Tucker Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tucker Creek Observatory clear sky chart from 2005-11-05 to 2017-03-15.

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
38%
15223
23%
45181
13%
15176
47%
15176
28%
27992

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
20%
900
22%
2467
6%
895
32%
895
22%
1614
January16th to endNight
19%
960
23%
2496
6%
960
30%
960
25%
1645
February1st to 15thNight
19%
803
19%
2211
5%
800
28%
800
20%
1504
February16th to endNight
19%
631
22%
1893
6%
631
31%
631
21%
1214
March1st to 15thNight
16%
660
17%
2100
7%
660
26%
660
19%
1415
March16th to endNight
27%
528
15%
1859
10%
528
35%
528
18%
1245
April1st to 15thNight
27%
494
25%
1647
12%
494
46%
494
26%
950
April16th to endNight
36%
495
20%
1650
14%
495
48%
495
26%
1009
May1st to 15thNight
35%
495
18%
1575
10%
494
45%
494
25%
1015
May16th to endNight
46%
515
18%
1374
11%
513
51%
513
27%
932
June1st to 15thNight
59%
495
23%
1320
15%
495
65%
495
38%
802
June16th to endNight
66%
495
23%
1320
17%
495
70%
495
43%
758
July1st to 15thNight
67%
465
20%
1240
16%
465
69%
465
39%
739
July16th to endNight
72%
522
20%
1397
19%
489
74%
489
41%
796
August1st to 15thNight
76%
494
25%
1565
29%
491
78%
491
43%
810
August16th to endNight
71%
525
24%
1750
27%
525
74%
525
36%
950
September1st to 15thNight
62%
495
28%
1650
26%
495
68%
495
31%
949
September16th to endNight
58%
613
30%
1771
21%
613
64%
613
35%
1049
October1st to 15thNight
50%
660
31%
1963
21%
660
58%
660
38%
1101
October16th to endNight
34%
704
28%
2115
15%
704
47%
704
31%
1249
November1st to 15thNight
39%
700
30%
2276
18%
700
54%
700
34%
1221
November16th to endNight
29%
720
24%
2340
17%
720
40%
720
24%
1458
December1st to 15thNight
23%
894
17%
2514
7%
894
32%
894
21%
1730
December16th to endNight
20%
960
20%
2688
6%
960
33%
960
21%
1837

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
12%6%25%5%3445%7%42%
45550
Night
12%6%24424446%46%
45366
TransparencyDay
39%5%12%23%15%2
45238
Night
37%5%11%24%17%3
45183
SeeingDay
14%8%25%26%18%7%
5004
Night
16%11%29%25%14%2
15223

By Month

Percentage Cloud Cover SE (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
16%7%34423335%44%
1470
16th to endDay
12%7%36%5%24336%43%
1728
February1st to 15thDay
14%9%36%5%24335%40%
1648
16th to endDay
12%9%36%5%3346%6%38%
1580
March1st to 15thDay
18%7%35%423435%40%
1866
16th to endDay
17%9%46%5%24445%34%
2009
April1st to 15thDay
13%7%34323446%46%
1971
16th to endDay
17%7%35%434447%38%
1980
May1st to 15thDay
17%6%25%5%245%6%7%35%
2042
16th to endDay
12%5%35%6%36%5%47%39%
2387
June1st to 15thDay
8%425%5%45%5%6%9%42%
2310
16th to endDay
43145%36%5%7%10%46%
2310
July1st to 15thDay
9%425%5%45%6%7%10%38%
2310
16th to endDay
4315%6%47%7%9%9%40%
2356
August1st to 15thDay
7%325%5%46%6%6%10%40%
2054
16th to endDay
8%5%245%36%5%7%10%41%
2100
September1st to 15thDay
10%6%35%43445%8%43%
1980
16th to endDay
12%42442445%8%46%
1847
October1st to 15thDay
11%424423445%50%
1665
16th to endDay
13%413322345%54%
1756
November1st to 15thDay
10%5%24323345%52%
1582
16th to endDay
19%7%2432333444%
1620
December1st to 15thDay
18%8%345%24246%38%
1443
16th to endDay
18%8%45%42445%5%37%
1536
January1st to 15thNight
15%8%34423445%43%
2467
16th to endNight
12%7%35%5%24436%44%
2496
February1st to 15thNight
15%9%45%423446%40%
2202
16th to endNight
12%6%37%424445%43%
1893
March1st to 15thNight
18%9%25%42434439%
2100
16th to endNight
18%6%37%433346%38%
1859
April1st to 15thNight
10%424424347%50%
1647
16th to endNight
16%5%24333346%45%
1650
May1st to 15thNight
15%5%245%2435%8%41%
1575
16th to endNight
10%5%35%5%35%5%6%8%41%
1373
June1st to 15thNight
6%315%426%5%5%10%49%
1320
16th to endNight
5%213325%5%6%10%53%
1320
July1st to 15thNight
6%215%42445%8%52%
1320
16th to endNight
5%423325%5%8%10%49%
1502
August1st to 15thNight
32133235%6%10%56%
1575
16th to endNight
45%1442446%8%52%
1750
September1st to 15thNight
8%4145%25%446%50%
1650
16th to endNight
10%413323446%52%
1771
October1st to 15thNight
9%414323346%56%
1963
16th to endNight
14%5%2431323353%
2115
November1st to 15thNight
9%5%1331335%6%56%
2276
16th to endNight
18%7%3432322447%
2340
December1st to 15thNight
19%8%3442335%6%37%
2514
16th to endNight
18%9%34313446%39%
2688

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
43%310%24%15%2
1471
16th to endDay
42%311%27%12%1
1728
February1st to 15thDay
45%311%24%12%1
1650
16th to endDay
44%5%12%23%12%2
1580
March1st to 15thDay
46%48%22%14%3
1866
16th to endDay
50%5%12%20%10%
2011
April1st to 15thDay
38%410%23%20%2
1971
16th to endDay
45%5%9%23%13%1
1980
May1st to 15thDay
46%7%12%21%12%
2042
16th to endDay
43%8%13%19%12%2
2391
June1st to 15thDay
35%7%15%24%15%1
2310
16th to endDay
30%7%16%25%17%3
2310
July1st to 15thDay
38%6%13%23%12%4
2161
16th to endDay
33%9%17%27%11%1
2198
August1st to 15thDay
34%9%13%25%15%1
2040
16th to endDay
34%7%16%20%16%5%
2100
September1st to 15thDay
36%6%12%22%18%3
1980
16th to endDay
35%5%8%25%21%3
1847
October1st to 15thDay
33%49%25%21%4
1665
16th to endDay
31%47%30%21%4
1756
November1st to 15thDay
33%48%24%20%8%
1582
16th to endDay
43%37%25%17%2
1620
December1st to 15thDay
47%411%22%13%1
1443
16th to endDay
47%5%11%21%11%2
1536
January1st to 15thNight
41%49%24%17%2
2467
16th to endNight
40%412%26%15%1
2496
February1st to 15thNight
45%48%23%15%2
2211
16th to endNight
41%5%12%23%15%1
1893
March1st to 15thNight
48%49%18%16%3
2100
16th to endNight
48%412%21%11%1
1859
April1st to 15thNight
32%6%10%27%19%2
1647
16th to endNight
40%39%26%17%3
1650
May1st to 15thNight
41%5%15%21%13%1
1576
16th to endNight
39%8%13%19%14%3
1375
June1st to 15thNight
29%7%13%29%18%1
1320
16th to endNight
24%7%14%28%19%5%
1320
July1st to 15thNight
29%6%15%28%13%6%
1240
16th to endNight
25%7%18%30%15%1
1397
August1st to 15thNight
21%7%14%30%21%3
1565
16th to endNight
28%6%14%24%19%5%
1750
September1st to 15thNight
32%6%8%26%19%6%
1650
16th to endNight
31%5%7%24%26%4
1771
October1st to 15thNight
29%410%23%26%6%
1963
16th to endNight
35%38%26%20%5%
2115
November1st to 15thNight
28%410%24%23%8%
2276
16th to endNight
41%37%24%20%2
2340
December1st to 15thNight
47%412%19%14%1
2514
16th to endNight
45%5%11%21%13%3
2688

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
33%15%38%10%11
90
16th to endDay
12%35%43%5%3
96
February1st to 15thDay
18%23%43%13%1
90
16th to endDay
22%24%39%7%6%
81
March1st to 15thDay
37%14%35%8%21
89
16th to endDay
19%19%35%21%4
123
April1st to 15thDay
22%17%31%20%7%
210
16th to endDay
19%10%31%22%14%1
210
May1st to 15thDay
19%14%25%25%11%2
228
16th to endDay
16%7%33%24%13%6%
431
June1st to 15thDay
10%426%29%19%9%
420
16th to endDay
3330%37%20%5%
420
July1st to 15thDay
12%219%36%20%9%
400
16th to endDay
4213%34%31%13%
445
August1st to 15thDay
9%11%28%36%13%
327
16th to endDay
14%11%26%32%14%
268
September1st to 15thDay
10%412%27%30%14%
255
16th to endDay
14%8%17%20%25%12%
254
October1st to 15thDay
15%230%40%8%2
105
16th to endDay
11%9%35%33%10%
96
November1st to 15thDay
8%12%27%33%12%5%
90
16th to endDay
40%15%26%10%6%1
90
December1st to 15thDay
20%16%32%21%6%3
90
16th to endDay
28%19%42%8%1
96
January1st to 15thNight
21%22%34%17%3
900
16th to endNight
18%18%41%19%2
960
February1st to 15thNight
21%21%35%19%2
803
16th to endNight
18%19%39%20%2
631
March1st to 15thNight
25%15%39%16%2
660
16th to endNight
21%13%32%25%6%
528
April1st to 15thNight
13%18%38%24%5%
494
16th to endNight
18%11%30%27%11%
495
May1st to 15thNight
17%7%36%25%11%1
495
16th to endNight
12%331%30%19%3
515
June1st to 15thNight
7%322%40%24%2
495
16th to endNight
6%218%42%28%1
495
July1st to 15thNight
7%116%40%30%4
465
16th to endNight
6%211%31%38%8%
522
August1st to 15thNight
4111%34%40%7%
494
16th to endNight
6%113%32%37%7%
525
September1st to 15thNight
9%315%29%35%6%
495
16th to endNight
12%6%17%25%31%7%
613
October1st to 15thNight
11%7%26%25%24%4
660
16th to endNight
17%12%33%25%11%
704
November1st to 15thNight
13%12%33%27%13%1
700
16th to endNight
22%14%30%24%7%
720
December1st to 15thNight
24%15%32%20%5%
894
16th to endNight
24%15%36%20%2
960
Page generated at 2017-03-16 10:05:29. Version ac04

Copyright 2017 A. Danko


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