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 2005-11-06 to 2024-11-04.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	8% 6% 2 5% 4 4 4 3 5% 7% 52%	105099
	Night	8% 7% 2 6% 4 4 4 3 5% 7% 50%	102579
Transparency	Day	30% 7% 14% 27% 18% 4	104843
	Night	32% 7% 14% 26% 18% 3	102425
Seeing	Day	11% 9% 31% 32% 14% 3	15857
	Night	11% 8% 38% 35% 8%	25764

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	3 8% 4 12% 6% 4 4 3 4 5% 48%	2538
	11th to 20th	Day	5% 8% 3 7% 5% 6% 5% 6% 6% 8% 40%	2540
	21st to end	Day	4 7% 2 6% 3 4 4 3 5% 7% 55%	2794
February	1st to 10th	Day	7% 13% 4 8% 6% 5% 4 3 5% 6% 38%	1765
	11th to 20th	Day	6% 10% 3 7% 4 5% 3 3 5% 7% 46%	1849
	21st to end	Day	7% 9% 3 5% 4 3 3 3 4 6% 51%	1570
March	1st to 10th	Day	7% 10% 2 5% 3 2 3 3 5% 6% 55%	3130
	11th to 20th	Day	8% 7% 2 5% 3 3 3 2 4 6% 56%	3376
	21st to end	Day	15% 12% 4 7% 4 3 4 3 5% 6% 38%	3955
April	1st to 10th	Day	13% 8% 2 5% 4 3 3 3 6% 7% 46%	2280
	11th to 20th	Day	14% 10% 3 6% 5% 4 4 3 5% 7% 40%	2291
	21st to end	Day	14% 8% 2 5% 4 4 4 3 5% 7% 45%	2470
May	1st to 10th	Day	13% 7% 3 6% 5% 4 5% 4 5% 7% 41%	4120
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 3 5% 7% 50%	4082
	21st to end	Day	13% 6% 2 5% 5% 4 4 4 5% 7% 46%	4824
June	1st to 10th	Day	7% 5% 2 4 3 4 4 3 6% 9% 53%	2660
	11th to 20th	Day	10% 4 2 5% 4 4 4 3 5% 8% 51%	2660
	21st to end	Day	5% 3 1 3 3 3 4 4 6% 9% 60%	2660
July	1st to 10th	Day	8% 5% 2 5% 4 4 4 4 6% 7% 51%	4430
	11th to 20th	Day	4 3 1 4 3 4 4 4 7% 9% 57%	4430
	21st to end	Day	3 3 1 3 3 4 5% 4 6% 9% 59%	4802
August	1st to 10th	Day	6% 4 2 6% 5% 5% 5% 4 6% 8% 50%	4141
	11th to 20th	Day	7% 6% 2 6% 4 4 4 4 6% 8% 50%	4041
	21st to end	Day	4 3 1 4 4 3 4 3 6% 8% 62%	4188
September	1st to 10th	Day	8% 3 2 4 3 3 3 3 4 6% 63%	2275
	11th to 20th	Day	6% 3 1 3 3 3 3 3 4 6% 64%	2090
	21st to end	Day	9% 4 1 4 3 3 3 3 5% 5% 62%	2090
October	1st to 10th	Day	8% 3 1 3 2 1 2 2 2 4 72%	3480
	11th to 20th	Day	6% 5% 2 4 3 3 3 3 4 7% 60%	3064
	21st to end	Day	8% 6% 2 5% 4 4 4 4 5% 7% 51%	3091
November	1st to 10th	Day	6% 6% 2 5% 3 4 4 4 5% 6% 55%	1700
	11th to 20th	Day	5% 7% 2 6% 4 3 4 3 5% 6% 54%	1710
	21st to end	Day	6% 8% 2 5% 4 3 3 2 5% 9% 53%	1710
December	1st to 10th	Day	5% 9% 3 6% 4 4 4 3 7% 7% 49%	1573
	11th to 20th	Day	5% 6% 3 6% 4 4 4 3 5% 7% 54%	1926
	21st to end	Day	10% 14% 5% 6% 4 4 4 3 4 6% 39%	2794
January	1st to 10th	Night	3 11% 4 12% 7% 4 4 3 5% 6% 41%	4417
	11th to 20th	Night	3 9% 5% 10% 4 5% 5% 4 5% 7% 44%	4430
	21st to end	Night	3 6% 2 7% 5% 4 4 4 6% 8% 52%	4873
February	1st to 10th	Night	10% 11% 4 8% 5% 4 4 3 5% 7% 40%	2428
	11th to 20th	Night	6% 9% 3 8% 5% 4 5% 4 5% 7% 44%	2218
	21st to end	Night	6% 8% 2 7% 3 4 4 3 6% 7% 49%	1884
March	1st to 10th	Night	9% 11% 3 6% 3 3 3 3 5% 5% 48%	3734
	11th to 20th	Night	7% 6% 2 5% 4 4 4 3 5% 8% 52%	3586
	21st to end	Night	13% 10% 3 9% 5% 4 4 4 5% 8% 33%	3677
April	1st to 10th	Night	12% 8% 3 6% 5% 4 5% 4 5% 9% 40%	1900
	11th to 20th	Night	14% 8% 2 5% 4 3 4 3 6% 5% 46%	1835
	21st to end	Night	14% 8% 1 6% 4 4 4 3 6% 7% 42%	1710
May	1st to 10th	Night	14% 8% 2 6% 4 4 4 3 5% 7% 43%	2850
	11th to 20th	Night	9% 5% 2 5% 3 3 4 3 6% 8% 52%	2810
	21st to end	Night	14% 5% 2 6% 4 4 5% 4 7% 7% 44%	2762
June	1st to 10th	Night	9% 5% 1 3 3 3 4 4 5% 9% 53%	1520
	11th to 20th	Night	12% 4 2 4 4 4 5% 4 7% 8% 46%	1520
	21st to end	Night	4 3 2 5% 3 4 5% 4 8% 10% 51%	1520
July	1st to 10th	Night	7% 4 2 5% 3 3 3 4 6% 8% 56%	2540
	11th to 20th	Night	5% 3 2 5% 4 4 4 4 6% 9% 54%	2540
	21st to end	Night	3 3 2 6% 4 4 5% 4 6% 8% 56%	2761
August	1st to 10th	Night	5% 4 2 8% 5% 5% 6% 5% 8% 8% 45%	2796
	11th to 20th	Night	6% 7% 2 6% 5% 4 5% 4 6% 7% 48%	2798
	21st to end	Night	5% 4 1 5% 4 4 4 4 6% 8% 55%	3476
September	1st to 10th	Night	9% 2 1 4 3 3 4 3 5% 6% 60%	1905
	11th to 20th	Night	8% 3 1 3 3 3 3 3 5% 7% 61%	2090
	21st to end	Night	10% 4 1 3 3 4 3 3 4 5% 61%	2090
October	1st to 10th	Night	7% 3 1 3 2 2 2 2 3 4 72%	3480
	11th to 20th	Night	9% 4 1 3 2 2 2 3 4 7% 64%	3824
	21st to end	Night	7% 7% 2 6% 4 3 4 3 5% 6% 52%	4467
November	1st to 10th	Night	8% 5% 2 5% 4 3 4 3 6% 7% 54%	2451
	11th to 20th	Night	5% 6% 2 5% 4 4 4 3 6% 6% 53%	2470
	21st to end	Night	5% 6% 3 6% 3 3 4 3 6% 8% 53%	2470
December	1st to 10th	Night	5% 7% 3 7% 4 4 4 4 4 7% 51%	2603
	11th to 20th	Night	4 6% 3 6% 4 3 4 3 6% 7% 53%	3271
	21st to end	Night	12% 13% 3 6% 4 3 3 3 4 6% 42%	4873

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	37% 6% 11% 29% 15% 1	2539
	11th to 20th	Day	38% 10% 17% 21% 11% 2	2540
	21st to end	Day	28% 7% 22% 27% 13% 3	2794
February	1st to 10th	Day	45% 6% 13% 21% 12% 2	1765
	11th to 20th	Day	38% 5% 14% 23% 15% 5%	1859
	21st to end	Day	34% 5% 15% 26% 16% 5%	1570
March	1st to 10th	Day	29% 5% 10% 26% 25% 4	3130
	11th to 20th	Day	29% 5% 15% 32% 18% 2	3376
	21st to end	Day	45% 8% 17% 24% 6% 1	3955
April	1st to 10th	Day	37% 7% 16% 25% 13% 3	2280
	11th to 20th	Day	42% 7% 13% 21% 14% 2	2294
	21st to end	Day	38% 7% 14% 28% 13% 1	2470
May	1st to 10th	Day	37% 9% 15% 21% 15% 3	4120
	11th to 20th	Day	30% 9% 16% 29% 15% 1	4086
	21st to end	Day	35% 9% 15% 27% 11% 2	4824
June	1st to 10th	Day	27% 9% 19% 30% 13% 2	2660
	11th to 20th	Day	29% 8% 15% 28% 16% 4	2660
	21st to end	Day	19% 9% 16% 31% 20% 4	2660
July	1st to 10th	Day	30% 7% 11% 28% 21% 3	4361
	11th to 20th	Day	22% 7% 15% 31% 20% 6%	4355
	21st to end	Day	19% 8% 13% 23% 27% 10%	4651
August	1st to 10th	Day	29% 8% 15% 23% 21% 3	4126
	11th to 20th	Day	32% 7% 13% 27% 18% 2	4080
	21st to end	Day	21% 6% 17% 23% 23% 10%	4187
September	1st to 10th	Day	23% 5% 11% 27% 24% 11%	2275
	11th to 20th	Day	21% 6% 12% 30% 25% 6%	2090
	21st to end	Day	24% 5% 9% 30% 27% 5%	2090
October	1st to 10th	Day	19% 3 8% 19% 34% 18%	3480
	11th to 20th	Day	24% 4 16% 33% 20% 4	3064
	21st to end	Day	33% 5% 11% 31% 15% 6%	3091
November	1st to 10th	Day	28% 5% 17% 24% 20% 5%	1700
	11th to 20th	Day	30% 5% 11% 28% 21% 6%	1710
	21st to end	Day	30% 4 15% 28% 18% 4	1710
December	1st to 10th	Day	33% 6% 14% 27% 17% 3	1573
	11th to 20th	Day	29% 7% 16% 32% 15% 2	1924
	21st to end	Day	45% 7% 9% 27% 10% 2	2794
January	1st to 10th	Night	42% 6% 12% 25% 14% 1	4417
	11th to 20th	Night	38% 7% 16% 25% 13% 1	4430
	21st to end	Night	29% 8% 20% 28% 15% 1	4873
February	1st to 10th	Night	42% 6% 14% 23% 12% 2	2428
	11th to 20th	Night	38% 7% 13% 26% 13% 4	2218
	21st to end	Night	32% 7% 15% 25% 15% 5%	1884
March	1st to 10th	Night	35% 7% 10% 21% 26% 2	3734
	11th to 20th	Night	29% 7% 14% 31% 18% 2	3586
	21st to end	Night	46% 11% 16% 20% 7% 1	3677
April	1st to 10th	Night	40% 8% 15% 20% 15% 3	1900
	11th to 20th	Night	39% 7% 11% 24% 16% 3	1835
	21st to end	Night	40% 9% 13% 26% 12% 1	1710
May	1st to 10th	Night	37% 8% 15% 22% 15% 3	2850
	11th to 20th	Night	26% 9% 17% 35% 11% 2	2811
	21st to end	Night	35% 11% 18% 24% 10% 2	2762
June	1st to 10th	Night	26% 10% 20% 27% 16% 2	1520
	11th to 20th	Night	33% 7% 17% 24% 14% 4	1520
	21st to end	Night	25% 9% 18% 29% 17% 3	1520
July	1st to 10th	Night	26% 5% 20% 28% 18% 4	2500
	11th to 20th	Night	25% 7% 16% 28% 20% 4	2492
	21st to end	Night	24% 8% 14% 23% 25% 6%	2674
August	1st to 10th	Night	33% 8% 17% 22% 17% 3	2788
	11th to 20th	Night	34% 6% 16% 27% 14% 3	2825
	21st to end	Night	25% 7% 13% 23% 21% 10%	3476
September	1st to 10th	Night	24% 6% 10% 26% 26% 8%	1905
	11th to 20th	Night	23% 7% 12% 29% 25% 5%	2090
	21st to end	Night	27% 4 8% 28% 27% 6%	2090
October	1st to 10th	Night	19% 3 6% 18% 44% 10%	3480
	11th to 20th	Night	23% 3 12% 31% 25% 5%	3824
	21st to end	Night	32% 5% 12% 25% 22% 5%	4467
November	1st to 10th	Night	28% 6% 14% 24% 22% 6%	2451
	11th to 20th	Night	29% 6% 13% 24% 23% 5%	2470
	21st to end	Night	29% 6% 14% 28% 20% 4	2470
December	1st to 10th	Night	32% 5% 16% 25% 18% 4	2603
	11th to 20th	Night	29% 6% 14% 35% 15% 1	3272
	21st to end	Night	43% 6% 11% 27% 11% 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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	6% 14% 34% 31% 12% 3	270
	11th to 20th	Day	11% 18% 33% 29% 9% 1	270
	21st to end	Day	12% 10% 43% 24% 8% 3	297
February	1st to 10th	Day	13% 11% 48% 24% 4	270
	11th to 20th	Day	11% 14% 43% 23% 9%	270
	21st to end	Day	11% 13% 48% 25% 4	225
March	1st to 10th	Day	10% 12% 41% 23% 13% 1	270
	11th to 20th	Day	10% 10% 37% 30% 12% 1	270
	21st to end	Day	18% 12% 37% 21% 9% 2	374
April	1st to 10th	Day	17% 17% 37% 22% 7%	460
	11th to 20th	Day	19% 20% 32% 23% 5% 1	492
	21st to end	Day	18% 12% 30% 29% 10% 1	650
May	1st to 10th	Day	15% 12% 31% 28% 11% 2	653
	11th to 20th	Day	18% 9% 30% 26% 14% 4	675
	21st to end	Day	15% 10% 31% 28% 12% 3	734
June	1st to 10th	Day	6% 5% 30% 31% 19% 8%	680
	11th to 20th	Day	11% 8% 31% 32% 15% 3	680
	21st to end	Day	6% 5% 28% 41% 18% 2	680
July	1st to 10th	Day	6% 3 25% 38% 22% 6%	671
	11th to 20th	Day	5% 4 23% 45% 20% 3	668
	21st to end	Day	6% 2 24% 42% 22% 3	739
August	1st to 10th	Day	7% 4 24% 43% 18% 5%	676
	11th to 20th	Day	8% 4 26% 40% 19% 3	665
	21st to end	Day	3 4 24% 40% 23% 5%	547
September	1st to 10th	Day	6% 3 26% 42% 19% 4	485
	11th to 20th	Day	5% 5% 26% 30% 27% 8%	300
	21st to end	Day	12% 11% 28% 28% 16% 4	300
October	1st to 10th	Day	15% 8% 22% 31% 17% 7%	300
	11th to 20th	Day	10% 13% 40% 26% 9% 2	300
	21st to end	Day	13% 15% 32% 28% 11% 2	330
November	1st to 10th	Day	10% 10% 37% 25% 15% 3	279
	11th to 20th	Day	12% 10% 36% 30% 11% 1	270
	21st to end	Day	14% 8% 39% 26% 10% 2	270
December	1st to 10th	Day	10% 11% 46% 25% 7% 1	270
	11th to 20th	Day	11% 11% 44% 22% 10% 1	270
	21st to end	Day	15% 16% 39% 24% 4 1	297
January	1st to 10th	Night	8% 14% 42% 29% 7% 1	950
	11th to 20th	Night	7% 14% 42% 32% 5%	950
	21st to end	Night	10% 9% 45% 28% 7%	1045
February	1st to 10th	Night	13% 11% 45% 25% 5%	879
	11th to 20th	Night	10% 10% 50% 23% 6%	744
	21st to end	Night	10% 10% 47% 29% 4	628
March	1st to 10th	Night	12% 11% 40% 33% 5%	760
	11th to 20th	Night	10% 9% 43% 30% 7% 1	637
	21st to end	Night	15% 10% 36% 30% 8%	627
April	1st to 10th	Night	17% 11% 40% 28% 4	570
	11th to 20th	Night	16% 13% 39% 29% 3	563
	21st to end	Night	17% 10% 32% 33% 7% 1	570
May	1st to 10th	Night	15% 8% 35% 34% 8%	570
	11th to 20th	Night	18% 7% 31% 34% 10%	561
	21st to end	Night	16% 8% 35% 34% 6% 1	617
June	1st to 10th	Night	10% 5% 29% 42% 14% 1	570
	11th to 20th	Night	12% 6% 37% 38% 8%	570
	21st to end	Night	5% 4 30% 49% 13%	570
July	1st to 10th	Night	6% 2 31% 46% 14%	555
	11th to 20th	Night	5% 3 30% 53% 9% 1	552
	21st to end	Night	4 3 29% 52% 12%	624
August	1st to 10th	Night	4 1 29% 50% 14% 1	567
	11th to 20th	Night	8% 3 30% 47% 12%	564
	21st to end	Night	4 4 34% 44% 14%	627
September	1st to 10th	Night	8% 4 31% 46% 10% 1	570
	11th to 20th	Night	9% 4 34% 39% 15%	570
	21st to end	Night	12% 7% 32% 39% 10% 1	570
October	1st to 10th	Night	14% 8% 34% 34% 9%	570
	11th to 20th	Night	12% 9% 36% 34% 9%	781
	21st to end	Night	13% 10% 36% 32% 9%	1045
November	1st to 10th	Night	10% 8% 41% 34% 7% 1	943
	11th to 20th	Night	9% 10% 41% 32% 8%	950
	21st to end	Night	8% 8% 42% 34% 8%	950
December	1st to 10th	Night	10% 11% 45% 28% 6%	950
	11th to 20th	Night	10% 8% 44% 31% 6%	950
	21st to end	Night	16% 13% 37% 29% 5%	1045

Page generated at 2024-11-01 21:47:35. Version ac07

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