Caroline
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caroline clear sky chart from 2005-11-05 to 2017-12-04.

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%
15466
12%
47817
8%
15439
45%
15439
20%
33268

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
32%
895
11%
2685
7%
895
36%
895
14%
2048
January16th to endNight
34%
829
18%
2749
12%
829
43%
829
18%
1906
February1st to 15thNight
38%
699
10%
2449
9%
697
41%
697
16%
1700
February16th to endNight
42%
632
13%
1971
11%
632
47%
632
20%
1372
March1st to 15thNight
37%
720
13%
2136
7%
720
43%
720
20%
1545
March16th to endNight
35%
768
12%
2061
5%
767
40%
767
19%
1526
April1st to 15thNight
34%
635
11%
1715
5%
635
38%
635
19%
1271
April16th to endNight
33%
540
10%
1620
7%
540
36%
540
18%
1172
May1st to 15thNight
44%
374
9%
1365
9%
374
48%
374
19%
905
May16th to endNight
45%
374
3%
1309
1%
374
46%
374
16%
930
June1st to 15thNight
41%
360
0%
1260
0%
360
41%
360
14%
932
June16th to endNight
49%
360
0%
1260
0%
360
49%
360
18%
868
July1st to 15thNight
59%
340
0%
1190
0%
340
59%
340
23%
769
July16th to endNight
59%
376
6%
1271
4%
354
61%
354
26%
753
August1st to 15thNight
65%
363
7%
1435
10%
361
65%
361
20%
898
August16th to endNight
60%
573
16%
1719
13%
573
63%
573
32%
1024
September1st to 15thNight
56%
675
15%
1803
11%
675
57%
675
32%
1158
September16th to endNight
50%
716
19%
1980
11%
716
55%
716
32%
1256
October1st to 15thNight
42%
720
14%
2139
9%
720
48%
720
22%
1486
October16th to endNight
42%
768
17%
2496
11%
768
51%
768
22%
1642
November1st to 15thNight
35%
894
16%
2639
9%
894
41%
894
20%
1867
November16th to endNight
29%
975
12%
2925
6%
975
36%
975
17%
2126
December1st to 15thNight
34%
920
11%
2760
8%
920
37%
920
16%
2045
December16th to endNight
35%
960
15%
2880
8%
960
41%
960
18%
2069

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%37%6%35%5%6%8%31%
48715
Night
8%9%48%6%35%5%6%8%33%
47968
TransparencyDay
48%9%17%17%6%
48369
Night
46%7%15%19%7%1
47820
SeeingDay
16%7%28%29%14%4
6269
Night
12%5%29%34%15%2
15478

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
7%14%5%8%6%3335%8%32%
1253
16th to endDay
6%12%5%9%6%36%5%5%7%31%
1485
February1st to 15thDay
5%14%49%8%35%5%5%7%29%
1416
16th to endDay
5%9%5%10%8%46%7%8%7%26%
1503
March1st to 15thDay
6%10%5%10%8%46%5%5%6%29%
1824
16th to endDay
7%14%5%9%7%45%6%7%7%24%
2159
April1st to 15thDay
10%15%5%7%7%46%6%6%7%22%
2233
16th to endDay
14%12%37%6%345%6%8%26%
2340
May1st to 15thDay
11%9%38%7%36%5%5%8%30%
2584
16th to endDay
20%8%26%7%345%6%8%24%
2802
June1st to 15thDay
20%7%36%6%46%6%6%7%22%
2700
16th to endDay
15%7%26%6%37%7%6%7%27%
2700
July1st to 15thDay
12%5%25%5%36%7%7%8%33%
2700
16th to endDay
10%425%5%35%6%8%9%38%
2810
August1st to 15thDay
14%5%25%5%35%5%6%9%36%
2516
16th to endDay
10%4244346%6%10%41%
2483
September1st to 15thDay
17%6%2442345%6%41%
2155
16th to endDay
11%6%245%3446%8%41%
1980
October1st to 15thDay
14%9%35%5%345%7%6%34%
1818
16th to endDay
9%8%36%7%36%5%6%8%34%
1728
November1st to 15thDay
5%12%5%8%6%45%5%6%7%31%
1535
16th to endDay
5%12%39%5%35%5%6%7%34%
1365
December1st to 15thDay
5%12%5%12%8%47%5%46%25%
1282
16th to endDay
311%5%10%8%445%7%6%31%
1344
January1st to 15thNight
5%13%7%11%7%46%5%5%6%25%
2685
16th to endNight
5%12%6%8%7%45%5%6%8%30%
2749
February1st to 15thNight
6%10%5%11%7%35%5%5%8%29%
2437
16th to endNight
410%5%9%7%47%45%8%32%
1971
March1st to 15thNight
411%5%6%7%46%7%7%8%29%
2136
16th to endNight
6%11%5%9%7%45%5%7%9%28%
2061
April1st to 15thNight
11%11%47%7%35%45%8%29%
1715
16th to endNight
13%11%47%6%3445%7%31%
1620
May1st to 15thNight
12%7%46%6%35%45%7%36%
1364
16th to endNight
20%7%26%5%246%6%8%29%
1309
June1st to 15thNight
17%8%46%6%36%6%6%7%26%
1260
16th to endNight
11%6%36%5%46%5%7%8%32%
1260
July1st to 15thNight
11%5%25%435%6%8%10%37%
1260
16th to endNight
6%5%25%435%5%7%9%43%
1357
August1st to 15thNight
11%425%5%35%5%7%8%41%
1443
16th to endNight
9%4244245%49%48%
1719
September1st to 15thNight
13%5%144235%46%46%
1803
16th to endNight
11%5%243245%6%8%44%
1980
October1st to 15thNight
10%8%37%6%4446%6%36%
2139
16th to endNight
9%9%26%6%35%5%6%8%36%
2496
November1st to 15thNight
6%11%47%6%45%6%7%7%32%
2639
16th to endNight
6%11%6%10%7%36%45%7%29%
2925
December1st to 15thNight
5%12%6%10%7%35%5%5%7%28%
2760
16th to endNight
312%5%10%8%45%5%6%7%29%
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
51%6%12%21%6%1
1253
16th to endDay
50%7%13%16%9%3
1485
February1st to 15thDay
50%7%15%17%6%2
1416
16th to endDay
50%10%14%16%6%
1503
March1st to 15thDay
52%8%16%15%7%
1824
16th to endDay
55%9%15%14%4
2160
April1st to 15thDay
58%8%14%13%4
2233
16th to endDay
53%8%14%15%5%1
2340
May1st to 15thDay
48%7%16%16%9%
2584
16th to endDay
54%8%17%13%5%
2807
June1st to 15thDay
57%8%15%14%3
2700
16th to endDay
50%10%17%17%3
2700
July1st to 15thDay
42%12%23%17%4
2541
16th to endDay
38%12%21%22%5%
2634
August1st to 15thDay
40%12%22%20%4
2499
16th to endDay
35%9%22%24%6%1
2483
September1st to 15thDay
41%5%19%19%11%1
2155
16th to endDay
38%8%15%25%9%2
1980
October1st to 15thDay
46%8%16%18%9%
1818
16th to endDay
45%8%15%21%8%
1728
November1st to 15thDay
50%9%13%17%8%
1535
16th to endDay
47%8%17%16%7%2
1365
December1st to 15thDay
59%5%12%15%7%
1282
16th to endDay
48%7%14%18%9%1
1344
January1st to 15thNight
56%7%11%15%6%2
2685
16th to endNight
48%6%11%19%9%3
2749
February1st to 15thNight
50%7%15%17%7%1
2449
16th to endNight
49%5%13%18%11%1
1971
March1st to 15thNight
47%9%16%18%7%
2136
16th to endNight
50%7%14%18%7%1
2064
April1st to 15thNight
51%7%15%16%8%
1715
16th to endNight
51%6%16%19%41
1620
May1st to 15thNight
45%7%16%20%9%
1365
16th to endNight
48%9%16%17%5%1
1309
June1st to 15thNight
53%10%14%17%5%
1260
16th to endNight
45%10%17%21%41
1260
July1st to 15thNight
37%11%20%24%4
1190
16th to endNight
34%8%21%25%8%
1271
August1st to 15thNight
37%12%23%20%5%
1435
16th to endNight
32%7%21%26%10%1
1719
September1st to 15thNight
36%6%18%22%13%2
1803
16th to endNight
35%6%16%25%11%4
1980
October1st to 15thNight
46%6%16%20%7%1
2139
16th to endNight
42%8%16%23%8%
2496
November1st to 15thNight
46%9%12%20%10%1
2639
16th to endNight
51%7%15%15%7%3
2925
December1st to 15thNight
53%6%14%18%5%
2760
16th to endNight
51%6%13%19%7%1
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
8%328%26%20%13%
60
16th to endDay
17%318%35%17%7%
64
February1st to 15thDay
9%9%31%30%14%4
63
16th to endDay
9%6%25%43%12%1
162
March1st to 15thDay
11%13%42%23%8%
270
16th to endDay
15%12%38%23%8%1
288
April1st to 15thDay
20%15%33%21%8%
269
16th to endDay
24%11%29%24%8%2
270
May1st to 15thDay
15%10%28%27%14%3
378
16th to endDay
21%6%19%32%16%4
517
June1st to 15thDay
20%7%25%30%12%3
495
16th to endDay
17%426%30%17%4
495
July1st to 15thDay
16%5%19%35%18%4
475
16th to endDay
10%5%28%31%19%5%
479
August1st to 15thDay
14%426%29%16%7%
315
16th to endDay
10%6%34%32%14%2
332
September1st to 15thDay
23%6%25%27%11%5%
315
16th to endDay
14%8%31%25%14%6%
315
October1st to 15thDay
24%8%26%24%12%4
216
16th to endDay
16%8%25%31%14%3
144
November1st to 15thDay
18%429%31%12%3
127
16th to endDay
10%8%31%25%15%8%
90
December1st to 15thDay
9%440%21%19%4
66
16th to endDay
6%6%26%31%25%4
64
January1st to 15thNight
10%9%35%31%11%2
900
16th to endNight
10%8%33%33%12%1
829
February1st to 15thNight
10%7%28%32%16%3
704
16th to endNight
8%331%33%19%3
632
March1st to 15thNight
8%5%34%38%10%2
720
16th to endNight
11%5%33%35%12%1
768
April1st to 15thNight
15%7%31%31%12%
635
16th to endNight
17%9%28%33%10%
540
May1st to 15thNight
14%6%28%35%13%1
375
16th to endNight
20%418%36%19%
375
June1st to 15thNight
20%325%31%17%1
360
16th to endNight
13%323%34%22%3
360
July1st to 15thNight
13%117%43%22%1
340
16th to endNight
8%219%47%21%1
376
August1st to 15thNight
13%112%34%34%3
363
16th to endNight
10%219%42%23%1
573
September1st to 15thNight
16%218%34%25%3
675
16th to endNight
13%427%35%17%3
716
October1st to 15thNight
16%428%32%15%2
720
16th to endNight
12%432%37%11%1
768
November1st to 15thNight
12%6%34%32%10%2
894
16th to endNight
10%6%40%31%8%2
975
December1st to 15thNight
9%8%33%33%13%1
920
16th to endNight
8%5%34%35%13%3
960
Page generated at 2017-12-05 08:19:01. Version ac04

Copyright 2017 A. Danko


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