Bad Creek Hydroelectric Dam
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bad Creek Hydroelectric Dam clear sky chart from 2005-11-06 to 2024-04-03.

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	16% 5% 2 5% 5% 3 5% 5% 6% 7% 42%	79209
	Night	17% 5% 2 4 4 3 4 4 5% 7% 45%	80929
Transparency	Day	27% 36% 7% 13% 13% 4	78932
	Night	27% 35% 7% 13% 14% 4	80725
Seeing	Day	19% 13% 24% 23% 14% 7%	14153
	Night	18% 11% 21% 27% 19% 4	24322

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	18% 4 2 3 3 2 3 3 5% 7% 51%	2836
	11th to 20th	Day	16% 5% 3 5% 4 2 3 3 2 4 53%	2840
	21st to end	Day	27% 3 1 2 2 2 3 3 4 4 48%	3124
February	1st to 10th	Day	17% 5% 3 5% 5% 3 3 4 5% 6% 45%	1843
	11th to 20th	Day	20% 5% 2 4 5% 2 4 4 4 5% 44%	1848
	21st to end	Day	21% 6% 2 5% 5% 3 4 3 4 4 42%	1570
March	1st to 10th	Day	18% 5% 2 3 3 2 3 3 5% 7% 48%	2019
	11th to 20th	Day	21% 5% 2 4 3 3 4 4 4 6% 42%	2090
	21st to end	Day	20% 5% 2 5% 4 2 4 4 6% 6% 41%	2299
April	1st to 10th	Day	13% 4 2 3 5% 2 5% 5% 6% 9% 45%	2002
	11th to 20th	Day	15% 5% 2 6% 5% 3 4 5% 6% 7% 43%	2144
	21st to end	Day	14% 4 2 4 4 3 4 4 5% 7% 49%	2340
May	1st to 10th	Day	12% 5% 2 6% 6% 3 4 5% 5% 8% 45%	2340
	11th to 20th	Day	18% 6% 1 5% 6% 4 6% 6% 6% 6% 36%	2301
	21st to end	Day	15% 4 2 5% 5% 3 6% 6% 7% 10% 37%	2531
June	1st to 10th	Day	13% 5% 2 5% 6% 4 6% 7% 8% 9% 32%	2340
	11th to 20th	Day	8% 5% 2 5% 7% 4 7% 7% 8% 10% 36%	2340
	21st to end	Day	8% 5% 2 5% 7% 5% 7% 7% 7% 11% 35%	2340
July	1st to 10th	Day	10% 5% 3 8% 7% 5% 9% 8% 9% 11% 26%	2340
	11th to 20th	Day	10% 5% 3 7% 8% 5% 8% 8% 8% 11% 27%	2340
	21st to end	Day	9% 5% 3 7% 9% 5% 8% 7% 8% 9% 30%	2547
August	1st to 10th	Day	13% 6% 3 6% 6% 5% 8% 8% 7% 10% 28%	2327
	11th to 20th	Day	14% 5% 2 6% 7% 4 6% 7% 7% 11% 30%	2303
	21st to end	Day	13% 6% 3 6% 7% 3 6% 7% 8% 9% 31%	2346
September	1st to 10th	Day	12% 6% 2 6% 5% 4 6% 6% 8% 8% 37%	1980
	11th to 20th	Day	17% 6% 2 5% 6% 3 5% 6% 7% 8% 35%	1980
	21st to end	Day	18% 5% 1 6% 5% 3 4 5% 5% 6% 42%	1980
October	1st to 10th	Day	17% 4 1 3 3 2 3 3 4 6% 52%	1978
	11th to 20th	Day	13% 4 2 3 3 2 3 4 5% 5% 56%	1800
	21st to end	Day	15% 4 1 3 3 2 3 3 4 5% 57%	1980
November	1st to 10th	Day	13% 4 2 3 3 2 3 3 3 5% 59%	1754
	11th to 20th	Day	16% 4 2 3 3 1 3 3 4 6% 55%	1710
	21st to end	Day	17% 4 2 3 3 2 4 4 4 7% 51%	1710
December	1st to 10th	Day	22% 6% 2 5% 4 3 4 4 5% 7% 39%	1710
	11th to 20th	Day	19% 4 2 3 3 2 3 3 4 5% 51%	2153
	21st to end	Day	23% 4 2 3 3 2 3 3 5% 6% 46%	3124
January	1st to 10th	Night	19% 5% 1 3 3 2 3 3 4 5% 51%	4109
	11th to 20th	Night	15% 5% 2 5% 5% 2 3 3 4 6% 50%	4120
	21st to end	Night	26% 5% 2 3 3 2 4 3 3 4 45%	4532
February	1st to 10th	Night	16% 5% 2 4 4 2 3 3 5% 6% 49%	2333
	11th to 20th	Night	21% 5% 1 4 5% 2 4 4 5% 4 45%	2218
	21st to end	Night	22% 5% 2 5% 4 3 4 4 4 7% 41%	1884
March	1st to 10th	Night	17% 6% 2 3 4 2 4 4 4 6% 48%	2159
	11th to 20th	Night	17% 5% 2 3 4 3 4 4 5% 7% 45%	2090
	21st to end	Night	20% 5% 2 5% 5% 2 4 4 4 6% 44%	2299
April	1st to 10th	Night	14% 5% 2 4 4 2 3 4 5% 6% 51%	2003
	11th to 20th	Night	16% 5% 2 4 3 2 3 2 5% 6% 52%	1779
	21st to end	Night	13% 3 2 4 3 2 4 4 4 8% 52%	1620
May	1st to 10th	Night	13% 5% 2 4 4 3 4 5% 6% 6% 47%	1620
	11th to 20th	Night	17% 7% 2 4 5% 4 5% 5% 5% 7% 40%	1592
	21st to end	Night	15% 5% 2 4 4 3 5% 5% 6% 9% 41%	1744
June	1st to 10th	Night	12% 5% 3 6% 5% 4 6% 6% 9% 12% 34%	1620
	11th to 20th	Night	9% 5% 2 5% 5% 4 5% 4 7% 10% 43%	1620
	21st to end	Night	9% 4 2 4 5% 3 5% 7% 9% 10% 41%	1620
July	1st to 10th	Night	11% 6% 3 5% 6% 4 7% 8% 8% 10% 31%	1620
	11th to 20th	Night	10% 5% 3 6% 6% 4 8% 7% 9% 12% 31%	1620
	21st to end	Night	8% 5% 3 6% 6% 4 5% 8% 9% 11% 35%	1771
August	1st to 10th	Night	14% 6% 2 6% 7% 4 5% 5% 7% 11% 33%	1611
	11th to 20th	Night	15% 7% 3 5% 5% 3 6% 5% 6% 10% 34%	1598
	21st to end	Night	13% 8% 3 5% 5% 4 5% 5% 7% 11% 34%	1987
September	1st to 10th	Night	14% 5% 2 5% 6% 3 4 5% 7% 8% 39%	1980
	11th to 20th	Night	18% 6% 3 5% 5% 3 5% 5% 6% 8% 37%	1980
	21st to end	Night	17% 6% 2 4 5% 2 4 4 3 7% 46%	1980
October	1st to 10th	Night	18% 5% 1 4 3 3 3 3 4 5% 52%	1980
	11th to 20th	Night	16% 4 3 4 4 3 3 3 3 5% 52%	2160
	21st to end	Night	16% 3 1 3 3 2 4 3 3 4 58%	2376
November	1st to 10th	Night	16% 4 2 4 3 1 3 3 4 5% 57%	2320
	11th to 20th	Night	17% 5% 2 3 3 2 3 4 4 5% 54%	2470
	21st to end	Night	17% 3 2 3 3 3 4 5% 5% 6% 48%	2470
December	1st to 10th	Night	22% 6% 3 5% 4 3 3 4 4 5% 42%	2470
	11th to 20th	Night	17% 5% 2 3 4 2 3 3 4 5% 54%	3042
	21st to end	Night	24% 5% 2 3 4 2 4 4 5% 7% 39%	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	25% 25% 3 18% 21% 8%	2837
	11th to 20th	Day	28% 25% 4 10% 24% 10%	2840
	21st to end	Day	34% 22% 3 13% 19% 8%	3124
February	1st to 10th	Day	27% 34% 5% 13% 15% 5%	1843
	11th to 20th	Day	28% 35% 4 13% 16% 5%	1858
	21st to end	Day	30% 33% 6% 12% 13% 6%	1570
March	1st to 10th	Day	23% 34% 5% 15% 17% 6%	2019
	11th to 20th	Day	30% 36% 6% 10% 12% 5%	2090
	21st to end	Day	31% 36% 8% 13% 11% 1	2299
April	1st to 10th	Day	21% 37% 7% 16% 14% 5%	2002
	11th to 20th	Day	24% 36% 5% 13% 17% 6%	2144
	21st to end	Day	23% 37% 7% 18% 12% 3	2340
May	1st to 10th	Day	27% 38% 10% 11% 11% 3	2340
	11th to 20th	Day	31% 40% 9% 11% 8% 1	2305
	21st to end	Day	26% 40% 10% 16% 8%	2531
June	1st to 10th	Day	27% 41% 13% 14% 5% 1	2340
	11th to 20th	Day	25% 40% 12% 14% 7% 1	2340
	21st to end	Day	25% 41% 10% 13% 8% 2	2340
July	1st to 10th	Day	33% 42% 10% 9% 5% 1	2275
	11th to 20th	Day	30% 43% 11% 7% 6% 2	2271
	21st to end	Day	28% 43% 14% 11% 4	2405
August	1st to 10th	Day	28% 42% 11% 15% 4	2314
	11th to 20th	Day	32% 40% 10% 13% 5% 1	2303
	21st to end	Day	31% 41% 9% 12% 5% 1	2346
September	1st to 10th	Day	27% 41% 9% 12% 10% 2	1980
	11th to 20th	Day	30% 39% 7% 12% 11% 1	1980
	21st to end	Day	27% 38% 6% 11% 13% 6%	1980
October	1st to 10th	Day	19% 36% 5% 13% 21% 5%	1978
	11th to 20th	Day	22% 36% 6% 16% 14% 7%	1800
	21st to end	Day	20% 37% 5% 13% 18% 8%	1980
November	1st to 10th	Day	14% 40% 5% 11% 22% 8%	1754
	11th to 20th	Day	21% 39% 4 14% 17% 5%	1710
	21st to end	Day	23% 39% 4 13% 15% 6%	1710
December	1st to 10th	Day	28% 40% 4 12% 12% 5%	1710
	11th to 20th	Day	26% 31% 6% 11% 16% 10%	2150
	21st to end	Day	25% 25% 7% 17% 21% 4	3124
January	1st to 10th	Night	26% 26% 5% 14% 23% 7%	4109
	11th to 20th	Night	27% 26% 4 10% 23% 10%	4120
	21st to end	Night	38% 22% 4 11% 17% 8%	4532
February	1st to 10th	Night	25% 34% 6% 14% 16% 5%	2333
	11th to 20th	Night	27% 35% 4 12% 16% 6%	2219
	21st to end	Night	28% 35% 6% 9% 17% 5%	1884
March	1st to 10th	Night	24% 35% 5% 13% 16% 7%	2159
	11th to 20th	Night	27% 35% 8% 12% 13% 4	2090
	21st to end	Night	29% 35% 6% 15% 12% 2	2299
April	1st to 10th	Night	22% 36% 7% 15% 17% 3	2003
	11th to 20th	Night	20% 34% 5% 17% 18% 5%	1779
	21st to end	Night	21% 37% 9% 17% 13% 2	1620
May	1st to 10th	Night	25% 39% 10% 12% 12% 1	1620
	11th to 20th	Night	30% 40% 11% 11% 7% 1	1593
	21st to end	Night	26% 40% 10% 16% 7% 1	1745
June	1st to 10th	Night	25% 42% 11% 16% 5%	1620
	11th to 20th	Night	24% 39% 14% 16% 6% 1	1620
	21st to end	Night	23% 42% 12% 10% 9% 4	1620
July	1st to 10th	Night	31% 43% 12% 7% 6% 1	1575
	11th to 20th	Night	28% 44% 14% 7% 5% 2	1566
	21st to end	Night	26% 44% 16% 11% 3 1	1672
August	1st to 10th	Night	27% 41% 13% 13% 6%	1600
	11th to 20th	Night	31% 40% 10% 11% 7% 1	1598
	21st to end	Night	33% 40% 11% 11% 3 2	1987
September	1st to 10th	Night	28% 40% 9% 12% 8% 3	1980
	11th to 20th	Night	31% 39% 7% 12% 10% 1	1980
	21st to end	Night	26% 37% 4 14% 14% 5%	1980
October	1st to 10th	Night	22% 37% 6% 11% 21% 4	1980
	11th to 20th	Night	25% 36% 5% 14% 14% 5%	2160
	21st to end	Night	21% 36% 3 15% 18% 7%	2376
November	1st to 10th	Night	15% 40% 5% 12% 19% 9%	2320
	11th to 20th	Night	23% 39% 3 11% 18% 6%	2470
	21st to end	Night	24% 39% 3 14% 15% 5%	2470
December	1st to 10th	Night	26% 40% 4 12% 13% 5%	2470
	11th to 20th	Night	24% 32% 6% 11% 23% 5%	3044
	21st to end	Night	31% 26% 6% 15% 17% 5%	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	26% 26% 33% 13% 1	270
	11th to 20th	Day	31% 25% 28% 15% 1	270
	21st to end	Day	29% 28% 34% 6% 2	297
February	1st to 10th	Day	24% 26% 38% 10% 1	270
	11th to 20th	Day	36% 30% 28% 6%	270
	21st to end	Day	36% 32% 25% 5% 1	225
March	1st to 10th	Day	27% 21% 31% 15% 6%	389
	11th to 20th	Day	25% 24% 31% 16% 4 1	460
	21st to end	Day	26% 22% 29% 17% 6% 1	506
April	1st to 10th	Day	23% 18% 29% 20% 8% 1	428
	11th to 20th	Day	17% 22% 27% 22% 11% 1	412
	21st to end	Day	19% 16% 25% 23% 12% 4	420
May	1st to 10th	Day	14% 20% 32% 18% 9% 6%	423
	11th to 20th	Day	20% 8% 22% 26% 15% 8%	447
	21st to end	Day	19% 8% 17% 28% 15% 13%	485
June	1st to 10th	Day	14% 6% 20% 31% 18% 11%	450
	11th to 20th	Day	13% 6% 20% 22% 24% 14%	450
	21st to end	Day	12% 5% 24% 29% 17% 13%	450
July	1st to 10th	Day	9% 5% 14% 27% 27% 18%	445
	11th to 20th	Day	8% 2 12% 31% 26% 21%	444
	21st to end	Day	9% 2 13% 30% 25% 20%	488
August	1st to 10th	Day	19% 4 16% 22% 22% 16%	446
	11th to 20th	Day	11% 3 13% 31% 28% 14%	439
	21st to end	Day	15% 3 13% 25% 30% 15%	495
September	1st to 10th	Day	11% 4 14% 29% 30% 11%	450
	11th to 20th	Day	17% 4 13% 28% 27% 10%	450
	21st to end	Day	20% 6% 17% 30% 21% 6%	450
October	1st to 10th	Day	21% 6% 22% 26% 17% 8%	450
	11th to 20th	Day	14% 12% 26% 30% 14% 3	450
	21st to end	Day	20% 10% 27% 30% 11% 3	495
November	1st to 10th	Day	20% 12% 28% 24% 13% 2	352
	11th to 20th	Day	21% 21% 33% 21% 4	270
	21st to end	Day	13% 18% 44% 17% 6% 1	270
December	1st to 10th	Day	28% 24% 32% 13% 2	270
	11th to 20th	Day	24% 18% 39% 14% 5%	270
	21st to end	Day	31% 18% 37% 11% 3 1	297
January	1st to 10th	Night	23% 18% 30% 24% 5%	760
	11th to 20th	Night	20% 20% 29% 25% 6%	760
	21st to end	Night	21% 18% 34% 24% 3	836
February	1st to 10th	Night	18% 17% 29% 32% 4	760
	11th to 20th	Night	23% 19% 34% 21% 2	743
	21st to end	Night	24% 21% 30% 22% 3	628
March	1st to 10th	Night	19% 17% 30% 27% 6%	760
	11th to 20th	Night	20% 16% 31% 23% 8% 1	760
	21st to end	Night	21% 15% 30% 23% 9%	836
April	1st to 10th	Night	17% 19% 27% 26% 9% 1	729
	11th to 20th	Night	20% 13% 24% 26% 16% 2	593
	21st to end	Night	14% 11% 21% 32% 20% 1	540
May	1st to 10th	Night	16% 12% 23% 26% 21% 2	540
	11th to 20th	Night	19% 7% 19% 27% 25% 3	531
	21st to end	Night	17% 3 12% 26% 34% 9%	584
June	1st to 10th	Night	14% 3 11% 33% 31% 7%	540
	11th to 20th	Night	9% 4 15% 25% 33% 14%	540
	21st to end	Night	8% 3 12% 31% 38% 7%	540
July	1st to 10th	Night	12% 2 9% 23% 43% 10%	525
	11th to 20th	Night	12% 2 7% 26% 40% 14%	522
	21st to end	Night	8% 2 8% 28% 42% 12%	591
August	1st to 10th	Night	16% 2 9% 23% 39% 12%	537
	11th to 20th	Night	16% 3 10% 24% 38% 9%	534
	21st to end	Night	15% 3 8% 25% 37% 11%	625
September	1st to 10th	Night	15% 4 10% 26% 36% 9%	720
	11th to 20th	Night	21% 3 13% 22% 35% 6%	720
	21st to end	Night	19% 4 14% 34% 24% 5%	720
October	1st to 10th	Night	18% 8% 18% 23% 25% 8%	720
	11th to 20th	Night	19% 10% 18% 29% 21% 3	720
	21st to end	Night	18% 10% 19% 33% 16% 4	792
November	1st to 10th	Night	17% 6% 20% 33% 20% 3	740
	11th to 20th	Night	17% 14% 24% 31% 12% 2	760
	21st to end	Night	18% 13% 21% 32% 13% 2	760
December	1st to 10th	Night	24% 15% 23% 31% 7%	760
	11th to 20th	Night	20% 13% 26% 31% 9% 1	760
	21st to end	Night	29% 13% 24% 27% 6%	836

Page generated at 2024-03-31 06:08:53. Version ac07

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