Northwest Nebraska Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Northwest Nebraska Star Party clear sky chart from 2005-11-06 to 2024-01-13.

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
38%
24763
23%
74449
12%
24711
49%
24711
33%
43039

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 10thNight
33%
950
24%
2647
11%
946
45%
946
32%
1578
January11th to 20thNight
30%
915
25%
2562
11%
915
43%
915
31%
1507
January21st to endNight
26%
963
22%
2745
7%
963
40%
963
27%
1697
February1st to 10thNight
25%
720
16%
2340
8%
720
35%
720
22%
1457
February11th to 20thNight
28%
700
18%
2112
8%
700
38%
700
24%
1355
February21st to endNight
25%
592
23%
1776
7%
592
39%
592
28%
1064
March1st to 10thNight
33%
720
23%
2160
9%
720
45%
720
31%
1280
March11th to 20thNight
35%
716
24%
2109
11%
716
47%
716
31%
1261
March21st to endNight
35%
594
21%
1980
13%
594
47%
594
24%
1222
April1st to 10thNight
30%
540
20%
1800
12%
540
43%
540
26%
1065
April11th to 20thNight
30%
533
19%
1777
10%
533
43%
533
23%
1107
April21st to endNight
37%
540
18%
1706
13%
540
46%
540
23%
1088
May1st to 10thNight
40%
540
20%
1602
14%
540
47%
540
28%
1008
May11th to 20thNight
40%
531
15%
1418
9%
531
45%
531
28%
944
May21st to endNight
37%
583
16%
1552
8%
582
41%
582
31%
997
June1st to 10thNight
48%
540
16%
1440
8%
540
51%
540
38%
868
June11th to 20thNight
39%
540
18%
1440
6%
540
45%
540
40%
845
June21st to endNight
53%
540
22%
1440
11%
540
58%
540
46%
802
July1st to 10thNight
55%
525
18%
1400
9%
525
60%
525
43%
804
July11th to 20thNight
57%
522
26%
1392
13%
522
65%
522
52%
742
July21st to endNight
58%
591
25%
1488
15%
558
62%
558
45%
835
August1st to 10thNight
59%
537
25%
1424
16%
534
66%
534
43%
815
August11th to 20thNight
61%
534
27%
1759
23%
534
69%
534
46%
855
August21st to endNight
59%
594
30%
1980
28%
594
69%
594
43%
975
September1st to 10thNight
55%
540
29%
1800
25%
540
65%
540
40%
917
September11th to 20thNight
49%
540
33%
1872
27%
540
61%
540
40%
921
September21st to endNight
46%
540
32%
1980
24%
540
61%
540
37%
969
October1st to 10thNight
42%
627
26%
2067
17%
627
52%
627
32%
1147
October11th to 20thNight
45%
720
30%
2160
16%
720
55%
720
37%
1202
October21st to endNight
37%
975
27%
2559
10%
975
47%
975
39%
1515
November1st to 10thNight
39%
925
27%
2405
11%
925
48%
925
41%
1406
November11th to 20thNight
31%
950
30%
2470
9%
950
45%
950
36%
1487
November21st to endNight
35%
950
27%
2607
11%
950
48%
950
38%
1500
December1st to 10thNight
26%
950
23%
2660
8%
950
40%
950
34%
1573
December11th to 20thNight
35%
949
25%
3116
12%
949
44%
949
33%
1625
December21st to endNight
26%
1037
16%
4704
7%
1026
41%
1026
19%
2606

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
7%5%2443446%8%53%
74813
Night
7%6%25%43445%8%51%
74956
TransparencyDay
29%6%13%27%19%5%
74517
Night
31%6%13%27%18%5%
74774
SeeingDay
12%12%30%29%15%3
14660
Night
10%11%36%34%9%1
24777

By Month

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 10thDay
47%35%6%345%5%9%50%
1518
11th to 20thDay
48%35%6%346%6%8%47%
1460
21st to endDay
5%8%26%6%2447%8%47%
1627
February1st to 10thDay
5%11%5%7%5%36%5%46%42%
1620
11th to 20thDay
5%8%37%7%35%5%6%8%45%
1735
21st to endDay
49%46%42446%7%50%
1480
March1st to 10thDay
6%8%35%42445%8%51%
1800
11th to 20thDay
7%7%3342445%7%53%
1847
21st to endDay
10%8%36%5%3446%8%44%
2376
April1st to 10thDay
9%7%35%44446%8%45%
2160
11th to 20thDay
13%7%26%5%335%6%8%42%
2131
21st to endDay
14%7%2442446%8%44%
2254
May1st to 10thDay
14%6%25%4445%5%8%44%
2354
11th to 20thDay
17%6%24435%5%6%8%38%
2478
21st to endDay
13%6%35%5%346%6%8%41%
2724
June1st to 10thDay
7%3143346%7%9%54%
2520
11th to 20thDay
9%3134345%6%9%53%
2520
21st to endDay
5%2123236%6%8%61%
2520
July1st to 10thDay
5%313435%5%7%9%54%
2520
11th to 20thDay
6%2123245%5%9%61%
2520
21st to endDay
6%313335%47%10%56%
2742
August1st to 10thDay
441443448%11%53%
2507
11th to 20thDay
5%2133245%5%7%62%
2137
21st to endDay
432342445%7%63%
2376
September1st to 10thDay
7%41342345%6%62%
2160
11th to 20thDay
8%213323347%65%
2087
21st to endDay
8%323322246%64%
1980
October1st to 10thDay
11%5%23324436%55%
1890
11th to 20thDay
9%5%23324345%61%
1796
21st to endDay
7%5%2442345%8%57%
1782
November1st to 10thDay
5%5%244245%6%9%54%
1673
11th to 20thDay
4425%435%45%6%58%
1710
21st to endDay
37%4432445%7%57%
1569
December1st to 10thDay
5%5%35%5%35%5%5%8%52%
1520
11th to 20thDay
4425%42446%9%57%
1926
21st to endDay
411%47%5%34445%49%
2794
January1st to 10thNight
27%36%6%3445%8%51%
2647
11th to 20thNight
46%36%5%35%5%7%8%50%
2562
21st to endNight
47%37%6%46%5%5%8%46%
2745
February1st to 10thNight
5%9%47%5%446%6%7%42%
2340
11th to 20thNight
5%9%47%6%45%5%6%7%43%
2112
21st to endNight
48%47%5%35%5%47%47%
1776
March1st to 10thNight
7%6%36%5%34446%52%
2160
11th to 20thNight
7%7%35%5%25%5%5%8%48%
2109
21st to endNight
10%7%35%5%35%47%7%43%
1980
April1st to 10thNight
11%7%344345%5%7%48%
1800
11th to 20thNight
12%8%35%5%345%5%8%44%
1777
21st to endNight
15%7%25%5%35%5%5%8%42%
1706
May1st to 10thNight
14%7%25%43445%7%46%
1602
11th to 20thNight
16%6%245%35%5%5%7%43%
1417
21st to endNight
15%5%23325%46%11%44%
1552
June1st to 10thNight
7%424435%5%6%11%50%
1440
11th to 20thNight
9%3143345%8%10%51%
1440
21st to endNight
5%3134246%6%9%56%
1440
July1st to 10thNight
6%3145%35%46%8%55%
1440
11th to 20thNight
33133245%5%11%60%
1440
21st to endNight
32135%35%5%7%8%56%
1576
August1st to 10thNight
43245%35%6%8%11%50%
1432
11th to 20thNight
332343436%8%62%
1759
21st to endNight
43144245%6%7%60%
1980
September1st to 10thNight
8%424324446%60%
1800
11th to 20thNight
6%42442345%7%60%
1872
21st to endNight
10%413323345%61%
1980
October1st to 10thNight
12%6%2432435%6%54%
2067
11th to 20thNight
9%5%24323446%57%
2160
21st to endNight
8%5%25%32345%8%54%
2559
November1st to 10thNight
7%5%2442446%7%55%
2405
11th to 20thNight
5%425%5%35%5%6%7%53%
2470
21st to endNight
5%6%3443445%8%54%
2607
December1st to 10thNight
46%35%435%6%5%8%52%
2660
11th to 20thNight
45%244345%5%8%56%
3271
21st to endNight
5%10%47%5%2445%7%48%
4873

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 10thDay
32%416%31%15%1
1519
11th to 20thDay
34%6%17%28%13%2
1460
21st to endDay
34%6%18%26%13%3
1627
February1st to 10thDay
42%7%15%21%13%3
1620
11th to 20thDay
38%6%15%23%13%5%
1745
21st to endDay
33%5%17%25%16%4
1480
March1st to 10thDay
32%414%30%18%2
1800
11th to 20thDay
31%5%14%28%19%4
1847
21st to endDay
38%7%15%27%11%2
2376
April1st to 10thDay
36%6%16%25%13%4
2160
11th to 20thDay
39%7%13%21%16%4
2134
21st to endDay
37%6%14%29%14%1
2254
May1st to 10thDay
38%6%14%30%11%1
2354
11th to 20thDay
42%7%17%24%9%1
2482
21st to endDay
39%7%18%24%12%1
2724
June1st to 10thDay
25%8%18%31%14%4
2520
11th to 20thDay
26%6%14%28%20%6%
2520
21st to endDay
19%6%11%30%26%8%
2520
July1st to 10thDay
25%6%13%25%26%7%
2451
11th to 20thDay
19%5%11%25%25%15%
2445
21st to endDay
23%5%12%27%22%11%
2590
August1st to 10thDay
23%6%16%29%19%7%
2491
11th to 20thDay
21%6%12%29%22%10%
2137
21st to endDay
21%5%8%24%29%14%
2376
September1st to 10thDay
23%5%8%22%28%15%
2160
11th to 20thDay
20%48%28%28%12%
2087
21st to endDay
23%38%31%29%5%
1980
October1st to 10thDay
31%5%10%25%25%5%
1890
11th to 20thDay
26%5%9%30%22%7%
1796
21st to endDay
26%416%31%17%5%
1782
November1st to 10thDay
26%6%15%27%20%7%
1673
11th to 20thDay
26%6%12%30%22%4
1710
21st to endDay
27%5%14%29%21%4
1569
December1st to 10thDay
31%5%17%26%19%3
1520
11th to 20thDay
25%5%16%36%16%1
1924
21st to endDay
38%410%30%17%2
2794
January1st to 10thNight
32%6%15%29%16%2
2647
11th to 20thNight
31%6%17%27%17%3
2562
21st to endNight
36%5%15%27%14%2
2745
February1st to 10thNight
39%7%16%24%12%3
2340
11th to 20thNight
40%6%14%22%13%4
2112
21st to endNight
36%413%26%16%5%
1776
March1st to 10thNight
34%413%26%19%3
2160
11th to 20thNight
34%5%11%27%19%4
2109
21st to endNight
38%7%14%26%14%2
1980
April1st to 10thNight
36%6%14%24%16%4
1800
11th to 20thNight
39%6%13%23%15%4
1777
21st to endNight
41%6%11%26%14%1
1706
May1st to 10thNight
38%5%15%27%14%1
1602
11th to 20thNight
39%8%17%25%10%1
1418
21st to endNight
35%7%21%22%13%3
1552
June1st to 10thNight
28%8%23%25%12%3
1440
11th to 20thNight
26%8%18%28%14%7%
1440
21st to endNight
21%7%13%32%21%6%
1440
July1st to 10thNight
27%5%13%30%20%5%
1400
11th to 20thNight
19%6%12%26%24%14%
1392
21st to endNight
24%6%15%27%19%8%
1488
August1st to 10thNight
24%8%17%29%17%5%
1424
11th to 20thNight
22%413%26%26%9%
1759
21st to endNight
21%6%9%24%26%13%
1980
September1st to 10thNight
25%5%7%24%28%11%
1800
11th to 20thNight
23%5%9%27%24%11%
1872
21st to endNight
26%47%29%24%10%
1980
October1st to 10thNight
32%412%22%24%5%
2067
11th to 20thNight
29%49%28%21%9%
2160
21st to endNight
28%5%12%27%19%7%
2559
November1st to 10thNight
28%414%27%22%6%
2405
11th to 20thNight
29%5%11%29%20%5%
2470
21st to endNight
28%5%12%28%22%5%
2607
December1st to 10thNight
30%6%15%27%18%4
2660
11th to 20thNight
26%5%17%35%14%2
3272
21st to endNight
36%5%11%33%12%2
4873

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 10thDay
9%14%34%29%12%2
270
11th to 20thDay
15%19%30%28%8%1
248
21st to endDay
10%26%44%16%31
264
February1st to 10thDay
14%20%43%20%3
240
11th to 20thDay
8%24%45%18%5%1
240
21st to endDay
13%25%35%22%5%
198
March1st to 10thDay
9%20%36%25%9%
240
11th to 20thDay
13%15%41%20%10%1
284
21st to endDay
21%17%32%22%7%2
462
April1st to 10thDay
16%18%36%22%6%1
420
11th to 20thDay
20%23%34%16%6%
412
21st to endDay
22%12%30%26%8%2
514
May1st to 10thDay
17%13%29%24%14%3
603
11th to 20thDay
22%8%24%28%15%4
625
21st to endDay
17%13%27%26%15%3
679
June1st to 10thDay
6%8%24%35%21%7%
630
11th to 20thDay
10%9%35%33%11%3
630
21st to endDay
7%6%27%36%20%3
630
July1st to 10thDay
6%423%40%22%4
621
11th to 20thDay
6%424%43%20%3
618
21st to endDay
8%320%41%26%3
684
August1st to 10thDay
6%324%39%24%4
626
11th to 20thDay
5%5%22%37%26%5%
446
21st to endDay
5%6%25%33%23%7%
495
September1st to 10thDay
9%6%24%37%20%5%
450
11th to 20thDay
9%7%21%32%26%6%
377
21st to endDay
11%10%29%31%12%6%
270
October1st to 10thDay
13%11%26%25%19%6%
270
11th to 20thDay
15%18%30%20%12%5%
270
21st to endDay
12%16%33%24%12%3
297
November1st to 10thDay
9%14%40%20%12%4
270
11th to 20thDay
11%17%38%24%9%1
270
21st to endDay
10%14%45%20%9%2
270
December1st to 10thDay
12%17%41%24%5%
270
11th to 20thDay
10%20%42%22%6%
270
21st to endDay
13%21%36%25%5%1
297
January1st to 10thNight
6%16%37%30%9%1
950
11th to 20thNight
9%19%36%28%7%1
915
21st to endNight
8%18%42%28%4
963
February1st to 10thNight
8%15%44%27%5%
720
11th to 20thNight
10%16%39%29%6%
704
21st to endNight
10%14%45%27%4
592
March1st to 10thNight
11%12%39%32%6%
720
11th to 20thNight
12%10%37%33%7%1
716
21st to endNight
15%12%33%34%5%
594
April1st to 10thNight
17%12%37%29%4
540
11th to 20thNight
16%15%35%30%4
533
21st to endNight
19%13%26%32%10%
540
May1st to 10thNight
18%9%29%30%13%1
540
11th to 20thNight
19%6%31%32%12%1
531
21st to endNight
17%8%34%33%8%1
584
June1st to 10thNight
9%6%34%37%13%2
540
11th to 20thNight
10%8%41%34%7%
540
21st to endNight
6%5%32%45%12%
540
July1st to 10thNight
6%5%26%43%18%1
525
11th to 20thNight
4430%50%11%1
522
21st to endNight
4328%47%18%
591
August1st to 10thNight
4427%47%17%1
537
11th to 20thNight
4228%51%14%
534
21st to endNight
4426%48%18%1
594
September1st to 10thNight
10%327%42%17%1
540
11th to 20thNight
8%6%34%37%15%1
540
21st to endNight
13%6%32%36%14%
540
October1st to 10thNight
16%9%29%31%14%1
627
11th to 20thNight
12%9%30%40%10%
720
21st to endNight
12%11%36%31%9%1
975
November1st to 10thNight
10%10%38%32%9%1
925
11th to 20thNight
8%14%43%28%6%1
950
21st to endNight
8%13%39%33%6%1
950
December1st to 10thNight
8%15%47%25%5%
950
11th to 20thNight
8%12%40%35%5%
950
21st to endNight
12%16%40%27%5%
1045
Page generated at 2024-01-10 17:35:24. Version ac07

Copyright 2024 Attilla Danko


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