Stokesville Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stokesville Observatory 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
45%
15736
21%
47930
13%
15699
53%
15699
26%
30052

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
26%
717
23%
2327
10%
716
41%
716
19%
1452
January16th to endNight
22%
768
22%
2496
8%
768
40%
768
22%
1536
February1st to 15thNight
26%
701
22%
2287
8%
701
43%
701
22%
1370
February16th to endNight
24%
631
24%
1910
10%
631
41%
631
22%
1212
March1st to 15thNight
30%
720
22%
1980
11%
720
41%
720
25%
1286
March16th to endNight
34%
768
18%
2112
10%
768
41%
768
24%
1401
April1st to 15thNight
34%
718
19%
1837
7%
718
42%
718
27%
1211
April16th to endNight
43%
673
21%
1753
9%
673
49%
673
32%
1136
May1st to 15thNight
46%
540
15%
1620
9%
540
51%
540
23%
1108
May16th to endNight
57%
510
16%
1633
13%
510
61%
510
27%
1047
June1st to 15thNight
67%
360
18%
1440
21%
360
71%
360
25%
838
June16th to endNight
66%
360
19%
1440
18%
360
73%
360
27%
802
July1st to 15thNight
66%
503
12%
1523
11%
503
68%
503
26%
996
July16th to endNight
76%
564
17%
1595
14%
531
78%
531
37%
940
August1st to 15thNight
69%
539
19%
1609
16%
536
70%
536
29%
1039
August16th to endNight
66%
695
19%
1841
14%
695
67%
695
29%
1237
September1st to 15thNight
63%
720
25%
1821
17%
720
65%
720
36%
1160
September16th to endNight
55%
717
22%
2002
19%
717
57%
717
27%
1327
October1st to 15thNight
52%
720
23%
2160
21%
720
58%
720
28%
1354
October16th to endNight
43%
768
30%
2304
20%
768
58%
768
31%
1360
November1st to 15thNight
46%
760
27%
2302
20%
760
56%
760
30%
1375
November16th to endNight
40%
780
23%
2724
18%
780
52%
780
25%
1581
December1st to 15thNight
34%
736
20%
2574
10%
736
47%
736
19%
1620
December16th to endNight
30%
768
22%
2640
10%
768
46%
768
20%
1664

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
13%5%25%5%35%5%5%7%40%
48536
Night
12%42442445%7%45%
48123
Cloud CoverDay
12%5%25%5%35%5%6%7%40%
48546
Night
12%42442445%7%45%
48127
TransparencyDay
42%6%11%21%14%3
48247
Night
37%6%12%23%16%3
47930
SeeingDay
16%7%21%25%19%10%
5859
Night
16%8%24%32%17%2
15744

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
11%6%25%6%36%6%5%5%40%
1611
16th to endDay
12%7%45%43435%445%
1728
February1st to 15thDay
10%7%36%5%345%5%7%41%
1575
16th to endDay
10%6%35%5%345%5%6%43%
1560
March1st to 15thDay
13%6%25%5%34445%44%
1969
16th to endDay
15%6%345%25%46%6%39%
2112
April1st to 15thDay
10%4245%345%47%47%
2110
16th to endDay
17%4245%34346%42%
2217
May1st to 15thDay
19%6%36%6%35%446%33%
2331
16th to endDay
14%6%35%6%36%5%6%7%34%
2479
June1st to 15thDay
11%325%436%6%7%9%38%
2520
16th to endDay
9%325%6%46%6%8%9%37%
2520
July1st to 15thDay
13%5%36%7%46%6%8%9%30%
2343
16th to endDay
8%436%6%46%7%8%10%32%
2465
August1st to 15thDay
12%436%7%5%6%6%5%8%32%
2340
16th to endDay
12%5%26%6%46%7%7%9%31%
2348
September1st to 15thDay
13%5%25%5%345%5%6%42%
2136
16th to endDay
19%5%15%5%3445%6%36%
1956
October1st to 15thDay
19%423423446%44%
1800
16th to endDay
13%413423435%51%
1920
November1st to 15thDay
13%5%2332335%5%51%
1884
16th to endDay
15%324434246%48%
1563
December1st to 15thDay
14%5%145%2445%7%43%
1468
16th to endDay
16%5%15%5%23447%41%
1581
January1st to 15thNight
13%5%23425%46%7%44%
2327
16th to endNight
12%7%24425%446%45%
2496
February1st to 15thNight
11%6%2432445%7%46%
2285
16th to endNight
10%5%25%435%47%8%42%
1910
March1st to 15thNight
14%42442445%6%46%
1968
16th to endNight
14%6%2442435%8%43%
2112
April1st to 15thNight
11%4145%25%5%5%6%46%
1837
16th to endNight
15%41342435%7%46%
1753
May1st to 15thNight
16%5%25%435%45%7%39%
1620
16th to endNight
13%4244245%5%9%43%
1631
June1st to 15thNight
9%214435%5%7%10%44%
1440
16th to endNight
8%3243346%7%8%48%
1440
July1st to 15thNight
9%426%436%46%9%42%
1613
16th to endNight
5%2136%25%5%8%11%46%
1703
August1st to 15thNight
11%315%5%345%6%7%44%
1620
16th to endNight
10%5%25%5%35%5%5%8%41%
1841
September1st to 15thNight
12%324423447%49%
1821
16th to endNight
17%5%1442445%6%43%
2002
October1st to 15thNight
16%423424445%46%
2160
16th to endNight
12%313324346%52%
2304
November1st to 15thNight
13%5%2332334452%
2302
16th to endNight
14%414324445%50%
2724
December1st to 15thNight
13%6%25%4345%45%43%
2574
16th to endNight
14%4245%35%46%7%41%
2640

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
11%7%246%35%5%5%6%40%
1611
16th to endDay
11%7%36%43435%444%
1728
February1st to 15thDay
10%6%45%5%25%5%5%7%41%
1575
16th to endDay
9%6%36%4345%6%6%42%
1560
March1st to 15thDay
12%6%345%34445%45%
1980
16th to endDay
14%7%345%25%45%6%39%
2111
April1st to 15thDay
10%4245%245%5%7%47%
2110
16th to endDay
16%5%24433447%42%
2217
May1st to 15thDay
17%6%35%5%35%45%7%33%
2331
16th to endDay
13%6%25%6%36%46%8%35%
2479
June1st to 15thDay
10%325%5%47%5%6%10%38%
2520
16th to endDay
7%425%6%46%6%7%10%38%
2520
July1st to 15thDay
11%5%35%7%46%7%7%10%31%
2343
16th to endDay
7%426%6%47%7%9%10%32%
2465
August1st to 15thDay
11%427%6%46%6%7%9%32%
2340
16th to endDay
11%5%25%7%5%6%6%7%9%32%
2348
September1st to 15thDay
12%5%25%5%35%45%6%42%
2136
16th to endDay
18%5%25%435%5%5%6%37%
1956
October1st to 15thDay
18%414323446%45%
1800
16th to endDay
13%313424446%51%
1920
November1st to 15thDay
11%5%2332435%5%51%
1884
16th to endDay
14%424423346%49%
1563
December1st to 15thDay
13%5%2443445%7%44%
1468
16th to endDay
15%6%25%5%34446%41%
1581
January1st to 15thNight
13%5%2443446%7%44%
2327
16th to endNight
12%7%24435%45%5%44%
2496
February1st to 15thNight
11%6%2442445%8%46%
2278
16th to endNight
10%6%25%5%35%5%5%8%43%
1910
March1st to 15thNight
13%42442345%7%45%
1980
16th to endNight
14%5%24433447%43%
2112
April1st to 15thNight
11%424435%5%6%5%46%
1837
16th to endNight
15%31342346%8%45%
1753
May1st to 15thNight
16%5%25%435%45%8%39%
1619
16th to endNight
13%415%3246%5%9%43%
1631
June1st to 15thNight
8%3145%25%5%7%12%44%
1440
16th to endNight
7%314325%5%7%9%47%
1440
July1st to 15thNight
8%425%5%35%5%7%9%41%
1613
16th to endNight
4224435%5%8%12%46%
1703
August1st to 15thNight
10%325%5%246%6%7%44%
1620
16th to endNight
9%5%25%6%445%7%8%40%
1841
September1st to 15thNight
11%41443445%7%49%
1821
16th to endNight
17%5%244245%5%6%42%
2002
October1st to 15thNight
16%414424445%46%
2160
16th to endNight
11%31441445%5%52%
2304
November1st to 15thNight
12%5%2332334452%
2302
16th to endNight
13%414323445%50%
2724
December1st to 15thNight
13%6%25%435%5%45%43%
2574
16th to endNight
13%5%245%35%45%7%41%
2640

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%6%11%19%15%3
1612
16th to endDay
42%39%22%17%4
1728
February1st to 15thDay
42%5%10%20%17%3
1577
16th to endDay
40%6%13%22%14%3
1560
March1st to 15thDay
41%5%10%22%15%4
1980
16th to endDay
45%6%10%20%13%4
2112
April1st to 15thDay
36%5%11%22%17%6%
2110
16th to endDay
41%6%10%20%16%5%
2217
May1st to 15thDay
50%6%11%18%11%1
2331
16th to endDay
46%7%13%21%9%1
2483
June1st to 15thDay
40%8%15%23%11%
2520
16th to endDay
39%9%15%20%13%1
2520
July1st to 15thDay
46%9%10%17%12%3
2204
16th to endDay
41%10%13%20%12%1
2310
August1st to 15thDay
45%8%12%20%12%
2327
16th to endDay
45%9%13%21%8%1
2348
September1st to 15thDay
41%5%12%19%18%3
2136
16th to endDay
46%6%7%20%17%1
1956
October1st to 15thDay
40%48%26%14%4
1800
16th to endDay
34%48%27%20%4
1920
November1st to 15thDay
34%410%20%23%6%
1884
16th to endDay
37%48%25%21%3
1563
December1st to 15thDay
39%411%22%16%4
1468
16th to endDay
43%410%24%13%2
1581
January1st to 15thNight
38%7%10%18%18%5%
2327
16th to endNight
40%411%24%17%3
2496
February1st to 15thNight
36%411%24%18%4
2287
16th to endNight
38%6%11%23%16%2
1910
March1st to 15thNight
38%5%10%27%13%3
1980
16th to endNight
40%6%13%20%16%1
2112
April1st to 15thNight
37%6%11%22%17%4
1837
16th to endNight
36%5%13%20%18%4
1753
May1st to 15thNight
44%6%14%19%12%1
1620
16th to endNight
37%9%15%26%9%1
1633
June1st to 15thNight
33%10%16%25%13%1
1440
16th to endNight
30%10%16%23%17%2
1440
July1st to 15thNight
38%9%16%20%12%3
1523
16th to endNight
27%9%21%27%14%
1595
August1st to 15thNight
36%8%14%23%15%1
1609
16th to endNight
39%7%14%26%10%2
1841
September1st to 15thNight
33%7%13%22%20%2
1821
16th to endNight
42%5%9%23%18%1
2002
October1st to 15thNight
39%49%26%17%2
2160
16th to endNight
32%5%8%24%24%3
2304
November1st to 15thNight
36%38%21%22%8%
2302
16th to endNight
36%49%23%22%4
2724
December1st to 15thNight
42%5%9%23%15%3
2574
16th to endNight
42%5%12%22%14%3
2640

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
22%27%30%13%5%1
90
16th to endDay
27%27%29%14%2
96
February1st to 15thDay
16%28%46%6%1
90
16th to endDay
18%15%35%26%4
149
March1st to 15thDay
16%16%32%25%7%1
270
16th to endDay
14%14%30%28%7%3
288
April1st to 15thDay
12%14%27%25%16%2
270
16th to endDay
23%5%21%26%15%7%
270
May1st to 15thDay
23%13%22%19%12%7%
288
16th to endDay
18%322%21%19%14%
331
June1st to 15thDay
11%320%25%24%14%
315
16th to endDay
9%424%29%22%9%
315
July1st to 15thDay
15%119%29%23%10%
305
16th to endDay
6%18%28%31%22%
326
August1st to 15thDay
14%112%26%25%19%
313
16th to endDay
11%8%25%29%25%
332
September1st to 15thDay
13%315%20%25%21%
315
16th to endDay
21%315%21%24%14%
314
October1st to 15thDay
21%313%27%27%6%
315
16th to endDay
12%11%22%30%19%4
336
November1st to 15thDay
20%5%21%28%19%4
302
16th to endDay
16%14%32%21%12%2
91
December1st to 15thDay
19%14%26%26%10%1
67
16th to endDay
19%23%38%11%7%
71
January1st to 15thNight
18%17%32%24%5%
720
16th to endNight
19%13%39%25%2
768
February1st to 15thNight
19%14%35%29%2
704
16th to endNight
17%17%36%26%2
631
March1st to 15thNight
18%13%32%29%6%
720
16th to endNight
19%10%30%29%8%1
768
April1st to 15thNight
14%15%32%29%7%
718
16th to endNight
17%6%26%32%15%1
673
May1st to 15thNight
18%5%23%34%16%2
540
16th to endNight
14%118%34%28%3
512
June1st to 15thNight
8%13%46%28%1
360
16th to endNight
8%15%46%26%1
360
July1st to 15thNight
12%18%38%35%2
503
16th to endNight
5%9%33%42%8%
564
August1st to 15thNight
11%9%39%33%5%
539
16th to endNight
12%19%33%37%5%
695
September1st to 15thNight
12%12%32%33%7%
720
16th to endNight
20%113%30%28%4
717
October1st to 15thNight
18%5%16%31%23%3
720
16th to endNight
14%9%27%30%16%2
768
November1st to 15thNight
16%7%23%35%13%3
760
16th to endNight
17%12%25%31%12%1
780
December1st to 15thNight
16%10%31%30%10%
736
16th to endNight
18%12%32%33%3
768
Page generated at 2017-12-05 10:19:05. Version ac04

Copyright 2017 A. Danko


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