Whitecourt
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whitecourt 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
37%
15147
10%
46681
6%
15121
41%
15121
17%
33652

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
27%
922
7%
2844
4%
922
30%
922
11%
2195
January16th to endNight
27%
864
14%
2784
7%
864
36%
864
15%
1945
February1st to 15thNight
33%
699
9%
2464
7%
697
38%
697
14%
1765
February16th to endNight
42%
632
11%
2006
11%
632
45%
632
18%
1422
March1st to 15thNight
32%
720
13%
2157
8%
720
38%
720
15%
1603
March16th to endNight
34%
768
10%
2030
5%
768
37%
768
16%
1604
April1st to 15thNight
32%
638
12%
1718
5%
638
36%
638
18%
1300
April16th to endNight
33%
486
9%
1566
7%
486
37%
486
15%
1153
May1st to 15thNight
37%
359
5%
1325
3%
359
39%
359
15%
901
May16th to endNight
41%
374
0%
1309
0%
374
41%
374
15%
941
June1st to 15thNight
40%
360
0%
1095
0%
360
40%
360
15%
831
June16th to endNight
46%
360
0%
1080
0%
360
46%
360
17%
799
July1st to 15thNight
55%
340
0%
1020
0%
340
55%
340
23%
694
July16th to endNight
56%
376
1%
1213
0%
354
56%
354
20%
803
August1st to 15thNight
60%
360
4%
1430
6%
358
60%
358
19%
907
August16th to endNight
52%
523
10%
1669
10%
523
55%
523
21%
1114
September1st to 15thNight
56%
681
14%
1782
9%
681
58%
681
33%
1145
September16th to endNight
45%
683
19%
1890
9%
683
52%
683
31%
1184
October1st to 15thNight
38%
660
15%
1991
10%
660
43%
660
19%
1430
October16th to endNight
34%
704
13%
2288
8%
704
41%
704
16%
1601
November1st to 15thNight
28%
841
12%
2521
7%
841
34%
841
15%
1868
November16th to endNight
27%
900
9%
2700
3%
900
33%
900
12%
2098
December1st to 15thNight
29%
905
11%
2727
7%
905
33%
905
14%
2041
December16th to endNight
32%
992
11%
3072
5%
992
38%
992
14%
2308

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%8%30%
48245
Night
9%10%47%6%35%5%6%8%30%
46816
TransparencyDay
49%9%17%17%5%
47884
Night
49%8%16%18%5%
46682
SeeingDay
16%10%28%27%13%3
6636
Night
14%8%28%32%14%1
15159

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
6%12%7%10%6%346%6%7%27%
1094
16th to endDay
5%12%45%7%5%7%6%5%6%33%
1449
February1st to 15thDay
8%9%5%10%6%47%5%6%8%27%
1400
16th to endDay
6%12%6%11%7%46%5%6%7%24%
1468
March1st to 15thDay
7%12%5%10%8%36%5%6%8%25%
1802
16th to endDay
11%13%6%7%6%36%5%6%8%24%
2189
April1st to 15thDay
10%12%6%7%6%46%5%6%8%25%
2230
16th to endDay
13%11%38%6%46%5%6%8%24%
2393
May1st to 15thDay
10%7%36%6%47%6%7%8%31%
2625
16th to endDay
19%6%37%6%45%45%7%29%
2802
June1st to 15thDay
17%8%37%7%36%5%6%7%25%
2862
16th to endDay
12%6%36%6%46%6%7%9%29%
2880
July1st to 15thDay
12%5%25%5%35%6%6%9%36%
2880
16th to endDay
9%425%6%35%6%9%10%36%
2870
August1st to 15thDay
10%5%16%6%35%5%8%9%35%
2521
16th to endDay
10%5%25%7%45%6%8%9%35%
2532
September1st to 15thDay
12%6%26%5%35%6%5%7%38%
2178
16th to endDay
12%5%25%5%345%5%7%42%
1882
October1st to 15thDay
13%11%46%7%3445%6%32%
1637
16th to endDay
10%12%49%5%35%45%7%32%
1584
November1st to 15thDay
12%12%6%7%5%245%6%6%29%
1325
16th to endDay
6%12%5%9%7%35%45%7%30%
1260
December1st to 15thDay
8%13%6%7%6%5%7%6%5%7%24%
1230
16th to endDay
5%13%5%9%7%5%5%5%6%7%27%
1152
January1st to 15thNight
6%13%6%9%8%46%6%6%7%24%
2844
16th to endNight
6%12%47%6%35%6%7%9%31%
2784
February1st to 15thNight
7%10%49%8%45%5%5%8%29%
2452
16th to endNight
5%11%5%8%6%45%6%7%7%31%
2006
March1st to 15thNight
8%9%6%8%7%46%5%6%7%28%
2157
16th to endNight
9%14%6%8%6%36%6%6%8%22%
2028
April1st to 15thNight
12%11%5%7%5%45%5%5%7%27%
1718
16th to endNight
13%13%46%6%25%5%5%8%27%
1566
May1st to 15thNight
11%8%47%6%35%6%5%7%32%
1324
16th to endNight
21%6%346%35%5%6%6%29%
1309
June1st to 15thNight
17%8%46%5%5%6%5%5%7%27%
1095
16th to endNight
11%5%38%9%47%6%6%9%27%
1080
July1st to 15thNight
10%425%6%35%6%8%9%35%
1080
16th to endNight
10%425%5%47%6%8%9%37%
1296
August1st to 15thNight
8%426%5%45%6%7%10%38%
1437
16th to endNight
9%5%25%6%46%7%7%8%37%
1669
September1st to 15thNight
10%5%2442447%8%44%
1782
16th to endNight
11%3244235%5%11%44%
1890
October1st to 15thNight
12%10%37%445%45%7%33%
1991
16th to endNight
9%12%36%6%345%6%8%32%
2288
November1st to 15thNight
13%11%48%6%445%5%7%28%
2521
16th to endNight
8%13%7%10%7%36%5%5%7%26%
2700
December1st to 15thNight
8%11%5%8%7%5%4448%29%
2727
16th to endNight
411%5%12%8%46%5%5%7%27%
3072

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
54%9%16%12%5%1
1094
16th to endDay
50%8%12%16%9%1
1449
February1st to 15thDay
52%11%14%14%6%
1400
16th to endDay
57%6%13%16%6%
1468
March1st to 15thDay
55%8%14%16%4
1802
16th to endDay
56%8%15%15%3
2190
April1st to 15thDay
53%9%14%15%6%
2230
16th to endDay
55%8%14%14%5%
2393
May1st to 15thDay
46%8%15%19%8%
2625
16th to endDay
53%6%13%16%9%
2807
June1st to 15thDay
54%8%17%15%2
2862
16th to endDay
48%10%18%17%4
2880
July1st to 15thDay
41%10%21%21%4
2711
16th to endDay
39%14%25%18%2
2690
August1st to 15thDay
41%12%26%16%2
2503
16th to endDay
40%11%25%17%5%
2532
September1st to 15thDay
41%9%22%21%4
2178
16th to endDay
40%9%18%24%6%1
1882
October1st to 15thDay
50%8%14%22%3
1637
16th to endDay
50%8%15%22%3
1584
November1st to 15thDay
52%8%16%16%5%
1325
16th to endDay
52%9%15%15%5%1
1260
December1st to 15thDay
58%9%13%15%3
1230
16th to endDay
52%8%17%15%5%
1152
January1st to 15thNight
56%10%14%14%31
2844
16th to endNight
47%8%17%16%7%1
2784
February1st to 15thNight
52%7%17%16%5%
2464
16th to endNight
49%7%16%18%7%1
2006
March1st to 15thNight
53%7%13%19%5%
2157
16th to endNight
57%7%12%15%6%
2031
April1st to 15thNight
55%5%14%15%7%
1718
16th to endNight
53%8%14%16%7%1
1566
May1st to 15thNight
48%7%14%18%10%
1325
16th to endNight
53%6%14%16%9%
1309
June1st to 15thNight
55%8%14%19%2
1095
16th to endNight
50%10%18%17%2
1080
July1st to 15thNight
40%11%20%20%6%
1020
16th to endNight
39%12%28%16%3
1213
August1st to 15thNight
37%13%23%21%3
1430
16th to endNight
39%12%22%20%5%
1669
September1st to 15thNight
35%6%22%26%7%1
1782
16th to endNight
33%7%19%28%8%1
1890
October1st to 15thNight
49%7%13%22%5%
1991
16th to endNight
48%8%17%22%3
2288
November1st to 15thNight
54%6%14%20%4
2521
16th to endNight
57%9%13%13%41
2700
December1st to 15thNight
54%7%15%17%4
2727
16th to endNight
54%8%13%18%4
3072

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
16%8%28%30%13%3
60
16th to endDay
7%10%32%31%12%4
64
February1st to 15thDay
13%10%41%28%6%
60
16th to endDay
12%11%26%37%9%3
154
March1st to 15thDay
15%19%31%26%6%
270
16th to endDay
19%11%36%25%5%1
288
April1st to 15thDay
18%20%37%18%4
269
16th to endDay
22%16%32%19%9%
270
May1st to 15thDay
11%16%27%29%11%4
402
16th to endDay
17%9%25%28%14%4
517
June1st to 15thDay
20%9%28%25%13%3
657
16th to endDay
14%8%27%26%17%5%
675
July1st to 15thDay
13%6%26%31%19%2
645
16th to endDay
10%7%30%27%18%4
538
August1st to 15thDay
12%7%26%27%18%7%
316
16th to endDay
13%11%36%26%12%
332
September1st to 15thDay
17%12%27%28%10%4
315
16th to endDay
16%14%28%26%11%2
280
October1st to 15thDay
26%11%20%28%12%
171
16th to endDay
23%5%17%32%17%3
96
November1st to 15thDay
21%5%26%38%6%1
73
16th to endDay
13%11%30%25%6%13%
60
December1st to 15thDay
13%8%28%31%15%3
60
16th to endDay
15%10%20%26%18%7%
64
January1st to 15thNight
13%12%31%30%9%2
927
16th to endNight
13%15%33%27%9%
864
February1st to 15thNight
11%10%28%32%14%1
704
16th to endNight
10%5%31%36%13%2
632
March1st to 15thNight
11%9%34%32%11%1
720
16th to endNight
15%8%29%32%12%1
768
April1st to 15thNight
17%8%32%29%11%
638
16th to endNight
19%10%25%30%12%1
486
May1st to 15thNight
16%10%24%33%13%1
360
16th to endNight
23%6%22%30%15%2
375
June1st to 15thNight
20%5%24%26%21%1
360
16th to endNight
12%422%31%27%1
360
July1st to 15thNight
14%220%38%24%
340
16th to endNight
10%421%38%22%2
376
August1st to 15thNight
10%119%31%31%5%
360
16th to endNight
12%222%40%20%
523
September1st to 15thNight
14%319%37%20%3
681
16th to endNight
13%6%28%33%16%1
683
October1st to 15thNight
18%7%26%31%15%
660
16th to endNight
17%9%29%31%11%
704
November1st to 15thNight
18%11%30%29%9%1
841
16th to endNight
14%10%33%29%8%1
900
December1st to 15thNight
14%14%30%30%9%1
905
16th to endNight
10%11%27%32%14%3
992
Page generated at 2017-09-23 04:43:44. Version ac04

Copyright 2017 A. Danko


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