Summer Village of Yellowstone
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Summer Village of Yellowstone clear sky chart from 2005-11-06 to 2024-11-04.

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% 9% 3 8% 6% 5% 5% 4 6% 8% 35%	106283
	Night	9% 10% 4 10% 6% 5% 5% 4 6% 8% 33%	101263
Transparency	Day	45% 8% 16% 22% 8% 1	106021
	Night	47% 8% 15% 20% 9% 1	101172
Seeing	Day	13% 7% 25% 30% 19% 6%	16009
	Night	13% 6% 28% 35% 16% 2	24368

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	4 15% 5% 14% 8% 5% 5% 4 6% 8% 25%	2188
	11th to 20th	Day	6% 11% 4 8% 6% 5% 5% 6% 7% 9% 33%	2199
	21st to end	Day	7% 12% 4 9% 6% 5% 5% 5% 6% 7% 34%	2666
February	1st to 10th	Day	9% 13% 6% 11% 8% 6% 6% 5% 9% 8% 21%	1520
	11th to 20th	Day	5% 14% 5% 11% 7% 6% 7% 4 6% 8% 28%	1576
	21st to end	Day	4 13% 5% 11% 9% 8% 6% 6% 8% 7% 25%	1494
March	1st to 10th	Day	4 14% 6% 12% 8% 7% 5% 4 5% 8% 28%	3138
	11th to 20th	Day	5% 11% 3 7% 5% 5% 5% 4 7% 9% 40%	3414
	21st to end	Day	7% 14% 6% 16% 7% 6% 6% 4 6% 7% 22%	3940
April	1st to 10th	Day	7% 13% 4 9% 6% 7% 6% 5% 7% 7% 29%	2349
	11th to 20th	Day	10% 10% 4 8% 7% 5% 6% 5% 7% 7% 31%	2440
	21st to end	Day	10% 12% 3 9% 7% 6% 5% 5% 6% 8% 30%	2485
May	1st to 10th	Day	15% 11% 3 8% 6% 5% 5% 4 6% 7% 30%	4634
	11th to 20th	Day	11% 10% 4 8% 6% 6% 6% 5% 7% 8% 30%	4694
	21st to end	Day	11% 8% 3 9% 6% 6% 6% 5% 7% 9% 28%	5161
June	1st to 10th	Day	16% 9% 3 8% 6% 5% 5% 5% 5% 7% 31%	2870
	11th to 20th	Day	18% 9% 3 9% 7% 6% 5% 5% 6% 7% 25%	3040
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 8% 39%	3040
July	1st to 10th	Day	9% 5% 2 5% 4 4 4 4 6% 8% 49%	5060
	11th to 20th	Day	8% 4 1 6% 5% 5% 4 4 7% 9% 48%	4740
	21st to end	Day	11% 5% 2 6% 4 4 4 4 6% 9% 44%	5138
August	1st to 10th	Day	12% 5% 2 5% 5% 4 4 4 7% 9% 42%	4470
	11th to 20th	Day	9% 6% 2 6% 4 4 4 5% 7% 10% 42%	4211
	21st to end	Day	11% 6% 3 7% 5% 5% 5% 4 6% 8% 41%	4521
September	1st to 10th	Day	12% 7% 3 7% 4 4 4 3 6% 8% 42%	2390
	11th to 20th	Day	14% 7% 2 6% 5% 4 4 3 5% 9% 42%	2109
	21st to end	Day	9% 6% 3 9% 5% 5% 5% 4 7% 8% 41%	2090
October	1st to 10th	Day	9% 8% 3 9% 5% 4 4 4 6% 7% 40%	3317
	11th to 20th	Day	12% 11% 5% 8% 5% 4 4 4 6% 8% 33%	2842
	21st to end	Day	6% 12% 6% 9% 5% 5% 5% 4 5% 8% 34%	3101
November	1st to 10th	Day	10% 15% 6% 10% 6% 5% 4 4 5% 7% 25%	1508
	11th to 20th	Day	7% 13% 4 11% 6% 5% 5% 3 6% 7% 32%	1330
	21st to end	Day	5% 11% 5% 13% 7% 7% 6% 3 6% 7% 29%	1330
December	1st to 10th	Day	5% 12% 5% 12% 8% 8% 6% 5% 4 7% 28%	1330
	11th to 20th	Day	6% 12% 5% 12% 7% 6% 7% 5% 5% 8% 28%	1682
	21st to end	Day	4 7% 3 8% 6% 5% 5% 5% 7% 9% 39%	2266
January	1st to 10th	Night	4 12% 5% 15% 9% 6% 5% 4 6% 7% 27%	4730
	11th to 20th	Night	5% 9% 3 11% 8% 6% 7% 5% 8% 7% 31%	4699
	21st to end	Night	7% 13% 5% 10% 6% 5% 5% 4 6% 7% 32%	5019
February	1st to 10th	Night	6% 12% 5% 14% 8% 7% 6% 4 7% 6% 26%	2660
	11th to 20th	Night	5% 12% 5% 12% 8% 7% 5% 6% 6% 7% 28%	2489
	21st to end	Night	6% 12% 4 10% 8% 6% 6% 5% 6% 8% 28%	1958
March	1st to 10th	Night	4 9% 5% 14% 8% 7% 6% 4 7% 8% 28%	3736
	11th to 20th	Night	5% 9% 3 8% 6% 5% 6% 5% 7% 10% 35%	3565
	21st to end	Night	7% 12% 6% 16% 7% 6% 6% 4 5% 7% 23%	3710
April	1st to 10th	Night	8% 11% 3 10% 8% 7% 7% 5% 6% 8% 28%	1830
	11th to 20th	Night	9% 12% 4 10% 7% 7% 6% 4 5% 8% 29%	1691
	21st to end	Night	12% 9% 4 8% 5% 5% 5% 4 7% 8% 33%	1692
May	1st to 10th	Night	19% 12% 4 10% 5% 5% 4 4 4 6% 28%	2326
	11th to 20th	Night	9% 10% 4 11% 6% 6% 6% 5% 7% 7% 30%	2199
	21st to end	Night	14% 9% 3 9% 6% 7% 6% 5% 6% 8% 27%	2414
June	1st to 10th	Night	15% 10% 3 8% 6% 5% 5% 4 7% 7% 29%	1306
	11th to 20th	Night	15% 8% 3 10% 7% 7% 9% 6% 8% 9% 19%	1140
	21st to end	Night	12% 6% 3 8% 4 5% 6% 6% 7% 9% 34%	1140
July	1st to 10th	Night	10% 5% 2 7% 3 5% 4 3 6% 8% 46%	1900
	11th to 20th	Night	9% 6% 2 7% 6% 5% 5% 5% 7% 11% 37%	2217
	21st to end	Night	14% 5% 2 6% 5% 5% 4 3 7% 8% 41%	2414
August	1st to 10th	Night	12% 6% 3 7% 5% 5% 5% 5% 6% 7% 40%	2458
	11th to 20th	Night	14% 8% 3 7% 4 4 4 4 6% 10% 35%	2620
	21st to end	Night	13% 5% 2 6% 4 3 4 4 7% 9% 43%	3146
September	1st to 10th	Night	12% 6% 2 5% 4 4 4 4 6% 8% 43%	1787
	11th to 20th	Night	11% 9% 2 6% 4 4 4 3 6% 8% 43%	2071
	21st to end	Night	10% 8% 2 7% 4 4 5% 3 7% 7% 42%	2090
October	1st to 10th	Night	9% 7% 3 9% 5% 6% 5% 4 6% 8% 37%	3657
	11th to 20th	Night	10% 8% 3 8% 5% 5% 5% 4 7% 8% 38%	4086
	21st to end	Night	7% 10% 4 8% 5% 5% 5% 4 7% 9% 35%	4457
November	1st to 10th	Night	13% 16% 5% 10% 6% 5% 5% 4 6% 6% 24%	2622
	11th to 20th	Night	8% 14% 5% 12% 6% 6% 5% 4 5% 7% 28%	2850
	21st to end	Night	7% 12% 4 12% 8% 6% 6% 4 6% 8% 28%	2850
December	1st to 10th	Night	8% 13% 4 11% 8% 5% 4 4 6% 7% 30%	2850
	11th to 20th	Night	8% 14% 6% 11% 6% 6% 6% 4 6% 7% 27%	3510
	21st to end	Night	3 8% 3 8% 6% 5% 5% 4 6% 8% 42%	5374

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	54% 7% 14% 18% 6% 1	2188
	11th to 20th	Day	45% 5% 13% 13% 22% 1	2220
	21st to end	Day	47% 8% 21% 18% 6%	2666
February	1st to 10th	Day	56% 6% 16% 13% 8% 1	1520
	11th to 20th	Day	52% 9% 14% 17% 8%	1584
	21st to end	Day	55% 8% 12% 18% 7%	1494
March	1st to 10th	Day	54% 5% 15% 19% 6%	3138
	11th to 20th	Day	38% 9% 18% 23% 12%	3415
	21st to end	Day	59% 9% 11% 17% 4	3940
April	1st to 10th	Day	49% 9% 15% 18% 8% 1	2349
	11th to 20th	Day	48% 8% 13% 21% 8%	2440
	21st to end	Day	50% 7% 13% 22% 7% 1	2485
May	1st to 10th	Day	51% 6% 10% 22% 10% 1	4634
	11th to 20th	Day	46% 8% 12% 24% 8%	4698
	21st to end	Day	47% 11% 17% 16% 9%	5162
June	1st to 10th	Day	50% 7% 15% 19% 8% 1	2870
	11th to 20th	Day	54% 10% 14% 16% 5%	3040
	21st to end	Day	39% 11% 19% 24% 6% 1	3040
July	1st to 10th	Day	32% 7% 15% 31% 13% 1	4981
	11th to 20th	Day	32% 9% 17% 29% 13%	4659
	21st to end	Day	36% 8% 22% 22% 12%	4976
August	1st to 10th	Day	37% 9% 19% 33% 2	4452
	11th to 20th	Day	34% 10% 21% 28% 7%	4253
	21st to end	Day	39% 9% 25% 23% 4	4520
September	1st to 10th	Day	39% 8% 18% 25% 7% 2	2390
	11th to 20th	Day	40% 8% 20% 26% 7%	2109
	21st to end	Day	39% 9% 16% 25% 8% 2	2090
October	1st to 10th	Day	41% 7% 24% 23% 5%	3317
	11th to 20th	Day	47% 6% 13% 26% 8%	2842
	21st to end	Day	47% 6% 17% 25% 4	3101
November	1st to 10th	Day	58% 7% 13% 16% 6% 1	1508
	11th to 20th	Day	50% 7% 16% 19% 8%	1330
	21st to end	Day	52% 8% 15% 17% 6% 1	1330
December	1st to 10th	Day	55% 7% 12% 15% 9% 1	1330
	11th to 20th	Day	53% 7% 14% 18% 7%	1684
	21st to end	Day	38% 6% 14% 24% 16% 2	2266
January	1st to 10th	Night	55% 6% 13% 16% 7% 2	4730
	11th to 20th	Night	49% 5% 13% 13% 18% 2	4740
	21st to end	Night	50% 8% 18% 15% 8%	5019
February	1st to 10th	Night	56% 7% 13% 16% 8% 1	2660
	11th to 20th	Night	53% 8% 14% 15% 10% 1	2491
	21st to end	Night	52% 7% 11% 20% 9% 1	1958
March	1st to 10th	Night	51% 7% 16% 19% 7%	3736
	11th to 20th	Night	41% 8% 19% 18% 13% 1	3565
	21st to end	Night	57% 9% 11% 17% 5%	3710
April	1st to 10th	Night	51% 7% 14% 18% 9% 1	1830
	11th to 20th	Night	53% 5% 11% 19% 11% 2	1691
	21st to end	Night	46% 8% 11% 22% 12% 1	1692
May	1st to 10th	Night	56% 6% 9% 17% 12% 1	2326
	11th to 20th	Night	48% 10% 11% 22% 9% 1	2199
	21st to end	Night	49% 13% 14% 14% 10% 1	2414
June	1st to 10th	Night	52% 7% 14% 18% 9% 1	1306
	11th to 20th	Night	56% 13% 13% 14% 4	1140
	21st to end	Night	42% 12% 19% 21% 6%	1140
July	1st to 10th	Night	35% 8% 16% 26% 15%	1870
	11th to 20th	Night	38% 10% 16% 26% 9%	2176
	21st to end	Night	39% 8% 18% 26% 9%	2337
August	1st to 10th	Night	41% 10% 18% 30% 1	2451
	11th to 20th	Night	43% 8% 18% 21% 9%	2644
	21st to end	Night	35% 8% 24% 27% 5%	3146
September	1st to 10th	Night	36% 9% 16% 28% 9% 2	1787
	11th to 20th	Night	38% 6% 16% 29% 9% 1	2071
	21st to end	Night	38% 9% 14% 25% 13% 2	2090
October	1st to 10th	Night	43% 7% 20% 24% 6%	3657
	11th to 20th	Night	41% 7% 14% 31% 7%	4086
	21st to end	Night	43% 7% 21% 22% 5%	4457
November	1st to 10th	Night	59% 6% 10% 18% 6%	2622
	11th to 20th	Night	56% 7% 12% 17% 7% 1	2850
	21st to end	Night	53% 8% 15% 17% 5% 1	2850
December	1st to 10th	Night	53% 5% 12% 18% 10% 1	2850
	11th to 20th	Night	55% 7% 15% 17% 6%	3507
	21st to end	Night	38% 6% 15% 23% 14% 2	5374

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	12% 4 30% 29% 18% 7%	180
	11th to 20th	Day	12% 8% 28% 31% 17% 5%	180
	21st to end	Day	12% 12% 25% 30% 17% 5%	198
February	1st to 10th	Day	16% 9% 31% 30% 13% 2	180
	11th to 20th	Day	15% 5% 29% 33% 14% 4	227
	21st to end	Day	6% 9% 33% 29% 18% 6%	306
March	1st to 10th	Day	12% 8% 30% 32% 16% 3	460
	11th to 20th	Day	10% 7% 29% 33% 17% 5%	460
	21st to end	Day	14% 7% 31% 25% 20% 3	506
April	1st to 10th	Day	10% 13% 32% 32% 10% 3	460
	11th to 20th	Day	13% 7% 23% 33% 17% 6%	452
	21st to end	Day	13% 10% 27% 30% 15% 5%	460
May	1st to 10th	Day	16% 10% 25% 29% 17% 3	586
	11th to 20th	Day	11% 6% 24% 35% 19% 5%	675
	21st to end	Day	17% 4 22% 29% 20% 7%	734
June	1st to 10th	Day	19% 9% 25% 30% 13% 4	700
	11th to 20th	Day	19% 6% 21% 27% 20% 7%	870
	21st to end	Day	12% 5% 18% 30% 26% 9%	870
July	1st to 10th	Day	13% 2 19% 34% 24% 8%	856
	11th to 20th	Day	12% 3 20% 33% 26% 7%	668
	21st to end	Day	12% 4 14% 32% 26% 11%	739
August	1st to 10th	Day	10% 5% 16% 31% 22% 15%	530
	11th to 20th	Day	8% 4 25% 32% 23% 8%	477
	21st to end	Day	16% 5% 18% 30% 23% 7%	539
September	1st to 10th	Day	15% 9% 26% 23% 21% 6%	490
	11th to 20th	Day	17% 6% 24% 30% 19% 6%	490
	21st to end	Day	12% 11% 31% 29% 13% 4	490
October	1st to 10th	Day	15% 8% 25% 30% 18% 4	403
	11th to 20th	Day	15% 9% 29% 27% 15% 4	300
	21st to end	Day	15% 10% 36% 26% 10% 2	330
November	1st to 10th	Day	18% 6% 31% 29% 12% 3	275
	11th to 20th	Day	12% 7% 37% 29% 12% 3	180
	21st to end	Day	8% 7% 36% 33% 12% 5%	180
December	1st to 10th	Day	9% 8% 30% 33% 13% 7%	180
	11th to 20th	Day	8% 11% 32% 34% 13% 2	180
	21st to end	Day	7% 4 24% 35% 27% 5%	198
January	1st to 10th	Night	12% 6% 35% 33% 13% 2	951
	11th to 20th	Night	11% 8% 33% 33% 13% 2	950
	21st to end	Night	13% 10% 35% 29% 11% 2	928
February	1st to 10th	Night	11% 7% 28% 34% 18% 3	760
	11th to 20th	Night	11% 5% 33% 34% 16% 2	744
	21st to end	Night	10% 5% 29% 35% 18% 4	628
March	1st to 10th	Night	10% 5% 32% 34% 17% 2	760
	11th to 20th	Night	11% 4 31% 37% 15% 2	760
	21st to end	Night	14% 5% 26% 38% 15% 3	836
April	1st to 10th	Night	11% 7% 28% 36% 16% 2	690
	11th to 20th	Night	14% 6% 28% 34% 17% 1	563
	21st to end	Night	15% 6% 27% 36% 15% 1	552
May	1st to 10th	Night	15% 6% 26% 37% 14% 2	380
	11th to 20th	Night	13% 3 28% 35% 20% 2	374
	21st to end	Night	19% 6% 23% 33% 18% 1	411
June	1st to 10th	Night	20% 6% 23% 36% 14% 2	380
	11th to 20th	Night	19% 4 21% 33% 20% 3	380
	21st to end	Night	14% 3 18% 37% 24% 4	380
July	1st to 10th	Night	15% 3 14% 43% 24% 1	370
	11th to 20th	Night	12% 5% 20% 37% 25% 2	368
	21st to end	Night	12% 3 17% 40% 25% 3	416
August	1st to 10th	Night	10% 4 18% 32% 31% 5%	378
	11th to 20th	Night	13% 4 17% 38% 25% 3	447
	21st to end	Night	13% 3 23% 37% 22% 1	627
September	1st to 10th	Night	15% 3 17% 40% 22% 2	647
	11th to 20th	Night	16% 4 19% 39% 21% 2	760
	21st to end	Night	14% 5% 30% 34% 15% 2	760
October	1st to 10th	Night	16% 4 27% 35% 16% 1	760
	11th to 20th	Night	14% 4 31% 36% 13% 1	760
	21st to end	Night	12% 9% 33% 33% 12% 1	836
November	1st to 10th	Night	21% 5% 30% 31% 11% 2	922
	11th to 20th	Night	13% 8% 37% 30% 10% 3	950
	21st to end	Night	12% 6% 37% 34% 10% 1	950
December	1st to 10th	Night	14% 6% 33% 30% 14% 3	950
	11th to 20th	Night	13% 7% 32% 34% 14% 1	950
	21st to end	Night	11% 4 30% 37% 15% 3	1090

Page generated at 2024-11-01 20:47:29. Version ac07

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