Abilene State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Abilene State Park clear sky chart from 2005-11-06 to 2024-11-01.

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	7% 4 2 4 3 3 4 3 5% 7% 58%	100941
	Night	6% 4 1 4 3 3 3 3 5% 7% 61%	98131
Transparency	Day	26% 4 9% 22% 26% 12%	100752
	Night	24% 4 9% 22% 26% 15%	97991
Seeing	Day	8% 8% 26% 31% 21% 6%	15034
	Night	8% 8% 35% 36% 13% 1	24932

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	7% 5% 2 6% 4 3 3 2 4 5% 59%	2847
	11th to 20th	Day	6% 5% 1 4 2 2 2 2 4 5% 66%	2850
	21st to end	Day	10% 6% 3 5% 3 3 3 3 5% 6% 53%	3455
February	1st to 10th	Day	9% 6% 2 4 3 2 3 3 5% 6% 57%	1900
	11th to 20th	Day	8% 8% 3 6% 4 4 3 3 3 5% 55%	1849
	21st to end	Day	11% 8% 1 4 2 2 2 3 3 5% 59%	1570
March	1st to 10th	Day	9% 6% 2 5% 4 3 3 3 5% 7% 53%	3184
	11th to 20th	Day	15% 6% 2 4 4 4 3 3 5% 6% 48%	3480
	21st to end	Day	5% 7% 2 5% 4 4 5% 4 6% 7% 52%	3814
April	1st to 10th	Day	7% 4 1 4 4 3 4 4 5% 7% 57%	2156
	11th to 20th	Day	10% 5% 2 4 3 4 3 3 5% 5% 55%	2254
	21st to end	Day	7% 5% 1 5% 4 3 3 3 4 6% 59%	2346
May	1st to 10th	Day	9% 6% 2 5% 4 3 4 3 5% 7% 53%	4082
	11th to 20th	Day	11% 6% 2 5% 4 3 3 3 5% 6% 52%	4082
	21st to end	Day	8% 5% 2 6% 4 4 5% 4 5% 7% 52%	4477
June	1st to 10th	Day	4 3 1 4 3 3 3 3 5% 7% 61%	2470
	11th to 20th	Day	4 3 1 4 3 3 3 4 6% 8% 61%	2470
	21st to end	Day	6% 3 1 4 3 3 4 4 5% 8% 59%	2470
July	1st to 10th	Day	5% 4 1 4 4 4 5% 4 7% 8% 54%	4120
	11th to 20th	Day	2 2 1 3 3 3 4 3 5% 8% 65%	4120
	21st to end	Day	3 2 1 4 3 4 4 4 6% 9% 60%	4465
August	1st to 10th	Day	1 1 2 2 3 4 3 5% 8% 70%	3920
	11th to 20th	Day	4 2 1 3 2 2 3 3 4 9% 65%	3726
	21st to end	Day	3 3 1 4 4 4 5% 4 6% 9% 58%	4180
September	1st to 10th	Day	11% 4 1 4 4 4 5% 3 5% 7% 51%	2128
	11th to 20th	Day	9% 5% 2 6% 4 4 4 3 6% 6% 51%	2090
	21st to end	Day	9% 4 1 4 3 3 3 3 5% 5% 60%	2090
October	1st to 10th	Day	4 3 1 3 3 3 3 4 4 6% 66%	2090
	11th to 20th	Day	8% 4 2 4 2 3 3 2 3 4 67%	2048
	21st to end	Day	10% 4 1 3 2 2 2 3 3 3 66%	2090
November	1st to 10th	Day	7% 4 1 3 2 3 3 3 5% 7% 62%	1692
	11th to 20th	Day	3 4 1 3 2 3 3 4 4 7% 65%	1710
	21st to end	Day	10% 5% 2 4 4 3 4 2 4 5% 58%	1710
December	1st to 10th	Day	10% 6% 1 5% 2 3 3 3 5% 7% 56%	1710
	11th to 20th	Day	6% 5% 1 5% 3 4 5% 4 6% 6% 55%	2161
	21st to end	Day	8% 6% 2 4 3 3 3 2 3 4 62%	3135
January	1st to 10th	Night	7% 5% 2 5% 3 3 2 2 4 5% 62%	4108
	11th to 20th	Night	7% 5% 1 3 2 2 2 3 3 5% 67%	4120
	21st to end	Night	8% 7% 3 5% 3 3 3 3 4 5% 55%	4240
February	1st to 10th	Night	9% 5% 2 4 4 3 3 2 4 5% 57%	2280
	11th to 20th	Night	10% 6% 2 5% 4 3 3 3 5% 5% 54%	2218
	21st to end	Night	10% 5% 1 3 3 3 3 3 3 6% 60%	1884
March	1st to 10th	Night	6% 7% 2 6% 3 3 4 4 4 5% 57%	3675
	11th to 20th	Night	13% 6% 1 4 3 2 3 4 5% 7% 53%	3480
	21st to end	Night	5% 6% 2 5% 4 4 4 4 5% 7% 56%	3817
April	1st to 10th	Night	5% 4 1 4 4 3 3 3 5% 7% 60%	2019
	11th to 20th	Night	8% 4 2 4 4 4 3 3 6% 7% 55%	1877
	21st to end	Night	6% 4 1 3 3 3 3 4 4 6% 64%	1830
May	1st to 10th	Night	10% 7% 2 5% 4 3 3 3 5% 6% 53%	2823
	11th to 20th	Night	6% 5% 2 5% 4 3 4 3 4 8% 57%	2823
	21st to end	Night	6% 4 2 4 3 3 3 3 6% 9% 56%	3090
June	1st to 10th	Night	2 2 1 3 4 2 4 4 8% 10% 60%	1710
	11th to 20th	Night	3 2 1 3 3 3 4 3 7% 9% 64%	1710
	21st to end	Night	3 3 1 4 2 3 3 2 5% 8% 65%	1710
July	1st to 10th	Night	4 3 1 4 3 3 3 3 6% 9% 61%	2850
	11th to 20th	Night	2 1 1 2 2 2 3 2 5% 10% 70%	2850
	21st to end	Night	2 2 1 3 2 3 3 3 5% 9% 65%	3098
August	1st to 10th	Night	1 1 3 2 2 2 2 4 8% 73%	3015
	11th to 20th	Night	2 2 1 2 2 2 3 3 5% 9% 68%	3113
	21st to end	Night	3 3 1 3 2 3 4 3 6% 9% 62%	3487
September	1st to 10th	Night	7% 4 1 4 3 3 4 3 5% 7% 58%	2049
	11th to 20th	Night	8% 4 1 5% 3 4 4 4 7% 7% 53%	2090
	21st to end	Night	8% 3 1 4 3 3 3 3 5% 7% 61%	2090
October	1st to 10th	Night	3 3 1 3 3 3 3 3 5% 7% 66%	2090
	11th to 20th	Night	7% 4 1 3 2 2 3 2 3 5% 68%	2110
	21st to end	Night	8% 5% 2 3 2 3 3 2 4 4 66%	2508
November	1st to 10th	Night	7% 4 2 3 2 2 3 3 3 5% 65%	2389
	11th to 20th	Night	4 3 1 4 3 3 4 3 4 6% 65%	2470
	21st to end	Night	11% 4 2 5% 3 3 3 3 5% 6% 55%	2470
December	1st to 10th	Night	9% 4 1 4 3 2 3 3 4 7% 60%	2470
	11th to 20th	Night	7% 4 2 6% 3 3 4 4 6% 7% 55%	3036
	21st to end	Night	8% 5% 2 5% 3 3 3 3 4 5% 59%	4532

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	28% 3 4 16% 31% 17%	2848
	11th to 20th	Day	22% 3 6% 18% 35% 15%	2850
	21st to end	Day	31% 3 6% 18% 30% 11%	3455
February	1st to 10th	Day	28% 3 7% 17% 26% 19%	1900
	11th to 20th	Day	34% 3 4 20% 24% 15%	1859
	21st to end	Day	31% 2 5% 11% 29% 22%	1570
March	1st to 10th	Day	31% 3 5% 11% 25% 25%	3184
	11th to 20th	Day	38% 4 11% 12% 24% 11%	3480
	21st to end	Day	30% 5% 9% 16% 25% 16%	3814
April	1st to 10th	Day	27% 5% 9% 18% 22% 19%	2156
	11th to 20th	Day	31% 5% 7% 15% 25% 18%	2254
	21st to end	Day	27% 4 8% 18% 28% 14%	2346
May	1st to 10th	Day	32% 5% 8% 16% 18% 20%	4120
	11th to 20th	Day	34% 5% 8% 18% 25% 10%	4086
	21st to end	Day	32% 6% 10% 22% 15% 15%	4489
June	1st to 10th	Day	22% 5% 15% 29% 22% 6%	2470
	11th to 20th	Day	21% 6% 11% 29% 25% 8%	2470
	21st to end	Day	23% 6% 11% 26% 24% 9%	2470
July	1st to 10th	Day	25% 6% 14% 34% 17% 4	4056
	11th to 20th	Day	18% 3 14% 35% 26% 4	4051
	21st to end	Day	19% 5% 11% 33% 28% 4	4325
August	1st to 10th	Day	14% 4 11% 29% 37% 6%	3906
	11th to 20th	Day	18% 5% 13% 35% 26% 4	3762
	21st to end	Day	22% 6% 17% 26% 23% 5%	4179
September	1st to 10th	Day	33% 6% 9% 20% 23% 11%	2128
	11th to 20th	Day	33% 6% 10% 21% 24% 7%	2090
	21st to end	Day	26% 5% 8% 20% 27% 14%	2090
October	1st to 10th	Day	20% 5% 11% 23% 26% 15%	2090
	11th to 20th	Day	24% 3 6% 17% 28% 22%	2048
	21st to end	Day	24% 3 4 21% 29% 19%	2090
November	1st to 10th	Day	24% 4 7% 23% 26% 15%	1692
	11th to 20th	Day	20% 4 9% 22% 29% 17%	1710
	21st to end	Day	30% 3 5% 19% 27% 16%	1710
December	1st to 10th	Day	30% 3 7% 19% 30% 12%	1710
	11th to 20th	Day	30% 5% 8% 15% 25% 17%	2159
	21st to end	Day	28% 2 3 20% 29% 18%	3135
January	1st to 10th	Night	26% 3 3 17% 35% 16%	4108
	11th to 20th	Night	22% 3 5% 21% 28% 21%	4120
	21st to end	Night	31% 4 6% 17% 28% 15%	4240
February	1st to 10th	Night	30% 3 6% 15% 26% 20%	2280
	11th to 20th	Night	32% 3 7% 16% 23% 19%	2218
	21st to end	Night	27% 4 4 14% 26% 25%	1884
March	1st to 10th	Night	29% 4 4 13% 28% 23%	3675
	11th to 20th	Night	32% 4 12% 20% 19% 13%	3480
	21st to end	Night	26% 5% 8% 20% 28% 12%	3817
April	1st to 10th	Night	24% 5% 10% 21% 18% 23%	2019
	11th to 20th	Night	28% 5% 9% 17% 21% 19%	1877
	21st to end	Night	23% 4 10% 24% 28% 12%	1830
May	1st to 10th	Night	34% 5% 8% 16% 19% 18%	2850
	11th to 20th	Night	27% 6% 11% 21% 23% 12%	2824
	21st to end	Night	25% 6% 12% 22% 20% 14%	3099
June	1st to 10th	Night	17% 8% 16% 32% 22% 5%	1710
	11th to 20th	Night	16% 5% 12% 32% 26% 9%	1710
	21st to end	Night	19% 5% 11% 29% 25% 11%	1710
July	1st to 10th	Night	20% 5% 13% 39% 19% 4	2805
	11th to 20th	Night	11% 3 10% 40% 30% 6%	2796
	21st to end	Night	16% 4 12% 34% 31% 3	2999
August	1st to 10th	Night	12% 2 9% 28% 42% 7%	3005
	11th to 20th	Night	14% 4 15% 37% 24% 6%	3143
	21st to end	Night	19% 6% 21% 26% 24% 4	3487
September	1st to 10th	Night	26% 5% 10% 24% 22% 13%	2049
	11th to 20th	Night	29% 6% 13% 22% 23% 8%	2090
	21st to end	Night	23% 4 8% 24% 24% 17%	2090
October	1st to 10th	Night	17% 5% 11% 23% 25% 18%	2090
	11th to 20th	Night	22% 3 6% 18% 27% 25%	2110
	21st to end	Night	23% 3 5% 20% 29% 20%	2508
November	1st to 10th	Night	24% 3 7% 21% 26% 19%	2389
	11th to 20th	Night	20% 5% 7% 21% 28% 19%	2470
	21st to end	Night	31% 3 6% 15% 29% 16%	2470
December	1st to 10th	Night	26% 3 7% 20% 26% 17%	2470
	11th to 20th	Night	30% 3 5% 18% 25% 18%	3037
	21st to end	Night	29% 3 4 17% 27% 20%	4532

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	8% 16% 43% 29% 4 1	270
	11th to 20th	Day	13% 16% 34% 26% 8% 2	270
	21st to end	Day	11% 14% 40% 26% 8%	297
February	1st to 10th	Day	15% 14% 41% 24% 6%	270
	11th to 20th	Day	16% 16% 43% 20% 4	270
	21st to end	Day	19% 17% 48% 14% 2	225
March	1st to 10th	Day	12% 17% 41% 26% 4	270
	11th to 20th	Day	16% 15% 37% 25% 6% 1	270
	21st to end	Day	12% 18% 46% 20% 4	297
April	1st to 10th	Day	11% 16% 47% 19% 7%	336
	11th to 20th	Day	12% 20% 46% 17% 4 1	452
	21st to end	Day	9% 17% 43% 23% 7%	526
May	1st to 10th	Day	9% 13% 41% 31% 6% 1	653
	11th to 20th	Day	11% 9% 33% 31% 12% 4	675
	21st to end	Day	8% 7% 36% 34% 13% 1	734
June	1st to 10th	Day	5% 4 22% 45% 22% 3	680
	11th to 20th	Day	4 1 26% 48% 18% 4	680
	21st to end	Day	4 2 13% 39% 35% 7%	680
July	1st to 10th	Day	6% 1 7% 37% 38% 11%	671
	11th to 20th	Day	3 6% 37% 43% 11%	668
	21st to end	Day	1 1 5% 33% 44% 16%	739
August	1st to 10th	Day	3 1 4 32% 45% 16%	570
	11th to 20th	Day	6% 2 6% 33% 40% 13%	477
	21st to end	Day	4 2 6% 35% 40% 14%	539
September	1st to 10th	Day	12% 1 7% 26% 36% 18%	338
	11th to 20th	Day	5% 1 8% 32% 36% 19%	300
	21st to end	Day	14% 3 8% 27% 36% 12%	300
October	1st to 10th	Day	3 2 16% 38% 30% 10%	300
	11th to 20th	Day	9% 5% 35% 35% 13% 3	300
	21st to end	Day	16% 9% 26% 31% 16% 2	330
November	1st to 10th	Day	12% 7% 31% 33% 15% 2	270
	11th to 20th	Day	10% 13% 30% 31% 14% 3	270
	21st to end	Day	14% 18% 36% 20% 9% 3	270
December	1st to 10th	Day	16% 10% 37% 26% 9% 2	270
	11th to 20th	Day	6% 15% 46% 26% 7%	270
	21st to end	Day	16% 14% 38% 28% 4	297
January	1st to 10th	Night	10% 10% 41% 32% 7%	950
	11th to 20th	Night	11% 12% 37% 32% 8%	950
	21st to end	Night	9% 13% 41% 31% 6%	870
February	1st to 10th	Night	12% 10% 48% 25% 5%	760
	11th to 20th	Night	12% 15% 44% 26% 4	744
	21st to end	Night	12% 15% 51% 18% 3	628
March	1st to 10th	Night	11% 13% 46% 25% 4	727
	11th to 20th	Night	13% 14% 40% 28% 5%	570
	21st to end	Night	5% 16% 51% 25% 2	627
April	1st to 10th	Night	5% 15% 54% 22% 4	570
	11th to 20th	Night	8% 15% 52% 22% 2	563
	21st to end	Night	8% 11% 53% 23% 5%	570
May	1st to 10th	Night	5% 10% 53% 27% 4	570
	11th to 20th	Night	8% 7% 44% 31% 10% 1	561
	21st to end	Night	5% 6% 47% 34% 8%	617
June	1st to 10th	Night	2 4 34% 46% 13%	570
	11th to 20th	Night	3 2 41% 49% 5%	570
	21st to end	Night	4 2 24% 50% 19% 1	570
July	1st to 10th	Night	4 1 13% 54% 26% 2	555
	11th to 20th	Night	3 1 11% 54% 30% 1	552
	21st to end	Night	1 6% 60% 32% 1	624
August	1st to 10th	Night	1 1 7% 57% 32% 1	567
	11th to 20th	Night	5% 10% 47% 36% 2	564
	21st to end	Night	2 1 9% 46% 38% 3	627
September	1st to 10th	Night	8% 1 11% 46% 31% 3	570
	11th to 20th	Night	9% 1 14% 47% 29% 1	570
	21st to end	Night	9% 1 19% 43% 27% 1	570
October	1st to 10th	Night	4 3 27% 45% 19% 2	570
	11th to 20th	Night	8% 4 34% 40% 13% 1	590
	21st to end	Night	10% 9% 32% 35% 13% 2	836
November	1st to 10th	Night	9% 6% 34% 36% 15% 1	905
	11th to 20th	Night	5% 10% 37% 37% 10% 1	950
	21st to end	Night	12% 11% 36% 30% 10%	950
December	1st to 10th	Night	11% 9% 35% 37% 7% 1	950
	11th to 20th	Night	11% 11% 41% 32% 5%	950
	21st to end	Night	10% 10% 41% 31% 8%	1045

Page generated at 2024-10-29 10:20:51. Version ac07

Copyright © 2024 Attilla Danko.