Siloam Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Siloam Springs clear sky chart from 2005-11-06 to 2024-10-24.

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% 7% 2 6% 4 4 4 4 5% 7% 46%	100989
	Night	11% 7% 2 5% 3 3 3 3 5% 6% 51%	97807
Transparency	Day	38% 4 11% 26% 18% 4	100802
	Night	35% 3 11% 26% 20% 4	97665
Seeing	Day	15% 8% 25% 27% 19% 6%	15427
	Night	15% 8% 28% 33% 15% 1	25223

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% 12% 3 5% 4 3 3 2 4 5% 46%	2847
	11th to 20th	Day	9% 7% 3 9% 3 3 3 2 4 5% 52%	2850
	21st to end	Day	22% 10% 2 5% 3 2 2 2 4 4 43%	3135
February	1st to 10th	Day	16% 10% 3 7% 5% 3 4 3 4 4 40%	1710
	11th to 20th	Day	15% 10% 3 6% 4 2 3 2 5% 6% 43%	1694
	21st to end	Day	18% 9% 2 6% 4 4 3 4 4 5% 41%	1691
March	1st to 10th	Day	16% 7% 3 5% 3 3 4 3 3 5% 48%	3436
	11th to 20th	Day	13% 7% 2 5% 3 3 4 4 5% 5% 49%	3480
	21st to end	Day	17% 10% 4 7% 5% 4 4 4 4 5% 36%	3814
April	1st to 10th	Day	12% 7% 2 6% 4 5% 4 3 5% 7% 44%	2175
	11th to 20th	Day	16% 7% 2 6% 4 5% 4 4 4 5% 42%	2254
	21st to end	Day	18% 9% 3 7% 3 4 4 4 5% 5% 39%	2308
May	1st to 10th	Day	20% 7% 3 7% 5% 4 4 3 5% 5% 36%	4082
	11th to 20th	Day	13% 7% 3 8% 4 4 5% 4 6% 7% 41%	4082
	21st to end	Day	15% 6% 2 7% 6% 5% 5% 4 6% 8% 37%	4477
June	1st to 10th	Day	8% 5% 2 7% 4 5% 5% 4 8% 9% 45%	2470
	11th to 20th	Day	7% 5% 2 4 4 4 5% 4 7% 8% 49%	2470
	21st to end	Day	4 3 1 4 4 4 4 5% 6% 8% 56%	2470
July	1st to 10th	Day	9% 5% 2 5% 4 5% 5% 5% 8% 10% 43%	4120
	11th to 20th	Day	4 4 2 5% 4 4 5% 4 6% 10% 52%	4120
	21st to end	Day	7% 4 2 5% 4 5% 6% 5% 7% 11% 45%	4465
August	1st to 10th	Day	5% 3 2 4 3 3 4 3 6% 9% 58%	4104
	11th to 20th	Day	9% 5% 2 5% 4 5% 4 4 5% 8% 47%	4021
	21st to end	Day	4 4 2 5% 4 4 5% 4 5% 8% 56%	4180
September	1st to 10th	Day	12% 5% 2 4 3 3 3 3 5% 7% 53%	2277
	11th to 20th	Day	12% 5% 1 5% 3 5% 5% 4 6% 8% 46%	2090
	21st to end	Day	7% 4 2 5% 4 4 4 3 7% 7% 53%	2081
October	1st to 10th	Day	10% 4 2 5% 3 3 3 3 5% 6% 57%	1900
	11th to 20th	Day	13% 5% 1 4 2 2 2 2 3 6% 59%	1900
	21st to end	Day	18% 6% 2 6% 4 2 3 2 3 4 50%	2010
November	1st to 10th	Day	10% 5% 2 4 4 3 2 3 4 6% 58%	1858
	11th to 20th	Day	11% 7% 2 5% 3 3 4 3 4 4 52%	1826
	21st to end	Day	17% 7% 2 4 2 3 4 3 4 7% 47%	1710
December	1st to 10th	Day	13% 8% 3 7% 4 4 3 3 5% 5% 46%	1586
	11th to 20th	Day	13% 11% 2 7% 5% 4 4 3 4 5% 43%	2161
	21st to end	Day	16% 16% 7% 6% 4 3 4 3 5% 5% 31%	3135
January	1st to 10th	Night	12% 9% 5% 8% 4 4 3 3 4 5% 43%	4108
	11th to 20th	Night	11% 6% 2 6% 3 3 5% 3 4 5% 52%	4120
	21st to end	Night	21% 10% 4 6% 2 2 2 2 3 4 43%	4532
February	1st to 10th	Night	15% 10% 2 6% 3 4 3 3 5% 5% 43%	2470
	11th to 20th	Night	14% 9% 2 6% 3 3 3 2 4 6% 48%	2389
	21st to end	Night	15% 8% 2 5% 4 3 4 3 5% 5% 46%	1761
March	1st to 10th	Night	17% 8% 2 6% 3 3 3 3 4 5% 45%	3419
	11th to 20th	Night	13% 7% 2 5% 3 3 3 3 5% 6% 50%	3480
	21st to end	Night	13% 8% 3 7% 4 4 4 3 5% 6% 43%	3817
April	1st to 10th	Night	12% 6% 2 5% 3 4 3 4 4 6% 51%	2005
	11th to 20th	Night	13% 7% 2 5% 3 4 3 3 4 6% 49%	1875
	21st to end	Night	17% 7% 2 6% 3 4 4 3 5% 5% 46%	1867
May	1st to 10th	Night	13% 9% 2 6% 3 4 3 3 5% 7% 45%	2823
	11th to 20th	Night	13% 7% 2 6% 4 4 4 4 5% 7% 44%	2823
	21st to end	Night	14% 6% 2 5% 4 3 4 4 7% 9% 42%	3090
June	1st to 10th	Night	7% 4 1 5% 3 3 3 3 5% 9% 57%	1710
	11th to 20th	Night	4 3 1 3 4 3 3 4 7% 10% 57%	1710
	21st to end	Night	3 3 3 3 3 3 4 6% 8% 64%	1710
July	1st to 10th	Night	10% 4 2 4 4 3 4 4 5% 9% 52%	2850
	11th to 20th	Night	4 2 1 3 3 3 3 3 5% 8% 64%	2850
	21st to end	Night	5% 3 2 5% 4 3 4 4 7% 10% 53%	3098
August	1st to 10th	Night	3 2 1 3 3 3 4 3 6% 10% 61%	2836
	11th to 20th	Night	6% 4 2 5% 4 5% 4 4 5% 7% 54%	2815
	21st to end	Night	3 3 1 3 3 3 4 3 5% 8% 65%	3476
September	1st to 10th	Night	8% 4 1 4 3 4 3 3 5% 7% 58%	1900
	11th to 20th	Night	10% 4 2 6% 3 3 4 3 5% 6% 54%	2088
	21st to end	Night	8% 5% 1 4 3 3 3 2 5% 7% 58%	2090
October	1st to 10th	Night	7% 3 1 4 3 3 4 3 4 7% 62%	2270
	11th to 20th	Night	12% 4 1 3 3 3 3 2 4 5% 58%	2280
	21st to end	Night	18% 6% 2 4 3 3 3 2 3 5% 54%	2413
November	1st to 10th	Night	10% 6% 1 3 2 3 3 2 3 5% 61%	2220
	11th to 20th	Night	11% 7% 2 4 2 3 3 3 4 5% 57%	2351
	21st to end	Night	15% 8% 2 4 3 2 2 3 4 5% 52%	2470
December	1st to 10th	Night	13% 9% 3 5% 3 4 3 3 4 5% 48%	2523
	11th to 20th	Night	13% 9% 3 8% 4 3 3 3 4 5% 45%	3036
	21st to end	Night	16% 13% 7% 7% 3 3 3 2 4 4 36%	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	43% 2 5% 27% 21% 2	2848
	11th to 20th	Day	36% 2 14% 27% 17% 4	2850
	21st to end	Day	47% 1 7% 22% 18% 5%	3135
February	1st to 10th	Day	48% 3 8% 22% 14% 4	1710
	11th to 20th	Day	44% 2 8% 25% 17% 3	1703
	21st to end	Day	46% 2 6% 21% 16% 8%	1691
March	1st to 10th	Day	41% 2 6% 21% 20% 10%	3436
	11th to 20th	Day	38% 2 11% 25% 20% 4	3480
	21st to end	Day	51% 3 10% 25% 11% 1	3814
April	1st to 10th	Day	39% 4 11% 23% 18% 5%	2175
	11th to 20th	Day	44% 3 11% 21% 17% 3	2254
	21st to end	Day	48% 4 9% 23% 16% 1	2308
May	1st to 10th	Day	51% 3 8% 21% 15% 2	4120
	11th to 20th	Day	43% 3 13% 25% 16%	4086
	21st to end	Day	45% 4 14% 22% 14% 1	4489
June	1st to 10th	Day	34% 4 17% 28% 15% 2	2470
	11th to 20th	Day	31% 5% 15% 30% 17% 2	2470
	21st to end	Day	25% 5% 16% 31% 20% 4	2470
July	1st to 10th	Day	33% 6% 19% 27% 13% 2	4056
	11th to 20th	Day	26% 5% 12% 37% 18% 2	4051
	21st to end	Day	30% 7% 22% 30% 11%	4325
August	1st to 10th	Day	23% 4 16% 30% 22% 5%	4090
	11th to 20th	Day	34% 5% 16% 27% 16% 1	4060
	21st to end	Day	26% 5% 13% 40% 13% 3	4179
September	1st to 10th	Day	31% 4 10% 26% 20% 9%	2277
	11th to 20th	Day	34% 5% 10% 24% 23% 4	2090
	21st to end	Day	29% 4 10% 26% 27% 5%	2081
October	1st to 10th	Day	30% 3 10% 25% 25% 8%	1900
	11th to 20th	Day	29% 2 6% 24% 31% 9%	1900
	21st to end	Day	40% 2 7% 26% 18% 7%	2010
November	1st to 10th	Day	29% 2 9% 28% 23% 8%	1858
	11th to 20th	Day	36% 2 6% 25% 22% 10%	1826
	21st to end	Day	39% 3 8% 22% 25% 4	1710
December	1st to 10th	Day	42% 2 8% 27% 18% 3	1586
	11th to 20th	Day	46% 2 5% 21% 23% 3	2159
	21st to end	Day	56% 2 7% 19% 13% 2	3135
January	1st to 10th	Night	44% 2 8% 23% 20% 3	4108
	11th to 20th	Night	36% 2 15% 23% 22% 2	4120
	21st to end	Night	47% 2 9% 19% 19% 4	4532
February	1st to 10th	Night	43% 3 10% 23% 16% 5%	2470
	11th to 20th	Night	41% 2 7% 27% 19% 4	2390
	21st to end	Night	41% 2 7% 20% 22% 8%	1761
March	1st to 10th	Night	42% 2 8% 21% 17% 10%	3419
	11th to 20th	Night	36% 2 10% 28% 18% 5%	3480
	21st to end	Night	44% 2 11% 29% 13% 2	3817
April	1st to 10th	Night	36% 2 9% 25% 20% 7%	2005
	11th to 20th	Night	37% 3 9% 24% 21% 7%	1875
	21st to end	Night	41% 3 10% 24% 19% 2	1867
May	1st to 10th	Night	40% 3 12% 24% 16% 4	2850
	11th to 20th	Night	41% 3 13% 27% 15% 1	2824
	21st to end	Night	38% 5% 16% 26% 15% 1	3099
June	1st to 10th	Night	25% 4 17% 32% 19% 3	1710
	11th to 20th	Night	21% 5% 15% 34% 23% 3	1710
	21st to end	Night	18% 5% 17% 31% 23% 6%	1710
July	1st to 10th	Night	30% 5% 19% 25% 16% 5%	2805
	11th to 20th	Night	17% 5% 11% 41% 24% 2	2796
	21st to end	Night	24% 6% 20% 35% 14% 1	2999
August	1st to 10th	Night	18% 5% 15% 34% 26% 2	2826
	11th to 20th	Night	29% 6% 18% 27% 18% 2	2842
	21st to end	Night	19% 3 11% 41% 22% 3	3476
September	1st to 10th	Night	26% 4 9% 30% 22% 10%	1900
	11th to 20th	Night	31% 3 10% 25% 26% 5%	2088
	21st to end	Night	27% 2 8% 26% 31% 6%	2090
October	1st to 10th	Night	23% 3 12% 24% 29% 10%	2270
	11th to 20th	Night	29% 2 6% 22% 30% 11%	2280
	21st to end	Night	36% 2 7% 23% 24% 9%	2413
November	1st to 10th	Night	28% 2 8% 26% 27% 9%	2220
	11th to 20th	Night	31% 3 7% 25% 26% 8%	2351
	21st to end	Night	36% 2 8% 21% 26% 6%	2470
December	1st to 10th	Night	40% 2 10% 24% 21% 3	2523
	11th to 20th	Night	44% 2 6% 23% 21% 4	3037
	21st to end	Night	54% 2 8% 19% 14% 3	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	24% 13% 39% 18% 6%	270
	11th to 20th	Day	20% 22% 39% 17% 1 1	270
	21st to end	Day	19% 19% 40% 17% 5%	297
February	1st to 10th	Day	27% 15% 38% 17% 3	270
	11th to 20th	Day	25% 22% 35% 16% 3	270
	21st to end	Day	32% 22% 33% 12% 2	225
March	1st to 10th	Day	22% 17% 36% 21% 3	270
	11th to 20th	Day	26% 19% 34% 17% 4	270
	21st to end	Day	28% 16% 39% 11% 4 1	297
April	1st to 10th	Day	20% 20% 34% 19% 6% 2	355
	11th to 20th	Day	24% 15% 35% 19% 7% 1	452
	21st to end	Day	24% 14% 34% 18% 8% 1	488
May	1st to 10th	Day	19% 11% 36% 27% 7%	653
	11th to 20th	Day	16% 8% 30% 30% 13% 3	675
	21st to end	Day	12% 6% 32% 27% 16% 7%	734
June	1st to 10th	Day	10% 3 18% 34% 27% 8%	680
	11th to 20th	Day	8% 3 16% 39% 27% 7%	680
	21st to end	Day	4 2 21% 39% 28% 6%	680
July	1st to 10th	Day	9% 2 13% 30% 32% 13%	671
	11th to 20th	Day	6% 1 12% 35% 35% 10%	668
	21st to end	Day	8% 2 8% 31% 35% 16%	739
August	1st to 10th	Day	9% 1 10% 38% 33% 9%	676
	11th to 20th	Day	11% 2 10% 34% 35% 9%	658
	21st to end	Day	7% 2 7% 32% 41% 12%	539
September	1st to 10th	Day	11% 2 9% 33% 34% 11%	487
	11th to 20th	Day	7% 16% 43% 23% 11%	300
	21st to end	Day	9% 5% 22% 30% 23% 10%	300
October	1st to 10th	Day	10% 6% 29% 28% 21% 6%	300
	11th to 20th	Day	14% 11% 34% 29% 11% 1	300
	21st to end	Day	26% 14% 30% 22% 6% 2	306
November	1st to 10th	Day	13% 9% 43% 25% 8% 2	270
	11th to 20th	Day	17% 15% 37% 21% 9% 1	270
	21st to end	Day	24% 15% 33% 21% 7%	270
December	1st to 10th	Day	20% 11% 44% 16% 7% 2	270
	11th to 20th	Day	23% 12% 40% 17% 6% 1	270
	21st to end	Day	25% 17% 41% 14% 3	297
January	1st to 10th	Night	18% 15% 32% 30% 5%	950
	11th to 20th	Night	19% 15% 37% 23% 5%	950
	21st to end	Night	16% 12% 37% 30% 4	1045
February	1st to 10th	Night	20% 13% 38% 25% 4	950
	11th to 20th	Night	20% 15% 39% 23% 3	915
	21st to end	Night	22% 14% 37% 23% 3	505
March	1st to 10th	Night	19% 11% 37% 28% 5%	570
	11th to 20th	Night	21% 10% 33% 32% 5%	570
	21st to end	Night	19% 12% 39% 25% 6%	627
April	1st to 10th	Night	16% 11% 39% 28% 5%	570
	11th to 20th	Night	17% 10% 35% 29% 9%	563
	21st to end	Night	22% 6% 40% 23% 9% 1	570
May	1st to 10th	Night	16% 6% 29% 39% 10%	570
	11th to 20th	Night	16% 3 23% 39% 17% 1	561
	21st to end	Night	13% 4 27% 32% 21% 2	617
June	1st to 10th	Night	8% 4 12% 41% 33% 1	570
	11th to 20th	Night	5% 1 20% 47% 26% 1	570
	21st to end	Night	3 1 17% 46% 30% 3	570
July	1st to 10th	Night	7% 2 8% 39% 38% 5%	555
	11th to 20th	Night	4 9% 41% 40% 6%	552
	21st to end	Night	5% 2 7% 39% 43% 5%	624
August	1st to 10th	Night	4 1 8% 45% 38% 4	567
	11th to 20th	Night	9% 1 7% 47% 32% 4	564
	21st to end	Night	4 1 7% 39% 43% 5%	627
September	1st to 10th	Night	10% 1 10% 41% 35% 2	570
	11th to 20th	Night	12% 1 11% 43% 30% 4	570
	21st to end	Night	11% 2 19% 38% 27% 3	570
October	1st to 10th	Night	8% 2 23% 38% 25% 4	750
	11th to 20th	Night	14% 6% 30% 38% 12%	760
	21st to end	Night	22% 7% 27% 33% 10% 1	805
November	1st to 10th	Night	13% 7% 37% 30% 12%	740
	11th to 20th	Night	15% 10% 35% 31% 8%	831
	21st to end	Night	20% 10% 33% 29% 9%	950
December	1st to 10th	Night	19% 12% 33% 30% 6%	950
	11th to 20th	Night	22% 11% 34% 28% 5%	950
	21st to end	Night	21% 13% 35% 27% 4	1045

Page generated at 2024-10-21 01:20:06. Version ac07

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