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 2017-12-02.

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%
15845
26%
47859
20%
15799
59%
15799
33%
28280

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%
540
26%
1800
23%
540
58%
540
32%
1004
May1st to 15thNight
58%
540
21%
1800
21%
540
63%
540
29%
1063
May16th to endNight
63%
563
23%
1684
22%
561
67%
561
35%
992
June1st to 15thNight
79%
540
24%
1440
21%
540
81%
540
44%
831
June16th to endNight
80%
540
27%
1440
24%
540
81%
540
45%
822
July1st to 15thNight
78%
510
19%
1499
21%
510
79%
510
38%
871
July16th to endNight
85%
564
23%
1594
27%
531
85%
531
42%
873
August1st to 15thNight
81%
539
20%
1772
25%
536
82%
536
37%
966
August16th to endNight
73%
573
24%
1910
30%
573
73%
573
31%
1122
September1st to 15thNight
69%
540
24%
1800
27%
540
71%
540
30%
1061
September16th to endNight
72%
656
34%
1919
30%
656
74%
656
41%
1065
October1st to 15thNight
66%
720
31%
2154
27%
720
69%
720
44%
1143
October16th to endNight
57%
768
38%
2304
28%
768
66%
768
42%
1231
November1st to 15thNight
54%
760
30%
2352
24%
760
62%
760
37%
1302
November16th to endNight
46%
780
29%
2535
22%
780
56%
780
32%
1446
December1st to 15thNight
38%
792
22%
2429
13%
792
47%
792
26%
1529
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%
48570
Night
11%424423447%49%
48056
TransparencyDay
37%6%11%21%18%4
48271
Night
33%5%10%21%21%7%
47860
SeeingDay
11%314%23%28%17%
5852
Night
13%421%31%23%4
15845

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%2443445%7%46%
2160
May1st to 15thDay
14%5%35%435%5%6%5%39%
2151
16th to endDay
8%426%6%47%5%7%9%38%
2424
June1st to 15thDay
4426%6%46%5%6%9%45%
2520
16th to endDay
5%4235%45%6%7%9%44%
2520
July1st to 15thDay
7%425%5%47%7%7%11%35%
2367
16th to endDay
7%3245%37%6%8%11%38%
2466
August1st to 15thDay
7%3246%46%7%7%10%40%
2178
16th to endDay
10%5%2443446%10%41%
2292
September1st to 15thDay
9%425%5%35%45%8%43%
2160
16th to endDay
10%414424447%51%
2028
October1st to 15thDay
8%324324345%55%
1803
16th to endDay
13%32221122461%
1920
November1st to 15thDay
11%325%42233457%
1833
16th to endDay
15%6%24223345%49%
1755
December1st to 15thDay
18%10%34423435%38%
1565
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%423447%52%
1800
May1st to 15thNight
12%434323448%47%
1799
16th to endNight
8%413335%46%9%48%
1683
June1st to 15thNight
3214425%6%7%11%50%
1440
16th to endNight
32133235%7%10%54%
1440
July1st to 15thNight
6%224436%5%7%12%44%
1589
16th to endNight
42123245%7%14%50%
1702
August1st to 15thNight
42135%346%7%11%49%
1782
16th to endNight
7%4245%345%5%10%46%
1910
September1st to 15thNight
9%4245%345%5%6%49%
1800
16th to endNight
7%31432435%7%55%
1919
October1st to 15thNight
8%313313247%59%
2154
16th to endNight
11%413212235%61%
2304
November1st to 15thNight
9%41342345%7%54%
2352
16th to endNight
14%41442333453%
2535
December1st to 15thNight
17%7%24413336%44%
2429
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
2160
May1st to 15thDay
43%7%10%15%18%4
2151
16th to endDay
39%8%16%22%11%1
2428
June1st to 15thDay
34%7%12%26%17%1
2520
16th to endDay
32%8%15%21%18%3
2520
July1st to 15thDay
35%11%18%21%9%3
2228
16th to endDay
35%9%17%24%12%1
2311
August1st to 15thDay
34%10%17%22%12%3
2164
16th to endDay
37%7%17%21%12%3
2292
September1st to 15thDay
37%8%12%19%15%6%
2160
16th to endDay
32%5%9%20%21%10%
2028
October1st to 15thDay
29%49%22%23%11%
1803
16th to endDay
29%2319%32%11%
1920
November1st to 15thDay
31%36%20%30%7%
1833
16th to endDay
37%37%18%25%7%
1755
December1st to 15thDay
47%5%7%18%14%6%
1565
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%
1800
May1st to 15thNight
34%6%10%22%21%5%
1800
16th to endNight
30%7%16%25%18%2
1685
June1st to 15thNight
23%8%15%30%19%1
1440
16th to endNight
22%7%13%27%22%5%
1440
July1st to 15thNight
27%8%20%27%11%4
1499
16th to endNight
22%9%21%28%16%2
1594
August1st to 15thNight
25%8%21%24%15%4
1772
16th to endNight
32%7%15%23%16%4
1910
September1st to 15thNight
33%7%12%21%16%8%
1800
16th to endNight
27%48%22%26%10%
1919
October1st to 15thNight
25%310%21%25%13%
2154
16th to endNight
27%2417%31%15%
2304
November1st to 15thNight
30%38%20%25%11%
2352
16th to endNight
34%35%17%27%11%
2535
December1st to 15thNight
41%38%20%18%6%
2429
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%19%33%20%2
270
May1st to 15thDay
15%5%19%33%21%4
288
16th to endDay
10%316%31%25%12%
412
June1st to 15thDay
8%7%28%37%18%
495
16th to endDay
6%28%22%39%21%
495
July1st to 15thDay
6%7%23%38%23%
475
16th to endDay
6%315%34%38%
515
August1st to 15thDay
10%213%39%33%
331
16th to endDay
19%313%34%28%
332
September1st to 15thDay
11%7%17%35%27%
315
16th to endDay
11%5%25%36%21%
314
October1st to 15thDay
3217%34%24%17%
138
16th to endDay
13%320%27%25%8%
144
November1st to 15thDay
19%225%26%23%1
135
16th to endDay
15%9%25%21%22%4
135
December1st to 15thDay
22%5%34%18%17%3
94
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
11%5%27%37%15%1
540
May1st to 15thNight
14%317%45%16%2
540
16th to endNight
11%215%33%33%4
563
June1st to 15thNight
37%38%44%6%
540
16th to endNight
315%28%48%12%
540
July1st to 15thNight
45%26%53%9%
510
16th to endNight
3323%51%17%
564
August1st to 15thNight
5%220%51%20%
539
16th to endNight
8%1423%47%14%
573
September1st to 15thNight
12%17%28%41%9%
540
16th to endNight
9%18%31%43%5%
656
October1st to 15thNight
10%115%32%35%5%
720
16th to endNight
13%419%34%25%1
768
November1st to 15thNight
11%5%23%34%23%2
760
16th to endNight
17%5%25%31%17%2
780
December1st to 15thNight
19%7%28%33%10%
792
16th to endNight
21%8%29%31%8%
960
Page generated at 2017-12-03 10:16:38. Version ac04

Copyright 2017 A. Danko


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