Robber's Cave State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Robber's Cave State Park clear sky chart from 2005-11-06 to 2024-11-12.

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	11% 7% 2 6% 4 4 4 3 5% 7% 48%	101310
	Night	11% 6% 2 5% 3 3 3 3 5% 6% 52%	97963
Transparency	Day	35% 5% 10% 25% 21% 5%	104987
	Night	31% 4 9% 24% 23% 7%	102413
Seeing	Day	15% 12% 27% 27% 15% 3	15384
	Night	14% 12% 26% 31% 15% 2	25202

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	12% 12% 4 6% 3 3 3 2 4 5% 46%	2847
	11th to 20th	Day	8% 6% 2 5% 4 2 3 2 4 5% 58%	2850
	21st to end	Day	20% 11% 2 5% 3 3 2 2 3 4 44%	3135
February	1st to 10th	Day	17% 11% 3 6% 4 4 3 3 4 4 41%	1710
	11th to 20th	Day	14% 9% 3 7% 4 3 4 3 4 5% 43%	1783
	21st to end	Day	18% 10% 4 6% 3 3 3 2 4 5% 42%	1660
March	1st to 10th	Day	14% 8% 3 6% 4 3 3 3 3 4 50%	3436
	11th to 20th	Day	12% 7% 2 6% 5% 4 4 4 5% 6% 46%	3480
	21st to end	Day	17% 11% 3 6% 4 3 3 4 5% 6% 38%	3814
April	1st to 10th	Day	12% 6% 3 5% 5% 4 5% 3 5% 7% 46%	2118
	11th to 20th	Day	16% 7% 2 6% 4 4 4 2 5% 5% 45%	2254
	21st to end	Day	19% 8% 3 6% 5% 4 3 3 4 5% 41%	2340
May	1st to 10th	Day	17% 8% 3 7% 4 3 4 3 4 6% 40%	4082
	11th to 20th	Day	12% 6% 2 7% 4 5% 4 3 5% 6% 43%	4082
	21st to end	Day	15% 7% 3 8% 5% 5% 4 4 6% 7% 37%	4477
June	1st to 10th	Day	9% 5% 2 6% 4 4 5% 5% 6% 8% 46%	2470
	11th to 20th	Day	6% 5% 2 5% 5% 3 5% 5% 6% 9% 48%	2470
	21st to end	Day	4 4 1 4 4 4 4 3 7% 8% 57%	2470
July	1st to 10th	Day	7% 4 2 6% 4 4 5% 4 7% 9% 46%	4120
	11th to 20th	Day	3 4 1 5% 4 3 4 4 6% 9% 56%	4120
	21st to end	Day	6% 4 1 6% 5% 6% 6% 5% 8% 9% 44%	4465
August	1st to 10th	Day	3 3 1 5% 4 4 4 4 6% 8% 57%	4104
	11th to 20th	Day	8% 4 2 4 3 4 4 4 6% 9% 50%	4041
	21st to end	Day	4 3 1 5% 4 5% 5% 4 7% 9% 53%	4197
September	1st to 10th	Day	10% 4 2 5% 4 4 4 4 4 6% 52%	2178
	11th to 20th	Day	11% 4 2 5% 4 3 5% 4 5% 7% 49%	2090
	21st to end	Day	7% 3 1 4 3 4 4 4 5% 7% 56%	2090
October	1st to 10th	Day	7% 5% 2 5% 3 4 3 3 5% 6% 57%	1938
	11th to 20th	Day	11% 5% 2 5% 2 3 2 2 2 5% 61%	1900
	21st to end	Day	16% 7% 1 5% 3 2 3 2 3 5% 52%	2090
November	1st to 10th	Day	10% 6% 2 4 3 3 3 4 5% 6% 56%	1958
	11th to 20th	Day	10% 6% 1 5% 2 3 3 2 3 5% 59%	1825
	21st to end	Day	15% 7% 3 4 4 3 3 3 5% 6% 50%	1710
December	1st to 10th	Day	14% 7% 3 5% 4 3 3 3 4 6% 48%	1710
	11th to 20th	Day	15% 9% 3 5% 4 4 3 3 4 5% 44%	2161
	21st to end	Day	15% 12% 5% 8% 4 4 4 3 4 5% 35%	3135
January	1st to 10th	Night	12% 9% 4 8% 4 3 3 2 3 5% 46%	4108
	11th to 20th	Night	9% 6% 2 5% 4 3 3 2 3 5% 57%	4120
	21st to end	Night	22% 9% 2 4 2 2 3 2 4 4 46%	4532
February	1st to 10th	Night	14% 10% 2 6% 3 3 3 3 5% 6% 45%	2470
	11th to 20th	Night	14% 8% 2 7% 3 3 3 3 4 5% 47%	2300
	21st to end	Night	13% 10% 3 6% 3 2 2 3 4 5% 48%	1792
March	1st to 10th	Night	17% 8% 2 6% 3 3 4 3 5% 5% 44%	3419
	11th to 20th	Night	13% 7% 2 4 3 2 3 3 4 6% 53%	3480
	21st to end	Night	13% 7% 3 7% 4 4 5% 3 4 6% 44%	3817
April	1st to 10th	Night	12% 6% 2 5% 4 4 3 3 4 6% 50%	2062
	11th to 20th	Night	12% 7% 3 4 3 3 3 3 5% 7% 50%	1875
	21st to end	Night	15% 6% 2 5% 3 4 4 4 4 7% 47%	1836
May	1st to 10th	Night	14% 8% 3 6% 5% 3 3 3 5% 8% 42%	2823
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 6% 8% 44%	2823
	21st to end	Night	14% 7% 2 5% 4 3 5% 3 6% 8% 44%	3090
June	1st to 10th	Night	4 3 1 4 3 3 4 3 6% 10% 58%	1710
	11th to 20th	Night	5% 4 1 4 3 2 3 4 6% 8% 61%	1710
	21st to end	Night	2 3 1 3 2 3 3 3 5% 9% 66%	1710
July	1st to 10th	Night	9% 4 2 5% 3 3 4 4 6% 8% 52%	2850
	11th to 20th	Night	3 2 1 3 2 2 3 3 4 7% 68%	2850
	21st to end	Night	4 3 1 4 3 4 4 5% 6% 10% 55%	3098
August	1st to 10th	Night	1 2 1 3 3 3 4 3 5% 8% 65%	2836
	11th to 20th	Night	4 3 2 4 3 3 4 3 6% 9% 61%	2798
	21st to end	Night	2 3 1 3 3 3 4 4 6% 8% 62%	3445
September	1st to 10th	Night	8% 5% 2 4 2 3 3 3 5% 6% 58%	1998
	11th to 20th	Night	9% 5% 2 4 3 3 4 4 6% 7% 53%	2090
	21st to end	Night	7% 4 1 4 2 4 3 3 5% 6% 60%	2090
October	1st to 10th	Night	5% 4 2 4 3 3 4 3 4 6% 63%	2221
	11th to 20th	Night	11% 4 1 4 3 3 3 2 3 4 62%	2280
	21st to end	Night	17% 6% 2 3 3 3 2 2 3 4 56%	2508
November	1st to 10th	Night	11% 4 2 5% 3 2 3 3 3 5% 60%	2340
	11th to 20th	Night	8% 6% 2 5% 3 2 3 3 4 5% 59%	2374
	21st to end	Night	14% 7% 1 4 3 3 2 3 4 6% 52%	2470
December	1st to 10th	Night	13% 6% 3 6% 3 3 3 3 4 6% 50%	2470
	11th to 20th	Night	13% 7% 3 7% 4 3 2 3 4 5% 49%	3036
	21st to end	Night	14% 9% 5% 8% 4 3 4 3 4 5% 41%	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% 24% 3	2848
	11th to 20th	Day	30% 3 13% 28% 22% 3	2850
	21st to end	Day	45% 3 6% 19% 23% 4	3135
February	1st to 10th	Day	49% 3 9% 18% 18% 4	1710
	11th to 20th	Day	45% 3 6% 23% 18% 5%	1792
	21st to end	Day	46% 3 5% 16% 22% 8%	1660
March	1st to 10th	Day	41% 3 7% 16% 21% 12%	3436
	11th to 20th	Day	39% 6% 10% 23% 17% 5%	3480
	21st to end	Day	47% 5% 8% 25% 13% 2	3814
April	1st to 10th	Day	39% 5% 10% 20% 20% 7%	2118
	11th to 20th	Day	42% 4 9% 23% 17% 5%	2254
	21st to end	Day	46% 5% 8% 20% 19% 3	2340
May	1st to 10th	Day	46% 5% 9% 22% 17% 2	4120
	11th to 20th	Day	40% 7% 10% 24% 19% 1	4086
	21st to end	Day	46% 7% 11% 19% 14% 3	4489
June	1st to 10th	Day	34% 8% 15% 27% 14% 3	2470
	11th to 20th	Day	31% 7% 12% 27% 20% 2	2470
	21st to end	Day	24% 6% 14% 29% 23% 3	2470
July	1st to 10th	Day	31% 7% 16% 30% 15% 2	4056
	11th to 20th	Day	22% 6% 10% 38% 22% 2	4051
	21st to end	Day	31% 8% 15% 32% 14%	4325
August	1st to 10th	Day	23% 5% 13% 28% 27% 4	4090
	11th to 20th	Day	30% 6% 16% 31% 16% 2	4080
	21st to end	Day	26% 7% 14% 38% 14% 2	4196
September	1st to 10th	Day	33% 5% 8% 23% 22% 9%	2178
	11th to 20th	Day	32% 6% 11% 23% 21% 7%	2090
	21st to end	Day	27% 5% 8% 24% 29% 8%	2090
October	1st to 10th	Day	17% 3 6% 12% 38% 24%	3224
	11th to 20th	Day	19% 2 4 17% 40% 18%	3140
	21st to end	Day	29% 3 6% 29% 26% 7%	3428
November	1st to 10th	Day	30% 3 9% 25% 26% 7%	1958
	11th to 20th	Day	29% 3 8% 25% 26% 8%	1825
	21st to end	Day	36% 3 7% 21% 26% 6%	1710
December	1st to 10th	Day	38% 3 9% 26% 19% 4	1710
	11th to 20th	Day	43% 3 5% 19% 24% 6%	2159
	21st to end	Day	49% 5% 7% 18% 17% 4	3135
January	1st to 10th	Night	41% 4 6% 20% 26% 4	4108
	11th to 20th	Night	31% 4 14% 20% 27% 4	4120
	21st to end	Night	43% 4 7% 18% 24% 5%	4532
February	1st to 10th	Night	41% 4 9% 23% 17% 6%	2470
	11th to 20th	Night	42% 3 5% 24% 21% 6%	2301
	21st to end	Night	39% 3 7% 20% 23% 9%	1792
March	1st to 10th	Night	42% 4 6% 17% 18% 11%	3419
	11th to 20th	Night	35% 4 9% 28% 16% 8%	3480
	21st to end	Night	41% 6% 9% 24% 19% 2	3817
April	1st to 10th	Night	35% 4 10% 20% 19% 11%	2062
	11th to 20th	Night	34% 4 8% 24% 19% 10%	1875
	21st to end	Night	37% 5% 10% 24% 21% 3	1836
May	1st to 10th	Night	41% 6% 11% 20% 16% 6%	2850
	11th to 20th	Night	37% 7% 12% 26% 16% 2	2824
	21st to end	Night	37% 7% 14% 23% 15% 4	3099
June	1st to 10th	Night	23% 5% 15% 33% 20% 3	1710
	11th to 20th	Night	20% 6% 13% 32% 25% 4	1710
	21st to end	Night	17% 4 14% 31% 28% 6%	1710
July	1st to 10th	Night	28% 8% 16% 27% 17% 4	2805
	11th to 20th	Night	16% 5% 10% 40% 27% 3	2796
	21st to end	Night	23% 6% 20% 32% 19% 1	2999
August	1st to 10th	Night	16% 4 13% 27% 32% 8%	2826
	11th to 20th	Night	20% 5% 17% 35% 20% 3	2825
	21st to end	Night	19% 5% 13% 39% 21% 3	3445
September	1st to 10th	Night	26% 4 9% 27% 23% 12%	1998
	11th to 20th	Night	30% 6% 9% 23% 25% 8%	2090
	21st to end	Night	24% 5% 7% 24% 30% 10%	2090
October	1st to 10th	Night	14% 3 6% 14% 34% 30%	3702
	11th to 20th	Night	20% 2 4 13% 42% 20%	3779
	21st to end	Night	29% 2 4 30% 25% 11%	4120
November	1st to 10th	Night	29% 4 6% 24% 26% 11%	2340
	11th to 20th	Night	28% 3 8% 24% 28% 10%	2374
	21st to end	Night	35% 3 7% 20% 28% 7%	2470
December	1st to 10th	Night	36% 4 9% 22% 22% 7%	2470
	11th to 20th	Night	40% 3 5% 20% 23% 8%	3037
	21st to end	Night	45% 5% 7% 19% 19% 6%	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% 22% 33% 16% 5%	270
	11th to 20th	Day	24% 27% 36% 10% 2	270
	21st to end	Day	22% 26% 35% 12% 5%	297
February	1st to 10th	Day	27% 23% 37% 9% 4	270
	11th to 20th	Day	31% 25% 32% 8% 3	270
	21st to end	Day	39% 28% 23% 9% 2	225
March	1st to 10th	Day	20% 27% 35% 16% 1	270
	11th to 20th	Day	30% 27% 29% 11% 3	270
	21st to end	Day	27% 28% 33% 10% 2	297
April	1st to 10th	Day	20% 29% 36% 10% 4 1	298
	11th to 20th	Day	28% 21% 32% 14% 5%	452
	21st to end	Day	26% 21% 32% 15% 6% 1	520
May	1st to 10th	Day	18% 14% 43% 19% 6%	653
	11th to 20th	Day	17% 11% 35% 26% 10% 1	675
	21st to end	Day	14% 10% 36% 23% 14% 3	734
June	1st to 10th	Day	10% 5% 25% 35% 20% 6%	680
	11th to 20th	Day	8% 5% 27% 37% 19% 4	680
	21st to end	Day	3 5% 29% 38% 21% 4	680
July	1st to 10th	Day	7% 3 18% 38% 26% 8%	671
	11th to 20th	Day	3 2 17% 42% 29% 7%	668
	21st to end	Day	4 1 11% 43% 32% 8%	739
August	1st to 10th	Day	6% 2 16% 43% 28% 5%	676
	11th to 20th	Day	11% 2 16% 41% 26% 4	665
	21st to end	Day	5% 1 10% 36% 36% 12%	556
September	1st to 10th	Day	9% 2 11% 37% 33% 8%	388
	11th to 20th	Day	6% 2 24% 37% 24% 7%	300
	21st to end	Day	14% 5% 22% 32% 20% 6%	300
October	1st to 10th	Day	6% 9% 33% 33% 15% 4	300
	11th to 20th	Day	13% 14% 39% 27% 7% 1	300
	21st to end	Day	30% 13% 31% 20% 5% 1	330
November	1st to 10th	Day	17% 16% 38% 21% 7% 1	300
	11th to 20th	Day	17% 21% 37% 19% 5% 1	273
	21st to end	Day	24% 20% 38% 13% 4 1	270
December	1st to 10th	Day	21% 24% 32% 17% 4 1	270
	11th to 20th	Day	28% 21% 34% 14% 4	270
	21st to end	Day	23% 24% 36% 12% 4	297
January	1st to 10th	Night	17% 19% 31% 26% 7% 1	950
	11th to 20th	Night	19% 20% 32% 24% 4	950
	21st to end	Night	17% 19% 30% 30% 5%	1045
February	1st to 10th	Night	22% 19% 31% 24% 5%	950
	11th to 20th	Night	21% 19% 34% 22% 3	826
	21st to end	Night	25% 19% 30% 24% 2	536
March	1st to 10th	Night	20% 16% 28% 32% 4	570
	11th to 20th	Night	21% 16% 33% 25% 5%	570
	21st to end	Night	19% 18% 32% 25% 6%	627
April	1st to 10th	Night	16% 21% 32% 26% 5%	570
	11th to 20th	Night	17% 17% 32% 25% 8%	563
	21st to end	Night	20% 12% 36% 22% 9% 1	570
May	1st to 10th	Night	12% 14% 33% 33% 8%	570
	11th to 20th	Night	14% 8% 28% 34% 15% 1	561
	21st to end	Night	13% 7% 29% 29% 19% 2	617
June	1st to 10th	Night	6% 4 17% 37% 34% 3	570
	11th to 20th	Night	6% 3 28% 41% 21% 1	570
	21st to end	Night	3 1 22% 41% 29% 5%	570
July	1st to 10th	Night	6% 1 13% 40% 35% 6%	555
	11th to 20th	Night	3 1 13% 41% 36% 6%	552
	21st to end	Night	3 2 10% 42% 39% 4	624
August	1st to 10th	Night	3 1 15% 43% 34% 3	567
	11th to 20th	Night	6% 1 12% 40% 36% 5%	564
	21st to end	Night	6% 2 9% 37% 41% 6%	627
September	1st to 10th	Night	9% 1 12% 37% 37% 4	570
	11th to 20th	Night	12% 2 15% 33% 34% 4	570
	21st to end	Night	8% 4 21% 32% 31% 5%	570
October	1st to 10th	Night	8% 4 21% 35% 28% 4	701
	11th to 20th	Night	14% 10% 29% 33% 13% 1	760
	21st to end	Night	21% 11% 26% 28% 13% 1	836
November	1st to 10th	Night	14% 12% 32% 31% 11% 1	780
	11th to 20th	Night	13% 14% 31% 31% 10%	846
	21st to end	Night	20% 17% 29% 26% 8%	950
December	1st to 10th	Night	20% 15% 29% 29% 7%	950
	11th to 20th	Night	21% 13% 32% 28% 5%	950
	21st to end	Night	17% 22% 30% 27% 5%	1045

Page generated at 2024-11-08 21:45:40. Version ac07

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