Lockwood Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lockwood Valley clear sky chart from 2005-11-06 to 2024-01-12.

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	3 3 1 3 3 2 3 3 4 6% 68%	74778
	Night	3 3 1 3 3 2 4 4 4 6% 65%	74936
Transparency	Day	18% 2 4 17% 30% 29%	74498
	Night	18% 2 4 17% 30% 29%	74738
Seeing	Day	8% 11% 27% 32% 16% 6%	14386
	Night	6% 6% 18% 35% 28% 7%	24196

By Month

Percentage Cloud Cover SW (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	6% 5% 2 6% 6% 3 5% 4 6% 8% 50%	1528
	11th to 20th	Day	5% 4 2 5% 4 3 4 3 4 7% 59%	1630
	21st to end	Day	7% 9% 3 5% 4 3 3 3 4 7% 52%	1823
February	1st to 10th	Day	6% 7% 2 4 4 2 4 4 4 6% 58%	1800
	11th to 20th	Day	4 7% 2 4 4 2 5% 4 5% 7% 56%	1750
	21st to end	Day	5% 7% 2 5% 5% 2 4 3 4 6% 56%	1480
March	1st to 10th	Day	5% 7% 3 5% 6% 3 6% 5% 6% 7% 47%	1800
	11th to 20th	Day	3 7% 3 4 4 3 5% 5% 6% 9% 51%	1913
	21st to end	Day	4 4 2 5% 4 2 4 5% 5% 7% 58%	2347
April	1st to 10th	Day	5% 4 2 4 4 3 4 4 4 8% 57%	2160
	11th to 20th	Day	3 3 2 3 3 2 4 3 5% 6% 66%	2129
	21st to end	Day	2 3 2 2 2 2 4 4 5% 7% 68%	2160
May	1st to 10th	Day	3 3 1 3 2 2 3 4 4 7% 67%	2160
	11th to 20th	Day	1 2 1 3 2 2 4 4 4 7% 71%	2296
	21st to end	Day	3 3 1 3 3 2 4 3 4 7% 69%	2544
June	1st to 10th	Day	1 2 1 2 3 2 3 3 4 7% 71%	2520
	11th to 20th	Day	1 1 1 1 1 2 2 3 4 84%	2520
	21st to end	Day	1 1 1 1 1 2 2 2 4 85%	2520
July	1st to 10th	Day	1 1 1 2 1 2 2 4 5% 81%	2520
	11th to 20th	Day	2 1 1 2 2 1 2 3 5% 6% 75%	2477
	21st to end	Day	2 1 1 2 2 1 3 3 5% 7% 73%	2474
August	1st to 10th	Day	1 1 1 2 2 1 2 3 3 5% 79%	2149
	11th to 20th	Day	1 1 1 1 1 2 3 5% 84%	2122
	21st to end	Day	1 1 1 2 2 1 2 2 3 4 81%	2376
September	1st to 10th	Day	1 1 1 2 2 2 3 3 5% 80%	2160
	11th to 20th	Day	1 2 1 1 2 3 4 86%	2083
	21st to end	Day	1 1 1 2 1 1 3 2 2 4 82%	1980
October	1st to 10th	Day	3 2 1 2 2 2 3 3 4 5% 73%	1942
	11th to 20th	Day	2 1 1 2 2 1 3 3 3 4 78%	1800
	21st to end	Day	1 2 1 2 2 2 2 4 3 6% 74%	1980
November	1st to 10th	Day	2 3 1 3 3 2 3 4 5% 5% 69%	1692
	11th to 20th	Day	2 4 2 3 3 2 3 4 5% 6% 67%	1710
	21st to end	Day	3 4 2 5% 4 2 5% 4 5% 7% 58%	1710
December	1st to 10th	Day	3 6% 3 5% 3 3 5% 5% 5% 7% 55%	1710
	11th to 20th	Day	8% 9% 3 5% 6% 3 5% 6% 6% 9% 41%	2019
	21st to end	Day	5% 9% 3 7% 7% 4 5% 5% 5% 7% 43%	2794
January	1st to 10th	Night	5% 6% 2 4 4 3 6% 5% 6% 8% 50%	2632
	11th to 20th	Night	3 4 2 4 4 2 5% 5% 5% 7% 58%	2353
	21st to end	Night	6% 6% 2 5% 5% 3 6% 4 5% 6% 53%	2529
February	1st to 10th	Night	5% 6% 3 4 4 3 6% 4 4 6% 56%	2160
	11th to 20th	Night	4 4 2 4 4 3 5% 4 5% 6% 59%	2098
	21st to end	Night	4 4 3 6% 4 3 6% 4 5% 6% 55%	1776
March	1st to 10th	Night	5% 5% 3 5% 5% 4 8% 5% 7% 9% 45%	2160
	11th to 20th	Night	2 5% 2 5% 4 4 7% 6% 6% 8% 49%	2044
	21st to end	Night	3 4 2 3 4 5% 7% 5% 6% 7% 55%	2008
April	1st to 10th	Night	3 4 3 4 4 3 4 5% 6% 8% 56%	1800
	11th to 20th	Night	3 2 1 2 3 3 5% 4 5% 6% 67%	1779
	21st to end	Night	2 1 1 1 2 2 4 4 5% 8% 69%	1800
May	1st to 10th	Night	2 1 1 2 3 2 3 4 5% 7% 69%	1800
	11th to 20th	Night	2 2 1 2 1 1 2 3 3 6% 76%	1594
	21st to end	Night	2 2 1 2 2 1 3 3 4 6% 75%	1727
June	1st to 10th	Night	1 2 1 1 2 1 3 3 4 6% 76%	1440
	11th to 20th	Night	1 1 1 1 2 2 4 88%	1440
	21st to end	Night	1 1 1 1 1 1 3 90%	1440
July	1st to 10th	Night	1 1 1 1 2 2 2 3 4 83%	1440
	11th to 20th	Night	1 1 1 1 1 2 3 3 4 82%	1479
	21st to end	Night	1 1 1 2 2 2 2 3 3 4 80%	1842
August	1st to 10th	Night	1 1 1 2 1 2 3 2 4 82%	1790
	11th to 20th	Night	1 1 1 1 1 2 2 3 3 87%	1780
	21st to end	Night	1 1 1 1 1 2 1 1 3 87%	1980
September	1st to 10th	Night	1 1 1 1 1 1 2 1 2 2 88%	1800
	11th to 20th	Night	1 1 1 2 2 3 3 87%	1876
	21st to end	Night	1 1 1 2 2 3 4 85%	1980
October	1st to 10th	Night	2 1 1 2 3 2 4 3 4 5% 75%	2015
	11th to 20th	Night	1 1 1 2 3 2 3 3 4 6% 73%	2160
	21st to end	Night	1 2 1 1 2 2 3 3 4 5% 76%	2376
November	1st to 10th	Night	1 2 1 3 3 3 5% 4 5% 8% 64%	2385
	11th to 20th	Night	2 3 1 3 4 3 5% 4 4 7% 65%	2470
	21st to end	Night	3 4 2 4 4 3 5% 5% 5% 8% 57%	2470
December	1st to 10th	Night	5% 5% 2 5% 4 4 4 4 5% 9% 55%	2470
	11th to 20th	Night	8% 10% 3 6% 6% 3 6% 5% 6% 8% 39%	3181
	21st to end	Night	6% 8% 3 5% 6% 4 6% 5% 6% 8% 43%	4862

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	30% 3 5% 18% 28% 16%	1528
	11th to 20th	Day	26% 2 6% 13% 30% 22%	1630
	21st to end	Day	31% 2 5% 18% 25% 19%	1823
February	1st to 10th	Day	27% 2 2 18% 27% 24%	1800
	11th to 20th	Day	25% 2 4 18% 30% 21%	1760
	21st to end	Day	29% 2 3 20% 29% 16%	1480
March	1st to 10th	Day	32% 4 6% 21% 22% 16%	1800
	11th to 20th	Day	28% 3 7% 21% 24% 16%	1913
	21st to end	Day	25% 2 9% 26% 27% 11%	2347
April	1st to 10th	Day	24% 3 9% 25% 25% 14%	2160
	11th to 20th	Day	18% 2 7% 25% 33% 15%	2132
	21st to end	Day	15% 3 8% 25% 37% 12%	2160
May	1st to 10th	Day	17% 3 7% 21% 38% 14%	2160
	11th to 20th	Day	14% 2 6% 24% 38% 16%	2299
	21st to end	Day	16% 2 5% 29% 35% 13%	2544
June	1st to 10th	Day	14% 2 6% 20% 32% 26%	2520
	11th to 20th	Day	7% 2 3 15% 33% 40%	2520
	21st to end	Day	6% 2 1 7% 31% 53%	2520
July	1st to 10th	Day	7% 2 2 8% 22% 59%	2451
	11th to 20th	Day	11% 2 4 15% 30% 37%	2402
	21st to end	Day	12% 3 5% 18% 32% 31%	2337
August	1st to 10th	Day	10% 2 2 8% 27% 50%	2135
	11th to 20th	Day	6% 1 1 12% 31% 48%	2122
	21st to end	Day	9% 2 1 8% 33% 47%	2376
September	1st to 10th	Day	8% 2 2 9% 29% 50%	2160
	11th to 20th	Day	6% 2 1 13% 33% 46%	2083
	21st to end	Day	9% 2 13% 40% 36%	1980
October	1st to 10th	Day	14% 2 3 17% 27% 38%	1942
	11th to 20th	Day	11% 2 3 13% 34% 38%	1800
	21st to end	Day	13% 3 3 12% 33% 38%	1980
November	1st to 10th	Day	16% 2 2 16% 36% 28%	1692
	11th to 20th	Day	18% 2 4 15% 31% 30%	1710
	21st to end	Day	24% 3 4 15% 28% 26%	1710
December	1st to 10th	Day	27% 3 5% 15% 28% 22%	1710
	11th to 20th	Day	38% 3 5% 18% 23% 13%	2018
	21st to end	Day	38% 3 3 19% 22% 15%	2794
January	1st to 10th	Night	30% 2 4 17% 29% 18%	2632
	11th to 20th	Night	24% 3 6% 15% 31% 22%	2353
	21st to end	Night	28% 3 5% 15% 23% 27%	2529
February	1st to 10th	Night	25% 4 3 15% 27% 27%	2160
	11th to 20th	Night	21% 3 2 19% 32% 22%	2099
	21st to end	Night	27% 3 3 19% 28% 20%	1776
March	1st to 10th	Night	30% 4 5% 21% 24% 17%	2160
	11th to 20th	Night	25% 4 7% 20% 26% 17%	2044
	21st to end	Night	22% 3 8% 25% 29% 12%	2008
April	1st to 10th	Night	23% 2 9% 27% 24% 15%	1800
	11th to 20th	Night	14% 2 6% 28% 31% 19%	1779
	21st to end	Night	11% 3 8% 28% 40% 11%	1800
May	1st to 10th	Night	13% 2 7% 24% 39% 15%	1800
	11th to 20th	Night	10% 2 4 27% 39% 18%	1595
	21st to end	Night	11% 2 6% 31% 38% 12%	1727
June	1st to 10th	Night	11% 2 7% 21% 35% 24%	1440
	11th to 20th	Night	5% 1 3 15% 34% 42%	1440
	21st to end	Night	4 1 2 7% 28% 58%	1440
July	1st to 10th	Night	7% 1 2 8% 24% 58%	1400
	11th to 20th	Night	7% 3 3 17% 30% 40%	1431
	21st to end	Night	10% 2 3 18% 31% 36%	1740
August	1st to 10th	Night	8% 2 2 9% 29% 51%	1780
	11th to 20th	Night	5% 2 1 10% 31% 51%	1780
	21st to end	Night	6% 1 1 7% 32% 52%	1980
September	1st to 10th	Night	6% 1 1 8% 29% 55%	1800
	11th to 20th	Night	6% 1 1 10% 37% 46%	1876
	21st to end	Night	6% 2 12% 40% 40%	1980
October	1st to 10th	Night	12% 2 2 16% 29% 39%	2015
	11th to 20th	Night	11% 2 2 15% 31% 38%	2160
	21st to end	Night	11% 2 3 10% 33% 41%	2376
November	1st to 10th	Night	15% 2 2 16% 36% 29%	2385
	11th to 20th	Night	17% 3 4 13% 29% 34%	2470
	21st to end	Night	22% 2 4 18% 25% 29%	2470
December	1st to 10th	Night	25% 3 4 13% 26% 28%	2470
	11th to 20th	Night	40% 3 5% 14% 22% 16%	3181
	21st to end	Night	35% 3 3 18% 25% 16%	4862

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	15% 18% 36% 20% 10% 2	189
	11th to 20th	Day	17% 19% 29% 26% 8% 1	344
	21st to end	Day	17% 21% 32% 19% 8% 3	393
February	1st to 10th	Day	13% 18% 33% 23% 9% 4	420
	11th to 20th	Day	20% 17% 30% 23% 9% 1	415
	21st to end	Day	17% 18% 34% 23% 7% 1	346
March	1st to 10th	Day	16% 21% 33% 23% 6% 1	420
	11th to 20th	Day	15% 19% 32% 25% 8% 1	420
	21st to end	Day	16% 21% 32% 22% 8% 1	462
April	1st to 10th	Day	12% 17% 32% 25% 11% 2	420
	11th to 20th	Day	14% 18% 32% 25% 10% 2	412
	21st to end	Day	9% 16% 29% 26% 14% 5%	420
May	1st to 10th	Day	9% 16% 30% 27% 15% 3	423
	11th to 20th	Day	6% 13% 32% 29% 13% 6%	448
	21st to end	Day	8% 10% 26% 35% 14% 7%	485
June	1st to 10th	Day	5% 6% 26% 35% 20% 8%	450
	11th to 20th	Day	2 7% 24% 38% 21% 8%	450
	21st to end	Day	1 5% 26% 37% 20% 10%	450
July	1st to 10th	Day	2 1 16% 42% 26% 14%	446
	11th to 20th	Day	2 1 9% 41% 29% 17%	444
	21st to end	Day	2 13% 40% 31% 15%	487
August	1st to 10th	Day	2 2 18% 43% 22% 14%	447
	11th to 20th	Day	2 2 15% 41% 31% 10%	437
	21st to end	Day	2 1 17% 47% 23% 11%	495
September	1st to 10th	Day	2 3 22% 42% 23% 8%	450
	11th to 20th	Day	1 5% 31% 41% 19% 3	450
	21st to end	Day	2 8% 28% 40% 18% 5%	450
October	1st to 10th	Day	6% 8% 30% 36% 17% 2	450
	11th to 20th	Day	4 10% 32% 35% 15% 4	450
	21st to end	Day	5% 11% 33% 32% 15% 4	495
November	1st to 10th	Day	8% 9% 30% 28% 22% 4	288
	11th to 20th	Day	8% 11% 27% 32% 17% 5%	270
	21st to end	Day	12% 11% 31% 28% 14% 4	270
December	1st to 10th	Day	9% 13% 31% 32% 12% 3	270
	11th to 20th	Day	14% 17% 21% 28% 17% 4	222
	21st to end	Day	18% 25% 23% 20% 11% 3	198
January	1st to 10th	Night	12% 8% 24% 32% 16% 7%	760
	11th to 20th	Night	8% 8% 28% 35% 16% 5%	724
	21st to end	Night	12% 12% 28% 29% 14% 5%	792
February	1st to 10th	Night	10% 10% 25% 32% 17% 6%	720
	11th to 20th	Night	10% 10% 26% 31% 16% 8%	704
	21st to end	Night	11% 10% 26% 34% 15% 3	592
March	1st to 10th	Night	10% 12% 24% 36% 17% 2	720
	11th to 20th	Night	7% 8% 24% 35% 20% 5%	720
	21st to end	Night	8% 11% 23% 36% 19% 2	792
April	1st to 10th	Night	9% 8% 27% 35% 17% 4	720
	11th to 20th	Night	8% 7% 26% 34% 23% 3	711
	21st to end	Night	5% 10% 27% 29% 23% 6%	720
May	1st to 10th	Night	3 7% 24% 37% 25% 5%	720
	11th to 20th	Night	5% 7% 17% 36% 32% 4	531
	21st to end	Night	5% 7% 21% 31% 32% 5%	565
June	1st to 10th	Night	3 3 14% 41% 34% 5%	360
	11th to 20th	Night	1 1 12% 43% 38% 6%	360
	21st to end	Night	1 1 10% 40% 42% 7%	360
July	1st to 10th	Night	1 2 33% 55% 11%	350
	11th to 20th	Night	1 1 28% 56% 13%	387
	21st to end	Night	1 1 2 24% 55% 17%	660
August	1st to 10th	Night	2 4 34% 50% 10%	716
	11th to 20th	Night	1 2 31% 53% 13%	712
	21st to end	Night	2 2 27% 56% 12%	792
September	1st to 10th	Night	2 1 7% 31% 47% 13%	720
	11th to 20th	Night	1 8% 44% 37% 9%	720
	21st to end	Night	1 2 12% 39% 39% 8%	720
October	1st to 10th	Night	2 3 16% 45% 29% 5%	720
	11th to 20th	Night	2 4 19% 38% 28% 9%	720
	21st to end	Night	3 6% 19% 33% 29% 10%	792
November	1st to 10th	Night	4 8% 18% 38% 25% 8%	740
	11th to 20th	Night	5% 4 20% 40% 23% 8%	760
	21st to end	Night	6% 8% 27% 33% 20% 6%	760
December	1st to 10th	Night	8% 9% 24% 34% 21% 4	760
	11th to 20th	Night	13% 9% 20% 38% 15% 4	760
	21st to end	Night	14% 10% 24% 34% 13% 6%	836

Page generated at 2024-01-08 19:31:25. Version ac07

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