Leduc
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Leduc clear sky chart from 2005-11-05 to

2017-09-12
.

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
42%
15155
10%
46604
7%
15129
45%
15129
18%
33325

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
33%
895
7%
2685
4%
895
36%
895
13%
2072
January16th to endNight
31%
895
15%
2815
8%
895
39%
895
16%
2011
February1st to 15thNight
40%
699
9%
2434
7%
698
44%
698
15%
1739
February16th to endNight
47%
632
12%
2016
13%
632
49%
632
18%
1425
March1st to 15thNight
40%
720
13%
2114
10%
720
44%
720
18%
1541
March16th to endNight
39%
768
10%
2088
5%
767
41%
767
17%
1612
April1st to 15thNight
39%
602
11%
1682
7%
602
42%
602
18%
1252
April16th to endNight
40%
540
11%
1620
9%
540
42%
540
18%
1159
May1st to 15thNight
45%
380
7%
1311
6%
380
46%
380
17%
902
May16th to endNight
39%
374
1%
1309
0%
374
40%
374
14%
950
June1st to 15thNight
41%
360
0%
1260
0%
360
41%
360
13%
935
June16th to endNight
50%
360
0%
1147
0%
360
50%
360
17%
832
July1st to 15thNight
58%
340
0%
1190
0%
340
58%
340
23%
773
July16th to endNight
58%
376
3%
1239
2%
354
59%
354
20%
795
August1st to 15thNight
63%
372
6%
1406
8%
370
64%
370
21%
876
August16th to endNight
57%
573
11%
1719
10%
573
58%
573
26%
1116
September1st to 15thNight
60%
616
15%
1739
11%
616
61%
616
32%
1099
September16th to endNight
52%
656
18%
1815
12%
656
57%
656
33%
1129
October1st to 15thNight
43%
660
15%
1969
10%
660
47%
660
21%
1384
October16th to endNight
41%
704
14%
2288
10%
704
46%
704
19%
1592
November1st to 15thNight
34%
873
14%
2478
9%
873
39%
873
17%
1835
November16th to endNight
29%
900
10%
2700
5%
900
34%
900
14%
2076
December1st to 15thNight
31%
900
9%
2700
5%
900
35%
900
13%
2103
December16th to endNight
37%
960
12%
2880
5%
960
42%
960
17%
2117

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
10%8%47%6%35%5%6%8%31%
48078
Night
9%10%48%7%45%5%6%8%30%
46758
TransparencyDay
48%8%17%19%5%
47728
Night
49%7%15%18%6%
46612
SeeingDay
15%5%22%31%19%5%
6177
Night
13%5%26%35%17%2
15167

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%13%6%9%9%5%6%448%24%
1253
16th to endDay
6%14%5%9%7%35%5%6%7%27%
1419
February1st to 15thDay
8%11%5%8%8%36%5%5%8%27%
1424
16th to endDay
5%13%8%10%7%47%6%5%7%22%
1458
March1st to 15thDay
7%12%6%10%9%45%5%6%7%25%
1846
16th to endDay
11%12%5%9%7%35%5%6%9%23%
2130
April1st to 15thDay
12%11%47%6%45%5%6%7%28%
2266
16th to endDay
14%10%47%6%25%5%7%8%28%
2340
May1st to 15thDay
8%8%38%7%36%6%6%7%33%
2636
16th to endDay
18%7%46%5%36%45%8%29%
2802
June1st to 15thDay
17%8%36%7%45%5%6%7%26%
2700
16th to endDay
13%6%35%5%46%5%6%9%32%
2799
July1st to 15thDay
11%5%26%6%35%5%7%9%37%
2700
16th to endDay
10%414336%6%7%9%41%
2846
August1st to 15thDay
10%5%25%6%35%6%8%10%35%
2546
16th to endDay
8%5%25%5%35%5%7%9%41%
2483
September1st to 15thDay
12%6%35%6%3445%7%41%
2140
16th to endDay
10%4245%345%5%10%44%
1815
October1st to 15thDay
12%8%48%6%45%446%34%
1660
16th to endDay
10%10%5%5%5%25%46%9%32%
1574
November1st to 15thDay
8%12%5%8%6%45%46%7%28%
1377
16th to endDay
6%11%6%12%8%36%346%30%
1260
December1st to 15thDay
7%13%7%11%11%46%5%5%6%20%
1260
16th to endDay
7%12%48%10%5%6%6%5%7%24%
1344
January1st to 15thNight
7%13%6%10%8%5%7%5%5%6%23%
2685
16th to endNight
7%11%410%7%35%5%5%6%31%
2815
February1st to 15thNight
5%9%6%12%8%46%5%47%28%
2428
16th to endNight
7%12%46%6%5%5%6%5%8%30%
2016
March1st to 15thNight
6%10%48%8%37%5%7%8%29%
2114
16th to endNight
8%13%7%9%7%35%6%7%8%22%
2088
April1st to 15thNight
10%9%47%8%47%5%5%7%28%
1682
16th to endNight
14%10%38%6%345%5%8%30%
1620
May1st to 15thNight
9%7%48%7%46%6%5%7%31%
1310
16th to endNight
20%7%47%5%25%46%6%28%
1309
June1st to 15thNight
16%8%47%6%36%7%6%7%25%
1260
16th to endNight
13%7%36%7%46%6%6%9%27%
1147
July1st to 15thNight
9%5%36%5%35%5%6%10%37%
1260
16th to endNight
9%5%145%36%7%8%9%36%
1323
August1st to 15thNight
10%5%25%5%345%8%9%39%
1413
16th to endNight
8%6%25%5%36%5%6%10%38%
1719
September1st to 15thNight
12%5%25%42345%8%46%
1739
16th to endNight
8%5%3442346%9%47%
1815
October1st to 15thNight
11%10%37%5%45%45%6%34%
1969
16th to endNight
8%8%38%6%45%5%6%8%32%
2288
November1st to 15thNight
11%12%6%7%7%35%45%7%28%
2478
16th to endNight
6%13%6%10%8%46%5%5%5%26%
2700
December1st to 15thNight
9%14%6%9%8%45%45%7%23%
2700
16th to endNight
412%6%10%8%46%5%6%8%25%
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%13%14%5%
1253
16th to endDay
53%7%14%16%7%1
1419
February1st to 15thDay
52%7%17%15%5%
1424
16th to endDay
57%8%12%15%5%
1458
March1st to 15thDay
55%8%15%15%3
1846
16th to endDay
56%8%13%16%3
2131
April1st to 15thDay
52%9%14%18%6%
2266
16th to endDay
51%7%16%15%7%1
2340
May1st to 15thDay
46%7%14%21%9%
2636
16th to endDay
52%7%14%17%7%
2807
June1st to 15thDay
54%6%17%17%3
2700
16th to endDay
47%9%20%18%4
2799
July1st to 15thDay
40%10%22%23%2
2541
16th to endDay
36%12%26%21%2
2667
August1st to 15thDay
39%12%27%17%2
2528
16th to endDay
36%8%25%22%6%
2483
September1st to 15thDay
40%7%19%23%6%1
2140
16th to endDay
34%8%19%29%6%1
1815
October1st to 15thDay
49%7%16%19%6%
1660
16th to endDay
46%8%14%25%4
1574
November1st to 15thDay
53%7%15%18%4
1377
16th to endDay
53%8%15%15%5%1
1260
December1st to 15thDay
63%7%11%14%2
1260
16th to endDay
55%7%13%15%7%
1344
January1st to 15thNight
58%7%16%12%31
2685
16th to endNight
51%6%14%17%7%1
2815
February1st to 15thNight
52%7%14%17%7%
2439
16th to endNight
49%7%14%17%10%1
2016
March1st to 15thNight
49%9%14%19%6%
2114
16th to endNight
55%7%13%17%5%
2091
April1st to 15thNight
52%8%13%17%6%1
1682
16th to endNight
50%7%12%18%10%1
1620
May1st to 15thNight
48%7%13%16%13%
1311
16th to endNight
54%7%10%18%7%2
1309
June1st to 15thNight
54%9%15%16%4
1260
16th to endNight
50%9%19%17%2
1147
July1st to 15thNight
40%9%22%22%4
1190
16th to endNight
38%12%23%22%2
1239
August1st to 15thNight
37%11%25%22%2
1406
16th to endNight
37%9%21%24%6%
1719
September1st to 15thNight
36%6%17%26%11%1
1739
16th to endNight
32%8%17%28%10%2
1815
October1st to 15thNight
47%7%14%22%7%
1969
16th to endNight
47%8%17%22%4
2288
November1st to 15thNight
53%6%12%19%6%1
2478
16th to endNight
57%7%14%13%6%1
2700
December1st to 15thNight
60%6%14%14%4
2700
16th to endNight
52%7%17%16%5%
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
10%330%30%20%6%
60
16th to endDay
4320%39%21%10%
64
February1st to 15thDay
13%6%32%27%16%3
65
16th to endDay
12%5%22%38%14%5%
117
March1st to 15thDay
14%5%34%33%10%2
270
16th to endDay
14%5%26%35%15%1
288
April1st to 15thDay
18%8%27%33%11%1
269
16th to endDay
24%9%20%27%15%3
270
May1st to 15thDay
12%7%22%34%18%4
437
16th to endDay
18%5%19%30%19%5%
517
June1st to 15thDay
18%6%24%31%15%5%
495
16th to endDay
15%421%29%21%7%
594
July1st to 15thDay
13%215%34%27%6%
475
16th to endDay
12%320%31%25%5%
515
August1st to 15thDay
11%217%29%24%15%
353
16th to endDay
11%5%21%29%26%4
332
September1st to 15thDay
16%6%24%26%20%6%
300
16th to endDay
11%12%25%29%15%5%
255
October1st to 15thDay
24%423%28%13%5%
136
16th to endDay
22%423%26%20%2
96
November1st to 15thDay
22%232%29%12%
85
16th to endDay
18%5%28%26%8%13%
60
December1st to 15thDay
6%333%28%21%6%
60
16th to endDay
10%418%34%26%4
64
January1st to 15thNight
11%8%30%33%13%2
900
16th to endNight
11%9%32%33%11%2
895
February1st to 15thNight
9%6%24%39%18%1
704
16th to endNight
13%421%35%21%2
632
March1st to 15thNight
11%429%38%14%2
720
16th to endNight
14%427%34%15%2
768
April1st to 15thNight
14%5%29%31%17%1
602
16th to endNight
20%5%22%34%15%1
540
May1st to 15thNight
11%7%24%39%15%2
381
16th to endNight
21%5%21%30%19%1
375
June1st to 15thNight
20%5%22%33%13%3
360
16th to endNight
15%321%31%26%1
360
July1st to 15thNight
15%15%42%24%1
340
16th to endNight
13%317%41%22%1
376
August1st to 15thNight
12%115%32%31%6%
372
16th to endNight
10%220%38%27%
573
September1st to 15thNight
14%116%39%24%2
616
16th to endNight
12%326%39%16%2
656
October1st to 15thNight
17%425%34%16%1
660
16th to endNight
14%329%37%13%
704
November1st to 15thNight
15%7%31%32%10%1
873
16th to endNight
11%6%34%32%12%2
900
December1st to 15thNight
16%8%29%28%14%2
900
16th to endNight
8%431%32%18%4
960
Page generated at 2017-09-13 05:39:08. Version ac04

Copyright 2017 A. Danko


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