to endNight
5%325%5%46%8%9%10%37%
1701
August1st to 15thNight
33145%45%6%6%9%49%
1620
16th to endNight
23144346%7%10%50%
1821
September1st to 15thNight
332443446%6%56%
1980
16th to endNight
211111223476%
1980
October1st to 15thNight
311221234472%
2082
16th to endNight
1312212335%72%
2304
November1st to 15thNight
3313224445%65%
2327
16th to endNight
3422222235%67%
2535
December1st to 15thNight
47%23224446%57%
2366
16th to endNight
5%8%35%424345%51%
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
24%37%20%32%11%
1612
16th to endDay
28%27%17%31%11%
1728
February1st to 15thDay
27%27%24%20%17%
1634
16th to endDay
28%37%21%27%11%
1594
March1st to 15thDay
23%25%18%35%13%
1980
16th to endDay
23%27%22%31%12%
2112
April1st to 15thDay
23%26%20%33%13%
2006
16th to endDay
19%25%17%37%16%
2262
May1st to 15thDay
18%36%18%34%18%
2331
16th to endDay
20%35%14%38%17%
2432
June1st to 15thDay
11%1310%31%41%
2340
16th to endDay
14%338%25%44%
2340
July1st to 15thDay
33%8%11%15%12%19%
2201
16th to endDay
42%13%16%13%11%1
2312
August1st to 15thDay
39%7%10%14%16%11%
2325
16th to endDay
34%9%11%16%20%6%
2378
September1st to 15thDay
35%7%8%15%18%14%
1980
16th to endDay
17%2417%34%23%
1980
October1st to 15thDay
18%3414%32%26%
1875
16th to endDay
17%2414%39%21%
1920
November1st to 15thDay
18%36%22%31%17%
1860
16th to endDay
19%1418%33%21%
1755
December1st to 15thDay
28%38%24%25%9%
1630
16th to endDay
36%28%21%24%6%
1728
January1st to 15thNight
25%37%20%30%12%
2327
16th to endNight
29%2417%30%14%
2496
February1st to 15thNight
22%29%21%23%19%
2226
16th to endNight
25%37%21%27%14%
1879
March1st to 15thNight
22%2419%36%13%
1980
16th to endNight
18%48%23%31%13%
2112
April1st to 15thNight
22%36%18%34%15%
1942
16th to endNight
13%15%20%38%20%
1695
May1st to 15thNight
14%36%22%30%22%
1620
16th to endNight
14%25%16%40%21%
1685
June1st to 15thNight
11%128%29%45%
1620
16th to endNight
11%136%21%55%
1620
July1st to 15thNight
26%8%14%13%16%20%
1530
16th to endNight
32%9%21%19%13%3
1593
August1st to 15thNight
27%7%12%18%21%12%
1611
16th to endNight
24%7%15%21%22%9%
1821
September1st to 15thNight
25%414%18%21%15%
1980
16th to endNight
12%2415%36%28%
1980
October1st to 15thNight
15%26%18%27%29%
2082
16th to endNight
15%25%12%34%28%
2304
November1st to 15thNight
18%46%20%32%16%
2327
16th to endNight
20%15%15%32%24%
2535
December1st to 15thNight
27%38%20%26%14%
2366
16th to endNight
34%47%20%24%8%
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
30%23%27%13%41
90
16th to endDay
18%25%25%16%12%2
96
February1st to 15thDay
6%29%33%16%12%2
149
16th to endDay
17%33%29%15%3
238
March1st to 15thDay
11%28%31%19%6%2
270
16th to endDay
11%29%31%19%42
288
April1st to 15thDay
13%30%34%11%6%3
269
16th to endDay
11%35%33%12%5%
270
May1st to 15thDay
11%28%36%18%41
288
16th to endDay
8%25%33%25%6%
330
June1st to 15thDay
421%42%21%8%1
315
16th to endDay
26%37%40%10%1
315
July1st to 15thDay
7%5%30%41%12%1
305
16th to endDay
10%121%41%19%4
327
August1st to 15thDay
9%117%50%15%4
315
16th to endDay
8%321%41%21%4
332
September1st to 15thDay
11%7%27%36%12%4
315
16th to endDay
8%15%27%35%10%2
315
October1st to 15thDay
430%30%25%6%2
210
16th to endDay
8%9%30%29%18%2
144
November1st to 15thDay
8%14%34%27%11%3
135
16th to endDay
8%24%25%27%10%2
135
December1st to 15thDay
7%17%39%19%15%1
94
16th to endDay
23%17%25%27%5%1
96
January1st to 15thNight
9%16%27%25%15%4
720
16th to endNight
12%14%27%27%14%2
768
February1st to 15thNight
6%15%27%33%13%2
704
16th to endNight
9%19%34%24%9%2
632
March1st to 15thNight
7%18%28%28%14%2
720
16th to endNight
5%15%30%30%15%2
768
April1st to 15thNight
6%21%31%28%11%1
683
16th to endNight
223%30%29%11%3
540
May1st to 15thNight
214%33%32%15%
540
16th to endNight
314%30%29%20%2
563
June1st to 15thNight
27%35%35%17%1
540
16th to endNight
1321%44%26%2
540
July1st to 15thNight
410%41%38%4
510
16th to endNight
45%34%44%10%
564
August1st to 15thNight
6%6%29%44%12%
539
16th to endNight
317%30%46%12%
594
September1st to 15thNight
413%28%43%9%
720
16th to endNight
38%15%29%34%8%
716
October1st to 15thNight
312%28%32%19%4
720
16th to endNight
310%22%29%25%7%
768
November1st to 15thNight
412%29%31%17%5%
760
16th to endNight
7%14%26%26%18%6%
780
December1st to 15thNight
10%13%25%31%17%1
728
16th to endNight
12%16%29%26%11%3
768
Page generated at 2017-12-03 09:16:40. Version ac04

Copyright 2017 A. Danko


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