Little Rock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Rock clear sky chart from 2005-11-06 to 2024-01-31.

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	13% 5% 3 5% 5% 3 5% 5% 6% 7% 45%	74758
	Night	12% 5% 2 4 4 3 4 4 5% 7% 51%	75373
Transparency	Day	37% 6% 11% 23% 19% 5%	74482
	Night	34% 5% 10% 23% 22% 6%	75170
Seeing	Day	15% 8% 23% 26% 21% 7%	14243
	Night	15% 7% 25% 32% 19% 2	24198

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	19% 7% 2 5% 4 2 3 3 4 6% 45%	1707
	11th to 20th	Day	17% 8% 4 5% 5% 3 4 5% 4 5% 43%	1710
	21st to end	Day	18% 6% 2 4 4 2 3 3 4 5% 49%	1872
February	1st to 10th	Day	21% 7% 3 5% 4 3 3 4 3 6% 41%	1620
	11th to 20th	Day	18% 8% 3 6% 4 2 4 3 4 6% 41%	1706
	21st to end	Day	24% 7% 3 5% 6% 3 4 3 4 4 37%	1514
March	1st to 10th	Day	18% 7% 3 5% 4 3 3 3 5% 5% 44%	1980
	11th to 20th	Day	19% 6% 4 6% 5% 3 4 4 4 5% 41%	1980
	21st to end	Day	18% 7% 3 5% 5% 3 4 4 5% 7% 40%	2183
April	1st to 10th	Day	13% 6% 3 5% 4 3 4 4 5% 7% 46%	2160
	11th to 20th	Day	16% 6% 3 5% 4 3 4 3 4 6% 46%	2134
	21st to end	Day	15% 7% 3 5% 6% 2 4 5% 5% 7% 42%	2160
May	1st to 10th	Day	16% 6% 3 6% 5% 3 5% 5% 5% 7% 41%	2160
	11th to 20th	Day	11% 4 2 6% 6% 3 7% 5% 6% 8% 42%	2252
	21st to end	Day	9% 5% 3 6% 7% 4 6% 6% 8% 10% 37%	2531
June	1st to 10th	Day	8% 4 2 5% 6% 3 6% 6% 8% 9% 43%	2497
	11th to 20th	Day	4 3 2 5% 5% 4 6% 6% 6% 11% 49%	2520
	21st to end	Day	4 3 2 4 4 4 6% 6% 7% 11% 48%	2383
July	1st to 10th	Day	5% 4 3 6% 6% 5% 7% 8% 8% 13% 35%	2340
	11th to 20th	Day	5% 3 2 5% 6% 4 6% 7% 8% 9% 44%	2340
	21st to end	Day	6% 4 2 4 6% 4 7% 7% 8% 12% 41%	2546
August	1st to 10th	Day	5% 5% 3 5% 6% 4 6% 8% 9% 11% 39%	2328
	11th to 20th	Day	10% 5% 2 5% 5% 4 6% 5% 7% 9% 41%	2125
	21st to end	Day	8% 4 2 5% 6% 4 5% 6% 8% 9% 43%	2376
September	1st to 10th	Day	11% 5% 3 5% 5% 3 5% 5% 6% 8% 45%	2160
	11th to 20th	Day	13% 5% 2 4 4 3 5% 5% 6% 7% 47%	2160
	21st to end	Day	10% 4 2 5% 4 3 4 4 5% 6% 55%	1890
October	1st to 10th	Day	8% 4 2 4 4 3 4 4 6% 7% 57%	1800
	11th to 20th	Day	16% 4 2 3 3 2 3 3 4 6% 55%	1800
	21st to end	Day	18% 5% 2 3 3 2 3 3 3 5% 52%	1980
November	1st to 10th	Day	11% 6% 2 3 3 2 3 3 4 5% 58%	1858
	11th to 20th	Day	11% 5% 2 3 4 2 3 3 5% 7% 55%	1821
	21st to end	Day	19% 7% 2 5% 4 2 3 4 4 5% 45%	1688
December	1st to 10th	Day	19% 7% 3 4 3 3 3 2 5% 5% 45%	1520
	11th to 20th	Day	15% 8% 4 5% 5% 2 4 5% 4 4 44%	1918
	21st to end	Day	15% 6% 3 6% 5% 4 5% 5% 6% 6% 39%	3039
January	1st to 10th	Night	19% 6% 2 4 4 2 3 2 4 5% 50%	2458
	11th to 20th	Night	19% 7% 2 4 4 2 3 3 3 5% 48%	2470
	21st to end	Night	19% 5% 2 3 4 2 3 3 4 4 52%	2711
February	1st to 10th	Night	21% 8% 3 5% 4 2 3 3 3 5% 43%	2340
	11th to 20th	Night	18% 7% 3 5% 5% 2 3 3 3 5% 45%	2138
	21st to end	Night	22% 6% 2 4 3 3 3 3 4 5% 45%	1757
March	1st to 10th	Night	18% 5% 2 5% 4 2 3 4 5% 6% 46%	1980
	11th to 20th	Night	17% 8% 4 6% 4 2 4 4 4 5% 43%	1980
	21st to end	Night	15% 6% 3 6% 5% 3 4 3 4 6% 44%	2171
April	1st to 10th	Night	12% 5% 2 4 5% 2 4 4 5% 8% 51%	1800
	11th to 20th	Night	12% 4 2 4 4 3 3 4 5% 8% 51%	1775
	21st to end	Night	13% 4 3 5% 4 2 3 4 4 8% 49%	1800
May	1st to 10th	Night	13% 4 2 4 4 2 5% 4 5% 8% 49%	1800
	11th to 20th	Night	13% 6% 2 4 4 2 4 4 5% 8% 46%	1639
	21st to end	Night	9% 4 3 5% 5% 3 5% 5% 6% 9% 46%	1745
June	1st to 10th	Night	5% 3 1 5% 4 2 4 6% 7% 11% 53%	1454
	11th to 20th	Night	3 3 2 3 3 3 4 4 5% 8% 61%	1440
	21st to end	Night	3 3 2 3 4 3 4 5% 6% 8% 61%	1567
July	1st to 10th	Night	3 4 2 4 6% 4 5% 5% 7% 13% 47%	1620
	11th to 20th	Night	3 3 2 4 3 4 6% 5% 8% 13% 49%	1620
	21st to end	Night	3 2 2 3 4 3 4 7% 8% 12% 52%	1772
August	1st to 10th	Night	3 2 1 4 6% 3 5% 5% 8% 12% 52%	1611
	11th to 20th	Night	6% 3 2 4 5% 3 4 5% 6% 10% 51%	1776
	21st to end	Night	5% 4 2 5% 5% 3 5% 6% 6% 10% 49%	1980
September	1st to 10th	Night	6% 4 2 4 4 2 5% 5% 5% 8% 56%	1800
	11th to 20th	Night	10% 4 2 4 4 2 4 4 5% 8% 53%	1800
	21st to end	Night	8% 3 1 4 4 2 2 4 5% 6% 60%	2048
October	1st to 10th	Night	8% 4 2 4 3 3 3 3 3 7% 60%	2160
	11th to 20th	Night	10% 4 2 5% 3 2 3 3 4 5% 59%	2160
	21st to end	Night	16% 5% 2 4 3 3 3 3 2 3 55%	2376
November	1st to 10th	Night	12% 4 2 4 3 2 3 3 4 6% 58%	2220
	11th to 20th	Night	11% 4 2 4 3 3 3 4 4 6% 57%	2356
	21st to end	Night	14% 6% 2 4 5% 3 3 4 4 5% 50%	2489
December	1st to 10th	Night	18% 6% 3 5% 5% 2 3 4 4 5% 47%	2660
	11th to 20th	Night	16% 6% 2 5% 6% 2 3 3 4 4 49%	3279
	21st to end	Night	15% 7% 3 5% 6% 3 4 5% 4 5% 44%	4621

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	42% 3 7% 23% 19% 6%	1708
	11th to 20th	Day	44% 4 8% 22% 20% 2	1710
	21st to end	Day	39% 3 6% 24% 23% 5%	1872
February	1st to 10th	Day	45% 5% 10% 21% 16% 4	1620
	11th to 20th	Day	47% 4 7% 20% 18% 5%	1716
	21st to end	Day	51% 4 6% 15% 17% 8%	1514
March	1st to 10th	Day	43% 3 9% 16% 19% 10%	1980
	11th to 20th	Day	46% 4 8% 21% 18% 3	1980
	21st to end	Day	45% 5% 10% 23% 14% 2	2183
April	1st to 10th	Day	36% 6% 9% 24% 19% 4	2160
	11th to 20th	Day	40% 4 9% 22% 17% 7%	2134
	21st to end	Day	42% 6% 9% 21% 20% 2	2160
May	1st to 10th	Day	42% 7% 11% 18% 19% 3	2160
	11th to 20th	Day	39% 7% 14% 25% 14% 2	2256
	21st to end	Day	38% 10% 14% 25% 13% 1	2531
June	1st to 10th	Day	34% 8% 14% 25% 16% 2	2497
	11th to 20th	Day	28% 7% 14% 30% 18% 2	2520
	21st to end	Day	27% 8% 13% 27% 21% 4	2383
July	1st to 10th	Day	33% 12% 16% 24% 13% 1	2276
	11th to 20th	Day	31% 9% 15% 26% 16% 4	2271
	21st to end	Day	31% 10% 18% 28% 12% 1	2405
August	1st to 10th	Day	33% 9% 18% 28% 11% 1	2314
	11th to 20th	Day	37% 8% 13% 24% 16% 2	2125
	21st to end	Day	33% 9% 14% 25% 14% 4	2376
September	1st to 10th	Day	34% 8% 11% 22% 18% 7%	2160
	11th to 20th	Day	34% 7% 11% 18% 24% 6%	2160
	21st to end	Day	31% 5% 7% 22% 26% 9%	1890
October	1st to 10th	Day	27% 5% 10% 23% 27% 9%	1800
	11th to 20th	Day	32% 4 6% 19% 29% 10%	1800
	21st to end	Day	35% 4 5% 22% 23% 9%	1980
November	1st to 10th	Day	29% 4 8% 27% 24% 8%	1858
	11th to 20th	Day	29% 4 8% 21% 28% 9%	1821
	21st to end	Day	44% 3 6% 17% 24% 6%	1688
December	1st to 10th	Day	42% 3 8% 24% 17% 6%	1520
	11th to 20th	Day	43% 3 6% 20% 22% 5%	1915
	21st to end	Day	44% 5% 10% 19% 16% 5%	3039
January	1st to 10th	Night	39% 2 8% 20% 26% 5%	2458
	11th to 20th	Night	42% 3 8% 21% 21% 5%	2470
	21st to end	Night	37% 4 6% 23% 25% 5%	2711
February	1st to 10th	Night	45% 3 7% 20% 19% 6%	2340
	11th to 20th	Night	44% 3 6% 22% 19% 6%	2139
	21st to end	Night	43% 3 8% 16% 21% 9%	1757
March	1st to 10th	Night	38% 4 9% 15% 21% 12%	1980
	11th to 20th	Night	45% 5% 7% 21% 17% 6%	1980
	21st to end	Night	41% 5% 8% 23% 20% 3	2171
April	1st to 10th	Night	33% 5% 10% 24% 20% 8%	1800
	11th to 20th	Night	31% 5% 9% 24% 22% 9%	1775
	21st to end	Night	35% 5% 10% 24% 23% 3	1800
May	1st to 10th	Night	35% 5% 12% 22% 19% 6%	1800
	11th to 20th	Night	35% 7% 12% 26% 18% 2	1640
	21st to end	Night	33% 9% 15% 26% 16% 2	1746
June	1st to 10th	Night	23% 8% 14% 30% 21% 2	1454
	11th to 20th	Night	21% 6% 14% 30% 25% 4	1440
	21st to end	Night	20% 6% 13% 30% 24% 7%	1567
July	1st to 10th	Night	25% 9% 21% 27% 16% 2	1575
	11th to 20th	Night	23% 9% 18% 27% 17% 6%	1566
	21st to end	Night	22% 11% 14% 34% 19% 1	1673
August	1st to 10th	Night	22% 8% 21% 34% 13% 1	1601
	11th to 20th	Night	26% 8% 15% 28% 19% 3	1776
	21st to end	Night	28% 8% 15% 27% 19% 4	1980
September	1st to 10th	Night	26% 7% 11% 26% 22% 8%	1800
	11th to 20th	Night	29% 6% 10% 21% 26% 7%	1800
	21st to end	Night	25% 5% 9% 22% 29% 10%	2048
October	1st to 10th	Night	26% 4 11% 24% 24% 12%	2160
	11th to 20th	Night	28% 4 6% 18% 32% 12%	2160
	21st to end	Night	36% 3 5% 19% 27% 10%	2376
November	1st to 10th	Night	29% 3 7% 23% 27% 11%	2220
	11th to 20th	Night	29% 3 6% 24% 27% 11%	2356
	21st to end	Night	37% 3 6% 19% 28% 6%	2489
December	1st to 10th	Night	41% 3 8% 20% 21% 7%	2660
	11th to 20th	Night	40% 3 5% 20% 25% 6%	3281
	21st to end	Night	41% 5% 9% 21% 21% 3	4621

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	26% 15% 36% 16% 6% 1	270
	11th to 20th	Day	29% 19% 32% 18% 2	270
	21st to end	Day	21% 21% 39% 14% 5%	294
February	1st to 10th	Day	24% 17% 35% 17% 6% 1	240
	11th to 20th	Day	30% 24% 32% 11% 2 1	240
	21st to end	Day	37% 14% 32% 14% 4	198
March	1st to 10th	Day	27% 18% 35% 13% 6%	240
	11th to 20th	Day	27% 21% 35% 16% 1	240
	21st to end	Day	25% 22% 35% 14% 4	269
April	1st to 10th	Day	17% 16% 36% 23% 7% 1	420
	11th to 20th	Day	22% 12% 33% 24% 9% 1	412
	21st to end	Day	20% 13% 33% 21% 11% 2	420
May	1st to 10th	Day	17% 12% 32% 28% 11% 1	423
	11th to 20th	Day	14% 6% 26% 33% 18% 3	575
	21st to end	Day	9% 5% 21% 34% 23% 7%	679
June	1st to 10th	Day	10% 3 16% 32% 28% 9%	630
	11th to 20th	Day	4 3 16% 37% 30% 9%	630
	21st to end	Day	5% 3 18% 36% 27% 11%	630
July	1st to 10th	Day	5% 3 13% 30% 34% 15%	621
	11th to 20th	Day	5% 3 11% 30% 35% 16%	618
	21st to end	Day	7% 1 7% 32% 35% 18%	684
August	1st to 10th	Day	6% 3 10% 34% 36% 11%	626
	11th to 20th	Day	15% 1 6% 31% 34% 13%	439
	21st to end	Day	12% 1 5% 21% 44% 17%	495
September	1st to 10th	Day	9% 2 9% 26% 41% 13%	450
	11th to 20th	Day	10% 3 12% 25% 37% 13%	450
	21st to end	Day	9% 3 19% 35% 26% 8%	296
October	1st to 10th	Day	9% 4 27% 33% 22% 5%	270
	11th to 20th	Day	14% 12% 33% 26% 13% 1	270
	21st to end	Day	26% 12% 33% 18% 8% 3	297
November	1st to 10th	Day	16% 9% 31% 26% 15% 2	270
	11th to 20th	Day	13% 12% 40% 28% 6% 1	270
	21st to end	Day	27% 13% 26% 23% 8% 1	270
December	1st to 10th	Day	23% 19% 31% 18% 7% 1	270
	11th to 20th	Day	26% 14% 31% 19% 10%	270
	21st to end	Day	23% 19% 39% 14% 3 1	297
January	1st to 10th	Night	22% 8% 35% 28% 7%	950
	11th to 20th	Night	22% 12% 35% 26% 5% 1	950
	21st to end	Night	21% 10% 37% 29% 3	1043
February	1st to 10th	Night	24% 11% 33% 26% 5%	900
	11th to 20th	Night	23% 11% 40% 24% 2	743
	21st to end	Night	25% 14% 34% 24% 3	573
March	1st to 10th	Night	20% 9% 32% 35% 5%	540
	11th to 20th	Night	19% 12% 36% 26% 6%	540
	21st to end	Night	18% 12% 34% 28% 7%	594
April	1st to 10th	Night	15% 12% 37% 29% 7%	540
	11th to 20th	Night	14% 9% 39% 25% 14%	533
	21st to end	Night	14% 8% 37% 30% 10% 1	540
May	1st to 10th	Night	13% 5% 27% 42% 11%	540
	11th to 20th	Night	15% 5% 27% 34% 17% 2	531
	21st to end	Night	9% 4 20% 35% 28% 4	584
June	1st to 10th	Night	6% 2 13% 39% 37% 4	540
	11th to 20th	Night	3 2 11% 46% 34% 4	540
	21st to end	Night	4 1 11% 43% 35% 6%	540
July	1st to 10th	Night	2 2 10% 34% 46% 7%	525
	11th to 20th	Night	3 1 7% 33% 46% 9%	522
	21st to end	Night	4 1 7% 35% 44% 10%	591
August	1st to 10th	Night	4 1 4 38% 46% 7%	537
	11th to 20th	Night	6% 1 7% 36% 43% 7%	534
	21st to end	Night	6% 1 7% 32% 47% 6%	594
September	1st to 10th	Night	8% 2 7% 35% 42% 7%	540
	11th to 20th	Night	11% 1 10% 32% 42% 4	540
	21st to end	Night	8% 2 14% 37% 34% 4	638
October	1st to 10th	Night	10% 2 17% 35% 32% 3	720
	11th to 20th	Night	12% 5% 27% 37% 18% 1	720
	21st to end	Night	19% 6% 27% 31% 15% 1	792
November	1st to 10th	Night	14% 6% 23% 37% 19% 1	740
	11th to 20th	Night	13% 9% 29% 38% 12%	760
	21st to end	Night	17% 9% 29% 33% 12%	779
December	1st to 10th	Night	22% 7% 31% 33% 7%	950
	11th to 20th	Night	21% 9% 30% 32% 7%	950
	21st to end	Night	22% 12% 31% 29% 5%	1045

Page generated at 2024-01-28 04:26:35. Version ac07

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