Crossville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Crossville clear sky chart from 2005-11-05 to 2019-06-24.

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
50%
17634
23%
54056
17%
17591
57%
17591
28%
33773

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
27%
840
22%
2717
10%
836
41%
836
21%
1753
January16th to endNight
30%
896
25%
2766
13%
896
43%
896
24%
1768
February1st to 15thNight
30%
824
23%
2472
11%
821
42%
821
24%
1603
February16th to endNight
25%
735
21%
2205
9%
735
35%
735
21%
1499
March1st to 15thNight
31%
840
20%
2483
11%
840
39%
840
23%
1648
March16th to endNight
40%
878
20%
2446
13%
878
45%
878
28%
1580
April1st to 15thNight
46%
629
25%
2097
19%
629
56%
629
31%
1199
April16th to endNight
51%
624
26%
2047
20%
624
61%
624
32%
1179
May1st to 15thNight
58%
630
24%
1890
18%
630
64%
630
32%
1146
May16th to endNight
69%
657
21%
1970
19%
657
71%
657
31%
1206
June1st to 15thNight
72%
630
20%
1890
18%
630
73%
630
34%
1138
June16th to endNight
79%
609
17%
1828
15%
609
80%
609
37%
1059
July1st to 15thNight
76%
555
15%
1665
15%
555
77%
555
32%
1022
July16th to endNight
73%
612
16%
1739
15%
579
75%
579
28%
1116
August1st to 15thNight
75%
575
20%
1861
22%
572
75%
572
29%
1140
August16th to endNight
71%
621
18%
2070
21%
621
71%
621
23%
1359
September1st to 15thNight
65%
694
17%
2059
17%
694
66%
694
26%
1349
September16th to endNight
65%
777
28%
2145
22%
777
68%
777
35%
1327
October1st to 15thNight
59%
780
33%
2145
25%
780
65%
780
39%
1272
October16th to endNight
52%
832
32%
2523
26%
832
60%
832
35%
1455
November1st to 15thNight
49%
820
27%
2666
23%
820
58%
820
31%
1541
November16th to endNight
43%
840
27%
2730
19%
840
55%
840
29%
1594
December1st to 15thNight
33%
840
22%
2730
14%
840
44%
840
22%
1783
December16th to endNight
30%
896
17%
2912
13%
896
37%
896
18%
2037

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%6%25%5%35%5%5%7%39%
54757
Night
12%5%25%42445%7%45%
54255
TransparencyDay
41%7%11%19%16%3
54458
Night
37%6%10%20%19%5%
54058
SeeingDay
16%6%18%22%22%14%
7491
Night
14%6%22%29%22%4
17636

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
18%8%25%424335%39%
1881
16th to endDay
17%6%24323345%44%
2159
February1st to 15thDay
18%9%35%5%23345%37%
2050
16th to endDay
21%6%37%5%2344437%
1840
March1st to 15thDay
17%7%36%5%24445%37%
2135
16th to endDay
12%7%35%435%5%5%7%37%
2492
April1st to 15thDay
13%6%245%1446%7%42%
2511
16th to endDay
10%5%25%5%35%45%5%46%
2518
May1st to 15thDay
11%5%245%45%45%6%44%
2721
16th to endDay
10%5%246%35%5%6%8%40%
2847
June1st to 15thDay
7%5%36%5%46%6%7%9%36%
2730
16th to endDay
5%3246%36%6%7%10%42%
2639
July1st to 15thDay
10%437%6%5%8%6%7%10%29%
2535
16th to endDay
6%426%8%48%8%8%11%29%
2673
August1st to 15thDay
7%435%6%5%7%8%8%11%32%
2337
16th to endDay
11%6%37%7%47%5%7%8%29%
2484
September1st to 15thDay
13%5%25%5%36%6%5%7%36%
2217
16th to endDay
12%5%245%24447%44%
2145
October1st to 15thDay
10%5%24424436%51%
2145
16th to endDay
11%5%2332232456%
2050
November1st to 15thDay
14%5%14423345%49%
1852
16th to endDay
14%5%34323446%46%
1890
December1st to 15thDay
19%8%35%423345%38%
1890
16th to endDay
24%9%35%5%3333432%
2016
January1st to 15thNight
17%7%35%5%25%346%41%
2717
16th to endNight
16%7%35%5%23345%43%
2766
February1st to 15thNight
18%6%25%423345%43%
2463
16th to endNight
19%6%36%433445%39%
2205
March1st to 15thNight
15%7%25%5%24445%42%
2483
16th to endNight
12%6%3442445%6%45%
2446
April1st to 15thNight
12%41332445%8%48%
2097
16th to endNight
9%5%15%422447%51%
2047
May1st to 15thNight
10%32443445%8%48%
1889
16th to endNight
6%5%24425%5%6%9%47%
1970
June1st to 15thNight
5%335%435%5%6%11%45%
1890
16th to endNight
33145%35%5%6%12%47%
1828
July1st to 15thNight
7%3245%35%6%7%11%42%
1755
16th to endNight
4425%6%46%6%8%11%38%
1847
August1st to 15thNight
6%325%5%35%6%7%11%42%
1872
16th to endNight
9%435%5%36%5%6%9%39%
2070
September1st to 15thNight
9%5%25%5%45%5%6%8%41%
2059
16th to endNight
8%5%25%425%45%7%49%
2145
October1st to 15thNight
11%414323436%55%
2145
16th to endNight
11%5%1432333455%
2523
November1st to 15thNight
12%5%24423446%51%
2666
16th to endNight
13%7%2431344450%
2730
December1st to 15thNight
17%7%26%5%2335%5%40%
2730
16th to endNight
22%8%35%423345%33%
2912

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
46%36%19%19%3
1882
16th to endDay
40%47%22%19%5%
2159
February1st to 15thDay
47%47%21%16%2
2052
16th to endDay
49%37%16%18%3
1840
March1st to 15thDay
48%47%15%18%5%
2135
16th to endDay
44%6%12%19%15%2
2493
April1st to 15thDay
38%5%11%21%17%5%
2511
16th to endDay
37%6%9%22%20%4
2518
May1st to 15thDay
39%5%11%24%15%3
2721
16th to endDay
39%7%13%22%14%2
2851
June1st to 15thDay
40%9%15%21%13%
2730
16th to endDay
32%10%17%22%13%2
2639
July1st to 15thDay
42%11%17%18%7%1
2396
16th to endDay
42%12%16%18%8%
2518
August1st to 15thDay
40%11%17%19%10%1
2324
16th to endDay
48%10%13%16%8%2
2484
September1st to 15thDay
44%9%15%14%11%4
2217
16th to endDay
38%6%12%19%18%4
2145
October1st to 15thDay
34%6%8%18%23%7%
2145
16th to endDay
32%35%18%29%10%
2050
November1st to 15thDay
37%46%17%26%8%
1852
16th to endDay
38%47%17%25%6%
1890
December1st to 15thDay
48%46%18%17%5%
1890
16th to endDay
55%38%17%11%3
2016
January1st to 15thNight
45%37%19%20%4
2717
16th to endNight
42%36%20%19%5%
2766
February1st to 15thNight
43%47%20%19%6%
2472
16th to endNight
46%46%18%18%3
2205
March1st to 15thNight
43%5%8%16%17%7%
2483
16th to endNight
38%5%9%23%19%3
2446
April1st to 15thNight
32%5%11%24%18%7%
2097
16th to endNight
33%5%8%24%22%6%
2047
May1st to 15thNight
33%6%12%21%23%2
1890
16th to endNight
30%10%14%23%16%3
1972
June1st to 15thNight
30%9%16%25%16%1
1890
16th to endNight
27%8%20%22%17%3
1828
July1st to 15thNight
31%10%22%21%10%3
1665
16th to endNight
34%11%19%20%12%1
1739
August1st to 15thNight
32%10%17%21%14%2
1861
16th to endNight
38%11%15%18%13%2
2070
September1st to 15thNight
38%10%18%15%14%3
2059
16th to endNight
33%6%10%22%22%5%
2145
October1st to 15thNight
30%5%8%24%20%9%
2145
16th to endNight
32%4416%30%12%
2523
November1st to 15thNight
34%47%18%24%11%
2666
16th to endNight
35%36%19%25%9%
2730
December1st to 15thNight
44%48%18%18%4
2730
16th to endNight
51%48%16%15%3
2912

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
24%18%30%20%5%1
180
16th to endDay
18%19%40%14%5%2
192
February1st to 15thDay
28%19%29%18%3
180
16th to endDay
37%10%30%20%1
159
March1st to 15thDay
20%22%33%19%21
215
16th to endDay
17%10%34%25%12%1
416
April1st to 15thDay
16%12%29%22%17%1
390
16th to endDay
15%6%22%28%24%3
379
May1st to 15thDay
13%422%25%22%11%
408
16th to endDay
15%212%22%27%19%
459
June1st to 15thDay
10%211%21%26%27%
435
16th to endDay
7%29%21%29%29%
407
July1st to 15thDay
9%7%17%30%34%
365
16th to endDay
8%7%14%32%36%
390
August1st to 15thDay
13%6%18%34%27%
358
16th to endDay
15%6%25%30%21%
396
September1st to 15thDay
15%9%20%30%23%
375
16th to endDay
14%28%24%38%11%
374
October1st to 15thDay
14%115%33%24%10%
375
16th to endDay
14%6%20%29%24%4
306
November1st to 15thDay
25%10%24%28%8%2
180
16th to endDay
13%11%26%30%15%2
180
December1st to 15thDay
30%13%27%20%8%
180
16th to endDay
35%10%29%20%3
192
January1st to 15thNight
21%14%33%23%7%
840
16th to endNight
18%12%34%28%5%
896
February1st to 15thNight
21%11%33%30%3
824
16th to endNight
21%13%36%25%3
735
March1st to 15thNight
18%11%34%28%5%
840
16th to endNight
15%11%28%30%13%1
878
April1st to 15thNight
13%6%30%32%15%
629
16th to endNight
10%5%26%36%19%1
624
May1st to 15thNight
10%221%33%26%5%
630
16th to endNight
9%10%33%35%9%
659
June1st to 15thNight
6%8%34%38%11%
630
16th to endNight
36%31%45%12%
609
July1st to 15thNight
7%5%21%45%19%
555
16th to endNight
6%5%22%46%18%
612
August1st to 15thNight
7%425%48%12%
575
16th to endNight
11%427%45%9%
621
September1st to 15thNight
11%18%28%39%11%
694
16th to endNight
11%112%32%38%4
777
October1st to 15thNight
14%218%32%26%6%
780
16th to endNight
13%5%24%32%20%3
832
November1st to 15thNight
15%5%23%35%17%2
820
16th to endNight
16%10%26%31%13%1
840
December1st to 15thNight
22%9%30%27%9%
840
16th to endNight
28%8%29%26%7%
896
Page generated at 2019-06-24 19:41:31. Version ac04

Copyright 2019 A. Danko


Crossville Clear Sky Chart |Charts Home