Stagg River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stagg River clear sky chart from 2005-11-05 to 2017-09-22.

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
41%
14904
6%
46444
4%
14878
42%
14878
13%
35388

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
38%
927
7%
3223
5%
925
41%
925
11%
2487
January16th to endNight
32%
992
7%
3145
6%
992
34%
992
10%
2545
February1st to 15thNight
43%
832
10%
2668
8%
832
45%
832
15%
1943
February16th to endNight
35%
632
10%
2186
10%
632
38%
632
10%
1716
March1st to 15thNight
49%
720
16%
2178
13%
720
50%
720
21%
1489
March16th to endNight
53%
767
12%
2025
8%
767
55%
767
25%
1389
April1st to 15thNight
50%
554
8%
1634
6%
554
52%
554
22%
1111
April16th to endNight
56%
360
1%
1333
0%
360
56%
360
25%
724
May1st to 15thNight
48%
359
0%
1082
0%
359
48%
359
21%
720
May16th to endNight
51%
374
0%
879
0%
374
51%
374
31%
597
June1st to 15thNight
55%
252
0%
612
0%
252
55%
252
29%
396
June16th to endNight
55%
180
0%
540
0%
180
55%
180
23%
334
July1st to 15thNight
57%
325
0%
665
0%
325
57%
325
31%
487
July16th to endNight
57%
376
0%
865
0%
354
61%
354
29%
585
August1st to 15thNight
60%
360
0%
1132
0%
358
60%
358
23%
733
August16th to endNight
50%
409
2%
1514
1%
409
51%
409
15%
1047
September1st to 15thNight
47%
606
5%
1686
3%
606
48%
606
19%
1253
September16th to endNight
33%
683
6%
1881
3%
683
35%
683
14%
1490
October1st to 15thNight
35%
660
6%
2082
5%
660
36%
660
11%
1651
October16th to endNight
24%
803
2%
2472
1%
803
26%
803
6%
2165
November1st to 15thNight
27%
881
3%
2724
3%
881
28%
881
6%
2394
November16th to endNight
33%
930
3%
3060
3%
930
34%
930
7%
2597
December1st to 15thNight
31%
930
5%
3282
5%
930
32%
930
8%
2637
December16th to endNight
38%
992
5%
3576
5%
992
39%
992
8%
2898

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
9%8%47%6%45%5%6%8%32%
48528
Night
10%11%5%9%7%46%5%5%7%25%
46536
TransparencyDay
47%9%17%20%5%
48125
Night
56%8%14%16%4
46444
SeeingDay
11%11%11%25%27%12%
7423
Night
13%15%13%27%22%6%
14914

By Month

Percentage Cloud Cover NW (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
7%12%8%10%9%6%7%48%5%18%
716
16th to endDay
6%13%6%13%9%47%6%6%5%20%
1077
February1st to 15thDay
28%39%11%6%8%6%11%9%21%
1208
16th to endDay
413%7%10%10%5%5%5%5%5%24%
1288
March1st to 15thDay
5%9%47%7%36%7%7%8%30%
1782
16th to endDay
5%10%48%8%47%7%6%7%28%
2198
April1st to 15thDay
8%10%36%6%346%6%8%35%
2312
16th to endDay
36%35%8%45%5%5%7%43%
2627
May1st to 15thDay
7%6%45%5%35%5%6%9%41%
2869
16th to endDay
11%5%34435%5%5%6%44%
3232
June1st to 15thDay
9%6%35%6%36%5%5%8%40%
3348
16th to endDay
8%426%5%35%5%6%9%41%
3420
July1st to 15thDay
8%5%26%6%47%6%7%9%35%
3254
16th to endDay
7%425%6%45%6%8%10%38%
3242
August1st to 15thDay
10%5%25%5%4445%7%43%
2822
16th to endDay
17%8%37%6%35%5%6%7%28%
2685
September1st to 15thDay
17%9%37%5%35%5%48%29%
2274
16th to endDay
19%11%47%6%3445%7%24%
1891
October1st to 15thDay
14%16%49%7%3446%6%21%
1546
16th to endDay
17%23%9%9%6%25%43413%
1386
November1st to 15thDay
13%20%8%11%8%46%43412%
1132
16th to endDay
11%12%8%14%8%45%6%47%15%
900
December1st to 15thDay
9%13%6%14%7%5%7%7%7%8%13%
674
16th to endDay
9%9%8%14%11%5%6%7%5%8%13%
645
January1st to 15thNight
8%13%6%10%8%47%7%6%7%20%
3223
16th to endNight
9%14%8%11%9%46%5%5%6%18%
3145
February1st to 15thNight
37%48%11%5%8%8%7%8%25%
2656
16th to endNight
8%13%5%10%10%46%5%5%6%22%
2186
March1st to 15thNight
5%8%48%7%36%5%5%7%36%
2178
16th to endNight
5%8%46%5%46%6%6%7%38%
2022
April1st to 15thNight
7%8%5%6%6%45%5%5%7%36%
1634
16th to endNight
34246%45%5%7%8%47%
1333
May1st to 15thNight
6%7%37%6%45%5%7%6%37%
1081
16th to endNight
14%6%24333447%45%
879
June1st to 15thNight
7%5%27%5%25%45%9%44%
612
16th to endNight
8%225%5%25%7%6%10%42%
540
July1st to 15thNight
7%5%28%5%37%6%5%9%36%
705
16th to endNight
6%5%25%5%45%5%5%11%41%
927
August1st to 15thNight
8%426%5%36%6%6%7%42%
1138
16th to endNight
16%8%26%5%345%6%8%33%
1514
September1st to 15thNight
14%9%16%5%35%5%5%7%33%
1686
16th to endNight
18%12%38%7%35%345%26%
1881
October1st to 15thNight
14%14%49%7%34446%25%
2082
16th to endNight
17%21%9%10%5%35%335%14%
2472
November1st to 15thNight
15%16%8%14%9%5%5%5%3413%
2724
16th to endNight
11%13%7%13%9%5%6%5%6%6%14%
3060
December1st to 15thNight
8%14%6%11%9%47%6%6%6%16%
3282
16th to endNight
9%13%7%12%9%5%6%6%5%5%16%
3576

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
63%6%12%15%2
716
16th to endDay
60%7%12%14%5%
1077
February1st to 15thDay
50%10%16%17%4
1208
16th to endDay
59%7%9%15%6%
1288
March1st to 15thDay
47%7%16%20%7%
1782
16th to endDay
50%8%18%17%5%
2199
April1st to 15thDay
44%6%19%23%6%
2312
16th to endDay
38%7%16%33%4
2627
May1st to 15thDay
38%7%18%27%9%
2869
16th to endDay
38%6%11%27%14%
3237
June1st to 15thDay
38%8%14%28%9%
3348
16th to endDay
36%10%17%25%8%
3420
July1st to 15thDay
40%11%20%23%4
3065
16th to endDay
35%13%26%23%1
3041
August1st to 15thDay
38%10%23%22%5%
2803
16th to endDay
53%11%21%12%
2685
September1st to 15thDay
52%10%21%12%1
2274
16th to endDay
58%10%19%10%1
1891
October1st to 15thDay
62%11%16%9%
1546
16th to endDay
73%8%11%6%
1386
November1st to 15thDay
74%8%10%5%1
1132
16th to endDay
66%10%14%8%
900
December1st to 15thDay
65%8%12%12%1
674
16th to endDay
66%7%11%12%1
645
January1st to 15thNight
59%8%13%16%2
3223
16th to endNight
65%6%10%12%4
3145
February1st to 15thNight
50%9%16%17%6%
2668
16th to endNight
61%6%11%12%6%
2186
March1st to 15thNight
46%5%14%24%7%1
2178
16th to endNight
41%7%17%24%8%
2025
April1st to 15thNight
44%6%17%22%8%1
1634
16th to endNight
31%5%18%34%9%
1333
May1st to 15thNight
42%7%18%23%8%
1082
16th to endNight
38%6%10%28%14%1
879
June1st to 15thNight
34%6%16%29%13%
612
16th to endNight
34%10%12%32%10%
540
July1st to 15thNight
38%9%18%28%5%
665
16th to endNight
35%10%22%27%3
865
August1st to 15thNight
37%11%22%21%6%1
1132
16th to endNight
46%11%20%19%1
1514
September1st to 15thNight
47%12%19%17%3
1686
16th to endNight
57%8%17%13%2
1881
October1st to 15thNight
59%10%17%11%1
2082
16th to endNight
72%9%11%6%
2472
November1st to 15thNight
73%8%9%6%2
2724
16th to endNight
68%10%13%7%
3060
December1st to 15thNight
64%7%14%12%1
3282
16th to endNight
67%6%13%11%1
3576

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
5%33%45%10%6%
60
16th to endDay
17%16%35%31%7%
64
February1st to 15thDay
10%113%38%26%10%
60
16th to endDay
12%12%34%27%13%
58
March1st to 15thDay
7%12%12%31%22%13%
252
16th to endDay
12%12%11%26%24%12%
288
April1st to 15thDay
11%13%18%26%23%7%
269
16th to endDay
6%14%9%29%32%7%
377
May1st to 15thDay
8%15%14%26%26%8%
594
16th to endDay
8%15%11%26%26%11%
705
June1st to 15thDay
9%14%12%25%25%11%
675
16th to endDay
8%14%8%24%30%14%
675
July1st to 15thDay
7%11%9%24%33%13%
645
16th to endDay
7%13%6%23%31%16%
703
August1st to 15thDay
10%8%6%19%33%21%
614
16th to endDay
19%6%11%24%25%12%
370
September1st to 15thDay
20%7%15%24%21%9%
315
16th to endDay
25%8%18%22%15%9%
280
October1st to 15thDay
26%6%19%27%14%5%
131
16th to endDay
38%115%22%15%7%
80
November1st to 15thDay
16%121%28%21%10%
60
16th to endDay
15%113%33%25%11%
60
December1st to 15thDay
26%22%26%15%8%
45
16th to endDay
413%32%34%13%
43
January1st to 15thNight
10%17%15%29%20%6%
930
16th to endNight
12%17%16%29%18%5%
992
February1st to 15thNight
6%17%14%29%22%8%
836
16th to endNight
13%17%13%31%18%5%
632
March1st to 15thNight
6%18%13%33%19%8%
720
16th to endNight
7%17%9%30%29%6%
768
April1st to 15thNight
7%17%13%29%26%5%
554
16th to endNight
5%18%11%33%26%4
360
May1st to 15thNight
6%17%17%28%27%2
360
16th to endNight
10%18%14%30%22%2
375
June1st to 15thNight
8%17%8%30%30%4
252
16th to endNight
8%16%8%25%33%6%
180
July1st to 15thNight
7%12%11%26%35%6%
325
16th to endNight
417%8%25%34%10%
376
August1st to 15thNight
11%10%6%23%35%11%
360
16th to endNight
18%10%10%23%30%8%
409
September1st to 15thNight
18%10%14%25%24%6%
606
16th to endNight
23%10%20%25%13%5%
683
October1st to 15thNight
24%11%14%30%16%3
660
16th to endNight
29%11%15%21%17%4
803
November1st to 15thNight
18%16%14%24%19%6%
881
16th to endNight
15%17%12%26%19%8%
930
December1st to 15thNight
15%18%17%26%15%7%
930
16th to endNight
10%17%11%26%23%10%
992
Page generated at 2017-09-23 04:43:43. Version ac04

Copyright 2017 A. Danko


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