Tanaeum Ridge and Peoh Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tanaeum Ridge and Peoh Point clear sky chart from 2005-11-06 to 2024-03-23.

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	7% 8% 4 7% 6% 4 5% 5% 6% 7% 39%	78557
	Night	7% 9% 4 7% 6% 4 6% 6% 6% 8% 36%	81290
Transparency	Day	38% 11% 14% 21% 13% 3	78284
	Night	39% 12% 16% 21% 11% 2	81143
Seeing	Day	17% 19% 34% 20% 8% 2	13512
	Night	14% 17% 30% 26% 12% 2	22667

By Month

Percentage Cloud Cover NW (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	9% 15% 7% 12% 8% 5% 7% 7% 6% 7% 17%	2539
	11th to 20th	Day	9% 17% 5% 9% 7% 4 4 6% 6% 7% 26%	2516
	21st to end	Day	17% 18% 7% 10% 8% 3 5% 6% 6% 6% 15%	2794
February	1st to 10th	Day	8% 10% 5% 10% 10% 5% 6% 6% 7% 7% 26%	1710
	11th to 20th	Day	7% 13% 5% 8% 7% 5% 6% 6% 7% 8% 28%	1665
	21st to end	Day	7% 12% 5% 11% 8% 5% 8% 7% 6% 8% 25%	1541
March	1st to 10th	Day	8% 12% 5% 9% 7% 4 7% 6% 7% 7% 27%	1900
	11th to 20th	Day	7% 12% 5% 11% 9% 4 7% 6% 5% 6% 29%	2066
	21st to end	Day	7% 11% 5% 9% 11% 7% 7% 7% 8% 8% 19%	2319
April	1st to 10th	Day	9% 11% 4 10% 9% 5% 8% 6% 7% 7% 24%	2160
	11th to 20th	Day	7% 11% 5% 9% 9% 4 6% 6% 6% 7% 30%	2132
	21st to end	Day	6% 9% 4 9% 7% 5% 6% 6% 7% 7% 33%	2364
May	1st to 10th	Day	6% 6% 3 7% 7% 4 6% 5% 7% 9% 40%	2520
	11th to 20th	Day	9% 8% 4 7% 6% 4 6% 6% 7% 9% 35%	2477
	21st to end	Day	11% 8% 3 7% 7% 4 6% 6% 6% 8% 33%	2723
June	1st to 10th	Day	9% 7% 3 7% 7% 4 5% 5% 7% 7% 38%	2520
	11th to 20th	Day	6% 5% 2 5% 6% 5% 7% 7% 8% 9% 40%	2520
	21st to end	Day	4 4 2 4 5% 3 5% 5% 5% 8% 55%	2520
July	1st to 10th	Day	2 2 1 3 4 3 4 4 5% 8% 63%	2520
	11th to 20th	Day	3 2 1 3 3 2 3 3 4 6% 68%	2520
	21st to end	Day	1 1 1 2 2 2 3 3 3 5% 78%	2741
August	1st to 10th	Day	2 2 1 3 3 2 3 4 6% 7% 69%	2507
	11th to 20th	Day	2 2 1 3 3 2 3 3 5% 7% 69%	2315
	21st to end	Day	2 3 2 4 4 3 5% 4 5% 8% 61%	2406
September	1st to 10th	Day	4 2 1 3 3 3 3 4 5% 8% 64%	2160
	11th to 20th	Day	4 4 2 4 6% 4 6% 7% 7% 7% 50%	2160
	21st to end	Day	7% 6% 2 6% 5% 3 4 4 5% 8% 50%	1928
October	1st to 10th	Day	8% 6% 2 6% 6% 2 5% 6% 6% 8% 45%	1800
	11th to 20th	Day	10% 7% 3 6% 5% 3 4 5% 7% 9% 41%	1800
	21st to end	Day	10% 9% 4 7% 6% 4 6% 6% 7% 7% 35%	1824
November	1st to 10th	Day	10% 11% 6% 10% 7% 4 7% 5% 7% 8% 26%	1611
	11th to 20th	Day	8% 14% 5% 9% 9% 5% 6% 4 7% 8% 26%	1520
	21st to end	Day	8% 13% 5% 8% 7% 4 6% 6% 6% 7% 28%	1520
December	1st to 10th	Day	8% 12% 6% 9% 7% 4 5% 6% 7% 8% 28%	1520
	11th to 20th	Day	9% 12% 5% 12% 8% 4 7% 7% 8% 8% 19%	1925
	21st to end	Day	10% 14% 7% 14% 10% 4 5% 6% 5% 6% 19%	2794
January	1st to 10th	Night	10% 15% 6% 10% 8% 5% 6% 8% 6% 8% 18%	4406
	11th to 20th	Night	10% 13% 4 9% 6% 4 6% 6% 6% 11% 26%	4382
	21st to end	Night	12% 19% 6% 10% 8% 5% 6% 6% 6% 6% 16%	4861
February	1st to 10th	Night	8% 11% 5% 8% 7% 4 6% 6% 8% 10% 28%	2470
	11th to 20th	Night	7% 11% 4 7% 6% 4 6% 5% 6% 9% 35%	2402
	21st to end	Night	7% 11% 5% 9% 8% 5% 5% 7% 6% 7% 29%	1913
March	1st to 10th	Night	8% 9% 4 7% 7% 5% 8% 6% 7% 8% 32%	2280
	11th to 20th	Night	5% 8% 4 6% 8% 4 6% 7% 7% 9% 35%	2110
	21st to end	Night	7% 9% 4 9% 8% 5% 8% 7% 9% 9% 25%	2081
April	1st to 10th	Night	7% 7% 4 7% 8% 5% 8% 9% 8% 9% 29%	1800
	11th to 20th	Night	5% 8% 4 8% 6% 4 6% 6% 7% 9% 39%	1779
	21st to end	Night	5% 7% 4 8% 9% 3 7% 8% 10% 9% 30%	1591
May	1st to 10th	Night	5% 5% 3 7% 6% 3 6% 7% 8% 10% 40%	1440
	11th to 20th	Night	8% 5% 2 5% 7% 5% 7% 6% 7% 9% 39%	1416
	21st to end	Night	6% 5% 3 8% 5% 4 7% 7% 8% 9% 37%	1552
June	1st to 10th	Night	7% 5% 2 8% 7% 3 6% 6% 6% 9% 42%	1440
	11th to 20th	Night	4 5% 3 6% 8% 4 6% 7% 8% 10% 39%	1440
	21st to end	Night	3 3 1 4 5% 3 6% 5% 7% 6% 57%	1440
July	1st to 10th	Night	3 1 1 2 2 2 4 4 7% 7% 66%	1440
	11th to 20th	Night	1 1 1 2 3 2 3 3 3 7% 73%	1440
	21st to end	Night	1 1 2 1 2 3 3 5% 80%	1576
August	1st to 10th	Night	2 1 1 1 3 2 3 3 5% 7% 73%	1432
	11th to 20th	Night	1 1 1 3 2 1 3 4 4 6% 73%	1583
	21st to end	Night	2 2 1 3 4 2 4 5% 6% 8% 63%	1949
September	1st to 10th	Night	3 2 1 3 3 2 3 4 5% 6% 67%	1800
	11th to 20th	Night	3 4 2 6% 4 3 5% 5% 6% 9% 53%	1800
	21st to end	Night	4 4 3 4 5% 3 4 6% 6% 9% 51%	2028
October	1st to 10th	Night	7% 6% 2 5% 6% 3 4 5% 5% 8% 49%	2160
	11th to 20th	Night	7% 6% 2 6% 6% 3 5% 7% 7% 8% 43%	2160
	21st to end	Night	10% 8% 3 6% 5% 3 6% 4 6% 10% 38%	2531
November	1st to 10th	Night	12% 11% 3 8% 6% 4 6% 6% 7% 9% 30%	2466
	11th to 20th	Night	8% 11% 4 8% 6% 4 6% 6% 7% 9% 30%	2660
	21st to end	Night	8% 10% 5% 9% 7% 4 6% 6% 7% 8% 30%	2660
December	1st to 10th	Night	9% 12% 7% 8% 8% 4 6% 5% 7% 8% 27%	2660
	11th to 20th	Night	10% 14% 5% 10% 9% 5% 8% 7% 7% 7% 19%	3280
	21st to end	Night	11% 15% 7% 14% 8% 4 5% 5% 6% 7% 17%	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	60% 13% 13% 12% 2	2539
	11th to 20th	Day	53% 9% 16% 17% 4 1	2540
	21st to end	Day	64% 12% 11% 10% 4	2794
February	1st to 10th	Day	51% 14% 16% 14% 4 1	1710
	11th to 20th	Day	46% 14% 16% 17% 8% 1	1674
	21st to end	Day	46% 17% 14% 15% 6% 1	1541
March	1st to 10th	Day	47% 12% 15% 17% 8% 1	1900
	11th to 20th	Day	50% 11% 12% 21% 5%	2066
	21st to end	Day	50% 17% 16% 13% 3	2319
April	1st to 10th	Day	49% 13% 15% 17% 6%	2160
	11th to 20th	Day	42% 14% 16% 18% 9% 1	2132
	21st to end	Day	37% 17% 15% 20% 10% 1	2364
May	1st to 10th	Day	32% 12% 20% 26% 10% 1	2520
	11th to 20th	Day	38% 11% 19% 24% 8%	2480
	21st to end	Day	40% 13% 18% 22% 7%	2724
June	1st to 10th	Day	37% 11% 15% 25% 11% 2	2520
	11th to 20th	Day	28% 13% 20% 27% 10% 2	2520
	21st to end	Day	22% 10% 17% 29% 19% 3	2520
July	1st to 10th	Day	17% 7% 13% 28% 24% 10%	2451
	11th to 20th	Day	16% 4 9% 24% 34% 13%	2445
	21st to end	Day	9% 4 7% 27% 40% 14%	2589
August	1st to 10th	Day	13% 5% 12% 29% 30% 10%	2490
	11th to 20th	Day	13% 5% 13% 31% 32% 6%	2315
	21st to end	Day	18% 8% 12% 33% 25% 4	2406
September	1st to 10th	Day	17% 6% 13% 32% 25% 8%	2160
	11th to 20th	Day	26% 10% 16% 22% 22% 5%	2160
	21st to end	Day	30% 7% 18% 24% 17% 4	1928
October	1st to 10th	Day	32% 9% 14% 31% 12% 2	1800
	11th to 20th	Day	34% 10% 17% 26% 13%	1800
	21st to end	Day	42% 10% 15% 21% 12%	1824
November	1st to 10th	Day	49% 13% 13% 18% 7% 1	1611
	11th to 20th	Day	51% 14% 16% 13% 5% 1	1520
	21st to end	Day	47% 13% 15% 16% 7% 1	1520
December	1st to 10th	Day	50% 11% 14% 18% 7%	1520
	11th to 20th	Day	57% 13% 15% 11% 3	1928
	21st to end	Day	62% 11% 9% 13% 5%	2794
January	1st to 10th	Night	57% 13% 16% 10% 4 1	4406
	11th to 20th	Night	47% 10% 17% 19% 5% 1	4420
	21st to end	Night	64% 11% 11% 10% 3 1	4861
February	1st to 10th	Night	46% 14% 18% 17% 5%	2470
	11th to 20th	Night	40% 14% 18% 20% 8% 1	2404
	21st to end	Night	46% 14% 15% 18% 7%	1913
March	1st to 10th	Night	44% 12% 15% 19% 9% 1	2280
	11th to 20th	Night	38% 11% 19% 25% 6% 1	2111
	21st to end	Night	43% 18% 19% 18% 3	2081
April	1st to 10th	Night	38% 17% 19% 20% 7%	1800
	11th to 20th	Night	34% 13% 17% 23% 12% 1	1779
	21st to end	Night	33% 19% 18% 19% 10% 1	1591
May	1st to 10th	Night	28% 14% 19% 28% 10% 1	1440
	11th to 20th	Night	31% 13% 18% 29% 8% 1	1416
	21st to end	Night	34% 13% 20% 26% 7%	1552
June	1st to 10th	Night	31% 13% 19% 24% 12% 1	1440
	11th to 20th	Night	29% 13% 21% 27% 9% 1	1440
	21st to end	Night	19% 10% 17% 35% 15% 4	1440
July	1st to 10th	Night	12% 8% 17% 33% 21% 9%	1400
	11th to 20th	Night	9% 7% 11% 32% 29% 11%	1392
	21st to end	Night	6% 5% 8% 28% 37% 16%	1488
August	1st to 10th	Night	11% 6% 12% 30% 32% 11%	1424
	11th to 20th	Night	11% 6% 15% 32% 29% 8%	1583
	21st to end	Night	13% 9% 14% 32% 27% 5%	1949
September	1st to 10th	Night	15% 7% 14% 30% 28% 6%	1800
	11th to 20th	Night	23% 9% 16% 24% 21% 7%	1800
	21st to end	Night	24% 9% 19% 27% 17% 5%	2028
October	1st to 10th	Night	30% 8% 13% 30% 18% 1	2160
	11th to 20th	Night	32% 12% 15% 26% 13% 2	2160
	21st to end	Night	38% 11% 14% 22% 15%	2531
November	1st to 10th	Night	45% 12% 15% 19% 8% 1	2466
	11th to 20th	Night	46% 14% 17% 17% 6% 1	2660
	21st to end	Night	46% 12% 16% 16% 9% 1	2660
December	1st to 10th	Night	52% 12% 13% 18% 5%	2660
	11th to 20th	Night	57% 16% 13% 10% 4	3276
	21st to end	Night	58% 12% 14% 12% 4	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	28% 12% 27% 18% 13% 2	180
	11th to 20th	Day	31% 7% 23% 27% 7% 4	180
	21st to end	Day	20% 13% 31% 25% 9% 2	198
February	1st to 10th	Day	25% 27% 27% 16% 5%	370
	11th to 20th	Day	29% 21% 33% 13% 3	365
	21st to end	Day	24% 20% 34% 16% 5% 1	368
March	1st to 10th	Day	22% 25% 28% 19% 5% 1	460
	11th to 20th	Day	18% 23% 33% 17% 8% 1	460
	21st to end	Day	25% 27% 31% 13% 4	471
April	1st to 10th	Day	27% 24% 28% 16% 4 1	420
	11th to 20th	Day	21% 29% 29% 15% 4 3	412
	21st to end	Day	22% 26% 34% 15% 3 1	420
May	1st to 10th	Day	19% 20% 38% 17% 5% 1	423
	11th to 20th	Day	20% 19% 33% 19% 7% 2	448
	21st to end	Day	14% 19% 34% 24% 7% 1	485
June	1st to 10th	Day	17% 22% 34% 19% 7% 1	450
	11th to 20th	Day	17% 27% 40% 12% 3 1	450
	21st to end	Day	8% 22% 38% 24% 8% 1	450
July	1st to 10th	Day	5% 14% 52% 24% 4	446
	11th to 20th	Day	9% 20% 44% 21% 5% 1	444
	21st to end	Day	5% 15% 45% 24% 9% 2	487
August	1st to 10th	Day	6% 13% 40% 28% 11% 2	447
	11th to 20th	Day	4 11% 37% 31% 12% 4	437
	21st to end	Day	8% 17% 39% 22% 11% 3	495
September	1st to 10th	Day	8% 19% 40% 21% 10% 2	450
	11th to 20th	Day	9% 18% 36% 26% 10% 1	450
	21st to end	Day	14% 17% 34% 24% 9% 2	450
October	1st to 10th	Day	16% 19% 27% 22% 12% 4	450
	11th to 20th	Day	17% 16% 30% 20% 13% 4	450
	21st to end	Day	25% 13% 31% 18% 10% 3	339
November	1st to 10th	Day	27% 15% 29% 22% 6% 1	239
	11th to 20th	Day	27% 13% 29% 18% 9% 3	180
	21st to end	Day	23% 13% 24% 24% 12% 3	180
December	1st to 10th	Day	27% 10% 26% 20% 11% 7%	180
	11th to 20th	Day	20% 18% 32% 22% 7% 2	180
	21st to end	Day	21% 16% 28% 24% 8% 3	198
January	1st to 10th	Night	24% 13% 24% 26% 12% 2	760
	11th to 20th	Night	21% 12% 25% 28% 13% 2	760
	21st to end	Night	19% 12% 25% 29% 13% 2	836
February	1st to 10th	Night	20% 17% 26% 27% 10% 1	760
	11th to 20th	Night	17% 18% 26% 27% 11% 1	744
	21st to end	Night	22% 18% 22% 25% 11% 2	628
March	1st to 10th	Night	16% 15% 26% 31% 11% 1	760
	11th to 20th	Night	14% 16% 28% 29% 12% 1	760
	21st to end	Night	17% 21% 28% 25% 8% 1	800
April	1st to 10th	Night	14% 22% 31% 24% 8% 1	720
	11th to 20th	Night	12% 23% 29% 25% 9% 2	711
	21st to end	Night	11% 28% 36% 17% 8% 1	511
May	1st to 10th	Night	13% 23% 33% 22% 7% 1	360
	11th to 20th	Night	11% 15% 36% 24% 12% 2	354
	21st to end	Night	10% 17% 35% 26% 10% 1	389
June	1st to 10th	Night	13% 20% 38% 20% 8% 1	360
	11th to 20th	Night	9% 31% 39% 17% 4	360
	21st to end	Night	6% 24% 38% 24% 8% 1	360
July	1st to 10th	Night	4 16% 51% 23% 6%	350
	11th to 20th	Night	2 25% 46% 21% 5%	348
	21st to end	Night	3 19% 45% 25% 9% 1	394
August	1st to 10th	Night	4 14% 46% 25% 10% 1	358
	11th to 20th	Night	3 13% 36% 27% 17% 4	515
	21st to end	Night	5% 20% 37% 22% 13% 3	761
September	1st to 10th	Night	5% 18% 34% 26% 14% 3	720
	11th to 20th	Night	7% 14% 28% 28% 18% 6%	720
	21st to end	Night	8% 16% 28% 28% 18% 2	720
October	1st to 10th	Night	12% 14% 26% 28% 18% 3	720
	11th to 20th	Night	13% 11% 24% 30% 17% 5%	720
	21st to end	Night	17% 16% 25% 26% 12% 3	792
November	1st to 10th	Night	19% 16% 25% 30% 10%	740
	11th to 20th	Night	21% 14% 25% 25% 13% 2	760
	21st to end	Night	16% 14% 25% 28% 14% 3	760
December	1st to 10th	Night	18% 14% 25% 28% 14% 2	760
	11th to 20th	Night	19% 13% 30% 28% 9% 1	760
	21st to end	Night	22% 18% 25% 28% 6%	836

Page generated at 2024-03-19 20:31:08. Version ac07

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