Eagle Plains
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eagle Plains 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
48%
13488
6%
46061
6%
13476
48%
13476
12%
35652

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
46%
955
7%
3548
8%
955
46%
955
10%
2694
January16th to endNight
47%
938
8%
3444
8%
938
48%
938
11%
2625
February1st to 15thNight
53%
726
11%
2804
13%
726
53%
726
14%
1981
February16th to endNight
57%
659
9%
2238
8%
659
57%
659
15%
1642
March1st to 15thNight
60%
734
13%
2245
12%
734
61%
734
19%
1620
March16th to endNight
63%
575
11%
2005
12%
575
63%
575
18%
1368
April1st to 15thNight
49%
539
1%
1545
1%
539
49%
539
12%
1242
April16th to endNight
57%
447
0%
1221
0%
447
57%
447
18%
929
May1st to 15thNight
52%
252
0%
882
0%
252
52%
252
16%
635
May16th to endNight
60%
187
0%
531
0%
187
60%
187
27%
354
June1st to 15thNight
49%
81
0%
132
0%
81
49%
81
28%
115
June16th to endNight00000
July1st to 15thNight
53%
134
0%
206
0%
134
53%
134
25%
177
July16th to endNight
44%
188
0%
589
0%
177
41%
177
10%
478
August1st to 15thNight
50%
266
0%
970
0%
265
50%
265
10%
762
August16th to endNight
42%
544
0%
1401
0%
544
42%
544
12%
1165
September1st to 15thNight
47%
540
2%
1659
2%
540
48%
540
15%
1274
September16th to endNight
33%
591
3%
1873
3%
591
34%
591
8%
1562
October1st to 15thNight
35%
667
3%
2095
3%
667
36%
667
9%
1759
October16th to endNight
38%
736
6%
2577
7%
736
38%
736
8%
2112
November1st to 15thNight
47%
808
6%
2910
8%
808
47%
808
10%
2310
November16th to endNight
46%
937
7%
3357
8%
937
46%
937
9%
2693
December1st to 15thNight
43%
960
5%
3669
6%
960
44%
960
8%
2953
December16th to endNight
51%
1024
5%
4160
6%
1024
51%
1024
9%
3202

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
12%10%49%7%46%6%6%7%23%
49178
Night
7%12%6%11%9%5%6%6%6%8%20%
46110
TransparencyDay
58%7%16%14%3
48728
Night
60%7%13%13%4
46066
SeeingDay
19%5%13%27%23%10%
8796
Night
14%39%28%32%12%
13503

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
416%6%11%8%6%5%5%10%9%16%
390
16th to endDay
313%7%10%9%47%8%8%8%18%
791
February1st to 15thDay
211%5%8%6%5%7%9%7%12%23%
1058
16th to endDay
26%413%11%6%10%8%8%10%18%
1236
March1st to 15thDay
18%411%10%5%8%8%6%7%26%
1715
16th to endDay
17%6%14%9%47%6%7%7%25%
2214
April1st to 15thDay
5%13%6%12%10%5%6%6%5%7%20%
2402
16th to endDay
311%5%9%7%35%5%7%9%30%
2738
May1st to 15thDay
10%13%5%9%7%36%5%5%7%24%
3069
16th to endDay
10%7%36%5%35%5%5%8%38%
3581
June1st to 15thDay
12%7%37%7%36%5%6%8%31%
3828
16th to endDay
12%6%37%6%37%6%6%8%30%
4182
July1st to 15thDay
17%8%37%7%46%6%7%8%22%
3738
16th to endDay
22%10%5%9%8%46%5%5%7%13%
3536
August1st to 15thDay
23%10%37%7%45%5%5%7%18%
2986
16th to endDay
23%12%38%7%35%5%5%6%17%
2800
September1st to 15thDay
20%13%36%5%345%46%26%
2301
16th to endDay
19%17%5%10%6%3335%5%19%
1896
October1st to 15thDay
14%14%6%13%7%45%45%6%17%
1532
16th to endDay
12%19%7%10%9%45%35%5%14%
1295
November1st to 15thDay
9%18%5%11%9%5%9%5%7%314%
933
16th to endDay
6%13%7%12%13%7%8%7%6%5%10%
603
December1st to 15thDay
7%12%7%14%10%5%8%5%10%414%
291
16th to endDay
317%37%12%16%19%12%23%
63
January1st to 15thNight
7%14%7%11%7%45%6%8%10%16%
3548
16th to endNight
413%6%12%10%5%7%7%6%9%17%
3444
February1st to 15thNight
39%411%10%5%7%7%7%10%23%
2792
16th to endNight
28%411%11%49%7%9%8%22%
2238
March1st to 15thNight
28%5%8%10%6%7%8%6%7%28%
2245
16th to endNight
17%5%11%9%45%47%9%33%
2005
April1st to 15thNight
5%12%7%10%9%6%6%5%7%8%20%
1545
16th to endNight
48%5%9%8%46%5%7%9%29%
1221
May1st to 15thNight
7%13%6%7%6%45%5%5%6%30%
881
16th to endNight
11%427%6%35%46%9%38%
531
June1st to 15thNight
9%12%36%345%5%5%7%35%
132
July1st to 15thNight
10%8%38%7%45%8%7%9%25%
222
16th to endNight
23%7%48%8%6%46%5%7%17%
631
August1st to 15thNight
17%8%38%8%5%6%5%8%8%20%
974
16th to endNight
21%11%5%7%5%45%5%47%21%
1401
September1st to 15thNight
19%8%35%7%35%6%6%7%25%
1659
16th to endNight
16%18%5%9%6%45%445%19%
1873
October1st to 15thNight
14%17%6%10%7%45%5%5%6%17%
2095
16th to endNight
13%19%7%10%8%4445%5%16%
2577
November1st to 15thNight
6%15%7%12%10%47%5%5%6%18%
2910
16th to endNight
5%11%6%14%12%6%7%7%8%7%12%
3357
December1st to 15thNight
6%13%6%13%9%5%8%6%7%8%12%
3669
16th to endNight
412%6%11%9%5%7%6%8%9%17%
4160

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
59%8%11%16%3
390
16th to endDay
58%6%13%14%6%1
791
February1st to 15thDay
47%8%14%20%6%2
1058
16th to endDay
56%11%13%12%4
1236
March1st to 15thDay
53%6%10%22%6%
1715
16th to endDay
55%7%11%16%7%
2214
April1st to 15thDay
63%8%16%10%1
2402
16th to endDay
49%8%21%15%4
2738
May1st to 15thDay
59%7%16%13%2
3069
16th to endDay
44%5%17%24%7%
3586
June1st to 15thDay
50%7%17%20%4
3828
16th to endDay
49%9%20%18%2
4182
July1st to 15thDay
57%9%18%12%1
3525
16th to endDay
69%7%17%5%
3315
August1st to 15thDay
63%9%18%7%
2965
16th to endDay
67%8%15%7%
2800
September1st to 15thDay
59%7%19%11%1
2301
16th to endDay
67%6%14%9%1
1896
October1st to 15thDay
68%6%15%9%
1532
16th to endDay
69%6%12%10%1
1295
November1st to 15thDay
69%6%12%10%1
933
16th to endDay
71%6%8%9%3
603
December1st to 15thDay
68%7%8%12%3
291
16th to endDay
52%17%11%12%41
63
January1st to 15thNight
60%7%11%16%4
3548
16th to endNight
61%5%12%11%7%
3444
February1st to 15thNight
52%7%10%19%7%1
2804
16th to endNight
54%6%13%15%8%
2238
March1st to 15thNight
51%6%10%24%6%
2245
16th to endNight
48%6%11%22%9%
2010
April1st to 15thNight
60%9%13%13%2
1545
16th to endNight
53%8%18%15%3
1221
May1st to 15thNight
53%6%21%15%3
882
16th to endNight
41%6%19%26%5%
531
June1st to 15thNight
48%13%17%18%1
132
July1st to 15thNight
50%14%23%11%
206
16th to endNight
64%7%18%8%
589
August1st to 15thNight
59%11%23%4
970
16th to endNight
62%9%17%8%
1401
September1st to 15thNight
57%7%22%11%
1659
16th to endNight
68%7%12%9%1
1873
October1st to 15thNight
67%8%15%8%
2095
16th to endNight
68%6%12%11%1
2577
November1st to 15thNight
65%6%13%12%2
2910
16th to endNight
65%7%12%10%4
3357
December1st to 15thNight
66%7%13%10%2
3669
16th to endNight
59%10%13%11%5%
4160

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%13%10%33%13%16%
30
16th to endDay
39%37%43%6%
32
February1st to 15thDay
10%410%30%27%16%
110
16th to endDay
5%212%25%27%26%
211
March1st to 15thDay
7%117%28%24%20%
240
16th to endDay
4313%26%26%26%
274
April1st to 15thDay
14%316%28%25%11%
425
16th to endDay
8%319%30%24%13%
450
May1st to 15thDay
16%6%13%30%23%8%
558
16th to endDay
15%5%14%34%23%6%
822
June1st to 15thDay
17%6%17%31%22%4
855
16th to endDay
15%410%31%28%8%
966
July1st to 15thDay
19%6%10%22%30%10%
815
16th to endDay
29%6%9%24%21%8%
803
August1st to 15thDay
26%37%30%21%10%
506
16th to endDay
33%5%13%25%15%6%
523
September1st to 15thDay
30%6%13%20%19%10%
405
16th to endDay
30%8%20%16%18%6%
265
October1st to 15thDay
19%420%24%19%12%
225
16th to endDay
28%46%16%23%20%
160
November1st to 15thDay
20%323%32%20%
55
16th to endDay
10%13%30%13%33%
30
December1st to 15thDay
24%20%40%16%
25
16th to endDay
18%18%18%36%9%
11
January1st to 15thNight
13%46%28%31%14%
960
16th to endNight
11%38%33%32%10%
938
February1st to 15thNight
8%28%26%36%17%
734
16th to endNight
6%212%32%31%14%
659
March1st to 15thNight
5%110%34%35%11%
734
16th to endNight
5%25%28%42%14%
576
April1st to 15thNight
12%410%28%34%10%
539
16th to endNight
6%310%34%35%9%
447
May1st to 15thNight
11%6%8%32%35%5%
252
16th to endNight
13%37%37%34%3
188
June1st to 15thNight
13%422%40%18%
81
July1st to 15thNight
20%5%5%28%34%4
134
16th to endNight
27%312%25%29%2
188
August1st to 15thNight
20%38%33%31%3
266
16th to endNight
27%49%20%28%8%
544
September1st to 15thNight
25%312%23%25%9%
540
16th to endNight
25%5%15%25%22%5%
591
October1st to 15thNight
26%311%24%26%7%
667
16th to endNight
25%37%17%27%17%
736
November1st to 15thNight
14%35%25%35%14%
808
16th to endNight
10%38%23%30%23%
937
December1st to 15thNight
12%38%35%28%11%
960
16th to endNight
8%37%25%37%16%
1024
Page generated at 2017-09-23 03:43:36. Version ac04

Copyright 2017 A. Danko


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