TAS-D Atoka
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the TAS-D Atoka clear sky chart from 2005-11-06 to 2025-11-03.

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	12% 6% 2 5% 4 3 4 3 5% 7% 50%	126866
	Night	12% 5% 2 4 3 3 3 3 4 6% 55%	123452
Transparency	Day	33% 5% 10% 24% 21% 6%	130531
	Night	30% 4 9% 23% 24% 9%	127850
Seeing	Day	13% 9% 24% 28% 20% 6%	16635
	Night	13% 9% 28% 33% 15% 1	26429

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	15% 8% 3 5% 3 3 3 2 4 5% 49%	4077
	11th to 20th	Day	7% 6% 2 4 2 2 3 2 3 5% 65%	4080
	21st to end	Day	20% 8% 2 4 2 2 2 2 4 5% 48%	4488
February	1st to 10th	Day	19% 7% 3 6% 4 3 4 3 4 4 44%	1819
	11th to 20th	Day	16% 8% 3 5% 4 4 3 2 4 6% 45%	1949
	21st to end	Day	20% 7% 3 5% 3 2 2 3 4 4 46%	1705
March	1st to 10th	Day	17% 6% 2 5% 3 3 3 3 4 5% 50%	4936
	11th to 20th	Day	11% 6% 2 5% 4 4 3 3 4 5% 53%	4980
	21st to end	Day	16% 8% 2 6% 4 4 4 3 5% 6% 42%	5462
April	1st to 10th	Day	14% 7% 3 6% 4 3 3 4 4 5% 48%	2200
	11th to 20th	Day	15% 5% 2 6% 5% 3 4 3 5% 6% 46%	2344
	21st to end	Day	15% 7% 2 7% 4 4 5% 3 5% 6% 41%	2515
May	1st to 10th	Day	17% 7% 3 7% 4 4 4 3 5% 6% 40%	5862
	11th to 20th	Day	13% 6% 2 6% 4 4 4 3 5% 6% 45%	5862
	21st to end	Day	15% 8% 3 7% 4 5% 5% 3 5% 7% 39%	6434
June	1st to 10th	Day	7% 6% 2 6% 5% 4 5% 4 6% 9% 46%	2600
	11th to 20th	Day	8% 4 2 5% 4 5% 5% 4 6% 9% 47%	2600
	21st to end	Day	4 3 1 4 4 4 4 5% 7% 9% 55%	2600
July	1st to 10th	Day	7% 5% 3 7% 5% 5% 5% 5% 7% 9% 41%	5900
	11th to 20th	Day	4 3 2 4 4 3 5% 4 6% 8% 59%	5900
	21st to end	Day	4 3 2 5% 4 4 5% 4 7% 10% 53%	6422
August	1st to 10th	Day	3 3 1 3 3 4 4 4 5% 8% 64%	4234
	11th to 20th	Day	6% 3 1 3 3 3 5% 4 6% 10% 55%	4171
	21st to end	Day	3 2 1 4 4 5% 5% 5% 7% 10% 54%	4361
September	1st to 10th	Day	10% 5% 2 4 4 4 4 3 6% 6% 53%	2200
	11th to 20th	Day	9% 4 3 5% 4 5% 5% 4 5% 7% 50%	2200
	21st to end	Day	7% 3 1 4 3 3 5% 3 4 7% 59%	2200
October	1st to 10th	Day	7% 4 1 4 4 3 4 3 4 5% 60%	2093
	11th to 20th	Day	11% 4 2 3 3 2 2 2 3 5% 63%	2000
	21st to end	Day	18% 5% 1 4 3 2 2 2 3 4 55%	2200
November	1st to 10th	Day	13% 5% 2 6% 2 3 3 3 5% 6% 53%	1978
	11th to 20th	Day	10% 4 2 4 2 2 3 3 4 5% 61%	1875
	21st to end	Day	17% 5% 2 3 3 2 4 2 3 5% 54%	1800
December	1st to 10th	Day	16% 7% 2 4 2 2 2 2 4 5% 53%	2940
	11th to 20th	Day	20% 7% 2 4 3 3 3 3 3 4 47%	3391
	21st to end	Day	24% 8% 2 4 2 2 2 2 3 5% 45%	4488
January	1st to 10th	Night	15% 6% 2 7% 3 3 3 3 4 5% 51%	5888
	11th to 20th	Night	6% 4 2 3 3 2 2 2 3 5% 67%	5900
	21st to end	Night	22% 8% 2 4 3 2 3 2 3 4 47%	6490
February	1st to 10th	Night	16% 7% 2 6% 3 3 3 3 5% 4 49%	2598
	11th to 20th	Night	16% 8% 2 5% 3 3 3 2 5% 5% 47%	2338
	21st to end	Night	16% 7% 2 5% 3 3 3 2 4 4 52%	1924
March	1st to 10th	Night	18% 7% 2 6% 3 3 3 3 4 5% 47%	4919
	11th to 20th	Night	9% 5% 2 5% 3 3 3 3 4 6% 59%	4980
	21st to end	Night	15% 6% 2 5% 3 3 4 4 5% 6% 47%	5467
April	1st to 10th	Night	12% 5% 2 6% 4 4 3 2 4 6% 52%	2200
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 5% 7% 52%	2004
	21st to end	Night	15% 5% 1 4 4 3 3 3 6% 7% 49%	1880
May	1st to 10th	Night	19% 6% 2 6% 4 3 4 4 5% 6% 41%	4053
	11th to 20th	Night	11% 4 2 4 3 3 4 3 6% 8% 50%	4053
	21st to end	Night	12% 6% 2 6% 4 4 4 4 6% 8% 46%	4443
June	1st to 10th	Night	5% 4 1 4 3 3 4 4 5% 9% 58%	1800
	11th to 20th	Night	4 4 1 4 2 3 3 3 6% 9% 60%	1800
	21st to end	Night	2 3 1 3 2 3 3 3 5% 8% 65%	1800
July	1st to 10th	Night	6% 4 2 6% 5% 5% 5% 5% 7% 10% 45%	4078
	11th to 20th	Night	4 2 1 3 2 3 3 3 5% 9% 66%	4077
	21st to end	Night	3 2 1 3 3 3 3 4 6% 8% 64%	4449
August	1st to 10th	Night	2 2 1 2 2 2 3 4 5% 7% 70%	2926
	11th to 20th	Night	3 2 1 3 2 3 3 3 5% 10% 65%	2888
	21st to end	Night	3 2 1 3 3 3 4 3 5% 8% 63%	3531
September	1st to 10th	Night	8% 4 1 4 3 3 4 3 5% 6% 59%	2200
	11th to 20th	Night	8% 4 2 5% 3 4 4 3 6% 6% 54%	2200
	21st to end	Night	7% 3 2 4 2 3 3 2 5% 7% 62%	2200
October	1st to 10th	Night	7% 3 1 4 3 3 3 3 4 5% 64%	2285
	11th to 20th	Night	11% 4 1 3 2 2 2 2 4 5% 63%	2400
	21st to end	Night	17% 4 2 4 3 2 2 2 3 4 58%	2640
November	1st to 10th	Night	12% 4 1 4 3 3 3 2 4 5% 58%	2365
	11th to 20th	Night	9% 5% 2 4 3 3 3 3 4 6% 60%	2520
	21st to end	Night	16% 6% 2 3 3 2 3 3 4 6% 54%	2600
December	1st to 10th	Night	12% 7% 2 5% 3 3 2 2 4 5% 55%	4250
	11th to 20th	Night	18% 6% 2 5% 4 3 3 2 3 4 51%	4816
	21st to end	Night	20% 9% 2 5% 2 2 2 2 3 4 49%	6490

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	38% 3 9% 26% 21% 3	4078
	11th to 20th	Day	25% 2 9% 22% 37% 5%	4080
	21st to end	Day	41% 2 4 19% 25% 10%	4488
February	1st to 10th	Day	44% 4 8% 17% 22% 5%	1819
	11th to 20th	Day	42% 4 8% 22% 19% 6%	1959
	21st to end	Day	43% 3 5% 14% 26% 10%	1705
March	1st to 10th	Day	38% 3 6% 15% 20% 18%	4936
	11th to 20th	Day	33% 4 7% 18% 19% 19%	4980
	21st to end	Day	42% 5% 9% 24% 17% 2	5464
April	1st to 10th	Day	40% 4 10% 20% 18% 8%	2200
	11th to 20th	Day	38% 6% 10% 21% 20% 6%	2344
	21st to end	Day	43% 5% 9% 20% 19% 3	2515
May	1st to 10th	Day	44% 6% 10% 24% 14% 3	5900
	11th to 20th	Day	39% 6% 12% 21% 20% 3	5866
	21st to end	Day	45% 7% 11% 19% 14% 5%	6447
June	1st to 10th	Day	34% 8% 15% 26% 15% 2	2600
	11th to 20th	Day	33% 8% 13% 26% 19% 2	2600
	21st to end	Day	25% 8% 14% 27% 23% 2	2600
July	1st to 10th	Day	37% 9% 15% 28% 11% 1	5836
	11th to 20th	Day	22% 5% 14% 36% 21% 2	5831
	21st to end	Day	25% 7% 14% 34% 20% 1	6240
August	1st to 10th	Day	18% 6% 12% 27% 29% 8%	4220
	11th to 20th	Day	23% 6% 17% 37% 15% 2	4210
	21st to end	Day	23% 8% 19% 34% 14% 3	4360
September	1st to 10th	Day	30% 5% 11% 24% 20% 10%	2200
	11th to 20th	Day	32% 8% 11% 23% 20% 7%	2200
	21st to end	Day	26% 5% 9% 22% 29% 10%	2200
October	1st to 10th	Day	17% 3 7% 12% 38% 23%	3405
	11th to 20th	Day	19% 3 4 17% 37% 20%	3240
	21st to end	Day	28% 3 6% 29% 27% 7%	3538
November	1st to 10th	Day	33% 3 9% 22% 25% 8%	1978
	11th to 20th	Day	27% 3 8% 23% 28% 11%	1875
	21st to end	Day	34% 3 7% 20% 28% 8%	1800
December	1st to 10th	Day	36% 3 7% 34% 18% 3	2940
	11th to 20th	Day	42% 3 4 18% 26% 7%	3389
	21st to end	Day	44% 3 5% 23% 20% 5%	4488
January	1st to 10th	Night	37% 3 7% 27% 23% 4	5888
	11th to 20th	Night	21% 3 9% 23% 32% 12%	5900
	21st to end	Night	43% 3 5% 14% 25% 10%	6490
February	1st to 10th	Night	39% 3 9% 19% 22% 7%	2598
	11th to 20th	Night	40% 4 7% 20% 22% 7%	2338
	21st to end	Night	37% 4 6% 17% 22% 14%	1924
March	1st to 10th	Night	41% 3 5% 14% 20% 17%	4919
	11th to 20th	Night	29% 3 6% 22% 16% 24%	4980
	21st to end	Night	38% 4 10% 18% 25% 4	5467
April	1st to 10th	Night	34% 4 10% 19% 20% 12%	2200
	11th to 20th	Night	34% 5% 9% 21% 20% 12%	2004
	21st to end	Night	34% 5% 11% 24% 22% 4	1880
May	1st to 10th	Night	44% 5% 11% 22% 13% 5%	4080
	11th to 20th	Night	31% 5% 13% 24% 21% 6%	4054
	21st to end	Night	35% 7% 16% 20% 14% 8%	4452
June	1st to 10th	Night	23% 7% 15% 31% 20% 3	1800
	11th to 20th	Night	21% 6% 13% 32% 24% 4	1800
	21st to end	Night	17% 6% 13% 30% 29% 5%	1800
July	1st to 10th	Night	32% 8% 17% 28% 13% 3	4035
	11th to 20th	Night	16% 5% 14% 35% 27% 3	4026
	21st to end	Night	18% 6% 15% 35% 25% 2	4320
August	1st to 10th	Night	13% 4 10% 31% 35% 8%	2916
	11th to 20th	Night	17% 4 15% 39% 20% 6%	2915
	21st to end	Night	19% 6% 17% 37% 19% 3	3531
September	1st to 10th	Night	24% 6% 11% 22% 27% 10%	2200
	11th to 20th	Night	30% 6% 10% 23% 21% 10%	2200
	21st to end	Night	23% 4 8% 24% 28% 13%	2200
October	1st to 10th	Night	14% 3 6% 13% 36% 29%	3740
	11th to 20th	Night	17% 2 5% 14% 39% 22%	3899
	21st to end	Night	28% 3 5% 28% 25% 12%	4252
November	1st to 10th	Night	30% 3 7% 22% 25% 12%	2365
	11th to 20th	Night	26% 4 7% 22% 27% 13%	2520
	21st to end	Night	33% 3 7% 19% 29% 8%	2600
December	1st to 10th	Night	32% 4 7% 28% 24% 5%	4250
	11th to 20th	Night	40% 3 5% 15% 26% 11%	4817
	21st to end	Night	41% 3 7% 21% 22% 6%	6490

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	23% 16% 34% 22% 5%	300
	11th to 20th	Day	20% 20% 36% 19% 4 1	300
	21st to end	Day	20% 20% 33% 19% 8% 1	330
February	1st to 10th	Day	26% 17% 35% 18% 4	300
	11th to 20th	Day	25% 23% 34% 15% 2	300
	21st to end	Day	27% 18% 39% 11% 5%	249
March	1st to 10th	Day	24% 18% 34% 18% 6%	300
	11th to 20th	Day	25% 24% 32% 13% 4 2	300
	21st to end	Day	22% 17% 41% 16% 4	330
April	1st to 10th	Day	22% 20% 33% 19% 5%	300
	11th to 20th	Day	22% 18% 33% 22% 4	462
	21st to end	Day	18% 17% 35% 22% 6% 2	615
May	1st to 10th	Day	16% 10% 39% 28% 7%	703
	11th to 20th	Day	16% 10% 31% 27% 13% 2	725
	21st to end	Day	12% 10% 32% 29% 14% 4	789
June	1st to 10th	Day	8% 5% 21% 35% 24% 8%	730
	11th to 20th	Day	8% 3 21% 38% 24% 5%	730
	21st to end	Day	4 2 16% 38% 30% 10%	730
July	1st to 10th	Day	6% 2 12% 36% 32% 13%	721
	11th to 20th	Day	3 1 9% 35% 40% 11%	718
	21st to end	Day	3 1 8% 35% 38% 15%	794
August	1st to 10th	Day	5% 1 10% 34% 41% 9%	726
	11th to 20th	Day	7% 2 9% 39% 36% 8%	715
	21st to end	Day	6% 1 6% 32% 40% 16%	619
September	1st to 10th	Day	7% 1 12% 31% 32% 18%	330
	11th to 20th	Day	5% 3 10% 35% 34% 15%	330
	21st to end	Day	11% 5% 15% 35% 23% 11%	330
October	1st to 10th	Day	3 4 25% 34% 27% 7%	330
	11th to 20th	Day	14% 9% 27% 32% 18% 1	330
	21st to end	Day	26% 10% 27% 21% 15% 1	363
November	1st to 10th	Day	18% 10% 36% 24% 11% 2	306
	11th to 20th	Day	14% 14% 34% 25% 11% 2	300
	21st to end	Day	22% 14% 32% 21% 9% 1	300
December	1st to 10th	Day	17% 15% 34% 25% 9%	300
	11th to 20th	Day	26% 11% 37% 20% 6%	300
	21st to end	Day	22% 19% 33% 21% 4	330
January	1st to 10th	Night	15% 15% 33% 29% 7%	1000
	11th to 20th	Night	17% 17% 33% 27% 5%	1000
	21st to end	Night	16% 12% 36% 30% 6%	1100
February	1st to 10th	Night	19% 18% 34% 26% 4	998
	11th to 20th	Night	22% 14% 36% 25% 3	784
	21st to end	Night	21% 16% 39% 21% 3	604
March	1st to 10th	Night	20% 13% 35% 28% 5%	600
	11th to 20th	Night	18% 13% 37% 26% 5%	600
	21st to end	Night	18% 12% 39% 25% 5% 1	660
April	1st to 10th	Night	14% 15% 39% 27% 4	600
	11th to 20th	Night	16% 15% 37% 25% 7%	593
	21st to end	Night	15% 11% 37% 28% 8% 1	600
May	1st to 10th	Night	13% 6% 37% 36% 8%	600
	11th to 20th	Night	13% 5% 33% 34% 14% 1	591
	21st to end	Night	9% 4 32% 36% 17% 2	650
June	1st to 10th	Night	6% 4 19% 41% 27% 3	600
	11th to 20th	Night	5% 2 20% 54% 18% 1	600
	21st to end	Night	2 1 15% 49% 29% 4	600
July	1st to 10th	Night	5% 1 9% 42% 39% 4	585
	11th to 20th	Night	3 1 10% 45% 38% 4	582
	21st to end	Night	2 1 8% 45% 39% 4	657
August	1st to 10th	Night	3 1 7% 49% 38% 3	597
	11th to 20th	Night	6% 1 9% 43% 37% 4	594
	21st to end	Night	4 1 7% 42% 41% 5%	660
September	1st to 10th	Night	8% 1 10% 39% 38% 4	600
	11th to 20th	Night	9% 2 14% 37% 35% 3	600
	21st to end	Night	7% 2 20% 38% 32% 2	600
October	1st to 10th	Night	9% 2 20% 43% 24% 2	685
	11th to 20th	Night	14% 6% 29% 35% 16% 1	800
	21st to end	Night	19% 9% 29% 30% 13% 1	880
November	1st to 10th	Night	14% 6% 32% 37% 11% 1	789
	11th to 20th	Night	12% 12% 31% 33% 11%	920
	21st to end	Night	18% 11% 33% 27% 10%	1000
December	1st to 10th	Night	17% 12% 34% 31% 7%	1000
	11th to 20th	Night	22% 10% 35% 28% 6%	1000
	21st to end	Night	20% 12% 35% 26% 6%	1100

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