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 2024-01-13.

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% 3 6% 5% 3 4 4 5% 7% 43%	74660
	Night	12% 7% 3 5% 5% 3 4 4 5% 7% 46%	75103
Transparency	Day	41% 6% 13% 24% 14% 2	74377
	Night	38% 5% 12% 25% 17% 3	74906
Seeing	Day	15% 9% 27% 28% 17% 4	14537
	Night	15% 8% 31% 32% 13% 1	24517

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% 10% 5% 8% 4 3 5% 4 5% 7% 38%	1640
	11th to 20th	Day	14% 11% 5% 9% 6% 3 5% 4 3 5% 35%	1638
	21st to end	Day	11% 11% 6% 10% 5% 3 4 5% 5% 5% 34%	1782
February	1st to 10th	Day	15% 11% 4 7% 6% 3 4 4 5% 7% 34%	1620
	11th to 20th	Day	14% 9% 5% 6% 5% 2 3 3 5% 8% 39%	1574
	21st to end	Day	13% 10% 3 7% 5% 3 4 4 4 6% 40%	1494
March	1st to 10th	Day	13% 10% 4 6% 5% 3 5% 5% 4 7% 39%	1980
	11th to 20th	Day	17% 10% 5% 7% 4 3 4 4 5% 6% 34%	1980
	21st to end	Day	22% 12% 4 7% 5% 4 4 4 5% 5% 28%	2178
April	1st to 10th	Day	16% 7% 3 6% 5% 3 4 3 5% 6% 42%	2132
	11th to 20th	Day	15% 10% 3 6% 5% 3 5% 4 4 6% 41%	2134
	21st to end	Day	21% 7% 4 6% 5% 3 4 4 5% 6% 34%	2223
May	1st to 10th	Day	16% 8% 4 7% 6% 4 5% 5% 5% 7% 33%	2340
	11th to 20th	Day	17% 7% 3 6% 6% 3 4 3 5% 7% 37%	2327
	21st to end	Day	13% 8% 3 7% 6% 4 5% 4 6% 8% 36%	2725
June	1st to 10th	Day	6% 4 2 5% 5% 3 6% 6% 7% 9% 47%	2520
	11th to 20th	Day	7% 4 2 5% 6% 3 4 6% 6% 9% 46%	2520
	21st to end	Day	7% 4 2 5% 5% 4 5% 5% 6% 9% 48%	2520
July	1st to 10th	Day	9% 4 2 4 5% 3 6% 5% 6% 10% 47%	2520
	11th to 20th	Day	5% 4 1 4 5% 4 5% 5% 6% 9% 50%	2348
	21st to end	Day	8% 4 2 5% 6% 3 5% 6% 6% 9% 46%	2546
August	1st to 10th	Day	6% 5% 3 5% 5% 3 5% 6% 7% 10% 44%	2328
	11th to 20th	Day	8% 5% 2 6% 5% 3 5% 5% 6% 8% 47%	2301
	21st to end	Day	7% 5% 2 4 4 3 4 4 5% 8% 54%	2386
September	1st to 10th	Day	13% 4 1 4 3 3 4 4 4 7% 53%	2160
	11th to 20th	Day	9% 4 2 4 5% 3 4 5% 5% 8% 51%	2088
	21st to end	Day	8% 4 2 4 4 3 5% 3 4 7% 56%	1918
October	1st to 10th	Day	14% 5% 2 4 4 3 3 4 4 7% 50%	1800
	11th to 20th	Day	13% 6% 3 4 4 2 4 3 3 4 53%	1800
	21st to end	Day	16% 8% 3 5% 4 2 4 3 5% 6% 46%	1980
November	1st to 10th	Day	9% 6% 3 4 4 2 4 4 5% 6% 53%	1844
	11th to 20th	Day	15% 6% 3 5% 5% 2 2 3 4 6% 48%	1573
	21st to end	Day	17% 9% 3 5% 4 2 4 3 4 5% 43%	1520
December	1st to 10th	Day	11% 8% 5% 6% 5% 3 4 4 5% 7% 42%	1520
	11th to 20th	Day	13% 9% 4 7% 5% 2 4 4 4 5% 41%	1918
	21st to end	Day	18% 14% 9% 9% 6% 3 3 4 4 4 24%	2783
January	1st to 10th	Night	9% 9% 4 6% 5% 3 4 4 4 6% 45%	2520
	11th to 20th	Night	13% 8% 5% 7% 6% 4 5% 5% 5% 6% 36%	2379
	21st to end	Night	10% 10% 4 8% 6% 3 4 4 5% 7% 38%	2574
February	1st to 10th	Night	14% 9% 5% 8% 6% 3 4 4 5% 6% 36%	2340
	11th to 20th	Night	14% 8% 3 7% 4 3 4 4 5% 7% 40%	2273
	21st to end	Night	14% 9% 3 5% 4 2 4 3 4 6% 45%	1775
March	1st to 10th	Night	14% 7% 3 5% 4 2 3 4 4 7% 48%	1980
	11th to 20th	Night	17% 8% 3 7% 5% 2 4 4 5% 7% 37%	1980
	21st to end	Night	22% 11% 3 6% 5% 4 5% 4 5% 5% 29%	2178
April	1st to 10th	Night	11% 7% 3 4 4 3 5% 4 4 7% 48%	1826
	11th to 20th	Night	14% 7% 3 6% 5% 3 4 3 4 6% 45%	1775
	21st to end	Night	17% 7% 3 6% 5% 3 4 3 5% 6% 42%	1733
May	1st to 10th	Night	14% 6% 2 5% 5% 3 6% 4 6% 9% 40%	1620
	11th to 20th	Night	14% 6% 2 5% 5% 2 4 4 5% 8% 45%	1568
	21st to end	Night	10% 5% 3 6% 6% 3 5% 5% 5% 8% 44%	1551
June	1st to 10th	Night	5% 3 2 3 4 2 4 6% 7% 10% 54%	1440
	11th to 20th	Night	5% 3 1 5% 5% 2 6% 5% 6% 11% 49%	1440
	21st to end	Night	4 3 2 4 4 2 4 5% 5% 9% 58%	1440
July	1st to 10th	Night	7% 4 2 3 5% 2 3 6% 6% 10% 52%	1440
	11th to 20th	Night	4 2 2 3 3 3 4 4 7% 8% 58%	1608
	21st to end	Night	6% 3 2 5% 6% 2 4 5% 5% 8% 54%	1772
August	1st to 10th	Night	5% 2 2 4 5% 4 5% 5% 6% 11% 50%	1611
	11th to 20th	Night	6% 4 2 4 4 3 3 5% 4 9% 57%	1600
	21st to end	Night	5% 3 2 4 4 2 3 4 4 7% 61%	1970
September	1st to 10th	Night	11% 4 2 4 3 2 4 4 4 6% 57%	1800
	11th to 20th	Night	10% 4 1 3 3 2 4 4 6% 8% 55%	1868
	21st to end	Night	7% 4 2 4 4 2 3 4 4 6% 58%	2024
October	1st to 10th	Night	11% 4 2 4 4 2 4 3 3 6% 56%	2160
	11th to 20th	Night	14% 4 2 4 4 2 4 3 4 4 54%	2160
	21st to end	Night	17% 7% 3 5% 4 1 3 3 3 5% 50%	2376
November	1st to 10th	Night	10% 4 2 3 2 2 3 4 4 6% 59%	2233
	11th to 20th	Night	12% 5% 3 4 4 2 4 4 4 6% 52%	2606
	21st to end	Night	17% 7% 3 5% 4 3 3 3 4 5% 47%	2660
December	1st to 10th	Night	12% 8% 3 5% 6% 3 5% 4 5% 6% 43%	2660
	11th to 20th	Night	13% 8% 3 7% 5% 2 4 5% 5% 6% 43%	3279
	21st to end	Night	21% 16% 6% 9% 5% 2 3 3 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	46% 5% 12% 21% 14% 1	1641
	11th to 20th	Day	53% 4 10% 23% 10%	1638
	21st to end	Day	52% 6% 13% 19% 9% 1	1782
February	1st to 10th	Day	50% 5% 14% 19% 10% 2	1620
	11th to 20th	Day	46% 4 14% 21% 13% 2	1583
	21st to end	Day	46% 4 12% 23% 13% 2	1494
March	1st to 10th	Day	46% 5% 12% 23% 12% 2	1980
	11th to 20th	Day	51% 5% 8% 23% 11% 2	1980
	21st to end	Day	58% 6% 12% 17% 6% 1	2178
April	1st to 10th	Day	43% 4 13% 25% 13% 1	2132
	11th to 20th	Day	46% 4 12% 24% 13% 1	2134
	21st to end	Day	50% 5% 11% 21% 11% 1	2223
May	1st to 10th	Day	49% 7% 12% 20% 11% 1	2340
	11th to 20th	Day	46% 6% 13% 23% 11% 1	2331
	21st to end	Day	46% 7% 13% 21% 11% 1	2725
June	1st to 10th	Day	31% 9% 15% 30% 13% 2	2520
	11th to 20th	Day	32% 8% 14% 26% 18% 2	2520
	21st to end	Day	31% 7% 17% 27% 14% 3	2520
July	1st to 10th	Day	32% 8% 16% 27% 13% 4	2451
	11th to 20th	Day	29% 7% 17% 27% 17% 3	2278
	21st to end	Day	32% 8% 13% 31% 15% 1	2405
August	1st to 10th	Day	33% 9% 19% 24% 14% 1	2314
	11th to 20th	Day	33% 7% 13% 29% 17% 1	2301
	21st to end	Day	28% 7% 14% 26% 20% 6%	2386
September	1st to 10th	Day	32% 6% 13% 25% 18% 6%	2160
	11th to 20th	Day	30% 6% 12% 27% 22% 3	2088
	21st to end	Day	30% 5% 10% 32% 21% 3	1918
October	1st to 10th	Day	34% 4 12% 27% 19% 3	1800
	11th to 20th	Day	36% 5% 7% 27% 22% 5%	1800
	21st to end	Day	40% 6% 10% 22% 18% 4	1980
November	1st to 10th	Day	32% 4 15% 27% 19% 4	1844
	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	41% 5% 11% 26% 16% 1	2520
	11th to 20th	Night	47% 6% 13% 23% 10% 1	2379
	21st to end	Night	46% 5% 15% 21% 11% 2	2574
February	1st to 10th	Night	49% 6% 11% 20% 12% 2	2340
	11th to 20th	Night	43% 5% 12% 22% 16% 2	2274
	21st to end	Night	41% 4 10% 23% 17% 4	1775
March	1st to 10th	Night	38% 4 12% 26% 17% 3	1980
	11th to 20th	Night	46% 5% 10% 22% 14% 2	1980
	21st to end	Night	56% 5% 13% 17% 8% 1	2178
April	1st to 10th	Night	36% 5% 10% 27% 18% 3	1826
	11th to 20th	Night	41% 5% 8% 27% 15% 3	1775
	21st to end	Night	44% 5% 10% 23% 16% 2	1733
May	1st to 10th	Night	41% 8% 14% 23% 13% 2	1620
	11th to 20th	Night	38% 6% 14% 24% 16% 1	1569
	21st to end	Night	38% 8% 13% 27% 13% 2	1552
June	1st to 10th	Night	23% 8% 18% 31% 16% 3	1440
	11th to 20th	Night	28% 8% 12% 26% 20% 5%	1440
	21st to end	Night	23% 6% 16% 32% 19% 4	1440
July	1st to 10th	Night	26% 7% 15% 30% 18% 4	1400
	11th to 20th	Night	21% 8% 14% 32% 21% 3	1555
	21st to end	Night	25% 6% 14% 35% 18% 1	1673
August	1st to 10th	Night	26% 7% 18% 30% 15% 2	1601
	11th to 20th	Night	26% 6% 12% 34% 22% 2	1600
	21st to end	Night	23% 5% 13% 26% 26% 7%	1970
September	1st to 10th	Night	29% 5% 12% 26% 22% 7%	1800
	11th to 20th	Night	27% 6% 12% 28% 24% 4	1868
	21st to end	Night	27% 5% 9% 29% 25% 4	2024
October	1st to 10th	Night	31% 4 11% 25% 24% 5%	2160
	11th to 20th	Night	34% 4 7% 25% 22% 8%	2160
	21st to end	Night	38% 4 10% 22% 23% 3	2376
November	1st to 10th	Night	27% 4 15% 25% 23% 6%	2233
	11th to 20th	Night	34% 4 9% 29% 20% 4	2606
	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	28% 17% 37% 17% 1	246
	21st to end	Day	13% 17% 49% 19% 2	264
February	1st to 10th	Day	23% 20% 39% 16% 2	240
	11th to 20th	Day	21% 21% 38% 14% 7%	240
	21st to end	Day	23% 21% 37% 15% 3	198
March	1st to 10th	Day	18% 16% 46% 19% 1	240
	11th to 20th	Day	30% 10% 33% 23% 5%	240
	21st to end	Day	41% 15% 28% 13% 3	264
April	1st to 10th	Day	20% 15% 34% 24% 7%	392
	11th to 20th	Day	18% 13% 37% 23% 8% 1	412
	21st to end	Day	22% 15% 31% 23% 8% 1	483
May	1st to 10th	Day	19% 11% 37% 22% 10% 1	603
	11th to 20th	Day	22% 8% 29% 27% 11% 3	625
	21st to end	Day	16% 6% 28% 27% 19% 4	679
June	1st to 10th	Day	7% 4 20% 35% 25% 10%	630
	11th to 20th	Day	8% 4 23% 37% 22% 5%	630
	21st to end	Day	8% 5% 32% 35% 18% 3	630
July	1st to 10th	Day	10% 3 12% 31% 31% 13%	621
	11th to 20th	Day	6% 3 19% 35% 28% 9%	618
	21st to end	Day	7% 2 15% 36% 34% 6%	684
August	1st to 10th	Day	7% 3 15% 41% 28% 7%	626
	11th to 20th	Day	9% 3 15% 34% 32% 7%	615
	21st to end	Day	9% 2 14% 31% 33% 12%	505
September	1st to 10th	Day	14% 4 15% 33% 28% 7%	450
	11th to 20th	Day	8% 2 19% 35% 27% 9%	378
	21st to end	Day	10% 7% 25% 31% 20% 7%	270
October	1st to 10th	Day	17% 5% 30% 27% 14% 6%	270
	11th to 20th	Day	13% 25% 36% 19% 7%	270
	21st to end	Day	23% 13% 34% 22% 7% 1	297
November	1st to 10th	Day	15% 10% 39% 24% 8% 4	270
	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% 14% 37% 25% 5% 1	915
	21st to end	Night	16% 12% 39% 29% 3	990
February	1st to 10th	Night	17% 13% 42% 24% 4	900
	11th to 20th	Night	19% 12% 38% 27% 4	879
	21st to end	Night	20% 14% 41% 20% 4 1	591
March	1st to 10th	Night	18% 12% 38% 26% 6%	540
	11th to 20th	Night	21% 10% 33% 29% 5% 1	540
	21st to end	Night	28% 8% 35% 23% 5%	594
April	1st to 10th	Night	15% 10% 41% 30% 4	540
	11th to 20th	Night	19% 11% 34% 28% 8%	533
	21st to end	Night	21% 9% 35% 28% 6% 1	540
May	1st to 10th	Night	16% 8% 35% 32% 9% 1	540
	11th to 20th	Night	17% 5% 28% 35% 15% 1	531
	21st to end	Night	12% 5% 24% 38% 18% 2	584
June	1st to 10th	Night	5% 4 20% 44% 24% 4	540
	11th to 20th	Night	7% 3 24% 46% 18% 2	540
	21st to end	Night	6% 2 25% 49% 18% 1	540
July	1st to 10th	Night	10% 2 10% 38% 36% 5%	525
	11th to 20th	Night	5% 2 16% 45% 29% 2	522
	21st to end	Night	7% 1 12% 45% 33% 2	591
August	1st to 10th	Night	6% 1 14% 48% 29% 1	537
	11th to 20th	Night	7% 2 12% 43% 33% 3	534
	21st to end	Night	6% 2 11% 41% 37% 4	594
September	1st to 10th	Night	11% 2 16% 40% 26% 4	540
	11th to 20th	Night	12% 2 17% 39% 26% 4	540
	21st to end	Night	8% 4 24% 40% 21% 3	584
October	1st to 10th	Night	13% 4 30% 33% 17% 3	720
	11th to 20th	Night	16% 9% 34% 32% 9%	720
	21st to end	Night	22% 9% 33% 27% 8%	792
November	1st to 10th	Night	11% 10% 34% 35% 10% 1	740
	11th to 20th	Night	15% 12% 39% 26% 8%	896
	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 2024-01-10 09:16:12. Version ac07

Copyright 2024 Attilla Danko