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 2017-09-23.

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%
15343
23%
47027
17%
15300
57%
15300
28%
29195

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
28%
720
22%
2327
10%
716
42%
716
21%
1494
January16th to endNight
28%
768
24%
2371
12%
768
41%
768
22%
1551
February1st to 15thNight
31%
704
24%
2112
10%
701
44%
701
27%
1322
February16th to endNight
27%
631
23%
1893
10%
631
38%
631
24%
1236
March1st to 15thNight
33%
720
19%
2128
12%
720
40%
720
24%
1401
March16th to endNight
42%
752
21%
2096
14%
752
47%
752
29%
1349
April1st to 15thNight
46%
539
25%
1797
18%
539
55%
539
32%
1013
April16th to endNight
52%
540
27%
1773
21%
540
61%
540
32%
1011
May1st to 15thNight
54%
540
22%
1620
15%
540
61%
540
31%
1003
May16th to endNight
68%
561
22%
1682
19%
561
71%
561
32%
1027
June1st to 15thNight
72%
540
19%
1620
17%
540
74%
540
34%
974
June16th to endNight
79%
540
18%
1620
16%
540
80%
540
37%
948
July1st to 15thNight
76%
510
15%
1530
15%
510
76%
510
32%
940
July16th to endNight
73%
564
17%
1595
16%
531
75%
531
28%
1022
August1st to 15thNight
76%
539
20%
1747
22%
536
76%
536
30%
1054
August16th to endNight
70%
573
19%
1910
23%
573
71%
573
23%
1257
September1st to 15thNight
65%
641
18%
1901
17%
641
66%
641
26%
1237
September16th to endNight
64%
689
27%
1903
21%
689
68%
689
34%
1181
October1st to 15thNight
59%
660
33%
1815
25%
660
64%
660
39%
1072
October16th to endNight
53%
704
32%
2135
26%
704
62%
704
36%
1219
November1st to 15thNight
51%
700
29%
2276
24%
700
60%
700
35%
1248
November16th to endNight
40%
720
26%
2340
18%
720
52%
720
28%
1391
December1st to 15thNight
34%
720
22%
2340
15%
720
44%
720
22%
1513
December16th to endNight
30%
768
19%
2496
14%
768
37%
768
18%
1732

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%35%5%5%7%40%
47873
Night
11%5%25%42445%7%45%
47226
TransparencyDay
41%6%11%19%16%4
47574
Night
37%6%10%20%19%5%
47029
SeeingDay
15%417%22%23%16%
5241
Night
14%6%22%29%22%4
15345

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%5%34335%39%
1611
16th to endDay
17%6%3432335%5%43%
1851
February1st to 15thDay
16%9%345%23346%39%
1750
16th to endDay
18%6%37%5%2333440%
1580
March1st to 15thDay
16%8%36%5%24346%37%
1830
16th to endDay
13%7%35%4345%5%7%37%
2136
April1st to 15thDay
13%6%245%1446%7%42%
2151
16th to endDay
10%5%35%5%35%45%5%45%
2187
May1st to 15thDay
12%5%25%5%45%45%6%42%
2331
16th to endDay
10%5%25%6%35%5%6%8%40%
2431
June1st to 15thDay
7%5%26%5%47%6%7%9%35%
2340
16th to endDay
5%3246%36%6%6%10%42%
2340
July1st to 15thDay
11%437%6%5%8%6%7%10%30%
2340
16th to endDay
6%426%8%48%8%8%11%29%
2465
August1st to 15thDay
7%435%6%5%7%8%8%11%32%
2199
16th to endDay
11%6%37%7%37%5%7%8%29%
2292
September1st to 15thDay
13%5%25%6%36%6%5%7%37%
2046
16th to endDay
13%5%245%24447%44%
1894
October1st to 15thDay
11%5%24423336%52%
1815
16th to endDay
11%6%2432232456%
1734
November1st to 15thDay
12%5%14323345%52%
1582
16th to endDay
16%5%33323446%46%
1620
December1st to 15thDay
18%8%35%434345%38%
1620
16th to endDay
24%8%35%5%3333434%
1728
January1st to 15thNight
17%6%25%425%346%41%
2327
16th to endNight
16%7%36%5%23345%40%
2371
February1st to 15thNight
17%6%24323345%46%
2103
16th to endNight
17%6%25%433335%43%
1893
March1st to 15thNight
15%7%245%24446%42%
2128
16th to endNight
13%5%34423446%46%
2096
April1st to 15thNight
11%42332345%8%49%
1797
16th to endNight
8%5%24422447%52%
1773
May1st to 15thNight
10%32443445%8%46%
1619
16th to endNight
6%424425%5%6%9%47%
1682
June1st to 15thNight
5%325%435%5%6%11%45%
1620
16th to endNight
33245%35%5%6%12%46%
1620
July1st to 15thNight
7%3345%35%6%7%11%42%
1620
16th to endNight
4425%6%47%6%8%10%39%
1703
August1st to 15thNight
6%3245%35%6%7%11%43%
1758
16th to endNight
9%435%5%36%5%7%8%39%
1910
September1st to 15thNight
9%425%5%45%5%6%7%42%
1901
16th to endNight
8%5%24425%45%7%48%
1903
October1st to 15thNight
11%413322336%55%
1815
16th to endNight
10%5%1432333456%
2135
November1st to 15thNight
10%5%24323346%54%
2276
16th to endNight
14%7%25%31334449%
2340
December1st to 15thNight
15%8%26%5%2335%6%40%
2340
16th to endNight
21%8%36%423345%35%
2496

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%46%17%20%4
1612
16th to endDay
42%47%21%19%5%
1851
February1st to 15thDay
44%47%22%17%2
1752
16th to endDay
47%36%17%20%4
1580
March1st to 15thDay
48%48%15%18%3
1830
16th to endDay
44%5%12%20%14%2
2137
April1st to 15thDay
39%5%11%20%17%5%
2151
16th to endDay
37%6%9%22%19%3
2187
May1st to 15thDay
41%5%11%21%16%3
2331
16th to endDay
39%7%14%23%12%2
2435
June1st to 15thDay
39%10%15%21%12%
2340
16th to endDay
33%9%16%22%15%3
2340
July1st to 15thDay
42%10%17%18%8%1
2201
16th to endDay
42%12%16%18%8%
2310
August1st to 15thDay
40%11%16%19%10%1
2186
16th to endDay
47%10%13%17%8%2
2292
September1st to 15thDay
43%8%14%15%12%4
2046
16th to endDay
39%6%11%19%18%5%
1894
October1st to 15thDay
34%5%7%17%26%8%
1815
16th to endDay
32%35%17%30%10%
1734
November1st to 15thDay
33%35%17%30%9%
1582
16th to endDay
37%5%7%17%26%5%
1620
December1st to 15thDay
47%46%18%16%5%
1620
16th to endDay
54%38%17%13%3
1728
January1st to 15thNight
44%37%17%21%4
2327
16th to endNight
44%46%18%19%5%
2371
February1st to 15thNight
39%37%20%20%7%
2112
16th to endNight
43%36%20%20%4
1893
March1st to 15thNight
43%5%9%17%17%7%
2128
16th to endNight
38%5%9%24%19%3
2096
April1st to 15thNight
32%5%11%23%19%8%
1797
16th to endNight
32%5%8%24%22%6%
1773
May1st to 15thNight
35%6%12%18%23%2
1620
16th to endNight
30%10%14%25%14%3
1684
June1st to 15thNight
29%9%16%27%15%1
1620
16th to endNight
28%8%19%20%18%4
1620
July1st to 15thNight
31%10%21%22%10%4
1530
16th to endNight
34%10%19%21%12%1
1595
August1st to 15thNight
31%10%18%22%14%2
1747
16th to endNight
39%10%15%18%14%2
1910
September1st to 15thNight
38%9%17%15%15%3
1901
16th to endNight
33%6%9%22%20%6%
1903
October1st to 15thNight
30%5%8%21%22%11%
1815
16th to endNight
31%4315%31%13%
2135
November1st to 15thNight
31%36%19%26%13%
2276
16th to endNight
37%35%17%25%8%
2340
December1st to 15thNight
43%48%17%19%5%
2340
16th to endNight
51%47%16%16%4
2496

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%14%33%21%6%2
90
16th to endDay
15%20%50%10%12
96
February1st to 15thDay
17%26%36%18%
90
16th to endDay
30%8%35%23%1
81
March1st to 15thDay
15%20%32%24%42
120
16th to endDay
19%6%30%26%15%1
288
April1st to 15thDay
16%11%27%21%20%1
270
16th to endDay
15%323%26%26%4
270
May1st to 15thDay
15%5%23%23%18%12%
288
16th to endDay
16%213%23%25%18%
331
June1st to 15thDay
9%111%19%26%31%
315
16th to endDay
8%18%23%29%29%
315
July1st to 15thDay
9%8%19%30%31%
305
16th to endDay
10%5%12%30%40%
326
August1st to 15thDay
12%7%19%34%25%
313
16th to endDay
15%5%25%30%22%
332
September1st to 15thDay
15%9%20%28%25%
315
16th to endDay
15%38%27%34%11%
283
October1st to 15thDay
17%114%32%24%8%
255
16th to endDay
15%319%27%28%6%
192
November1st to 15thDay
21%10%21%28%14%4
90
16th to endDay
15%8%33%26%12%3
90
December1st to 15thDay
24%14%30%22%8%
90
16th to endDay
35%9%23%25%5%1
96
January1st to 15thNight
21%14%32%25%6%
720
16th to endNight
19%12%35%27%4
768
February1st to 15thNight
19%11%34%31%3
704
16th to endNight
19%13%37%26%3
631
March1st to 15thNight
18%11%33%29%6%
720
16th to endNight
16%11%25%31%14%1
752
April1st to 15thNight
12%7%30%31%16%1
539
16th to endNight
10%5%27%36%19%1
540
May1st to 15thNight
10%324%32%24%5%
540
16th to endNight
9%11%35%35%7%
563
June1st to 15thNight
5%9%33%40%11%
540
16th to endNight
35%30%46%13%
540
July1st to 15thNight
7%5%23%45%16%
510
16th to endNight
6%5%21%47%18%
564
August1st to 15thNight
6%5%26%49%11%
539
16th to endNight
11%5%27%45%9%
573
September1st to 15thNight
11%18%29%37%11%
641
16th to endNight
12%112%32%38%3
689
October1st to 15thNight
14%218%33%25%4
660
16th to endNight
13%5%23%32%21%3
704
November1st to 15thNight
13%6%24%34%19%3
700
16th to endNight
17%10%28%30%12%
720
December1st to 15thNight
20%10%30%28%10%
720
16th to endNight
26%8%29%26%8%
768
Page generated at 2017-09-24 08:15:44. Version ac04

Copyright 2017 A. Danko


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