Bunch Hollow Conservation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bunch Hollow Conservation Area clear sky chart from 2005-11-06 to 2024-11-11.

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% 8% 3 6% 4 4 4 4 5% 7% 43%	101298
	Night	12% 7% 3 7% 4 4 4 3 5% 6% 46%	97966
Transparency	Day	39% 6% 12% 25% 16% 2	104943
	Night	37% 5% 12% 25% 18% 3	102461
Seeing	Day	15% 9% 28% 28% 16% 4	15730
	Night	15% 8% 31% 32% 12% 1	25555

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	13% 12% 5% 11% 4 4 4 2 5% 7% 33%	2728
	11th to 20th	Day	11% 12% 4 9% 5% 6% 8% 3 3 5% 35%	2850
	21st to end	Day	14% 17% 6% 12% 5% 4 4 3 4 5% 26%	3135
February	1st to 10th	Day	14% 12% 3 7% 5% 4 4 3 5% 7% 34%	1710
	11th to 20th	Day	13% 11% 4 6% 5% 3 3 3 5% 7% 40%	1664
	21st to end	Day	12% 10% 3 7% 4 4 3 3 5% 6% 42%	1585
March	1st to 10th	Day	15% 11% 3 5% 3 3 3 3 4 6% 45%	3436
	11th to 20th	Day	10% 7% 3 6% 3 3 4 3 5% 7% 48%	3480
	21st to end	Day	18% 14% 4 8% 5% 4 4 3 5% 6% 29%	3814
April	1st to 10th	Day	15% 8% 3 7% 4 4 3 3 5% 6% 42%	2251
	11th to 20th	Day	14% 10% 2 7% 4 4 4 3 4 6% 41%	2254
	21st to end	Day	20% 8% 4 6% 5% 4 4 4 5% 6% 35%	2347
May	1st to 10th	Day	15% 8% 2 7% 5% 4 4 4 6% 7% 37%	4082
	11th to 20th	Day	17% 8% 3 7% 4 4 4 3 5% 7% 38%	4135
	21st to end	Day	13% 7% 2 6% 4 4 4 3 5% 7% 46%	4824
June	1st to 10th	Day	6% 5% 2 5% 5% 4 5% 5% 7% 8% 47%	2660
	11th to 20th	Day	7% 5% 2 6% 5% 4 5% 5% 6% 9% 46%	2660
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 4 6% 8% 48%	2660
July	1st to 10th	Day	11% 7% 2 7% 5% 5% 5% 4 6% 9% 39%	4440
	11th to 20th	Day	6% 4 2 5% 3 4 4 4 6% 9% 53%	4128
	21st to end	Day	5% 4 2 6% 5% 5% 6% 5% 8% 10% 44%	4465
August	1st to 10th	Day	4 4 2 5% 4 4 5% 4 7% 10% 52%	4104
	11th to 20th	Day	11% 5% 2 6% 4 4 5% 4 5% 7% 46%	4041
	21st to end	Day	5% 5% 2 5% 4 4 4 4 6% 8% 54%	4190
September	1st to 10th	Day	12% 4 1 4 3 4 4 3 4 6% 54%	2280
	11th to 20th	Day	9% 5% 2 5% 4 4 4 4 5% 8% 50%	2204
	21st to end	Day	9% 5% 1 5% 4 4 5% 3 4 7% 55%	2024
October	1st to 10th	Day	13% 5% 2 5% 3 4 2 3 4 7% 52%	1900
	11th to 20th	Day	13% 6% 2 5% 3 3 3 3 3 4 54%	1900
	21st to end	Day	15% 8% 2 6% 3 3 3 3 5% 6% 46%	2090
November	1st to 10th	Day	10% 7% 3 5% 3 3 3 3 5% 6% 52%	1943
	11th to 20th	Day	15% 7% 2 6% 4 3 2 3 4 6% 48%	1573
	21st to end	Day	17% 11% 3 5% 3 3 4 3 4 5% 43%	1520
December	1st to 10th	Day	11% 9% 4 7% 5% 4 3 3 6% 6% 41%	1520
	11th to 20th	Day	13% 10% 4 8% 4 3 4 4 4 5% 41%	1918
	21st to end	Day	18% 15% 8% 11% 5% 4 4 4 4 4 24%	2783
January	1st to 10th	Night	9% 10% 4 14% 6% 5% 4 3 4 5% 35%	4222
	11th to 20th	Night	12% 11% 4 8% 5% 7% 6% 5% 6% 5% 32%	4120
	21st to end	Night	16% 12% 6% 12% 5% 3 3 3 4 5% 31%	4532
February	1st to 10th	Night	13% 10% 4 9% 5% 4 4 3 6% 6% 36%	2470
	11th to 20th	Night	13% 9% 2 7% 4 4 4 4 5% 7% 41%	2403
	21st to end	Night	13% 9% 3 6% 3 3 3 2 5% 6% 46%	1883
March	1st to 10th	Night	15% 10% 3 5% 3 3 3 3 4 5% 46%	3419
	11th to 20th	Night	12% 7% 2 5% 3 2 3 3 5% 6% 53%	3480
	21st to end	Night	17% 10% 5% 9% 5% 4 4 4 5% 6% 30%	3817
April	1st to 10th	Night	11% 7% 2 5% 3 4 5% 3 4 7% 48%	1927
	11th to 20th	Night	13% 7% 3 7% 4 5% 3 3 4 6% 45%	1875
	21st to end	Night	17% 8% 3 6% 4 4 4 2 5% 6% 41%	1829
May	1st to 10th	Night	15% 6% 2 6% 5% 4 5% 4 6% 8% 38%	2823
	11th to 20th	Night	14% 8% 2 6% 4 4 4 2 5% 9% 42%	2770
	21st to end	Night	11% 5% 2 5% 4 4 3 3 4 6% 51%	2743
June	1st to 10th	Night	6% 3 2 4 4 3 4 5% 7% 10% 53%	1520
	11th to 20th	Night	5% 3 2 6% 5% 4 5% 5% 6% 11% 50%	1520
	21st to end	Night	5% 4 1 5% 3 3 4 4 5% 9% 57%	1520
July	1st to 10th	Night	12% 7% 2 5% 4 4 3 4 5% 9% 45%	2530
	11th to 20th	Night	3 2 1 3 3 3 4 3 6% 9% 61%	2838
	21st to end	Night	6% 4 1 6% 5% 4 5% 4 7% 9% 50%	3098
August	1st to 10th	Night	3 2 2 3 3 3 4 4 6% 11% 59%	2836
	11th to 20th	Night	12% 6% 2 5% 3 3 3 3 3 8% 53%	2798
	21st to end	Night	4 3 1 5% 3 3 4 4 5% 8% 59%	3466
September	1st to 10th	Night	10% 4 2 4 2 3 4 3 4 5% 58%	1900
	11th to 20th	Night	10% 4 1 3 2 3 4 4 6% 8% 54%	1972
	21st to end	Night	8% 4 2 5% 4 3 3 3 4 6% 57%	2137
October	1st to 10th	Night	11% 4 2 4 3 3 3 2 4 6% 58%	2280
	11th to 20th	Night	14% 4 2 5% 3 3 3 3 4 4 55%	2280
	21st to end	Night	16% 7% 2 5% 3 2 3 2 3 5% 51%	2508
November	1st to 10th	Night	11% 4 1 4 2 3 3 3 4 6% 58%	2354
	11th to 20th	Night	12% 6% 3 5% 4 3 3 3 4 6% 52%	2613
	21st to end	Night	17% 8% 2 5% 4 3 3 2 4 5% 47%	2660
December	1st to 10th	Night	12% 9% 3 6% 5% 4 4 3 5% 6% 43%	2660
	11th to 20th	Night	12% 8% 3 8% 4 3 4 4 5% 5% 43%	3279
	21st to end	Night	21% 17% 6% 10% 4 3 3 2 3 4 26%	4884

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	50% 6% 13% 21% 9% 1	2729
	11th to 20th	Day	54% 5% 13% 20% 9%	2850
	21st to end	Day	60% 6% 10% 15% 8% 1	3135
February	1st to 10th	Day	49% 5% 14% 19% 10% 2	1710
	11th to 20th	Day	44% 4 14% 22% 14% 2	1673
	21st to end	Day	43% 4 12% 23% 15% 2	1585
March	1st to 10th	Day	42% 4 10% 24% 19% 1	3436
	11th to 20th	Day	34% 7% 11% 27% 18% 3	3480
	21st to end	Day	54% 8% 14% 19% 4 1	3814
April	1st to 10th	Day	43% 4 12% 25% 14% 2	2251
	11th to 20th	Day	44% 4 12% 24% 14% 1	2254
	21st to end	Day	50% 5% 11% 21% 12% 1	2347
May	1st to 10th	Day	43% 8% 12% 23% 13% 1	4120
	11th to 20th	Day	46% 7% 12% 25% 10%	4139
	21st to end	Day	37% 6% 11% 28% 16% 1	4837
June	1st to 10th	Day	31% 9% 15% 29% 14% 2	2660
	11th to 20th	Day	32% 8% 14% 27% 17% 2	2660
	21st to end	Day	31% 7% 18% 27% 14% 3	2660
July	1st to 10th	Day	41% 7% 12% 25% 12% 3	4371
	11th to 20th	Day	28% 5% 13% 33% 18% 2	4058
	21st to end	Day	30% 9% 17% 30% 13% 1	4325
August	1st to 10th	Day	27% 7% 16% 31% 19% 1	4090
	11th to 20th	Day	36% 6% 13% 27% 17% 1	4080
	21st to end	Day	28% 6% 17% 31% 13% 6%	4189
September	1st to 10th	Day	30% 6% 12% 25% 20% 6%	2280
	11th to 20th	Day	31% 6% 12% 27% 21% 3	2204
	21st to end	Day	31% 4 10% 31% 21% 3	2024
October	1st to 10th	Day	20% 3 7% 21% 40% 9%	3160
	11th to 20th	Day	22% 3 4 22% 40% 9%	3140
	21st to end	Day	35% 4 8% 25% 25% 2	3428
November	1st to 10th	Day	33% 4 14% 27% 18% 4	1943
	11th to 20th	Day	38% 4 10% 27% 20% 2	1573
	21st to end	Day	44% 4 10% 28% 15%	1520
December	1st to 10th	Day	43% 6% 13% 25% 13% 1	1520
	11th to 20th	Day	45% 4 15% 28% 6% 1	1915
	21st to end	Day	63% 5% 10% 15% 7% 1	2783
January	1st to 10th	Night	51% 6% 11% 22% 10% 1	4222
	11th to 20th	Night	51% 5% 13% 19% 11% 1	4120
	21st to end	Night	57% 5% 12% 17% 8% 1	4532
February	1st to 10th	Night	48% 6% 12% 20% 13% 3	2470
	11th to 20th	Night	42% 5% 12% 22% 16% 2	2404
	21st to end	Night	40% 4 10% 23% 19% 4	1883
March	1st to 10th	Night	41% 5% 10% 23% 18% 3	3419
	11th to 20th	Night	33% 5% 9% 29% 20% 4	3480
	21st to end	Night	52% 7% 15% 19% 5% 1	3817
April	1st to 10th	Night	36% 5% 10% 27% 18% 4	1927
	11th to 20th	Night	40% 5% 8% 27% 16% 4	1875
	21st to end	Night	44% 5% 10% 23% 16% 1	1829
May	1st to 10th	Night	40% 9% 14% 22% 14% 1	2850
	11th to 20th	Night	39% 7% 12% 29% 12% 1	2771
	21st to end	Night	33% 7% 10% 25% 23% 2	2751
June	1st to 10th	Night	24% 8% 18% 30% 16% 4	1520
	11th to 20th	Night	28% 8% 13% 27% 19% 5%	1520
	21st to end	Night	24% 6% 16% 31% 19% 4	1520
July	1st to 10th	Night	36% 5% 12% 24% 19% 4	2490
	11th to 20th	Night	19% 7% 15% 35% 22% 2	2785
	21st to end	Night	27% 7% 21% 31% 13% 1	2999
August	1st to 10th	Night	19% 6% 19% 31% 23% 2	2826
	11th to 20th	Night	33% 4 11% 29% 22% 1	2825
	21st to end	Night	24% 5% 16% 34% 16% 4	3466
September	1st to 10th	Night	28% 4 11% 25% 24% 8%	1900
	11th to 20th	Night	27% 5% 12% 28% 24% 4	1972
	21st to end	Night	28% 5% 9% 28% 26% 4	2137
October	1st to 10th	Night	18% 2 7% 19% 47% 7%	3800
	11th to 20th	Night	23% 3 6% 23% 34% 12%	3779
	21st to end	Night	36% 3 8% 26% 25% 2	4120
November	1st to 10th	Night	28% 4 14% 26% 22% 6%	2354
	11th to 20th	Night	34% 4 9% 29% 20% 4	2613
	21st to end	Night	41% 4 10% 27% 16% 2	2660
December	1st to 10th	Night	42% 4 13% 27% 13% 1	2660
	11th to 20th	Night	41% 6% 13% 28% 11% 1	3281
	21st to end	Night	63% 5% 7% 16% 7% 1	4884

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% 16% 34% 25% 6%	270
	11th to 20th	Day	27% 18% 36% 18% 1	270
	21st to end	Day	15% 16% 46% 20% 3	297
February	1st to 10th	Day	22% 19% 39% 17% 3	270
	11th to 20th	Day	19% 19% 39% 14% 8%	270
	21st to end	Day	20% 21% 40% 15% 4	225
March	1st to 10th	Day	18% 15% 45% 19% 2	270
	11th to 20th	Day	27% 12% 34% 22% 5%	270
	21st to end	Day	39% 14% 29% 14% 3	297
April	1st to 10th	Day	21% 15% 36% 22% 6%	431
	11th to 20th	Day	19% 14% 36% 22% 7% 1	452
	21st to end	Day	22% 16% 32% 22% 7% 1	527
May	1st to 10th	Day	18% 12% 38% 22% 9% 1	653
	11th to 20th	Day	21% 9% 28% 28% 11% 3	675
	21st to end	Day	16% 6% 30% 27% 18% 4	734
June	1st to 10th	Day	7% 4 21% 36% 24% 9%	680
	11th to 20th	Day	8% 5% 25% 36% 21% 5%	680
	21st to end	Day	8% 5% 33% 34% 17% 3	680
July	1st to 10th	Day	11% 4 14% 31% 29% 12%	671
	11th to 20th	Day	6% 2 20% 35% 28% 9%	668
	21st to end	Day	7% 2 16% 36% 33% 7%	739
August	1st to 10th	Day	7% 3 16% 41% 27% 7%	676
	11th to 20th	Day	9% 3 17% 34% 30% 7%	665
	21st to end	Day	9% 2 14% 32% 32% 11%	549
September	1st to 10th	Day	13% 3 15% 34% 29% 6%	490
	11th to 20th	Day	9% 2 19% 36% 26% 8%	414
	21st to end	Day	12% 7% 25% 30% 19% 7%	300
October	1st to 10th	Day	16% 5% 30% 28% 15% 6%	300
	11th to 20th	Day	12% 24% 35% 21% 7% 1	300
	21st to end	Day	22% 15% 35% 22% 6% 1	330
November	1st to 10th	Day	16% 11% 38% 24% 7% 4	300
	11th to 20th	Day	18% 17% 33% 23% 6% 2	270
	21st to end	Day	21% 16% 29% 28% 5% 1	270
December	1st to 10th	Day	11% 16% 39% 24% 8% 3	270
	11th to 20th	Day	20% 14% 36% 23% 5% 1	270
	21st to end	Day	22% 21% 38% 18% 1	297
January	1st to 10th	Night	13% 14% 39% 27% 7%	950
	11th to 20th	Night	17% 15% 37% 25% 5% 1	950
	21st to end	Night	17% 12% 38% 29% 4	1045
February	1st to 10th	Night	17% 13% 42% 23% 5%	950
	11th to 20th	Night	18% 12% 38% 28% 4	929
	21st to end	Night	19% 14% 43% 19% 4 1	627
March	1st to 10th	Night	18% 12% 39% 26% 5%	570
	11th to 20th	Night	21% 10% 35% 29% 5% 1	570
	21st to end	Night	28% 9% 36% 23% 5%	627
April	1st to 10th	Night	15% 11% 41% 29% 3	570
	11th to 20th	Night	18% 12% 34% 28% 7%	563
	21st to end	Night	21% 9% 34% 29% 6% 1	570
May	1st to 10th	Night	16% 8% 36% 31% 8% 1	570
	11th to 20th	Night	17% 5% 27% 36% 15% 1	561
	21st to end	Night	12% 5% 25% 38% 18% 2	617
June	1st to 10th	Night	6% 4 21% 44% 23% 3	570
	11th to 20th	Night	6% 3 25% 45% 17% 2	570
	21st to end	Night	6% 3 26% 47% 17% 1	570
July	1st to 10th	Night	10% 2 12% 37% 35% 5%	555
	11th to 20th	Night	5% 2 18% 45% 28% 2	552
	21st to end	Night	7% 1 12% 44% 33% 3	624
August	1st to 10th	Night	6% 1 16% 48% 29% 1	567
	11th to 20th	Night	8% 2 13% 42% 32% 3	564
	21st to end	Night	6% 2 12% 41% 36% 4	627
September	1st to 10th	Night	11% 2 16% 40% 27% 4	570
	11th to 20th	Night	12% 2 18% 39% 25% 4	570
	21st to end	Night	8% 5% 24% 40% 20% 3	617
October	1st to 10th	Night	12% 4 29% 33% 18% 3	760
	11th to 20th	Night	15% 9% 35% 32% 9%	760
	21st to end	Night	21% 10% 33% 27% 8%	836
November	1st to 10th	Night	12% 10% 33% 35% 9% 1	780
	11th to 20th	Night	15% 12% 39% 26% 8%	899
	21st to end	Night	21% 10% 36% 27% 7%	950
December	1st to 10th	Night	18% 11% 37% 27% 7% 1	950
	11th to 20th	Night	20% 8% 35% 31% 5%	950
	21st to end	Night	23% 15% 34% 24% 4	1045

Page generated at 2024-11-08 05:44:46. Version ac07

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