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 2017-05-01.

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
40%
14804
12%
45726
8%
14777
45%
14777
20%
31933

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%
346
9%
1261
9%
346
48%
346
20%
829
May16th to endNight
43%
342
3%
1197
1%
342
43%
342
16%
853
June1st to 15thNight
40%
330
0%
1155
0%
330
40%
330
13%
860
June16th to endNight
52%
330
0%
1155
0%
330
52%
330
18%
790
July1st to 15thNight
56%
310
0%
1085
0%
310
56%
310
20%
724
July16th to endNight
59%
348
5%
1170
3%
326
60%
326
25%
707
August1st to 15thNight
64%
333
7%
1315
10%
331
65%
331
20%
836
August16th to endNight
58%
525
14%
1575
11%
525
61%
525
31%
955
September1st to 15thNight
55%
619
16%
1653
11%
619
56%
619
32%
1069
September16th to endNight
50%
656
18%
1815
11%
656
55%
656
33%
1139
October1st to 15thNight
42%
660
15%
1961
9%
660
48%
660
22%
1360
October16th to endNight
43%
704
16%
2288
11%
704
50%
704
21%
1522
November1st to 15thNight
34%
823
16%
2430
10%
823
41%
823
21%
1697
November16th to endNight
30%
900
12%
2700
6%
900
36%
900
17%
1969
December1st to 15thNight
33%
900
12%
2700
8%
900
36%
900
16%
2014
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%7%31%
46074
Night
8%9%48%6%35%5%6%8%33%
45877
TransparencyDay
49%9%17%17%6%
45728
Night
47%7%15%19%7%1
45729
SeeingDay
16%7%28%29%13%3
5408
Night
12%5%29%34%15%2
14816

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
12%9%37%6%36%5%5%8%31%
2369
16th to endDay
21%8%37%7%345%6%8%23%
2562
June1st to 15thDay
20%7%36%6%46%6%6%7%22%
2475
16th to endDay
16%7%26%6%47%7%6%7%27%
2475
July1st to 15thDay
12%5%26%5%36%7%8%8%32%
2475
16th to endDay
11%425%5%35%6%7%9%36%
2603
August1st to 15thDay
15%5%25%5%35%5%7%9%35%
2307
16th to endDay
11%424435%6%6%9%39%
2275
September1st to 15thDay
17%6%25%42445%6%40%
1976
16th to endDay
11%6%25%5%3346%8%42%
1815
October1st to 15thDay
14%9%35%5%345%7%6%33%
1666
16th to endDay
9%8%36%6%35%5%6%8%35%
1584
November1st to 15thDay
6%11%5%8%6%45%46%7%32%
1415
16th to endDay
6%13%39%5%35%5%6%6%33%
1260
December1st to 15thDay
5%12%5%12%9%47%5%46%25%
1260
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%8%45%6%35%45%7%37%
1260
16th to endNight
20%7%27%5%245%6%8%29%
1197
June1st to 15thNight
17%8%45%6%37%6%6%7%25%
1155
16th to endNight
12%6%35%5%45%5%7%8%34%
1155
July1st to 15thNight
12%5%25%5%35%7%8%10%34%
1155
16th to endNight
7%5%26%5%35%6%7%9%41%
1256
August1st to 15thNight
11%425%5%35%6%7%8%39%
1323
16th to endNight
9%4244245%49%46%
1575
September1st to 15thNight
14%6%245%235%46%45%
1653
16th to endNight
11%5%2332446%8%45%
1815
October1st to 15thNight
10%8%37%6%4446%6%36%
1961
16th to endNight
10%9%26%5%35%45%9%36%
2288
November1st to 15thNight
7%11%47%6%45%6%7%7%33%
2430
16th to endNight
6%12%6%10%7%36%45%7%29%
2700
December1st to 15thNight
6%12%6%11%7%35%5%5%7%27%
2700
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%17%9%
2369
16th to endDay
56%8%16%11%5%
2567
June1st to 15thDay
58%8%14%14%2
2475
16th to endDay
51%11%17%17%3
2475
July1st to 15thDay
43%12%23%17%3
2316
16th to endDay
40%12%22%20%4
2427
August1st to 15thDay
41%12%23%19%3
2290
16th to endDay
37%10%21%22%6%1
2275
September1st to 15thDay
42%5%20%19%11%1
1976
16th to endDay
38%8%15%26%9%2
1815
October1st to 15thDay
46%8%16%18%8%
1666
16th to endDay
45%8%15%22%8%
1584
November1st to 15thDay
48%8%14%18%8%
1415
16th to endDay
48%7%16%15%8%2
1260
December1st to 15thDay
59%5%12%14%7%
1260
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
44%7%17%20%9%
1261
16th to endNight
49%9%17%16%5%1
1197
June1st to 15thNight
54%9%13%17%5%
1155
16th to endNight
45%10%18%21%31
1155
July1st to 15thNight
40%12%20%22%3
1085
16th to endNight
36%9%22%25%6%
1170
August1st to 15thNight
38%12%24%19%5%
1315
16th to endNight
33%7%21%26%9%2
1575
September1st to 15thNight
37%6%18%21%14%1
1653
16th to endNight
34%6%16%25%11%4
1815
October1st to 15thNight
46%6%16%20%7%1
1961
16th to endNight
43%8%16%23%7%
2288
November1st to 15thNight
45%9%12%21%10%1
2430
16th to endNight
52%7%15%15%7%3
2700
December1st to 15thNight
54%6%14%17%5%
2700
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
16%9%28%27%14%3
311
16th to endDay
22%6%19%29%16%4
437
June1st to 15thDay
20%7%26%31%11%3
420
16th to endDay
18%423%30%18%5%
420
July1st to 15thDay
17%5%20%33%17%5%
400
16th to endDay
11%428%32%18%4
412
August1st to 15thDay
14%5%29%30%12%7%
255
16th to endDay
12%7%35%31%11%1
268
September1st to 15thDay
23%7%25%25%12%5%
255
16th to endDay
13%10%35%25%11%3
255
October1st to 15thDay
23%8%27%28%10%1
164
16th to endDay
15%6%18%35%18%5%
96
November1st to 15thDay
20%5%31%30%10%1
85
16th to endDay
11%6%18%26%23%13%
60
December1st to 15thDay
10%5%38%20%21%5%
60
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
13%7%28%35%13%1
347
16th to endNight
21%419%35%18%
343
June1st to 15thNight
20%325%31%17%1
330
16th to endNight
13%320%34%24%3
330
July1st to 15thNight
14%118%42%21%
310
16th to endNight
8%220%47%20%1
348
August1st to 15thNight
14%12%33%34%3
333
16th to endNight
11%220%41%23%
525
September1st to 15thNight
16%218%33%25%4
619
16th to endNight
12%428%36%14%3
656
October1st to 15thNight
16%427%33%16%2
660
16th to endNight
13%430%38%12%1
704
November1st to 15thNight
11%7%36%32%9%2
823
16th to endNight
11%6%39%31%9%2
900
December1st to 15thNight
9%8%34%32%13%1
900
16th to endNight
8%5%34%35%13%3
960
Page generated at 2017-05-02 06:43:25. Version ac04

Copyright 2017 A. Danko


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