Nebraska Nature and Visitor Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nebraska Nature and Visitor Center clear sky chart from 2005-11-06 to 2024-04-10.

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	10% 6% 3 5% 4 3 4 4 5% 7% 49%	83524
	Night	9% 6% 2 5% 4 2 4 4 5% 7% 51%	85273
Transparency	Day	35% 4 14% 27% 17% 3	83241
	Night	33% 4 13% 27% 19% 3	85079
Seeing	Day	13% 8% 31% 31% 14% 3	14859
	Night	12% 8% 36% 34% 10% 1	24976

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	6% 14% 4 7% 6% 3 4 4 5% 6% 41%	2538
	11th to 20th	Day	6% 11% 4 8% 6% 3 3 6% 5% 8% 40%	2733
	21st to end	Day	6% 8% 5% 12% 6% 3 4 3 4 5% 44%	3135
February	1st to 10th	Day	9% 9% 4 8% 7% 3 5% 5% 5% 6% 40%	1710
	11th to 20th	Day	6% 8% 3 7% 4 3 4 4 6% 7% 48%	1844
	21st to end	Day	9% 7% 2 5% 4 3 4 5% 4 6% 51%	1570
March	1st to 10th	Day	10% 5% 3 5% 3 3 3 3 4 6% 56%	3215
	11th to 20th	Day	11% 7% 2 5% 4 2 2 3 4 6% 53%	3480
	21st to end	Day	15% 10% 3 6% 5% 3 4 5% 5% 8% 38%	3814
April	1st to 10th	Day	11% 7% 2 5% 4 3 4 3 5% 7% 49%	2161
	11th to 20th	Day	14% 7% 3 5% 5% 3 4 3 5% 7% 44%	2250
	21st to end	Day	17% 6% 2 5% 5% 3 4 4 5% 7% 42%	2340
May	1st to 10th	Day	15% 6% 3 5% 5% 3 4 4 6% 8% 42%	2340
	11th to 20th	Day	16% 7% 3 5% 5% 3 4 4 5% 7% 43%	2302
	21st to end	Day	13% 6% 3 6% 5% 3 6% 6% 6% 9% 38%	2531
June	1st to 10th	Day	6% 3 1 4 5% 3 4 4 6% 8% 56%	2370
	11th to 20th	Day	9% 4 2 4 4 2 4 5% 6% 8% 52%	2520
	21st to end	Day	6% 4 2 3 3 2 5% 4 6% 10% 54%	2520
July	1st to 10th	Day	7% 4 2 4 4 3 4 5% 6% 9% 52%	2520
	11th to 20th	Day	5% 4 2 4 4 2 4 4 5% 8% 57%	2451
	21st to end	Day	6% 4 2 4 5% 3 5% 5% 6% 10% 50%	2546
August	1st to 10th	Day	7% 4 2 5% 5% 4 5% 6% 8% 10% 44%	2328
	11th to 20th	Day	7% 4 2 4 4 3 4 4 5% 9% 55%	2301
	21st to end	Day	8% 4 2 4 4 3 4 4 5% 6% 55%	2507
September	1st to 10th	Day	11% 6% 2 4 4 2 4 3 5% 5% 55%	2039
	11th to 20th	Day	9% 5% 2 4 3 2 3 3 5% 6% 58%	1980
	21st to end	Day	10% 3 1 3 3 2 3 3 3 7% 61%	1980
October	1st to 10th	Day	15% 6% 2 3 3 2 3 4 3 6% 54%	1949
	11th to 20th	Day	11% 5% 2 3 3 2 3 3 3 6% 59%	1800
	21st to end	Day	13% 7% 2 4 3 2 2 2 3 5% 55%	1868
November	1st to 10th	Day	7% 4 2 4 4 3 5% 4 5% 8% 56%	1673
	11th to 20th	Day	7% 6% 2 5% 4 2 3 3 4 6% 57%	1710
	21st to end	Day	10% 8% 2 5% 3 3 3 4 4 6% 52%	1710
December	1st to 10th	Day	6% 6% 3 6% 4 3 4 4 5% 7% 51%	1710
	11th to 20th	Day	7% 8% 3 5% 5% 3 4 4 5% 6% 49%	2161
	21st to end	Day	13% 9% 4 11% 6% 3 4 4 4 5% 36%	2918
January	1st to 10th	Night	6% 12% 4 10% 7% 2 3 4 6% 6% 41%	4417
	11th to 20th	Night	6% 9% 3 6% 5% 3 5% 4 5% 6% 49%	4217
	21st to end	Night	7% 9% 5% 11% 5% 2 4 4 5% 5% 43%	4532
February	1st to 10th	Night	8% 10% 4 7% 6% 3 4 5% 4 6% 43%	2470
	11th to 20th	Night	5% 7% 3 6% 6% 3 5% 5% 5% 8% 46%	2237
	21st to end	Night	6% 7% 2 5% 4 3 3 3 5% 6% 53%	1884
March	1st to 10th	Night	10% 5% 2 4 3 2 3 3 4 5% 58%	3644
	11th to 20th	Night	10% 5% 2 4 3 2 3 3 4 6% 59%	3480
	21st to end	Night	16% 7% 3 5% 4 3 4 5% 6% 8% 41%	3817
April	1st to 10th	Night	11% 6% 2 4 4 3 4 5% 5% 7% 48%	2005
	11th to 20th	Night	13% 6% 2 4 4 3 5% 5% 5% 8% 44%	1658
	21st to end	Night	13% 5% 2 4 3 2 4 4 5% 8% 49%	1620
May	1st to 10th	Night	15% 5% 2 4 5% 2 4 5% 6% 7% 45%	1620
	11th to 20th	Night	12% 7% 3 5% 5% 3 4 4 5% 9% 44%	1593
	21st to end	Night	13% 5% 2 4 5% 3 5% 5% 6% 10% 42%	1745
June	1st to 10th	Night	5% 3 2 4 4 2 4 5% 5% 11% 55%	1584
	11th to 20th	Night	8% 4 2 3 5% 3 4 3 4 10% 55%	1440
	21st to end	Night	4 3 2 4 4 2 5% 4 5% 9% 59%	1440
July	1st to 10th	Night	5% 3 2 4 4 3 5% 6% 7% 10% 51%	1440
	11th to 20th	Night	2 3 1 4 3 3 3 5% 7% 9% 60%	1506
	21st to end	Night	4 3 2 4 4 2 4 5% 6% 11% 55%	1772
August	1st to 10th	Night	5% 4 2 4 5% 3 4 6% 8% 9% 50%	1611
	11th to 20th	Night	6% 4 1 4 4 3 4 4 6% 9% 55%	1600
	21st to end	Night	6% 4 1 4 3 2 3 4 4 6% 62%	1845
September	1st to 10th	Night	8% 3 2 2 3 2 3 4 4 7% 63%	1921
	11th to 20th	Night	8% 3 2 4 3 2 3 4 5% 6% 60%	1980
	21st to end	Night	8% 3 2 3 4 2 4 4 5% 6% 61%	1980
October	1st to 10th	Night	15% 4 2 3 3 2 3 4 4 6% 54%	1993
	11th to 20th	Night	10% 4 2 4 3 1 3 3 4 6% 60%	2160
	21st to end	Night	12% 5% 2 3 3 2 2 3 4 6% 57%	2484
November	1st to 10th	Night	4 4 1 4 3 2 3 3 6% 7% 63%	2405
	11th to 20th	Night	7% 5% 2 3 4 3 4 4 4 7% 57%	2470
	21st to end	Night	8% 6% 2 4 3 2 3 3 5% 6% 57%	2470
December	1st to 10th	Night	5% 7% 3 5% 5% 3 4 4 5% 7% 53%	2470
	11th to 20th	Night	7% 5% 3 5% 4 3 3 4 5% 8% 54%	3036
	21st to end	Night	15% 11% 4 7% 5% 2 3 3 4 5% 40%	4727

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	46% 3 14% 25% 11% 1	2539
	11th to 20th	Day	44% 4 17% 19% 14% 2	2733
	21st to end	Day	45% 2 14% 25% 13% 1	3135
February	1st to 10th	Day	45% 5% 15% 22% 10% 3	1710
	11th to 20th	Day	35% 4 16% 25% 15% 4	1854
	21st to end	Day	34% 4 12% 28% 16% 6%	1570
March	1st to 10th	Day	32% 3 9% 24% 28% 4	3215
	11th to 20th	Day	34% 3 12% 30% 20% 2	3480
	21st to end	Day	46% 3 25% 21% 5% 1	3814
April	1st to 10th	Day	36% 4 14% 27% 16% 2	2161
	11th to 20th	Day	41% 3 14% 24% 15% 3	2253
	21st to end	Day	42% 5% 12% 27% 14% 1	2340
May	1st to 10th	Day	41% 6% 15% 23% 14% 2	2340
	11th to 20th	Day	41% 5% 16% 25% 12%	2306
	21st to end	Day	42% 7% 17% 23% 10% 2	2531
June	1st to 10th	Day	26% 6% 19% 33% 15% 2	2370
	11th to 20th	Day	30% 5% 14% 29% 18% 3	2520
	21st to end	Day	26% 6% 15% 31% 19% 4	2520
July	1st to 10th	Day	28% 4 15% 30% 20% 2	2451
	11th to 20th	Day	25% 6% 13% 30% 22% 5%	2376
	21st to end	Day	28% 6% 17% 32% 16% 1	2405
August	1st to 10th	Day	32% 8% 19% 28% 13% 1	2314
	11th to 20th	Day	26% 6% 14% 33% 19% 2	2301
	21st to end	Day	30% 5% 12% 24% 24% 6%	2507
September	1st to 10th	Day	33% 4 10% 25% 22% 7%	2039
	11th to 20th	Day	28% 4 12% 30% 23% 3	1980
	21st to end	Day	26% 4 9% 34% 26% 1	1980
October	1st to 10th	Day	34% 3 9% 27% 26% 2	1949
	11th to 20th	Day	29% 2 9% 29% 22% 8%	1800
	21st to end	Day	34% 2 12% 25% 22% 5%	1868
November	1st to 10th	Day	26% 4 14% 30% 22% 3	1673
	11th to 20th	Day	30% 3 10% 27% 26% 4	1710
	21st to end	Day	35% 3 12% 26% 20% 4	1710
December	1st to 10th	Day	33% 4 15% 29% 15% 2	1710
	11th to 20th	Day	36% 4 13% 32% 14%	2159
	21st to end	Day	51% 3 10% 22% 12% 1	2918
January	1st to 10th	Night	44% 3 13% 25% 14% 1	4417
	11th to 20th	Night	37% 3 15% 27% 17% 1	4217
	21st to end	Night	45% 3 13% 23% 16% 1	4532
February	1st to 10th	Night	43% 5% 13% 22% 14% 4	2470
	11th to 20th	Night	35% 5% 14% 27% 16% 3	2237
	21st to end	Night	32% 3 13% 21% 23% 8%	1884
March	1st to 10th	Night	29% 3 9% 26% 26% 6%	3644
	11th to 20th	Night	28% 3 9% 28% 27% 4	3480
	21st to end	Night	43% 3 24% 22% 7% 1	3817
April	1st to 10th	Night	35% 5% 13% 24% 20% 3	2005
	11th to 20th	Night	37% 5% 15% 26% 15% 2	1658
	21st to end	Night	34% 5% 14% 27% 18% 2	1620
May	1st to 10th	Night	38% 6% 14% 25% 14% 1	1620
	11th to 20th	Night	38% 5% 17% 25% 14% 1	1594
	21st to end	Night	38% 8% 18% 22% 12% 2	1746
June	1st to 10th	Night	24% 6% 22% 30% 17% 2	1584
	11th to 20th	Night	27% 6% 16% 27% 19% 5%	1440
	21st to end	Night	23% 6% 17% 31% 21% 4	1440
July	1st to 10th	Night	27% 6% 16% 28% 19% 4	1400
	11th to 20th	Night	20% 6% 17% 28% 24% 5%	1458
	21st to end	Night	22% 5% 19% 34% 17% 3	1673
August	1st to 10th	Night	28% 6% 21% 28% 14% 3	1601
	11th to 20th	Night	25% 5% 15% 33% 19% 3	1600
	21st to end	Night	23% 5% 14% 24% 26% 8%	1845
September	1st to 10th	Night	22% 4 10% 29% 25% 10%	1921
	11th to 20th	Night	26% 4 9% 31% 25% 5%	1980
	21st to end	Night	25% 4 9% 29% 29% 3	1980
October	1st to 10th	Night	33% 4 10% 26% 24% 4	1993
	11th to 20th	Night	28% 2 8% 27% 27% 8%	2160
	21st to end	Night	30% 3 10% 27% 23% 7%	2484
November	1st to 10th	Night	20% 4 13% 30% 27% 7%	2405
	11th to 20th	Night	28% 3 9% 30% 25% 5%	2470
	21st to end	Night	29% 3 12% 28% 24% 4	2470
December	1st to 10th	Night	31% 3 15% 30% 18% 2	2470
	11th to 20th	Night	30% 3 13% 36% 18% 1	3037
	21st to end	Night	47% 3 11% 26% 11% 1	4727

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	14% 11% 41% 24% 8% 1	270
	11th to 20th	Day	17% 15% 33% 27% 9%	270
	21st to end	Day	15% 8% 41% 25% 9% 1	297
February	1st to 10th	Day	14% 12% 43% 26% 4 1	270
	11th to 20th	Day	11% 11% 44% 26% 7% 1	270
	21st to end	Day	14% 17% 48% 18% 3	225
March	1st to 10th	Day	13% 12% 44% 24% 6% 1	270
	11th to 20th	Day	23% 10% 37% 20% 9% 1	270
	21st to end	Day	23% 15% 38% 18% 4 1	297
April	1st to 10th	Day	16% 19% 41% 20% 3	349
	11th to 20th	Day	21% 12% 37% 26% 4	531
	21st to end	Day	20% 15% 33% 21% 9% 3	600
May	1st to 10th	Day	16% 11% 30% 31% 10% 1	603
	11th to 20th	Day	20% 9% 32% 23% 13% 3	625
	21st to end	Day	16% 9% 31% 29% 13% 2	679
June	1st to 10th	Day	6% 5% 27% 36% 21% 6%	630
	11th to 20th	Day	9% 6% 35% 32% 16% 2	630
	21st to end	Day	8% 7% 29% 35% 19% 2	630
July	1st to 10th	Day	9% 2 18% 40% 26% 6%	621
	11th to 20th	Day	6% 4 19% 44% 22% 6%	618
	21st to end	Day	8% 1 18% 41% 27% 5%	684
August	1st to 10th	Day	8% 2 16% 46% 23% 4	626
	11th to 20th	Day	7% 3 20% 43% 26% 2	615
	21st to end	Day	9% 2 23% 38% 22% 6%	626
September	1st to 10th	Day	15% 4 24% 36% 16% 5%	329
	11th to 20th	Day	7% 7% 27% 36% 17% 6%	270
	21st to end	Day	17% 7% 29% 29% 16% 2	270
October	1st to 10th	Day	22% 8% 23% 29% 13% 4	270
	11th to 20th	Day	11% 13% 38% 25% 10% 2	270
	21st to end	Day	19% 15% 33% 24% 8% 1	297
November	1st to 10th	Day	10% 15% 40% 24% 9% 3	270
	11th to 20th	Day	11% 14% 45% 21% 9%	270
	21st to end	Day	20% 13% 33% 22% 9% 2	270
December	1st to 10th	Day	8% 9% 44% 32% 7% 1	270
	11th to 20th	Day	15% 9% 40% 28% 8%	270
	21st to end	Day	18% 12% 47% 21% 2	297
January	1st to 10th	Night	12% 10% 39% 32% 6% 1	950
	11th to 20th	Night	11% 11% 40% 30% 7% 1	950
	21st to end	Night	11% 9% 41% 32% 7%	1045
February	1st to 10th	Night	14% 11% 42% 28% 5%	950
	11th to 20th	Night	10% 10% 44% 31% 4 1	763
	21st to end	Night	11% 12% 46% 27% 5%	628
March	1st to 10th	Night	13% 11% 43% 28% 4 1	709
	11th to 20th	Night	16% 9% 41% 28% 5% 1	570
	21st to end	Night	19% 11% 41% 24% 5%	627
April	1st to 10th	Night	15% 14% 43% 25% 3	570
	11th to 20th	Night	17% 12% 42% 26% 3	533
	21st to end	Night	16% 11% 32% 32% 8% 1	540
May	1st to 10th	Night	17% 8% 37% 30% 8%	540
	11th to 20th	Night	16% 7% 36% 33% 8%	531
	21st to end	Night	15% 8% 33% 30% 13% 1	584
June	1st to 10th	Night	7% 5% 25% 47% 14% 2	540
	11th to 20th	Night	8% 6% 38% 36% 12%	540
	21st to end	Night	6% 4 34% 42% 14%	540
July	1st to 10th	Night	6% 3 19% 45% 25% 1	525
	11th to 20th	Night	3 1 21% 50% 23% 2	522
	21st to end	Night	4 2 18% 53% 23%	591
August	1st to 10th	Night	6% 2 19% 49% 21% 2	537
	11th to 20th	Night	7% 3 26% 46% 18%	534
	21st to end	Night	7% 2 22% 47% 20% 2	594
September	1st to 10th	Night	10% 2 28% 44% 15% 1	540
	11th to 20th	Night	10% 4 32% 39% 14% 1	540
	21st to end	Night	9% 5% 37% 36% 12% 1	540
October	1st to 10th	Night	18% 7% 31% 31% 12%	553
	11th to 20th	Night	14% 9% 38% 30% 8%	720
	21st to end	Night	16% 11% 31% 32% 10%	900
November	1st to 10th	Night	6% 11% 37% 38% 7%	925
	11th to 20th	Night	10% 11% 41% 31% 6% 1	950
	21st to end	Night	11% 11% 36% 32% 11% 1	950
December	1st to 10th	Night	10% 10% 44% 31% 5%	950
	11th to 20th	Night	12% 10% 40% 31% 7%	950
	21st to end	Night	16% 11% 38% 29% 6%	1045

Page generated at 2024-04-07 08:28:15. Version ac07

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