Nebraska Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nebraska Star Party clear sky chart from 2005-11-05 to 2017-08-12.

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
40%
15945
21%
46451
12%
15899
49%
15899
33%
28010

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
30%
900
21%
2506
9%
895
39%
895
29%
1580
January16th to endNight
30%
960
22%
2688
9%
960
40%
960
31%
1662
February1st to 15thNight
26%
778
16%
2205
5%
774
34%
774
25%
1458
February16th to endNight
31%
632
22%
1894
8%
632
43%
632
30%
1150
March1st to 15thNight
35%
702
22%
2142
11%
702
44%
702
31%
1261
March16th to endNight
34%
576
18%
2061
12%
576
44%
576
23%
1267
April1st to 15thNight
32%
539
16%
1798
9%
539
43%
539
25%
1138
April16th to endNight
34%
540
16%
1653
12%
540
42%
540
22%
1127
May1st to 15thNight
40%
540
17%
1620
10%
540
47%
540
27%
1023
May16th to endNight
38%
562
14%
1553
8%
561
42%
561
27%
1048
June1st to 15thNight
44%
540
13%
1440
5%
540
48%
540
31%
944
June16th to endNight
57%
540
17%
1440
8%
540
60%
540
46%
809
July1st to 15thNight
60%
510
15%
1360
7%
510
63%
510
42%
787
July16th to endNight
63%
564
24%
1416
14%
531
68%
531
47%
800
August1st to 15thNight
61%
527
21%
1559
19%
524
65%
524
39%
903
August16th to endNight
57%
525
25%
1690
22%
525
66%
525
43%
863
September1st to 15thNight
50%
495
27%
1708
21%
495
63%
495
35%
912
September16th to endNight
54%
492
30%
1815
27%
492
64%
492
40%
866
October1st to 15thNight
42%
508
29%
1828
23%
508
51%
508
28%
1027
October16th to endNight
45%
880
27%
2288
12%
880
52%
880
39%
1363
November1st to 15thNight
42%
875
27%
2275
11%
875
51%
875
41%
1337
November16th to endNight
37%
900
29%
2340
13%
900
48%
900
41%
1398
December1st to 15thNight
32%
900
18%
2484
8%
900
41%
900
30%
1598
December16th to endNight
33%
960
21%
2688
8%
960
45%
960
30%
1689

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
9%5%2442445%7%50%
47532
Night
8%5%2442445%7%50%
46618
Cloud CoverDay
9%5%2442445%7%50%
47542
Night
8%5%2442445%7%50%
46623
Cloud CoverDay
9%5%2442445%7%50%
47540
Night
8%5%2442445%7%50%
46623
TransparencyDay
32%6%15%25%15%3
47216
Night
33%6%15%25%16%3
46451
SeeingDay
11%6%30%32%15%2
5883
Night
10%7%36%35%9%
15947

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
5%6%37%5%34436%48%
1432
16th to endDay
6%7%25%5%3345%7%50%
1536
February1st to 15thDay
8%9%46%6%33347%40%
1665
16th to endDay
6%8%3442345%7%49%
1580
March1st to 15thDay
7%7%23313448%52%
1808
16th to endDay
10%8%35%5%345%5%8%40%
2161
April1st to 15thDay
12%8%24423347%45%
2150
16th to endDay
17%8%35%323446%39%
2307
May1st to 15thDay
12%6%24423447%46%
2331
16th to endDay
15%5%2443445%7%42%
2559
June1st to 15thDay
10%42332445%9%48%
2520
16th to endDay
5%21322445%7%61%
2520
July1st to 15thDay
5%313425%5%6%8%52%
2520
16th to endDay
321332446%8%58%
2656
August1st to 15thDay
6%4145%45%5%7%8%46%
2306
16th to endDay
6%314323345%59%
2159
September1st to 15thDay
10%413323445%57%
1922
16th to endDay
7%32212245%65%
1815
October1st to 15thDay
14%6%24312245%52%
1789
16th to endDay
10%6%13213337%56%
1584
November1st to 15thDay
6%424324446%55%
1583
16th to endDay
7%5%25%42435%8%50%
1620
December1st to 15thDay
7%7%36%42445%6%47%
1473
16th to endDay
7%6%45%5%25%348%45%
1536
January1st to 15thNight
46%37%6%3435%7%47%
2506
16th to endNight
6%7%26%5%2445%6%48%
2688
February1st to 15thNight
10%8%36%424347%43%
2202
16th to endNight
7%6%35%42445%6%49%
1894
March1st to 15thNight
6%6%3442445%7%49%
2129
16th to endNight
11%6%35%4245%5%8%41%
2061
April1st to 15thNight
11%7%25%42445%7%42%
1798
16th to endNight
16%7%25%423446%40%
1653
May1st to 15thNight
11%6%245%24446%46%
1620
16th to endNight
14%5%143245%7%7%42%
1552
June1st to 15thNight
14%423344448%45%
1440
16th to endNight
421332447%9%55%
1440
July1st to 15thNight
6%21333347%8%54%
1440
16th to endNight
32133245%6%8%58%
1512
August1st to 15thNight
4214435%5%6%8%53%
1567
16th to endNight
5%313213448%60%
1690
September1st to 15thNight
10%213324345%57%
1708
16th to endNight
8%212222337%62%
1815
October1st to 15thNight
13%5%14422245%52%
1828
16th to endNight
9%5%14213347%54%
2288
November1st to 15thNight
6%42342335%7%55%
2275
16th to endNight
5%42442435%8%54%
2340
December1st to 15thNight
7%6%46%42445%7%45%
2484
16th to endNight
6%8%25%5%24347%48%
2688

Percentage Cloud Cover SW (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
46%37%5%34436%48%
1432
16th to endDay
6%7%25%43335%7%50%
1536
February1st to 15thDay
8%10%45%6%3435%6%41%
1665
16th to endDay
6%7%34423447%49%
1580
March1st to 15thDay
7%7%2432335%7%52%
1818
16th to endDay
11%7%35%5%2446%8%40%
2161
April1st to 15thDay
13%7%2442335%7%45%
2150
16th to endDay
18%8%25%424446%39%
2307
May1st to 15thDay
12%5%24423447%46%
2331
16th to endDay
15%5%25%434448%42%
2559
June1st to 15thDay
10%42442445%9%48%
2520
16th to endDay
5%2232435%8%61%
2520
July1st to 15thDay
5%323435%5%6%7%52%
2520
16th to endDay
421332446%7%58%
2656
August1st to 15thDay
6%4245%35%5%6%8%46%
2306
16th to endDay
6%314324346%59%
2159
September1st to 15thDay
10%313313345%57%
1922
16th to endDay
7%32212245%65%
1815
October1st to 15thDay
14%5%24312335%52%
1789
16th to endDay
10%6%23213337%56%
1584
November1st to 15thDay
6%4243245%46%55%
1583
16th to endDay
6%6%25%41435%9%49%
1620
December1st to 15thDay
6%8%36%42346%6%47%
1473
16th to endDay
7%6%5%5%424448%46%
1536
January1st to 15thNight
36%37%6%25%448%47%
2506
16th to endNight
6%7%26%5%3445%6%48%
2688
February1st to 15thNight
9%8%46%5%24347%42%
2195
16th to endNight
7%6%35%42445%6%49%
1894
March1st to 15thNight
6%6%25%42446%7%49%
2142
16th to endNight
10%7%35%4145%5%8%42%
2061
April1st to 15thNight
12%6%35%5%25%45%8%42%
1798
16th to endNight
17%7%25%43435%6%40%
1653
May1st to 15thNight
12%6%24424447%46%
1619
16th to endNight
14%5%1442446%7%42%
1552
June1st to 15thNight
14%413334448%46%
1440
16th to endNight
421342447%9%54%
1440
July1st to 15thNight
5%2143235%7%9%53%
1440
16th to endNight
321422446%8%58%
1512
August1st to 15thNight
42135%345%7%7%53%
1567
16th to endNight
5%413314448%60%
1690
September1st to 15thNight
10%213323445%57%
1708
16th to endNight
8%212222236%62%
1815
October1st to 15thNight
13%5%1441225%5%52%
1828
16th to endNight
9%5%14322347%54%
2288
November1st to 15thNight
6%41442445%7%55%
2275
16th to endNight
5%42442445%7%53%
2340
December1st to 15thNight
7%7%46%5%2445%7%45%
2484
16th to endNight
6%8%25%5%23347%48%
2688

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
5%6%37%5%33446%48%
1432
16th to endDay
6%7%25%423447%50%
1536
February1st to 15thDay
9%9%46%6%34447%41%
1665
16th to endDay
6%7%3432345%7%49%
1580
March1st to 15thDay
7%7%23313448%52%
1818
16th to endDay
11%8%35%5%335%5%8%40%
2159
April1st to 15thDay
13%8%23424347%45%
2150
16th to endDay
17%8%35%324446%39%
2307
May1st to 15thDay
12%6%24424447%46%
2331
16th to endDay
16%5%24434448%42%
2559
June1st to 15thDay
10%42342445%9%48%
2520
16th to endDay
5%21322345%7%61%
2520
July1st to 15thDay
5%3144345%6%9%51%
2520
16th to endDay
421332446%8%58%
2656
August1st to 15thDay
6%4245%36%5%6%8%46%
2306
16th to endDay
6%313323446%59%
2159
September1st to 15thDay
10%414223436%56%
1922
16th to endDay
7%22312245%65%
1815
October1st to 15thDay
14%6%24311335%53%
1789
16th to endDay
10%6%13212347%55%
1584
November1st to 15thDay
6%5%14324445%55%
1583
16th to endDay
7%6%25%42445%8%49%
1620
December1st to 15thDay
7%8%36%42436%6%46%
1473
16th to endDay
8%6%45%5%25%35%8%45%
1536
January1st to 15thNight
46%36%6%25%35%8%46%
2506
16th to endNight
6%7%35%5%2445%6%48%
2688
February1st to 15thNight
10%8%46%5%24447%42%
2195
16th to endNight
6%7%25%4245%5%5%49%
1894
March1st to 15thNight
6%7%2442446%7%48%
2142
16th to endNight
11%6%45%4245%5%9%41%
2061
April1st to 15thNight
12%6%36%43436%7%42%
1798
16th to endNight
16%7%25%423446%40%
1653
May1st to 15thNight
11%6%245%24447%46%
1619
16th to endNight
14%4143245%6%8%42%
1552
June1st to 15thNight
13%5%23334448%46%
1440
16th to endNight
42134245%6%9%55%
1440
July1st to 15thNight
5%3133235%7%9%54%
1440
16th to endNight
32133245%6%8%58%
1512
August1st to 15thNight
4214435%5%6%8%53%
1567
16th to endNight
5%313313448%60%
1690
September1st to 15thNight
10%33324445%57%
1708
16th to endNight
8%212313237%62%
1815
October1st to 15thNight
13%5%24323245%52%
1828
16th to endNight
9%5%14322348%54%
2288
November1st to 15thNight
6%42342335%7%55%
2275
16th to endNight
5%425%41435%8%53%
2340
December1st to 15thNight
7%7%46%43445%7%45%
2484
16th to endNight
6%8%25%5%24347%48%
2688

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
36%6%17%24%13%1
1433
16th to endDay
33%5%22%23%11%3
1536
February1st to 15thDay
43%415%23%8%3
1666
16th to endDay
33%5%17%26%11%4
1580
March1st to 15thDay
30%6%16%26%16%3
1818
16th to endDay
40%8%17%19%12%1
2161
April1st to 15thDay
38%6%14%28%10%1
2150
16th to endDay
44%6%14%23%9%
2307
May1st to 15thDay
36%6%16%27%12%
2331
16th to endDay
40%7%18%21%10%1
2563
June1st to 15thDay
32%8%17%26%13%1
2520
16th to endDay
19%7%16%31%19%4
2520
July1st to 15thDay
27%8%14%24%19%6%
2371
16th to endDay
21%7%13%27%21%8%
2489
August1st to 15thDay
32%9%14%24%14%4
2290
16th to endDay
26%411%28%21%7%
2159
September1st to 15thDay
29%49%25%19%11%
1922
16th to endDay
20%411%32%27%3
1815
October1st to 15thDay
34%411%22%21%5%
1789
16th to endDay
29%413%31%18%3
1584
November1st to 15thDay
28%416%22%21%5%
1583
16th to endDay
31%5%16%27%17%1
1620
December1st to 15thDay
36%6%17%23%12%2
1473
16th to endDay
36%5%17%25%14%1
1536
January1st to 15thNight
35%7%16%26%12%1
2506
16th to endNight
35%5%16%25%15%1
2688
February1st to 15thNight
41%6%15%24%10%1
2205
16th to endNight
34%6%15%26%12%5%
1894
March1st to 15thNight
33%5%14%26%18%2
2142
16th to endNight
38%7%15%21%14%1
2061
April1st to 15thNight
40%6%14%24%13%1
1798
16th to endNight
44%7%11%23%11%1
1653
May1st to 15thNight
37%6%15%23%14%
1620
16th to endNight
38%9%19%20%9%2
1553
June1st to 15thNight
37%7%17%22%13%2
1440
16th to endNight
23%5%19%30%16%4
1440
July1st to 15thNight
26%6%16%25%19%6%
1360
16th to endNight
21%8%13%26%24%6%
1416
August1st to 15thNight
26%9%17%24%17%4
1559
16th to endNight
22%6%10%28%22%9%
1690
September1st to 15thNight
27%6%10%23%24%6%
1708
16th to endNight
23%410%30%27%4
1815
October1st to 15thNight
34%411%22%22%4
1828
16th to endNight
29%413%26%20%4
2288
November1st to 15thNight
28%413%22%24%6%
2275
16th to endNight
28%5%16%26%19%3
2340
December1st to 15thNight
37%6%17%25%11%2
2484
16th to endNight
37%5%17%24%13%2
2688

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
5%13%31%30%14%5%
90
16th to endDay
13%10%35%29%10%1
96
February1st to 15thDay
20%10%43%23%3
90
16th to endDay
6%11%45%24%11%1
81
March1st to 15thDay
10%6%41%31%11%
90
16th to endDay
13%9%36%26%14%
145
April1st to 15thDay
17%12%36%24%7%
269
16th to endDay
24%9%31%23%8%1
417
May1st to 15thDay
13%10%33%26%14%1
468
16th to endDay
18%9%29%28%9%4
517
June1st to 15thDay
10%433%27%17%6%
495
16th to endDay
5%433%39%16%1
495
July1st to 15thDay
6%425%37%22%4
475
16th to endDay
4224%44%21%2
515
August1st to 15thDay
6%227%43%17%2
474
16th to endDay
8%322%40%20%3
327
September1st to 15thDay
10%425%40%15%3
197
16th to endDay
13%426%32%21%2
90
October1st to 15thDay
13%6%31%33%13%2
90
16th to endDay
10%5%23%38%14%7%
96
November1st to 15thDay
3217%37%32%6%
90
16th to endDay
32%7%27%20%12%
90
December1st to 15thDay
17%15%41%14%7%3
90
16th to endDay
11%14%46%21%41
96
January1st to 15thNight
7%13%43%28%7%
900
16th to endNight
10%9%45%29%4
960
February1st to 15thNight
12%9%46%24%6%
779
16th to endNight
11%8%45%27%6%
632
March1st to 15thNight
10%8%39%33%7%
702
16th to endNight
14%8%37%31%7%
576
April1st to 15thNight
15%7%42%30%4
539
16th to endNight
20%8%33%30%7%
540
May1st to 15thNight
15%6%33%36%7%
540
16th to endNight
17%7%32%33%8%
563
June1st to 15thNight
14%433%35%11%
540
16th to endNight
4232%49%11%
540
July1st to 15thNight
6%225%49%15%
510
16th to endNight
2127%56%11%
564
August1st to 15thNight
427%49%17%
527
16th to endNight
6%230%44%17%
525
September1st to 15thNight
10%331%41%11%1
495
16th to endNight
9%5%27%41%14%
492
October1st to 15thNight
15%8%30%35%9%
508
16th to endNight
13%7%29%37%11%
880
November1st to 15thNight
9%7%37%36%9%
875
16th to endNight
7%7%43%32%8%
900
December1st to 15thNight
10%8%43%31%5%
900
16th to endNight
11%9%38%33%6%
960
Page generated at 2017-08-13 13:16:43. Version ac04

Copyright 2017 A. Danko


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