Fort Smith
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Smith clear sky chart from 2005-11-06 to 2024-10-20.

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% 6% 2 6% 4 4 4 3 5% 7% 47%	101066
	Night	13% 5% 2 5% 3 3 3 3 5% 6% 50%	97717
Transparency	Day	36% 6% 11% 24% 19% 4	100879
	Night	34% 5% 11% 24% 21% 6%	97575
Seeing	Day	13% 7% 20% 27% 25% 8%	15351
	Night	14% 5% 22% 37% 20% 2	25136

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% 4 6% 4 4 3 3 3 4 46%	2847
	11th to 20th	Day	11% 7% 2 6% 4 3 3 2 4 5% 54%	2850
	21st to end	Day	24% 7% 2 5% 3 2 3 2 3 4 44%	3135
February	1st to 10th	Day	21% 9% 3 5% 4 3 3 2 3 4 43%	1710
	11th to 20th	Day	18% 7% 2 6% 4 3 4 3 4 6% 43%	1702
	21st to end	Day	20% 7% 3 6% 4 3 4 3 5% 5% 41%	1712
March	1st to 10th	Day	18% 7% 3 6% 3 3 3 2 4 5% 47%	3436
	11th to 20th	Day	14% 5% 2 6% 4 4 3 3 5% 6% 47%	3480
	21st to end	Day	18% 8% 3 7% 4 4 4 3 4 6% 40%	3814
April	1st to 10th	Day	14% 5% 3 5% 4 4 5% 3 4 6% 46%	2175
	11th to 20th	Day	17% 7% 3 6% 4 4 3 3 5% 5% 44%	2254
	21st to end	Day	19% 8% 3 6% 4 5% 4 3 4 5% 40%	2280
May	1st to 10th	Day	21% 8% 2 6% 4 4 4 4 5% 5% 37%	4068
	11th to 20th	Day	12% 6% 3 8% 4 4 4 4 6% 8% 42%	4082
	21st to end	Day	17% 6% 2 7% 5% 5% 5% 4 5% 7% 37%	4477
June	1st to 10th	Day	9% 5% 2 7% 5% 4 5% 4 7% 10% 43%	2470
	11th to 20th	Day	6% 4 2 6% 5% 5% 6% 4 7% 9% 47%	2470
	21st to end	Day	5% 3 2 3 4 4 6% 4 7% 9% 53%	2470
July	1st to 10th	Day	9% 4 2 6% 5% 4 5% 4 7% 10% 45%	4120
	11th to 20th	Day	4 3 2 5% 4 4 4 4 6% 9% 56%	4120
	21st to end	Day	7% 4 2 7% 5% 5% 6% 5% 8% 10% 40%	4465
August	1st to 10th	Day	3 3 1 5% 3 4 4 4 6% 8% 59%	4104
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 6% 9% 48%	3982
	21st to end	Day	4 3 1 5% 4 4 5% 4 6% 8% 56%	4180
September	1st to 10th	Day	11% 4 1 5% 3 4 4 3 5% 6% 54%	2280
	11th to 20th	Day	12% 4 1 5% 4 4 4 3 6% 8% 49%	2091
	21st to end	Day	7% 3 2 5% 3 4 5% 3 5% 7% 56%	2076
October	1st to 10th	Day	8% 4 2 5% 3 3 3 3 4 6% 58%	1900
	11th to 20th	Day	13% 3 1 4 3 3 2 2 4 5% 60%	1890
	21st to end	Day	19% 6% 2 5% 3 2 3 2 4 5% 50%	1980
November	1st to 10th	Day	11% 5% 2 4 3 2 3 3 5% 6% 56%	1858
	11th to 20th	Day	12% 4 2 4 4 2 3 2 4 5% 57%	1872
	21st to end	Day	18% 6% 3 4 3 3 3 2 4 6% 48%	1710
December	1st to 10th	Day	17% 6% 2 6% 3 2 3 3 5% 6% 47%	1710
	11th to 20th	Day	16% 7% 2 7% 4 4 3 2 5% 5% 43%	2161
	21st to end	Day	19% 12% 3 7% 4 3 4 3 5% 6% 34%	3135
January	1st to 10th	Night	14% 9% 3 7% 4 4 4 4 4 4 43%	4108
	11th to 20th	Night	12% 7% 2 4 3 2 3 2 4 6% 57%	4120
	21st to end	Night	24% 7% 2 4 3 2 2 3 3 4 45%	4532
February	1st to 10th	Night	18% 8% 2 6% 3 3 3 3 4 6% 43%	2470
	11th to 20th	Night	17% 7% 2 5% 2 3 3 3 5% 6% 48%	2380
	21st to end	Night	18% 6% 3 5% 3 3 3 3 4 5% 47%	1740
March	1st to 10th	Night	21% 6% 2 6% 3 3 3 3 4 5% 44%	3419
	11th to 20th	Night	17% 6% 2 4 3 3 3 3 4 6% 50%	3480
	21st to end	Night	17% 7% 2 5% 4 4 4 3 5% 5% 44%	3817
April	1st to 10th	Night	15% 5% 1 4 4 3 3 3 5% 7% 49%	2005
	11th to 20th	Night	15% 5% 2 4 4 3 3 3 5% 7% 49%	1875
	21st to end	Night	15% 5% 3 6% 4 4 3 4 5% 6% 46%	1900
May	1st to 10th	Night	16% 7% 3 6% 4 4 4 3 5% 7% 43%	2833
	11th to 20th	Night	14% 6% 2 6% 4 4 4 4 6% 8% 42%	2823
	21st to end	Night	16% 6% 2 5% 4 4 4 4 6% 8% 42%	3090
June	1st to 10th	Night	5% 4 1 4 4 4 4 4 5% 11% 55%	1710
	11th to 20th	Night	4 3 1 4 4 4 4 3 5% 10% 58%	1710
	21st to end	Night	4 2 1 3 3 3 3 3 6% 8% 63%	1710
July	1st to 10th	Night	8% 5% 2 5% 4 5% 4 4 6% 8% 49%	2850
	11th to 20th	Night	4 2 1 4 3 3 4 4 6% 8% 61%	2850
	21st to end	Night	5% 5% 2 6% 5% 5% 5% 5% 7% 9% 48%	3098
August	1st to 10th	Night	5% 2 1 4 3 4 4 4 6% 8% 58%	2836
	11th to 20th	Night	6% 3 1 4 3 4 4 4 6% 8% 56%	2854
	21st to end	Night	4 3 1 4 3 4 4 4 6% 8% 60%	3476
September	1st to 10th	Night	7% 4 2 4 3 3 3 2 5% 7% 59%	1900
	11th to 20th	Night	10% 4 2 6% 4 3 4 4 6% 6% 52%	2084
	21st to end	Night	7% 4 1 4 4 3 4 3 4 6% 59%	2090
October	1st to 10th	Night	7% 3 1 4 4 3 3 3 4 7% 61%	2273
	11th to 20th	Night	13% 3 2 3 2 3 3 3 4 4 60%	2275
	21st to end	Night	19% 4 2 4 3 2 3 2 3 4 54%	2376
November	1st to 10th	Night	11% 4 2 4 3 3 3 3 3 5% 59%	2220
	11th to 20th	Night	10% 5% 2 4 3 3 2 3 5% 6% 57%	2305
	21st to end	Night	19% 5% 1 4 3 3 3 3 4 6% 50%	2470
December	1st to 10th	Night	16% 6% 2 5% 3 3 3 3 4 5% 50%	2470
	11th to 20th	Night	16% 7% 2 6% 4 3 4 3 4 4 47%	3036
	21st to end	Night	19% 10% 3 7% 4 3 3 3 5% 5% 38%	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	42% 3 6% 23% 23% 3	2848
	11th to 20th	Day	34% 4 13% 26% 20% 3	2850
	21st to end	Day	45% 3 6% 19% 22% 5%	3135
February	1st to 10th	Day	46% 4 10% 20% 17% 3	1710
	11th to 20th	Day	43% 4 7% 22% 20% 4	1711
	21st to end	Day	46% 4 6% 18% 19% 7%	1712
March	1st to 10th	Day	40% 5% 7% 19% 19% 11%	3436
	11th to 20th	Day	38% 5% 11% 22% 19% 4	3480
	21st to end	Day	46% 4 9% 26% 14% 1	3814
April	1st to 10th	Day	39% 5% 10% 20% 20% 6%	2175
	11th to 20th	Day	41% 5% 9% 22% 18% 5%	2254
	21st to end	Day	46% 6% 7% 21% 18% 2	2280
May	1st to 10th	Day	46% 7% 8% 22% 15% 1	4106
	11th to 20th	Day	38% 8% 11% 25% 17% 1	4086
	21st to end	Day	44% 7% 12% 20% 16% 1	4489
June	1st to 10th	Day	35% 9% 14% 25% 16% 2	2470
	11th to 20th	Day	33% 7% 14% 25% 19% 2	2470
	21st to end	Day	25% 8% 14% 29% 20% 4	2470
July	1st to 10th	Day	33% 7% 17% 29% 13% 2	4056
	11th to 20th	Day	23% 6% 11% 35% 22% 2	4051
	21st to end	Day	36% 8% 16% 27% 13% 1	4325
August	1st to 10th	Day	23% 6% 12% 29% 24% 6%	4090
	11th to 20th	Day	33% 6% 15% 30% 15% 1	4021
	21st to end	Day	25% 8% 15% 36% 15% 2	4179
September	1st to 10th	Day	30% 6% 10% 25% 19% 10%	2280
	11th to 20th	Day	33% 6% 10% 23% 22% 5%	2091
	21st to end	Day	27% 5% 13% 19% 28% 8%	2076
October	1st to 10th	Day	27% 6% 10% 19% 27% 11%	1900
	11th to 20th	Day	29% 3 6% 20% 30% 11%	1890
	21st to end	Day	38% 4 8% 23% 20% 8%	1980
November	1st to 10th	Day	28% 4 10% 25% 25% 7%	1858
	11th to 20th	Day	30% 3 6% 26% 25% 9%	1872
	21st to end	Day	38% 3 7% 19% 27% 5%	1710
December	1st to 10th	Day	37% 4 10% 25% 20% 4	1710
	11th to 20th	Day	44% 3 6% 21% 22% 5%	2159
	21st to end	Day	51% 4 9% 19% 13% 4	3135
January	1st to 10th	Night	43% 3 8% 19% 23% 3	4108
	11th to 20th	Night	30% 4 13% 24% 26% 3	4120
	21st to end	Night	43% 3 10% 18% 22% 4	4532
February	1st to 10th	Night	43% 4 8% 24% 17% 5%	2470
	11th to 20th	Night	39% 4 7% 24% 20% 6%	2381
	21st to end	Night	40% 3 7% 19% 22% 9%	1740
March	1st to 10th	Night	42% 5% 8% 17% 17% 11%	3419
	11th to 20th	Night	36% 4 8% 27% 18% 6%	3480
	21st to end	Night	41% 5% 10% 25% 17% 3	3817
April	1st to 10th	Night	35% 5% 9% 20% 22% 9%	2005
	11th to 20th	Night	35% 5% 7% 22% 20% 10%	1875
	21st to end	Night	38% 6% 8% 23% 23% 2	1900
May	1st to 10th	Night	39% 7% 11% 22% 17% 4	2860
	11th to 20th	Night	38% 8% 12% 24% 17% 1	2824
	21st to end	Night	38% 8% 14% 24% 13% 3	3099
June	1st to 10th	Night	23% 8% 15% 32% 19% 4	1710
	11th to 20th	Night	22% 5% 13% 32% 25% 3	1710
	21st to end	Night	19% 5% 13% 31% 27% 6%	1710
July	1st to 10th	Night	31% 7% 16% 25% 18% 4	2805
	11th to 20th	Night	19% 5% 11% 36% 26% 2	2796
	21st to end	Night	30% 7% 18% 29% 15% 1	2999
August	1st to 10th	Night	22% 6% 13% 31% 23% 4	2826
	11th to 20th	Night	26% 5% 19% 31% 17% 2	2881
	21st to end	Night	22% 6% 12% 33% 25% 3	3476
September	1st to 10th	Night	25% 6% 10% 25% 23% 11%	1900
	11th to 20th	Night	31% 6% 11% 21% 25% 6%	2084
	21st to end	Night	26% 4 9% 23% 29% 8%	2090
October	1st to 10th	Night	23% 5% 12% 21% 26% 13%	2273
	11th to 20th	Night	27% 4 6% 16% 32% 14%	2275
	21st to end	Night	36% 3 6% 20% 23% 12%	2376
November	1st to 10th	Night	29% 4 7% 23% 27% 10%	2220
	11th to 20th	Night	28% 3 7% 24% 27% 10%	2305
	21st to end	Night	37% 4 8% 19% 27% 6%	2470
December	1st to 10th	Night	37% 4 9% 21% 22% 6%	2470
	11th to 20th	Night	42% 3 7% 21% 22% 6%	3037
	21st to end	Night	47% 4 10% 19% 16% 4	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	20% 13% 32% 24% 9% 1	270
	11th to 20th	Day	22% 13% 38% 20% 7%	270
	21st to end	Day	20% 14% 35% 21% 9% 1	297
February	1st to 10th	Day	30% 9% 34% 20% 7%	270
	11th to 20th	Day	28% 12% 34% 19% 7%	270
	21st to end	Day	32% 16% 34% 12% 4	225
March	1st to 10th	Day	21% 13% 33% 25% 8%	270
	11th to 20th	Day	26% 16% 35% 17% 7%	270
	21st to end	Day	23% 16% 35% 18% 7%	297
April	1st to 10th	Day	20% 14% 33% 22% 8% 3	355
	11th to 20th	Day	20% 12% 30% 28% 8% 1	452
	21st to end	Day	20% 13% 28% 29% 9% 2	460
May	1st to 10th	Day	16% 10% 26% 35% 12% 1	639
	11th to 20th	Day	13% 6% 24% 31% 23% 4	675
	21st to end	Day	11% 5% 23% 33% 22% 6%	734
June	1st to 10th	Day	9% 4 12% 29% 35% 12%	680
	11th to 20th	Day	6% 1 12% 33% 35% 12%	680
	21st to end	Day	4 1 13% 33% 35% 13%	680
July	1st to 10th	Day	7% 2 9% 24% 41% 17%	671
	11th to 20th	Day	4 1 7% 28% 39% 21%	668
	21st to end	Day	5% 1 6% 26% 41% 21%	739
August	1st to 10th	Day	6% 2 7% 28% 44% 13%	676
	11th to 20th	Day	11% 1 8% 29% 38% 12%	632
	21st to end	Day	7% 6% 18% 46% 24%	539
September	1st to 10th	Day	9% 1 6% 23% 45% 16%	490
	11th to 20th	Day	6% 2 10% 29% 38% 16%	301
	21st to end	Day	10% 4 12% 28% 28% 17%	300
October	1st to 10th	Day	5% 2 23% 31% 30% 8%	300
	11th to 20th	Day	11% 11% 25% 31% 20% 3	297
	21st to end	Day	23% 16% 23% 24% 12% 3	297
November	1st to 10th	Day	15% 4 30% 26% 23% 2	270
	11th to 20th	Day	14% 11% 31% 28% 15% 1	270
	21st to end	Day	21% 12% 22% 29% 15% 1	270
December	1st to 10th	Day	16% 11% 39% 18% 12% 3	270
	11th to 20th	Day	21% 14% 29% 26% 10%	270
	21st to end	Day	21% 15% 33% 25% 5% 1	297
January	1st to 10th	Night	18% 7% 33% 36% 6%	950
	11th to 20th	Night	19% 8% 33% 34% 6%	950
	21st to end	Night	18% 5% 35% 38% 5%	1045
February	1st to 10th	Night	22% 8% 30% 35% 4	950
	11th to 20th	Night	21% 6% 36% 34% 4	906
	21st to end	Night	22% 8% 36% 32% 2	484
March	1st to 10th	Night	19% 7% 30% 40% 5%	570
	11th to 20th	Night	21% 7% 27% 37% 8%	570
	21st to end	Night	20% 9% 30% 34% 7%	627
April	1st to 10th	Night	16% 7% 33% 35% 9%	570
	11th to 20th	Night	13% 10% 30% 38% 9%	563
	21st to end	Night	17% 6% 32% 33% 11%	570
May	1st to 10th	Night	13% 4 26% 46% 12%	570
	11th to 20th	Night	14% 4 18% 44% 18% 1	561
	21st to end	Night	10% 3 17% 41% 27% 2	617
June	1st to 10th	Night	5% 3 8% 40% 43% 2	570
	11th to 20th	Night	5% 8% 48% 36% 3	570
	21st to end	Night	3 1 7% 40% 43% 5%	570
July	1st to 10th	Night	6% 1 5% 33% 50% 6%	555
	11th to 20th	Night	3 1 6% 34% 48% 8%	552
	21st to end	Night	4 1 4 31% 52% 8%	624
August	1st to 10th	Night	3 1 6% 36% 49% 5%	567
	11th to 20th	Night	7% 2 8% 37% 41% 5%	564
	21st to end	Night	5% 1 4 35% 49% 6%	627
September	1st to 10th	Night	9% 1 6% 34% 47% 3	570
	11th to 20th	Night	12% 1 7% 38% 38% 3	570
	21st to end	Night	10% 1 12% 38% 34% 4	570
October	1st to 10th	Night	7% 2 14% 42% 33% 3	753
	11th to 20th	Night	13% 4 24% 42% 18%	759
	21st to end	Night	21% 5% 22% 35% 17% 1	792
November	1st to 10th	Night	12% 5% 24% 43% 16% 1	740
	11th to 20th	Night	12% 6% 29% 40% 12% 1	785
	21st to end	Night	21% 7% 26% 34% 12%	950
December	1st to 10th	Night	19% 7% 28% 40% 7%	950
	11th to 20th	Night	21% 7% 26% 41% 5%	950
	21st to end	Night	18% 8% 32% 35% 6%	1045

Page generated at 2024-10-17 12:09:41. Version ac07

Copyright © 2024 Attilla Danko.