Carcross
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carcross clear sky chart from 2005-11-05 to 2017-09-20.

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
36%
14052
4%
46509
3%
14018
37%
14018
10%
37359

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
29%
802
3%
3041
3%
797
30%
797
6%
2599
January16th to endNight
25%
800
6%
3060
5%
800
29%
800
7%
2481
February1st to 15thNight
32%
732
5%
2559
3%
728
34%
728
9%
2068
February16th to endNight
42%
659
9%
2127
7%
659
43%
659
13%
1640
March1st to 15thNight
38%
722
10%
2172
8%
722
40%
722
14%
1677
March16th to endNight
44%
595
6%
2009
6%
595
46%
595
11%
1592
April1st to 15thNight
49%
539
6%
1676
5%
539
50%
539
17%
1212
April16th to endNight
49%
540
2%
1440
1%
540
50%
540
19%
1075
May1st to 15thNight
55%
368
0%
1143
0%
368
55%
368
18%
824
May16th to endNight
56%
375
0%
1076
0%
374
56%
374
22%
750
June1st to 15thNight
51%
189
0%
729
0%
189
51%
189
16%
486
June16th to endNight
52%
180
0%
720
0%
180
52%
180
12%
537
July1st to 15thNight
52%
170
0%
738
0%
170
52%
170
14%
515
July16th to endNight
45%
373
0%
1059
0%
351
44%
351
13%
829
August1st to 15thNight
51%
456
0%
1225
0%
454
51%
454
21%
891
August16th to endNight
35%
573
1%
1528
0%
573
36%
573
12%
1263
September1st to 15thNight
38%
540
5%
1782
4%
540
39%
540
11%
1395
September16th to endNight
33%
612
6%
1843
5%
612
35%
612
11%
1446
October1st to 15thNight
32%
660
7%
2035
6%
660
33%
660
11%
1652
October16th to endNight
29%
725
2%
2401
1%
725
30%
725
8%
1996
November1st to 15thNight
27%
730
2%
2653
2%
730
27%
730
6%
2275
November16th to endNight
24%
790
4%
2920
4%
790
25%
790
5%
2499
December1st to 15thNight
31%
930
4%
3117
3%
930
33%
930
7%
2662
December16th to endNight
28%
992
4%
3456
3%
992
30%
992
5%
2995

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
9%11%5%9%8%47%6%6%7%22%
48408
Night
7%12%6%11%9%5%7%6%6%7%19%
46613
TransparencyDay
57%11%17%10%2
48017
Night
60%10%15%10%2
46509
SeeingDay
16%12%28%27%12%2
7608
Night
13%7%25%31%18%2
14055

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%15%6%14%10%48%8%5%8%11%
906
16th to endDay
5%14%7%13%8%5%7%7%8%8%13%
1164
February1st to 15thDay
210%5%13%10%6%10%8%6%7%18%
1305
16th to endDay
39%7%12%9%6%10%7%7%8%16%
1344
March1st to 15thDay
210%7%12%10%8%9%6%7%6%17%
1788
16th to endDay
312%6%12%11%48%9%7%5%18%
2213
April1st to 15thDay
410%7%9%9%5%8%5%6%8%24%
2268
16th to endDay
412%8%10%8%47%6%6%7%22%
2520
May1st to 15thDay
7%13%5%8%7%46%5%7%6%26%
2808
16th to endDay
8%8%47%7%46%5%6%9%32%
3036
June1st to 15thDay
10%8%37%6%45%6%7%9%30%
3230
16th to endDay
12%7%48%7%5%6%6%6%9%25%
3240
July1st to 15thDay
13%7%38%7%5%8%7%7%7%23%
3176
16th to endDay
13%7%37%7%36%6%6%8%27%
3038
August1st to 15thDay
11%6%36%7%46%6%6%8%31%
2727
16th to endDay
22%12%37%7%46%46%5%20%
2674
September1st to 15thDay
17%10%47%7%47%5%5%6%22%
2178
16th to endDay
16%14%49%7%36%5%6%6%19%
1885
October1st to 15thDay
12%15%48%7%446%5%7%22%
1595
16th to endDay
8%15%6%11%9%5%7%6%6%7%16%
1471
November1st to 15thDay
7%16%6%15%11%5%5%447%14%
1205
16th to endDay
417%8%15%10%46%7%5%7%12%
1026
December1st to 15thDay
6%15%7%12%10%5%9%5%9%8%9%
843
16th to endDay
315%7%16%13%6%8%5%5%7%8%
768
January1st to 15thNight
6%15%8%11%9%6%7%6%5%6%14%
3041
16th to endNight
413%7%13%10%5%8%7%8%8%14%
3060
February1st to 15thNight
311%6%12%10%5%8%7%7%8%17%
2547
16th to endNight
29%6%11%9%48%7%7%10%21%
2127
March1st to 15thNight
312%7%11%7%7%7%7%5%8%21%
2172
16th to endNight
412%7%12%9%5%8%7%6%6%20%
2004
April1st to 15thNight
49%49%9%47%5%7%8%29%
1676
16th to endNight
411%37%7%47%7%6%8%29%
1440
May1st to 15thNight
5%8%48%6%37%7%7%9%31%
1142
16th to endNight
8%6%26%6%45%8%8%10%32%
1076
June1st to 15thNight
10%5%48%6%45%46%8%33%
729
16th to endNight
11%7%37%9%36%6%9%9%26%
720
July1st to 15thNight
10%5%48%7%35%6%9%9%27%
783
16th to endNight
13%6%39%7%5%7%6%7%8%25%
1130
August1st to 15thNight
11%6%25%6%35%48%9%36%
1231
16th to endNight
17%10%38%6%46%5%6%7%22%
1528
September1st to 15thNight
12%9%48%7%47%5%7%7%25%
1782
16th to endNight
12%12%5%7%7%46%5%47%24%
1843
October1st to 15thNight
13%17%5%6%7%45%5%5%6%24%
2035
16th to endNight
8%16%8%12%8%36%45%5%19%
2401
November1st to 15thNight
6%15%8%14%11%5%6%5%5%8%11%
2653
16th to endNight
316%8%15%12%6%6%5%6%7%11%
2920
December1st to 15thNight
7%14%7%12%11%5%7%6%7%8%13%
3117
16th to endNight
5%16%7%13%12%6%8%6%6%7%8%
3456

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
72%10%8%6%2
906
16th to endDay
65%10%12%8%2
1164
February1st to 15thDay
62%10%11%11%4
1305
16th to endDay
63%9%12%9%5%
1344
March1st to 15thDay
63%8%12%9%41
1788
16th to endDay
62%11%11%7%6%
2213
April1st to 15thDay
56%11%19%10%2
2268
16th to endDay
57%10%18%10%2
2520
May1st to 15thDay
55%10%15%15%2
2808
16th to endDay
45%10%20%19%2
3040
June1st to 15thDay
46%12%25%12%2
3230
16th to endDay
53%13%20%11%1
3240
July1st to 15thDay
55%12%19%10%1
2992
16th to endDay
51%15%23%9%
2846
August1st to 15thDay
47%13%24%12%1
2708
16th to endDay
64%13%15%6%
2674
September1st to 15thDay
61%12%14%11%
2178
16th to endDay
64%10%15%7%
1885
October1st to 15thDay
61%12%14%8%2
1595
16th to endDay
66%10%17%4
1471
November1st to 15thDay
67%11%14%5%1
1205
16th to endDay
69%8%11%7%2
1026
December1st to 15thDay
67%13%11%7%
843
16th to endDay
71%10%8%7%2
768
January1st to 15thNight
68%10%9%6%3
3041
16th to endNight
64%9%13%10%1
3060
February1st to 15thNight
61%11%11%11%3
2559
16th to endNight
55%10%13%13%6%
2127
March1st to 15thNight
59%5%13%14%5%1
2172
16th to endNight
60%9%13%10%6%
2009
April1st to 15thNight
49%10%18%18%3
1676
16th to endNight
50%9%18%17%2
1440
May1st to 15thNight
45%12%21%16%3
1143
16th to endNight
41%11%19%21%5%
1076
June1st to 15thNight
45%10%28%13%1
729
16th to endNight
51%14%22%11%
720
July1st to 15thNight
47%12%24%14%1
738
16th to endNight
51%15%24%7%
1059
August1st to 15thNight
41%15%25%14%2
1225
16th to endNight
60%12%20%6%
1528
September1st to 15thNight
54%13%17%13%
1782
16th to endNight
57%10%18%12%
1843
October1st to 15thNight
61%10%14%11%3
2035
16th to endNight
64%11%18%6%
2401
November1st to 15thNight
68%11%13%5%
2653
16th to endNight
70%9%10%7%1
2920
December1st to 15thNight
67%11%11%8%1
3117
16th to endNight
71%9%8%6%2
3456

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
20%15%15%23%17%7%
39
16th to endDay
18%10%28%23%18%
76
February1st to 15thDay
9%10%37%26%11%4
236
16th to endDay
9%8%33%26%16%6%
211
March1st to 15thDay
7%16%36%25%9%4
240
16th to endDay
10%12%31%25%17%2
277
April1st to 15thDay
8%16%27%30%13%3
326
16th to endDay
11%13%24%34%14%1
450
May1st to 15thDay
16%12%27%30%10%3
468
16th to endDay
11%7%30%28%16%5%
563
June1st to 15thDay
12%9%28%32%16%
675
16th to endDay
15%9%29%28%15%1
675
July1st to 15thDay
17%8%26%31%12%2
586
16th to endDay
18%12%26%30%11%
515
August1st to 15thDay
16%13%27%26%12%2
494
16th to endDay
30%14%28%19%6%
523
September1st to 15thDay
30%14%25%18%8%1
321
16th to endDay
28%20%24%18%7%1
265
October1st to 15thDay
20%17%35%16%6%3
225
16th to endDay
20%10%31%23%10%3
240
November1st to 15thDay
16%11%33%31%33
60
16th to endDay
11%8%25%31%20%3
60
December1st to 15thDay
9%23%21%31%13%
51
16th to endDay
9%12%18%31%21%6%
32
January1st to 15thNight
13%9%31%29%14%1
802
16th to endNight
11%11%34%27%14%1
800
February1st to 15thNight
9%8%32%35%12%1
734
16th to endNight
6%6%30%35%17%3
659
March1st to 15thNight
8%8%31%34%14%3
722
16th to endNight
8%5%17%34%28%6%
595
April1st to 15thNight
7%5%19%34%29%3
539
16th to endNight
11%423%30%25%4
540
May1st to 15thNight
10%6%17%32%26%5%
369
16th to endNight
13%316%32%30%4
375
June1st to 15thNight
11%219%37%29%
189
16th to endNight
13%219%37%26%
180
July1st to 15thNight
12%120%43%21%
170
16th to endNight
16%5%20%36%20%
373
August1st to 15thNight
14%324%32%22%3
456
16th to endNight
24%5%22%28%17%2
573
September1st to 15thNight
19%8%23%31%15%1
540
16th to endNight
22%11%22%25%15%2
612
October1st to 15thNight
25%7%23%28%13%1
660
16th to endNight
17%6%28%28%15%2
725
November1st to 15thNight
13%8%28%33%13%3
730
16th to endNight
12%9%28%28%19%1
790
December1st to 15thNight
15%7%26%32%16%2
930
16th to endNight
13%6%27%32%16%4
992
Page generated at 2017-09-21 04:18:11. Version ac04

Copyright 2017 A. Danko


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