Delta State University
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Delta State University clear sky chart from 2005-11-05 to 2017-04-25.

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
53%
15115
25%
45619
20%
15069
59%
15069
33%
27078

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
35%
900
26%
2327
11%
895
45%
895
31%
1504
January16th to endNight
30%
960
25%
2496
10%
960
39%
960
29%
1668
February1st to 15thNight
33%
749
22%
2157
10%
746
41%
746
28%
1377
February16th to endNight
29%
631
26%
1893
12%
631
40%
631
28%
1174
March1st to 15thNight
38%
605
21%
2045
14%
605
45%
605
25%
1271
March16th to endNight
44%
576
25%
2055
20%
576
53%
576
29%
1174
April1st to 15thNight
43%
539
25%
1797
20%
539
54%
539
32%
1019
April16th to endNight
49%
525
26%
1750
22%
525
59%
525
32%
979
May1st to 15thNight
57%
495
21%
1650
21%
495
62%
495
28%
991
May16th to endNight
65%
515
22%
1540
21%
513
68%
513
35%
908
June1st to 15thNight
79%
495
25%
1320
23%
495
81%
495
45%
754
June16th to endNight
81%
495
27%
1320
25%
495
82%
495
47%
739
July1st to 15thNight
77%
465
20%
1366
22%
465
78%
465
36%
812
July16th to endNight
85%
522
21%
1468
25%
489
85%
489
41%
805
August1st to 15thNight
83%
494
22%
1623
26%
491
84%
491
39%
864
August16th to endNight
74%
525
24%
1750
30%
525
74%
525
31%
1019
September1st to 15thNight
69%
495
25%
1650
29%
495
71%
495
29%
984
September16th to endNight
70%
601
31%
1759
27%
601
72%
601
39%
999
October1st to 15thNight
66%
660
32%
1974
28%
660
69%
660
43%
1057
October16th to endNight
58%
704
36%
2112
28%
704
65%
704
40%
1147
November1st to 15thNight
54%
700
31%
2166
24%
700
62%
700
38%
1186
November16th to endNight
45%
720
28%
2340
21%
720
54%
720
31%
1359
December1st to 15thNight
38%
784
22%
2404
14%
784
47%
784
26%
1516
December16th to endNight
36%
960
20%
2657
12%
960
43%
960
26%
1772

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%5%25%43445%7%44%
45999
Night
11%424423447%49%
45816
TransparencyDay
38%6%11%20%18%4
45700
Night
33%5%10%21%21%7%
45620
SeeingDay
11%314%23%28%17%
4974
Night
14%5%21%31%23%4
15115

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
19%5%3442334445%
1611
16th to endDay
19%7%3432223346%
1728
February1st to 15thDay
17%6%24313345%45%
1704
16th to endDay
19%6%35%423346%40%
1580
March1st to 15thDay
16%7%36%5%3445%5%37%
1926
16th to endDay
11%5%35%5%2445%7%42%
2165
April1st to 15thDay
11%425%43446%7%44%
2151
16th to endDay
10%5%24434447%46%
2098
May1st to 15thDay
15%5%36%435%5%6%6%37%
1971
16th to endDay
8%436%6%47%5%6%9%37%
2217
June1st to 15thDay
4325%5%47%46%8%46%
2310
16th to endDay
44235%46%6%7%9%45%
2310
July1st to 15thDay
8%425%5%47%7%7%11%35%
2170
16th to endDay
7%3245%37%6%8%11%36%
2284
August1st to 15thDay
6%2145%36%7%7%10%42%
1997
16th to endDay
9%5%244345%5%10%42%
2100
September1st to 15thDay
9%426%5%35%45%8%41%
1980
16th to endDay
11%415%423347%51%
1859
October1st to 15thDay
8%32432435%5%55%
1653
16th to endDay
14%32221123460%
1760
November1st to 15thDay
10%32432233458%
1689
16th to endDay
16%6%24223335%48%
1620
December1st to 15thDay
19%10%34423435%38%
1553
16th to endDay
18%6%2443435%6%40%
1563
January1st to 15thNight
17%6%24322345%46%
2327
16th to endNight
19%7%2332234445%
2496
February1st to 15thNight
17%5%25%423326%46%
2148
16th to endNight
15%5%26%423345%47%
1893
March1st to 15thNight
14%5%245%2445%7%43%
2045
16th to endNight
14%424323337%49%
2055
April1st to 15thNight
11%42442346%6%50%
1797
16th to endNight
9%425%423446%52%
1750
May1st to 15thNight
12%43432445%9%46%
1649
16th to endNight
7%423435%5%6%9%48%
1539
June1st to 15thNight
32134246%7%11%51%
1320
16th to endNight
32133235%7%11%56%
1320
July1st to 15thNight
6%224436%6%7%12%42%
1456
16th to endNight
42123245%8%14%49%
1576
August1st to 15thNight
32134346%7%11%51%
1633
16th to endNight
6%3245%345%5%10%47%
1750
September1st to 15thNight
9%4245%345%5%6%48%
1650
16th to endNight
8%31432435%8%52%
1759
October1st to 15thNight
9%313323347%58%
1974
16th to endNight
12%413212235%60%
2112
November1st to 15thNight
9%41342345%6%54%
2166
16th to endNight
15%41442333452%
2340
December1st to 15thNight
17%7%24413336%44%
2404
16th to endNight
17%7%35%423335%44%
2657

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%26%21%21%4
1612
16th to endDay
44%25%21%21%4
1728
February1st to 15thDay
41%37%25%16%5%
1706
16th to endDay
46%36%20%17%5%
1580
March1st to 15thDay
48%47%19%14%5%
1926
16th to endDay
40%5%12%20%19%1
2167
April1st to 15thDay
37%6%10%20%20%4
2151
16th to endDay
36%6%9%21%24%2
2098
May1st to 15thDay
45%7%10%16%15%4
1971
16th to endDay
40%8%16%22%10%1
2221
June1st to 15thDay
33%7%13%26%17%1
2310
16th to endDay
32%8%14%21%19%3
2310
July1st to 15thDay
36%11%18%21%9%3
2031
16th to endDay
36%9%18%23%11%1
2129
August1st to 15thDay
31%10%16%23%13%3
1983
16th to endDay
36%7%17%21%13%3
2100
September1st to 15thDay
39%8%12%18%13%6%
1980
16th to endDay
33%5%8%18%22%11%
1859
October1st to 15thDay
29%49%19%24%12%
1653
16th to endDay
29%3319%32%11%
1760
November1st to 15thDay
29%36%21%31%8%
1689
16th to endDay
38%37%19%24%6%
1620
December1st to 15thDay
47%5%7%18%14%6%
1553
16th to endDay
43%411%17%19%4
1563
January1st to 15thNight
39%36%20%23%6%
2327
16th to endNight
42%35%19%21%7%
2496
February1st to 15thNight
41%27%20%21%5%
2157
16th to endNight
39%46%21%20%8%
1893
March1st to 15thNight
40%5%9%19%17%8%
2045
16th to endNight
35%49%22%23%3
2055
April1st to 15thNight
32%5%9%22%22%8%
1797
16th to endNight
32%410%20%25%6%
1750
May1st to 15thNight
35%7%11%22%18%4
1650
16th to endNight
30%7%16%24%18%2
1541
June1st to 15thNight
22%8%15%31%19%2
1320
16th to endNight
21%7%13%28%22%6%
1320
July1st to 15thNight
28%9%19%26%12%3
1366
16th to endNight
22%9%22%27%15%1
1468
August1st to 15thNight
23%8%21%25%15%4
1623
16th to endNight
31%8%14%23%18%4
1750
September1st to 15thNight
34%8%12%21%14%9%
1650
16th to endNight
29%48%18%27%11%
1759
October1st to 15thNight
25%49%18%26%14%
1974
16th to endNight
29%2317%30%16%
2112
November1st to 15thNight
29%37%20%26%12%
2166
16th to endNight
36%35%17%27%10%
2340
December1st to 15thNight
41%38%20%19%6%
2404
16th to endNight
43%48%19%18%5%
2657

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
16%12%35%21%11%3
90
16th to endDay
28%12%41%10%6%1
96
February1st to 15thDay
15%11%38%25%7%1
90
16th to endDay
17%12%35%25%8%
81
March1st to 15thDay
26%11%36%21%4
90
16th to endDay
10%12%23%30%19%2
151
April1st to 15thDay
11%9%31%29%13%3
270
16th to endDay
16%6%17%35%21%3
250
May1st to 15thDay
16%319%35%21%2
228
16th to endDay
11%214%29%26%14%
341
June1st to 15thDay
6%7%28%37%19%
420
16th to endDay
418%20%39%24%
420
July1st to 15thDay
7%8%25%39%19%
400
16th to endDay
6%1214%35%38%
445
August1st to 15thDay
8%213%37%37%
270
16th to endDay
14%314%35%30%
268
September1st to 15thDay
11%6%16%36%28%
255
16th to endDay
14%6%25%35%17%
254
October1st to 15thDay
1319%36%24%15%
93
16th to endDay
15%311%29%31%9%
96
November1st to 15thDay
14%327%25%28%
90
16th to endDay
23%8%26%21%16%3
90
December1st to 15thDay
23%5%35%17%14%3
90
16th to endDay
14%14%40%19%9%1
96
January1st to 15thNight
21%9%30%29%9%
900
16th to endNight
22%8%35%30%3
960
February1st to 15thNight
21%7%33%31%5%
749
16th to endNight
18%9%38%29%4
631
March1st to 15thNight
17%8%30%36%6%
605
16th to endNight
17%5%28%32%14%1
576
April1st to 15thNight
11%6%34%34%11%1
539
16th to endNight
12%5%26%37%15%1
525
May1st to 15thNight
14%218%46%15%2
495
16th to endNight
10%214%32%35%5%
515
June1st to 15thNight
37%38%42%6%
495
16th to endNight
315%27%49%13%
495
July1st to 15thNight
45%28%51%9%
465
16th to endNight
3323%51%17%
522
August1st to 15thNight
3221%51%21%
494
16th to endNight
7%423%48%15%
525
September1st to 15thNight
11%17%29%41%8%
495
16th to endNight
9%19%32%42%4
601
October1st to 15thNight
10%115%31%34%5%
660
16th to endNight
14%417%34%26%1
704
November1st to 15thNight
10%5%24%33%23%2
700
16th to endNight
18%5%26%30%16%2
720
December1st to 15thNight
20%7%28%33%10%
784
16th to endNight
21%8%29%31%8%
960
Page generated at 2017-04-26 16:21:42. Version ac04

Copyright 2017 A. Danko


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