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 2017-03-22.

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
40%
14495
6%
45282
4%
14469
41%
14469
13%
34669

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%
731
12%
1934
8%
731
55%
731
26%
1309
April1st to 15thNight
48%
508
8%
1498
6%
508
51%
508
21%
1022
April16th to endNight
55%
330
1%
1222
0%
330
55%
330
25%
666
May1st to 15thNight
48%
329
0%
993
0%
329
48%
329
21%
661
May16th to endNight
49%
342
0%
804
0%
342
49%
342
30%
552
June1st to 15thNight
54%
231
0%
561
0%
231
54%
231
28%
365
June16th to endNight
53%
165
0%
495
0%
165
53%
165
22%
305
July1st to 15thNight
57%
296
0%
606
0%
296
57%
296
30%
445
July16th to endNight
56%
348
0%
797
0%
326
60%
326
27%
545
August1st to 15thNight
57%
330
0%
1037
0%
328
57%
328
21%
687
August16th to endNight
49%
375
1%
1387
1%
375
50%
375
15%
967
September1st to 15thNight
46%
555
5%
1545
4%
555
47%
555
18%
1166
September16th to endNight
30%
656
5%
1807
2%
656
32%
656
13%
1457
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%7%32%
45692
Night
10%11%5%9%8%46%5%5%6%25%
45374
TransparencyDay
48%9%17%19%5%
45289
Night
56%8%14%15%4
45282
SeeingDay
11%13%12%25%26%11%
6483
Night
13%16%13%27%22%6%
14505

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%47%7%47%7%7%7%29%
2085
April1st to 15thDay
8%10%35%6%35%6%6%8%35%
2118
16th to endDay
36%35%7%35%5%5%7%44%
2408
May1st to 15thDay
6%6%45%6%35%5%6%9%40%
2628
16th to endDay
12%6%34435%5%5%6%43%
2955
June1st to 15thDay
9%6%35%6%36%5%5%8%40%
3069
16th to endDay
7%426%446%6%7%9%41%
3135
July1st to 15thDay
8%5%26%7%47%6%7%9%34%
2983
16th to endDay
6%425%6%45%7%8%10%38%
3002
August1st to 15thDay
11%6%35%5%45%45%7%41%
2587
16th to endDay
16%8%47%6%45%5%6%7%27%
2460
September1st to 15thDay
18%9%37%5%35%5%48%29%
2085
16th to endDay
20%11%47%6%3445%7%23%
1823
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%45%5%46%5%6%8%39%
1931
April1st to 15thNight
8%9%5%6%6%45%5%5%7%35%
1498
16th to endNight
34246%45%5%6%9%47%
1222
May1st to 15thNight
6%7%37%7%45%5%7%6%37%
992
16th to endNight
15%6%24323347%45%
804
June1st to 15thNight
6%5%36%5%26%5%5%9%43%
561
16th to endNight
8%225%5%35%7%6%10%43%
495
July1st to 15thNight
6%5%38%5%48%6%5%10%36%
646
16th to endNight
6%425%6%45%5%5%11%40%
859
August1st to 15thNight
9%5%27%5%36%6%6%6%40%
1043
16th to endNight
16%8%26%5%245%6%8%32%
1387
September1st to 15thNight
14%9%16%6%46%5%6%8%31%
1545
16th to endNight
19%13%48%7%35%345%24%
1807
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
48%8%18%18%5%
2086
April1st to 15thDay
44%6%19%21%6%
2118
16th to endDay
37%7%16%33%4
2408
May1st to 15thDay
38%7%19%25%9%
2628
16th to endDay
40%6%11%27%14%
2960
June1st to 15thDay
39%8%15%27%9%
3069
16th to endDay
35%11%18%24%8%
3135
July1st to 15thDay
41%11%20%22%3
2794
16th to endDay
35%13%27%22%1
2801
August1st to 15thDay
41%10%23%19%5%
2568
16th to endDay
53%11%22%12%
2460
September1st to 15thDay
53%11%21%11%1
2085
16th to endDay
59%10%18%9%2
1823
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
40%6%17%25%9%
1934
April1st to 15thNight
44%6%17%22%7%1
1498
16th to endNight
31%6%18%33%9%
1222
May1st to 15thNight
41%8%19%22%8%
993
16th to endNight
39%6%10%28%14%
804
June1st to 15thNight
35%6%16%28%13%
561
16th to endNight
33%10%12%32%10%
495
July1st to 15thNight
39%9%18%27%5%
606
16th to endNight
36%11%23%27%1
797
August1st to 15thNight
39%11%23%19%5%
1037
16th to endNight
47%11%20%20%1
1387
September1st to 15thNight
48%12%19%16%2
1545
16th to endNight
60%8%16%11%2
1807
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
11%14%11%27%24%10%
250
April1st to 15thDay
12%16%18%27%20%3
209
16th to endDay
5%17%10%34%28%4
308
May1st to 15thDay
6%18%14%24%27%8%
508
16th to endDay
9%17%11%24%25%11%
609
June1st to 15thDay
9%16%12%23%24%12%
585
16th to endDay
6%16%9%24%29%14%
585
July1st to 15thDay
7%13%10%24%32%12%
555
16th to endDay
6%15%7%22%31%16%
619
August1st to 15thDay
10%10%6%20%31%19%
529
16th to endDay
17%7%10%24%25%13%
303
September1st to 15thDay
20%9%15%23%19%10%
255
16th to endDay
27%9%20%23%13%5%
255
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%18%8%30%28%6%
732
April1st to 15thNight
6%19%13%29%25%5%
508
16th to endNight
419%11%33%26%4
330
May1st to 15thNight
5%19%15%27%28%3
330
16th to endNight
10%20%14%28%23%2
343
June1st to 15thNight
7%19%8%29%30%5%
231
16th to endNight
7%18%8%24%33%6%
165
July1st to 15thNight
6%13%11%26%35%6%
296
16th to endNight
418%8%24%34%10%
348
August1st to 15thNight
12%10%7%24%33%10%
330
16th to endNight
18%10%9%21%30%9%
375
September1st to 15thNight
19%10%13%25%23%6%
555
16th to endNight
24%11%21%25%12%3
656
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 2017-03-23 05:36:14. Version ac04

Copyright 2017 A. Danko


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