White River Canyon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White River Canyon 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	9% 12% 5% 8% 7% 4 5% 5% 4 5% 36%	74758
	Night	9% 11% 5% 9% 8% 5% 6% 6% 5% 6% 31%	74988
Transparency	Day	43% 11% 11% 16% 14% 4	74461
	Night	44% 14% 12% 14% 12% 4	74806
Seeing	Day	18% 20% 28% 22% 9% 2	13466
	Night	15% 18% 23% 27% 14% 2	22588

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	13% 23% 8% 12% 11% 4 4 5% 3 4 12%	1519
	11th to 20th	Day	11% 18% 7% 10% 9% 5% 5% 6% 3 7% 19%	1456
	21st to end	Day	11% 15% 7% 9% 8% 5% 7% 5% 5% 6% 21%	1683
February	1st to 10th	Day	14% 17% 6% 10% 10% 4 6% 6% 4 5% 17%	1620
	11th to 20th	Day	10% 13% 7% 13% 10% 6% 7% 5% 5% 4 20%	1575
	21st to end	Day	10% 20% 10% 13% 8% 5% 6% 4 4 4 17%	1449
March	1st to 10th	Day	11% 18% 9% 10% 8% 5% 6% 7% 5% 5% 16%	1828
	11th to 20th	Day	11% 22% 7% 12% 8% 4 6% 4 4 5% 18%	1980
	21st to end	Day	11% 24% 8% 12% 10% 6% 5% 5% 3 4 12%	2263
April	1st to 10th	Day	13% 17% 7% 12% 10% 5% 6% 6% 4 4 16%	2160
	11th to 20th	Day	12% 17% 8% 11% 9% 3 5% 5% 4 4 23%	2129
	21st to end	Day	8% 14% 5% 9% 8% 5% 6% 7% 6% 8% 24%	2276
May	1st to 10th	Day	8% 12% 5% 9% 7% 5% 5% 6% 5% 5% 34%	2520
	11th to 20th	Day	11% 11% 5% 9% 8% 5% 6% 7% 6% 6% 26%	2477
	21st to end	Day	13% 11% 4 9% 8% 5% 7% 6% 5% 7% 26%	2723
June	1st to 10th	Day	14% 11% 5% 7% 6% 4 6% 5% 4 5% 32%	2520
	11th to 20th	Day	9% 10% 5% 7% 7% 5% 7% 7% 6% 6% 31%	2520
	21st to end	Day	6% 5% 2 5% 5% 3 4 4 5% 7% 55%	2520
July	1st to 10th	Day	3 3 1 4 3 2 4 4 5% 7% 66%	2520
	11th to 20th	Day	4 3 2 3 3 2 3 3 4 4 69%	2520
	21st to end	Day	3 2 1 2 2 1 2 2 3 5% 79%	2741
August	1st to 10th	Day	1 2 1 3 3 2 3 4 5% 6% 69%	2414
	11th to 20th	Day	3 2 1 3 3 2 2 4 4 5% 69%	2298
	21st to end	Day	4 2 1 4 4 3 4 4 6% 6% 61%	2403
September	1st to 10th	Day	3 3 2 4 4 2 4 4 4 7% 63%	2160
	11th to 20th	Day	6% 6% 3 6% 6% 3 5% 5% 5% 8% 48%	2160
	21st to end	Day	10% 8% 3 6% 7% 3 4 3 5% 5% 46%	1918
October	1st to 10th	Day	11% 11% 4 7% 6% 3 5% 4 4 5% 41%	1800
	11th to 20th	Day	12% 12% 4 8% 6% 3 5% 5% 5% 6% 35%	1800
	21st to end	Day	12% 13% 5% 10% 8% 4 5% 4 3 5% 31%	1890
November	1st to 10th	Day	14% 18% 6% 12% 8% 5% 6% 5% 4 5% 18%	1634
	11th to 20th	Day	11% 20% 7% 11% 9% 4 6% 5% 5% 5% 16%	1520
	21st to end	Day	12% 16% 6% 9% 10% 4 6% 5% 4 4 23%	1520
December	1st to 10th	Day	11% 15% 7% 10% 10% 5% 6% 6% 4 4 23%	1520
	11th to 20th	Day	12% 19% 7% 10% 9% 5% 7% 6% 6% 5% 15%	1928
	21st to end	Day	11% 21% 7% 13% 10% 5% 6% 5% 3 4 15%	2794
January	1st to 10th	Night	13% 21% 7% 11% 11% 5% 6% 6% 4 4 13%	2646
	11th to 20th	Night	14% 12% 7% 10% 11% 6% 6% 4 5% 6% 18%	2548
	21st to end	Night	10% 14% 7% 10% 8% 7% 6% 6% 4 6% 21%	2671
February	1st to 10th	Night	10% 16% 7% 11% 9% 5% 6% 7% 4 6% 18%	2340
	11th to 20th	Night	10% 13% 6% 10% 11% 6% 6% 6% 5% 5% 22%	2272
	21st to end	Night	10% 15% 9% 12% 10% 6% 7% 5% 4 5% 17%	1805
March	1st to 10th	Night	10% 14% 7% 10% 9% 6% 8% 6% 5% 6% 19%	2129
	11th to 20th	Night	8% 14% 6% 11% 12% 7% 7% 6% 5% 5% 20%	1980
	21st to end	Night	11% 15% 7% 13% 12% 7% 7% 7% 5% 5% 13%	2093
April	1st to 10th	Night	12% 13% 7% 11% 10% 6% 8% 7% 4 4 18%	1800
	11th to 20th	Night	8% 10% 7% 10% 10% 5% 8% 7% 4 6% 24%	1779
	21st to end	Night	9% 11% 4 8% 9% 6% 8% 7% 7% 7% 23%	1680
May	1st to 10th	Night	8% 8% 4 9% 7% 5% 6% 7% 5% 7% 33%	1440
	11th to 20th	Night	9% 8% 4 6% 9% 6% 6% 9% 7% 7% 27%	1416
	21st to end	Night	7% 10% 4 9% 9% 5% 7% 6% 6% 9% 27%	1552
June	1st to 10th	Night	12% 11% 5% 8% 6% 3 6% 5% 6% 6% 32%	1440
	11th to 20th	Night	8% 7% 4 7% 8% 5% 8% 7% 7% 8% 32%	1440
	21st to end	Night	5% 6% 2 4 4 3 4 4 5% 7% 55%	1440
July	1st to 10th	Night	4 2 1 4 4 2 4 3 4 8% 64%	1440
	11th to 20th	Night	2 2 1 2 2 2 4 4 5% 8% 69%	1440
	21st to end	Night	2 2 1 2 1 1 2 3 3 6% 76%	1576
August	1st to 10th	Night	2 2 1 2 3 3 4 3 6% 7% 67%	1522
	11th to 20th	Night	3 2 1 2 3 2 3 4 4 6% 70%	1602
	21st to end	Night	3 3 2 3 2 2 3 5% 5% 6% 66%	1952
September	1st to 10th	Night	3 3 1 2 3 2 4 5% 6% 7% 64%	1800
	11th to 20th	Night	6% 5% 2 5% 6% 3 5% 5% 6% 7% 49%	1800
	21st to end	Night	8% 7% 3 6% 5% 3 4 5% 6% 8% 46%	2039
October	1st to 10th	Night	10% 8% 4 7% 5% 2 5% 5% 4 5% 45%	2160
	11th to 20th	Night	9% 9% 4 8% 7% 3 5% 5% 5% 6% 38%	2160
	21st to end	Night	12% 10% 4 8% 8% 4 6% 6% 4 4 34%	2465
November	1st to 10th	Night	15% 13% 5% 11% 10% 5% 7% 6% 4 4 21%	2443
	11th to 20th	Night	13% 14% 6% 11% 10% 6% 6% 7% 5% 5% 17%	2660
	21st to end	Night	9% 13% 5% 11% 9% 5% 8% 7% 6% 5% 23%	2660
December	1st to 10th	Night	11% 14% 6% 10% 10% 6% 7% 5% 5% 5% 23%	2660
	11th to 20th	Night	12% 16% 6% 12% 11% 6% 7% 6% 5% 6% 13%	3276
	21st to end	Night	12% 15% 7% 12% 10% 5% 7% 6% 4 4 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	69% 12% 9% 7% 3	1519
	11th to 20th	Day	60% 12% 11% 9% 5% 3	1456
	21st to end	Day	57% 13% 10% 10% 8% 2	1683
February	1st to 10th	Day	59% 14% 13% 10% 4	1620
	11th to 20th	Day	57% 14% 11% 12% 6% 1	1584
	21st to end	Day	60% 13% 11% 8% 6% 1	1449
March	1st to 10th	Day	60% 12% 13% 10% 4 1	1828
	11th to 20th	Day	63% 11% 7% 16% 4	1980
	21st to end	Day	67% 13% 10% 9% 1	2263
April	1st to 10th	Day	59% 16% 11% 10% 4	2160
	11th to 20th	Day	57% 10% 13% 9% 8% 2	2132
	21st to end	Day	48% 16% 14% 14% 7% 2	2276
May	1st to 10th	Day	43% 12% 14% 22% 9%	2520
	11th to 20th	Day	46% 13% 14% 19% 7%	2480
	21st to end	Day	47% 16% 13% 19% 5%	2724
June	1st to 10th	Day	47% 9% 15% 19% 9% 1	2520
	11th to 20th	Day	40% 16% 16% 19% 7% 2	2520
	21st to end	Day	25% 9% 12% 28% 20% 5%	2520
July	1st to 10th	Day	15% 8% 13% 22% 28% 14%	2451
	11th to 20th	Day	17% 6% 7% 16% 35% 20%	2445
	21st to end	Day	9% 3 6% 20% 43% 18%	2589
August	1st to 10th	Day	13% 7% 12% 27% 31% 11%	2397
	11th to 20th	Day	15% 6% 9% 26% 34% 11%	2298
	21st to end	Day	17% 8% 11% 27% 29% 7%	2403
September	1st to 10th	Day	16% 8% 10% 25% 26% 15%	2160
	11th to 20th	Day	30% 9% 12% 21% 21% 8%	2160
	21st to end	Day	35% 8% 12% 19% 19% 8%	1918
October	1st to 10th	Day	40% 9% 8% 20% 17% 5%	1800
	11th to 20th	Day	44% 10% 12% 15% 18% 2	1800
	21st to end	Day	48% 13% 8% 16% 14% 2	1890
November	1st to 10th	Day	58% 12% 11% 12% 6% 1	1634
	11th to 20th	Day	61% 15% 10% 8% 5% 1	1520
	21st to end	Day	56% 13% 9% 8% 13% 1	1520
December	1st to 10th	Day	57% 14% 8% 13% 7% 1	1520
	11th to 20th	Day	61% 15% 11% 9% 4	1928
	21st to end	Day	65% 12% 9% 11% 2 1	2794
January	1st to 10th	Night	66% 13% 11% 7% 3	2646
	11th to 20th	Night	59% 13% 11% 10% 5% 3	2548
	21st to end	Night	55% 13% 11% 11% 9% 1	2671
February	1st to 10th	Night	57% 17% 10% 11% 4	2340
	11th to 20th	Night	52% 16% 13% 11% 8% 1	2274
	21st to end	Night	56% 15% 11% 10% 8% 1	1805
March	1st to 10th	Night	54% 16% 13% 13% 4 1	2129
	11th to 20th	Night	53% 15% 11% 15% 4 1	1980
	21st to end	Night	59% 19% 12% 8% 3	2093
April	1st to 10th	Night	52% 19% 13% 11% 5%	1800
	11th to 20th	Night	48% 17% 14% 11% 8% 3	1779
	21st to end	Night	43% 19% 14% 14% 8% 2	1680
May	1st to 10th	Night	37% 18% 12% 22% 10% 1	1440
	11th to 20th	Night	39% 18% 15% 18% 8% 2	1416
	21st to end	Night	41% 20% 15% 17% 7%	1552
June	1st to 10th	Night	44% 14% 13% 19% 9% 1	1440
	11th to 20th	Night	34% 19% 17% 21% 6% 3	1440
	21st to end	Night	24% 10% 13% 25% 21% 6%	1440
July	1st to 10th	Night	16% 9% 13% 20% 25% 18%	1400
	11th to 20th	Night	11% 7% 12% 14% 30% 25%	1392
	21st to end	Night	9% 3 9% 14% 39% 26%	1488
August	1st to 10th	Night	12% 8% 13% 22% 32% 13%	1514
	11th to 20th	Night	14% 6% 10% 23% 34% 13%	1602
	21st to end	Night	14% 8% 12% 26% 31% 9%	1952
September	1st to 10th	Night	13% 7% 15% 24% 26% 15%	1800
	11th to 20th	Night	28% 11% 12% 18% 20% 12%	1800
	21st to end	Night	30% 11% 12% 20% 18% 9%	2039
October	1st to 10th	Night	35% 9% 11% 19% 20% 6%	2160
	11th to 20th	Night	39% 12% 9% 16% 19% 5%	2160
	21st to end	Night	41% 15% 10% 13% 18% 3	2465
November	1st to 10th	Night	55% 15% 10% 12% 7% 2	2443
	11th to 20th	Night	57% 17% 9% 10% 7%	2660
	21st to end	Night	49% 15% 11% 11% 12% 2	2660
December	1st to 10th	Night	53% 15% 12% 13% 7%	2660
	11th to 20th	Night	61% 17% 10% 7% 5%	3276
	21st to end	Night	56% 17% 16% 8% 2 1	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	34% 26% 21% 13% 5% 1	180
	11th to 20th	Day	29% 25% 25% 13% 8% 1	164
	21st to end	Day	24% 23% 25% 19% 8%	275
February	1st to 10th	Day	27% 30% 23% 14% 6%	340
	11th to 20th	Day	27% 29% 30% 13% 2	335
	21st to end	Day	30% 24% 26% 16% 4	333
March	1st to 10th	Day	25% 27% 31% 12% 4 1	420
	11th to 20th	Day	23% 27% 26% 17% 6%	420
	21st to end	Day	32% 27% 23% 14% 4	462
April	1st to 10th	Day	28% 26% 23% 15% 6% 1	420
	11th to 20th	Day	29% 28% 23% 14% 4 3	412
	21st to end	Day	23% 27% 26% 18% 5% 1	420
May	1st to 10th	Day	18% 24% 30% 19% 8% 2	423
	11th to 20th	Day	24% 20% 26% 19% 8% 3	448
	21st to end	Day	17% 20% 25% 27% 8% 3	485
June	1st to 10th	Day	17% 20% 27% 23% 10% 3	450
	11th to 20th	Day	18% 26% 30% 19% 6% 1	450
	21st to end	Day	8% 14% 36% 28% 12% 2	450
July	1st to 10th	Day	4 13% 39% 33% 10% 2	446
	11th to 20th	Day	4 13% 37% 29% 14% 3	444
	21st to end	Day	3 8% 35% 33% 16% 4	487
August	1st to 10th	Day	2 8% 37% 31% 16% 6%	447
	11th to 20th	Day	4 7% 32% 36% 16% 6%	437
	21st to end	Day	6% 14% 33% 30% 11% 5%	495
September	1st to 10th	Day	5% 14% 35% 30% 14% 3	450
	11th to 20th	Day	14% 12% 30% 31% 14% 1	450
	21st to end	Day	14% 19% 30% 26% 11% 1	450
October	1st to 10th	Day	20% 16% 28% 26% 9% 1	450
	11th to 20th	Day	21% 21% 21% 24% 13% 1	450
	21st to end	Day	26% 26% 21% 16% 9% 2	405
November	1st to 10th	Day	24% 26% 24% 19% 6% 1	250
	11th to 20th	Day	29% 23% 19% 20% 7% 2	180
	21st to end	Day	23% 21% 27% 23% 6% 1	180
December	1st to 10th	Day	24% 20% 25% 18% 8% 4	180
	11th to 20th	Day	25% 29% 28% 12% 5%	180
	21st to end	Day	25% 28% 21% 17% 7% 2	198
January	1st to 10th	Night	27% 24% 21% 18% 10% 1	760
	11th to 20th	Night	21% 21% 23% 22% 11% 2	728
	21st to end	Night	19% 18% 24% 28% 10% 1	792
February	1st to 10th	Night	21% 23% 23% 24% 9% 1	720
	11th to 20th	Night	21% 22% 22% 24% 10% 1	704
	21st to end	Night	22% 24% 25% 22% 7% 1	592
March	1st to 10th	Night	17% 25% 23% 24% 10% 1	720
	11th to 20th	Night	15% 25% 24% 27% 10% 1	720
	21st to end	Night	20% 27% 24% 18% 9% 2	792
April	1st to 10th	Night	21% 20% 26% 21% 11% 2	720
	11th to 20th	Night	14% 26% 27% 17% 13% 3	711
	21st to end	Night	13% 26% 25% 22% 13% 1	600
May	1st to 10th	Night	12% 22% 23% 25% 16% 2	360
	11th to 20th	Night	14% 14% 20% 30% 20% 3	354
	21st to end	Night	10% 15% 25% 32% 15% 3	389
June	1st to 10th	Night	17% 16% 21% 29% 15% 1	360
	11th to 20th	Night	9% 23% 28% 28% 13% 1	360
	21st to end	Night	9% 9% 24% 39% 18% 1	360
July	1st to 10th	Night	5% 5% 28% 40% 21% 1	350
	11th to 20th	Night	2 5% 32% 42% 16% 2	348
	21st to end	Night	2 4 21% 48% 22% 3	394
August	1st to 10th	Night	3 4 20% 41% 27% 5%	448
	11th to 20th	Night	4 3 16% 35% 32% 10%	534
	21st to end	Night	4 8% 26% 35% 23% 4	764
September	1st to 10th	Night	5% 8% 22% 38% 23% 4	720
	11th to 20th	Night	9% 8% 21% 30% 28% 5%	720
	21st to end	Night	13% 9% 20% 34% 22% 2	720
October	1st to 10th	Night	13% 12% 25% 28% 17% 4	720
	11th to 20th	Night	15% 16% 19% 27% 19% 4	720
	21st to end	Night	19% 22% 19% 24% 12% 4	792
November	1st to 10th	Night	21% 21% 25% 24% 9% 1	740
	11th to 20th	Night	21% 27% 22% 21% 8% 1	760
	21st to end	Night	16% 23% 23% 26% 11% 1	760
December	1st to 10th	Night	18% 21% 23% 25% 12% 1	760
	11th to 20th	Night	22% 23% 28% 19% 8% 1	760
	21st to end	Night	23% 28% 23% 19% 6% 1	836

Page generated at 2024-01-09 22:25:01. Version ac07

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