This page made possible by the sponsorship of: Grenfell Campus observatory.

Corner Brook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Corner Brook clear sky chart from 2005-11-05 to 2017-08-12.

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
20%
14995
5%
46476
3%
14954
22%
14954
8%
39473

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
6%
747
2%
2506
1%
746
7%
746
2%
2369
January16th to endNight
12%
800
3%
2688
2%
800
12%
800
2%
2497
February1st to 15thNight
9%
721
1%
2400
0%
720
10%
720
2%
2268
February16th to endNight
17%
631
2%
1913
1%
631
18%
631
6%
1696
March1st to 15thNight
18%
717
7%
2148
4%
716
20%
716
6%
1874
March16th to endNight
19%
618
7%
2007
4%
618
23%
618
7%
1707
April1st to 15thNight
19%
539
6%
1796
5%
539
22%
539
8%
1484
April16th to endNight
24%
540
9%
1616
7%
540
27%
540
10%
1288
May1st to 15thNight
32%
540
8%
1440
5%
540
33%
540
17%
1108
May16th to endNight
29%
561
7%
1448
3%
560
31%
560
15%
1159
June1st to 15thNight
32%
540
2%
1260
1%
540
33%
540
14%
1039
June16th to endNight
31%
540
3%
1260
2%
540
32%
540
18%
995
July1st to 15thNight
33%
510
3%
1292
3%
510
34%
510
20%
959
July16th to endNight
35%
565
7%
1419
4%
532
38%
532
18%
1071
August1st to 15thNight
36%
528
7%
1400
2%
524
39%
524
19%
1057
August16th to endNight
36%
525
8%
1649
6%
525
38%
525
16%
1213
September1st to 15thNight
28%
495
6%
1650
6%
495
31%
495
12%
1248
September16th to endNight
21%
493
10%
1815
7%
493
27%
493
11%
1354
October1st to 15thNight
22%
619
7%
1952
4%
619
26%
619
10%
1570
October16th to endNight
17%
736
5%
2288
2%
736
19%
736
5%
1969
November1st to 15thNight
16%
730
5%
2323
3%
730
18%
730
6%
2016
November16th to endNight
12%
750
4%
2629
2%
750
15%
750
3%
2322
December1st to 15thNight
10%
750
2%
2700
0%
750
11%
750
2%
2495
December16th to endNight
10%
800
2%
2877
2%
800
11%
800
1%
2715

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
20%14%6%10%8%34345%18%
47493
Night
18%16%7%11%9%4433415%
46658
TransparencyDay
69%49%12%4
47181
Night
72%48%10%3
46488
SeeingDay
29%18%23%17%8%2
7872
Night
29%17%23%21%7%1
15003

By Month

Percentage Cloud Cover NE (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
14%17%11%23%14%442114
1432
16th to endDay
11%16%11%19%20%6%42114
1536
February1st to 15thDay
15%11%8%16%19%7%5%3326%
1459
16th to endDay
12%20%11%18%12%3421110%
1560
March1st to 15thDay
14%19%8%11%10%5%5%43413%
1790
16th to endDay
15%19%10%11%9%4432314%
2216
April1st to 15thDay
18%17%7%13%8%3334415%
2153
16th to endDay
18%15%5%9%6%2433424%
2342
May1st to 15thDay
22%12%47%5%2334427%
2512
16th to endDay
25%13%47%5%24345%22%
2665
June1st to 15thDay
26%10%37%6%35%45%6%20%
2700
16th to endDay
24%10%47%5%3445%6%25%
2700
July1st to 15thDay
17%8%36%5%25%5%5%8%31%
2586
16th to endDay
21%10%37%6%3445%6%25%
2653
August1st to 15thDay
21%8%38%6%445%5%7%24%
2464
16th to endDay
27%8%26%6%2445%8%22%
2200
September1st to 15thDay
27%10%36%5%24346%25%
1979
16th to endDay
24%12%46%6%2445%7%21%
1815
October1st to 15thDay
27%13%35%5%23345%25%
1678
16th to endDay
31%23%7%8%42222212%
1584
November1st to 15thDay
23%30%7%8%5%2322310%
1535
16th to endDay
15%24%10%12%6%344448%
1329
December1st to 15thDay
17%20%11%22%8%343223
1260
16th to endDay
19%19%12%15%14%422116%
1345
January1st to 15thNight
14%20%12%19%13%442114
2506
16th to endNight
11%13%8%19%18%8%5%4224
2688
February1st to 15thNight
13%15%8%17%21%7%6%2124
2399
16th to endNight
11%16%9%17%13%45%32311%
1913
March1st to 15thNight
13%16%7%11%12%6%6%43313%
2147
16th to endNight
14%19%8%12%9%4443314%
2007
April1st to 15thNight
17%19%8%9%7%34345%16%
1796
16th to endNight
14%13%7%12%7%34445%21%
1616
May1st to 15thNight
20%12%36%425%446%28%
1440
16th to endNight
28%10%35%424446%24%
1446
June1st to 15thNight
24%8%5%7%6%445%47%20%
1260
16th to endNight
21%9%46%5%246%5%6%27%
1260
July1st to 15thNight
17%8%38%5%3436%8%30%
1371
16th to endNight
21%8%47%5%35%45%7%27%
1515
August1st to 15thNight
16%8%36%6%36%5%7%7%26%
1411
16th to endNight
21%8%36%5%35%45%7%28%
1649
September1st to 15thNight
25%10%46%5%24435%27%
1650
16th to endNight
23%11%46%5%3445%6%25%
1815
October1st to 15thNight
23%15%46%6%34446%20%
1952
16th to endNight
27%22%5%8%5%2343313%
2288
November1st to 15thNight
21%25%6%8%5%3434411%
2323
16th to endNight
19%21%10%13%6%343349%
2629
December1st to 15thNight
16%23%11%18%9%332225%
2700
16th to endNight
15%21%14%18%12%331115%
2877

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
89%243
1433
16th to endDay
90%2241
1536
February1st to 15thDay
84%25%5%
1462
16th to endDay
83%137%3
1560
March1st to 15thDay
75%45%10%3
1800
16th to endDay
76%35%10%4
2216
April1st to 15thDay
73%37%10%4
2153
16th to endDay
64%37%14%9%
2342
May1st to 15thDay
60%48%17%8%
2512
16th to endDay
65%410%14%5%
2669
June1st to 15thDay
65%5%9%14%4
2700
16th to endDay
60%5%12%16%5%
2700
July1st to 15thDay
50%6%15%22%5%
2437
16th to endDay
59%5%12%18%3
2486
August1st to 15thDay
57%8%13%16%3
2450
16th to endDay
60%6%15%14%3
2200
September1st to 15thDay
60%313%16%5%
1979
16th to endDay
62%5%13%14%3
1815
October1st to 15thDay
62%411%14%6%
1678
16th to endDay
80%36%8%1
1584
November1st to 15thDay
81%36%7%1
1535
16th to endDay
79%6%6%6%1
1329
December1st to 15thDay
88%343
1260
16th to endDay
88%2331
1345
January1st to 15thNight
89%233
2506
16th to endNight
87%3431
2688
February1st to 15thNight
89%233
2400
16th to endNight
78%36%7%3
1913
March1st to 15thNight
75%35%11%2
2160
16th to endNight
73%47%10%4
2007
April1st to 15thNight
70%48%12%3
1796
16th to endNight
64%5%8%13%7%
1616
May1st to 15thNight
56%6%11%18%6%1
1440
16th to endNight
60%6%10%16%5%
1448
June1st to 15thNight
61%7%12%14%4
1260
16th to endNight
56%7%13%16%6%
1260
July1st to 15thNight
51%6%17%20%4
1292
16th to endNight
55%413%20%4
1419
August1st to 15thNight
53%7%19%17%3
1400
16th to endNight
54%6%18%17%3
1649
September1st to 15thNight
60%414%16%4
1650
16th to endNight
59%5%14%14%5%
1815
October1st to 15thNight
64%5%12%10%5%1
1952
16th to endNight
75%38%8%3
2288
November1st to 15thNight
75%5%9%8%1
2323
16th to endNight
80%37%6%1
2629
December1st to 15thNight
86%35%4
2700
16th to endNight
88%3232
2877

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
23%35%26%9%21
240
16th to endDay
27%26%21%17%7%
256
February1st to 15thDay
25%29%22%15%5%
236
16th to endDay
26%21%26%11%10%3
212
March1st to 15thDay
24%27%24%16%5%2
240
16th to endDay
28%28%21%11%6%2
281
April1st to 15thDay
31%28%21%12%41
270
16th to endDay
27%18%23%18%8%2
429
May1st to 15thDay
30%11%21%20%12%3
468
16th to endDay
31%14%22%18%10%2
519
June1st to 15thDay
33%11%21%21%10%2
495
16th to endDay
30%14%27%15%8%2
495
July1st to 15thDay
21%13%30%21%11%2
475
16th to endDay
27%10%23%23%12%1
514
August1st to 15thDay
22%13%25%23%11%2
473
16th to endDay
29%8%23%24%9%3
355
September1st to 15thDay
35%12%31%14%5%
254
16th to endDay
33%17%27%15%41
224
October1st to 15thDay
35%16%22%15%7%4
225
16th to endDay
45%18%16%10%7%1
240
November1st to 15thDay
41%18%17%14%6%1
235
16th to endDay
32%21%23%16%5%1
240
December1st to 15thDay
33%26%25%11%4
240
16th to endDay
30%28%21%12%5%1
256
January1st to 15thNight
28%28%25%14%2
750
16th to endNight
24%25%27%17%5%
800
February1st to 15thNight
26%25%25%17%4
723
16th to endNight
25%18%26%18%8%2
631
March1st to 15thNight
25%24%21%20%8%
720
16th to endNight
25%18%25%22%7%
618
April1st to 15thNight
30%18%22%20%7%
539
16th to endNight
23%15%24%26%8%1
540
May1st to 15thNight
27%10%23%26%9%2
540
16th to endNight
34%9%21%22%10%1
561
June1st to 15thNight
27%8%20%29%12%
540
16th to endNight
27%9%25%26%10%2
540
July1st to 15thNight
21%10%28%25%13%1
510
16th to endNight
25%8%20%32%12%
565
August1st to 15thNight
24%8%23%26%16%
528
16th to endNight
25%8%24%25%13%2
525
September1st to 15thNight
34%13%18%24%8%
495
16th to endNight
33%13%26%22%4
493
October1st to 15thNight
35%14%21%18%7%2
619
16th to endNight
41%17%16%17%5%
736
November1st to 15thNight
38%15%20%17%7%
730
16th to endNight
36%22%18%16%41
750
December1st to 15thNight
29%26%23%15%3
750
16th to endNight
30%22%23%15%5%1
800
Page generated at 2017-08-13 15:46:48. Version ac04

Copyright 2017 A. Danko


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