Wainwright
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wainwright clear sky chart from 2005-11-05 to 2017-12-01.

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%
15648
11%
47734
7%
15623
45%
15623
19%
33893

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
34%
895
7%
2685
4%
895
37%
895
14%
2068
January16th to endNight
29%
951
14%
2871
6%
951
37%
951
16%
2089
February1st to 15thNight
39%
696
9%
2360
6%
696
44%
696
15%
1713
February16th to endNight
44%
632
13%
2052
11%
632
48%
632
16%
1507
March1st to 15thNight
37%
720
13%
2085
8%
720
41%
720
18%
1526
March16th to endNight
38%
768
10%
2111
6%
767
40%
767
16%
1625
April1st to 15thNight
39%
548
12%
1682
7%
548
44%
548
18%
1208
April16th to endNight
40%
540
15%
1594
12%
540
44%
540
20%
1121
May1st to 15thNight
47%
467
10%
1367
8%
467
49%
467
24%
909
May16th to endNight
42%
374
3%
1309
2%
374
43%
374
16%
914
June1st to 15thNight
43%
360
0%
1260
0%
360
43%
360
14%
902
June16th to endNight
50%
360
0%
1260
0%
360
50%
360
19%
837
July1st to 15thNight
58%
340
0%
1190
0%
340
58%
340
27%
708
July16th to endNight
58%
376
5%
1239
4%
354
59%
354
28%
721
August1st to 15thNight
65%
444
8%
1411
8%
442
66%
442
26%
889
August16th to endNight
58%
573
17%
1719
14%
573
61%
573
33%
1040
September1st to 15thNight
57%
556
14%
1760
12%
556
59%
556
28%
1074
September16th to endNight
55%
716
21%
1983
14%
716
61%
716
37%
1187
October1st to 15thNight
44%
720
17%
2160
10%
720
50%
720
23%
1477
October16th to endNight
38%
822
16%
2514
10%
822
45%
822
20%
1762
November1st to 15thNight
34%
950
14%
2660
8%
950
39%
950
18%
1984
November16th to endNight
30%
975
10%
2867
5%
975
35%
975
16%
2151
December1st to 15thNight
28%
905
7%
2715
4%
905
31%
905
10%
2215
December16th to endNight
33%
960
10%
2880
5%
960
37%
960
13%
2266

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
11%9%47%6%35%5%6%7%31%
48723
Night
9%9%48%7%45%5%5%7%32%
47888
TransparencyDay
49%8%16%19%5%
48373
Night
48%7%15%20%7%
47742
SeeingDay
15%6%25%28%18%5%
6360
Night
13%5%26%34%17%2
15663

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
8%11%5%9%9%5%5%6%6%7%22%
1253
16th to endDay
5%14%7%8%9%45%5%5%5%27%
1362
February1st to 15thDay
9%11%5%11%7%5%5%45%7%25%
1497
16th to endDay
6%15%7%12%8%36%6%7%7%18%
1422
March1st to 15thDay
9%12%49%8%5%5%6%6%8%23%
1874
16th to endDay
14%13%5%10%7%35%447%23%
2111
April1st to 15thDay
11%11%5%8%7%446%5%7%28%
2264
16th to endDay
16%11%45%5%35%45%8%28%
2365
May1st to 15thDay
10%7%37%6%36%5%6%8%33%
2580
16th to endDay
17%8%35%6%36%6%6%7%29%
2802
June1st to 15thDay
16%8%46%7%46%6%6%6%26%
2700
16th to endDay
16%6%26%5%36%7%6%8%28%
2700
July1st to 15thDay
10%4245%35%6%7%9%38%
2700
16th to endDay
8%5%245%46%5%6%9%41%
2846
August1st to 15thDay
12%6%25%5%36%6%6%9%35%
2540
16th to endDay
8%5%25%4335%6%9%44%
2483
September1st to 15thDay
12%6%26%6%34345%43%
2198
16th to endDay
10%6%2442335%8%47%
1977
October1st to 15thDay
14%12%45%5%335%46%35%
1800
16th to endDay
9%11%5%6%5%335%6%7%34%
1697
November1st to 15thDay
10%13%6%7%6%345%6%7%28%
1528
16th to endDay
8%12%5%10%7%45%45%8%28%
1420
December1st to 15thDay
9%14%9%10%8%5%9%6%46%15%
1260
16th to endDay
6%13%6%11%11%6%8%5%46%20%
1344
January1st to 15thNight
7%10%49%8%6%7%7%6%7%22%
2685
16th to endNight
5%11%410%8%45%5%5%7%30%
2871
February1st to 15thNight
6%9%5%11%9%46%6%5%7%27%
2355
16th to endNight
7%10%6%9%7%45%6%6%8%27%
2052
March1st to 15thNight
7%8%410%8%36%6%6%8%28%
2085
16th to endNight
9%13%6%8%8%345%5%7%25%
2109
April1st to 15thNight
10%11%36%6%37%6%6%8%30%
1682
16th to endNight
13%11%47%5%33346%35%
1594
May1st to 15thNight
11%7%25%6%36%46%8%36%
1367
16th to endNight
19%5%25%5%35%5%5%7%32%
1309
June1st to 15thNight
13%9%47%6%46%6%5%7%29%
1260
16th to endNight
12%6%36%5%36%6%5%9%35%
1260
July1st to 15thNight
8%425%5%335%8%9%43%
1260
16th to endNight
7%3235%25%7%6%10%45%
1323
August1st to 15thNight
8%4145%45%5%7%10%40%
1418
16th to endNight
6%425%436%45%9%47%
1719
September1st to 15thNight
11%5%25%423446%47%
1760
16th to endNight
7%414325%45%9%50%
1983
October1st to 15thNight
11%9%36%5%25%46%7%37%
2160
16th to endNight
10%10%45%6%45%6%6%8%32%
2514
November1st to 15thNight
11%12%47%7%35%45%6%29%
2660
16th to endNight
7%11%5%10%8%45%5%5%6%29%
2867
December1st to 15thNight
8%14%6%12%9%46%5%5%6%18%
2715
16th to endNight
411%6%12%10%6%7%6%6%6%21%
2880

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
57%8%14%13%4
1253
16th to endDay
56%6%12%15%8%1
1362
February1st to 15thDay
56%7%13%18%4
1497
16th to endDay
62%7%10%13%6%
1422
March1st to 15thDay
57%8%16%14%3
1874
16th to endDay
60%6%13%15%4
2112
April1st to 15thDay
54%7%13%17%5%1
2264
16th to endDay
53%7%13%17%7%1
2365
May1st to 15thDay
47%7%11%23%9%
2580
16th to endDay
50%8%13%17%9%
2807
June1st to 15thDay
53%10%13%17%5%
2700
16th to endDay
49%10%18%17%4
2700
July1st to 15thDay
37%11%22%24%4
2541
16th to endDay
37%11%23%25%3
2667
August1st to 15thDay
41%11%23%18%4
2522
16th to endDay
33%9%22%27%6%
2483
September1st to 15thDay
42%5%17%24%8%2
2198
16th to endDay
35%7%16%29%9%1
1977
October1st to 15thDay
47%6%16%24%4
1800
16th to endDay
46%7%16%22%5%
1697
November1st to 15thDay
54%5%15%19%4
1528
16th to endDay
54%7%17%16%3
1420
December1st to 15thDay
66%8%9%12%1
1260
16th to endDay
63%6%10%14%4
1344
January1st to 15thNight
56%8%15%14%4
2685
16th to endNight
51%7%14%18%6%1
2871
February1st to 15thNight
52%7%15%16%7%
2366
16th to endNight
51%9%11%18%7%
2052
March1st to 15thNight
51%7%16%18%5%
2085
16th to endNight
56%6%12%18%6%
2112
April1st to 15thNight
48%9%14%18%8%1
1682
16th to endNight
49%6%9%18%13%2
1594
May1st to 15thNight
44%5%10%25%13%
1368
16th to endNight
48%9%10%22%7%2
1309
June1st to 15thNight
51%9%13%19%6%
1260
16th to endNight
44%9%18%20%7%
1260
July1st to 15thNight
32%10%21%28%6%
1190
16th to endNight
31%10%23%28%6%
1239
August1st to 15thNight
34%11%24%23%5%
1411
16th to endNight
32%7%17%31%10%
1719
September1st to 15thNight
36%7%16%23%11%4
1760
16th to endNight
29%7%16%32%11%2
1983
October1st to 15thNight
44%7%13%26%8%
2160
16th to endNight
47%7%16%23%5%
2514
November1st to 15thNight
53%6%13%18%6%1
2660
16th to endNight
54%7%18%13%5%
2867
December1st to 15thNight
64%7%11%12%2
2715
16th to endNight
59%8%13%14%3
2880

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%326%35%16%5%
60
16th to endDay
12%6%23%31%21%4
64
February1st to 15thDay
14%133%29%16%3
77
16th to endDay
23%230%17%23%2
81
March1st to 15thDay
15%7%39%28%7%1
242
16th to endDay
21%7%32%26%11%1
288
April1st to 15thDay
18%8%36%25%7%1
269
16th to endDay
25%10%22%26%13%2
295
May1st to 15thDay
12%7%25%32%16%4
468
16th to endDay
19%6%22%25%17%8%
517
June1st to 15thDay
17%8%26%26%15%5%
495
16th to endDay
15%5%22%29%17%8%
495
July1st to 15thDay
13%317%32%25%7%
475
16th to endDay
10%5%24%28%26%3
515
August1st to 15thDay
13%315%27%29%10%
419
16th to endDay
7%6%24%33%24%3
332
September1st to 15thDay
18%430%26%14%5%
315
16th to endDay
15%8%26%28%16%4
312
October1st to 15thDay
25%5%25%28%11%4
135
16th to endDay
15%8%31%25%14%3
144
November1st to 15thDay
17%328%38%10%1
135
16th to endDay
15%9%31%27%7%8%
103
December1st to 15thDay
13%5%31%25%16%8%
60
16th to endDay
15%428%28%17%6%
64
January1st to 15thNight
12%6%30%35%12%1
900
16th to endNight
11%9%34%32%10%1
951
February1st to 15thNight
10%6%26%35%18%2
704
16th to endNight
13%322%37%19%4
632
March1st to 15thNight
10%5%30%36%13%2
720
16th to endNight
15%428%32%16%3
768
April1st to 15thNight
15%7%28%32%14%1
548
16th to endNight
19%5%24%34%15%1
540
May1st to 15thNight
16%5%20%37%19%1
468
16th to endNight
19%425%26%21%2
375
June1st to 15thNight
19%5%21%30%20%2
360
16th to endNight
13%322%31%25%3
360
July1st to 15thNight
10%319%40%25%1
340
16th to endNight
7%419%40%24%2
376
August1st to 15thNight
11%113%36%32%4
444
16th to endNight
8%223%38%25%1
573
September1st to 15thNight
14%317%39%21%2
556
16th to endNight
9%424%38%20%1
716
October1st to 15thNight
15%427%31%18%2
720
16th to endNight
16%429%36%11%
822
November1st to 15thNight
18%5%31%30%12%2
950
16th to endNight
13%8%31%32%10%2
975
December1st to 15thNight
15%7%29%27%17%3
905
16th to endNight
9%5%29%34%17%3
960
Page generated at 2017-12-02 07:14:19. Version ac04

Copyright 2017 A. Danko


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