Stage Line Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stage Line Ranch clear sky chart from 2005-11-06 to 2024-12-02.

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	8% 7% 3 6% 4 4 4 4 5% 6% 49%	105185
	Night	10% 8% 3 7% 4 4 4 4 5% 7% 44%	103014
Transparency	Day	35% 6% 11% 22% 18% 8%	104953
	Night	40% 6% 11% 21% 16% 7%	102892
Seeing	Day	11% 7% 22% 29% 23% 10%	14323
	Night	14% 5% 21% 36% 21% 3	23718

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	16% 17% 7% 11% 6% 5% 5% 4 5% 5% 19%	2539
	11th to 20th	Day	19% 13% 4 11% 6% 5% 7% 3 5% 5% 21%	2516
	21st to end	Day	24% 22% 6% 13% 4 3 3 2 3 4 16%	2794
February	1st to 10th	Day	14% 12% 5% 10% 6% 6% 5% 4 5% 6% 27%	1577
	11th to 20th	Day	12% 11% 4 9% 5% 5% 4 3 5% 7% 34%	1731
	21st to end	Day	10% 12% 5% 10% 6% 4 5% 4 4 5% 35%	1570
March	1st to 10th	Day	10% 9% 2 6% 5% 6% 5% 5% 7% 8% 36%	3138
	11th to 20th	Day	6% 8% 2 5% 4 3 4 3 5% 6% 53%	3263
	21st to end	Day	10% 10% 3 7% 6% 6% 6% 5% 6% 8% 34%	4165
April	1st to 10th	Day	10% 9% 3 8% 6% 5% 6% 6% 6% 8% 33%	2280
	11th to 20th	Day	6% 8% 2 7% 5% 5% 5% 4 7% 9% 41%	2268
	21st to end	Day	7% 7% 3 8% 5% 5% 4 4 7% 7% 44%	2476
May	1st to 10th	Day	7% 6% 2 5% 4 3 4 4 6% 8% 51%	4420
	11th to 20th	Day	6% 4 2 5% 4 4 4 3 5% 9% 54%	4377
	21st to end	Day	7% 7% 3 8% 6% 6% 6% 5% 7% 8% 39%	4813
June	1st to 10th	Day	12% 7% 2 6% 5% 5% 5% 3 6% 7% 43%	2660
	11th to 20th	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 7% 46%	2660
	21st to end	Day	4 4 2 5% 3 4 3 4 5% 7% 60%	2660
July	1st to 10th	Day	1 1 1 2 2 2 2 2 3 4 80%	4420
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 3 80%	4420
	21st to end	Day	1 1 1 2 2 2 2 2 3 5% 78%	4790
August	1st to 10th	Day	3 2 1 3 2 2 3 2 3 6% 72%	4401
	11th to 20th	Day	2 2 1 2 3 3 3 3 5% 6% 71%	4191
	21st to end	Day	3 4 2 5% 3 3 4 3 5% 6% 63%	4180
September	1st to 10th	Day	4 3 1 3 2 2 3 3 5% 6% 69%	2280
	11th to 20th	Day	5% 4 2 5% 3 4 4 4 6% 8% 55%	2216
	21st to end	Day	6% 4 1 5% 3 4 4 4 4 7% 56%	2090
October	1st to 10th	Day	6% 5% 2 3 3 3 3 3 6% 7% 60%	3256
	11th to 20th	Day	7% 4 2 6% 5% 5% 6% 5% 6% 7% 47%	3046
	21st to end	Day	11% 8% 3 5% 4 4 4 4 5% 7% 45%	3101
November	1st to 10th	Day	18% 9% 3 8% 5% 5% 4 5% 6% 6% 33%	1764
	11th to 20th	Day	15% 12% 3 8% 6% 5% 6% 4 5% 6% 30%	1644
	21st to end	Day	13% 15% 5% 11% 6% 4 5% 4 5% 7% 24%	1600
December	1st to 10th	Day	13% 16% 5% 11% 7% 4 5% 4 5% 6% 24%	1367
	11th to 20th	Day	21% 17% 7% 15% 6% 4 5% 3 5% 4 13%	1718
	21st to end	Day	14% 19% 8% 12% 5% 4 4 4 5% 6% 19%	2794
January	1st to 10th	Night	19% 18% 6% 11% 6% 5% 5% 4 4 5% 18%	4406
	11th to 20th	Night	18% 13% 4 11% 5% 5% 5% 3 5% 6% 25%	4382
	21st to end	Night	21% 19% 8% 11% 4 4 4 3 4 5% 17%	4862
February	1st to 10th	Night	14% 13% 3 8% 5% 4 4 4 6% 6% 32%	2599
	11th to 20th	Night	11% 10% 4 9% 5% 4 4 4 6% 7% 35%	2335
	21st to end	Night	10% 11% 3 8% 6% 5% 5% 5% 6% 8% 33%	1884
March	1st to 10th	Night	8% 8% 3 6% 5% 5% 5% 5% 8% 10% 39%	3736
	11th to 20th	Night	7% 7% 2 5% 3 3 4 3 4 6% 55%	3703
	21st to end	Night	8% 9% 3 10% 8% 8% 6% 5% 7% 9% 28%	3488
April	1st to 10th	Night	9% 9% 2 8% 6% 4 4 4 6% 8% 38%	1900
	11th to 20th	Night	7% 10% 3 7% 5% 4 5% 3 5% 6% 46%	1862
	21st to end	Night	5% 7% 2 6% 7% 5% 5% 5% 7% 8% 41%	1701
May	1st to 10th	Night	7% 6% 3 6% 5% 5% 5% 3 4 7% 49%	2540
	11th to 20th	Night	6% 4 1 5% 3 4 3 4 6% 9% 56%	2516
	21st to end	Night	6% 4 2 6% 5% 4 4 5% 7% 10% 47%	2762
June	1st to 10th	Night	7% 6% 2 6% 4 4 4 4 6% 8% 47%	1520
	11th to 20th	Night	6% 6% 2 6% 3 4 6% 4 6% 7% 49%	1501
	21st to end	Night	5% 3 1 4 4 4 4 3 5% 7% 60%	1520
July	1st to 10th	Night	2 1 1 2 1 1 2 2 3 5% 80%	2540
	11th to 20th	Night	1 1 1 1 1 2 1 2 4 85%	2540
	21st to end	Night	1 1 1 1 1 1 1 2 4 4 83%	2762
August	1st to 10th	Night	4 2 1 3 2 1 2 2 3 6% 73%	2529
	11th to 20th	Night	2 3 1 5% 4 3 4 3 4 5% 66%	2638
	21st to end	Night	2 2 1 4 3 3 4 3 5% 5% 67%	3498
September	1st to 10th	Night	2 2 1 3 3 2 3 3 5% 7% 68%	1900
	11th to 20th	Night	4 4 2 5% 4 4 4 4 6% 8% 56%	1963
	21st to end	Night	6% 4 2 5% 3 3 4 4 7% 8% 55%	2090
October	1st to 10th	Night	6% 3 1 4 2 3 4 3 5% 8% 60%	3721
	11th to 20th	Night	7% 5% 2 5% 4 4 4 5% 7% 8% 50%	3887
	21st to end	Night	12% 6% 2 6% 4 5% 5% 4 4 6% 45%	4457
November	1st to 10th	Night	16% 10% 3 7% 5% 4 5% 3 6% 7% 35%	2535
	11th to 20th	Night	15% 10% 3 8% 4 5% 5% 4 5% 6% 34%	2755
	21st to end	Night	16% 12% 4 10% 5% 5% 5% 3 5% 6% 29%	2800
December	1st to 10th	Night	12% 13% 6% 10% 6% 4 5% 4 6% 8% 27%	2823
	11th to 20th	Night	18% 17% 7% 14% 7% 4 4 4 6% 5% 14%	3497
	21st to end	Night	18% 16% 7% 10% 5% 5% 5% 3 5% 6% 20%	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	64% 9% 10% 12% 5%	2539
	11th to 20th	Day	62% 7% 11% 15% 3 2	2540
	21st to end	Day	73% 5% 11% 8% 2	2794
February	1st to 10th	Day	58% 8% 15% 12% 6% 1	1577
	11th to 20th	Day	50% 9% 15% 18% 9%	1740
	21st to end	Day	50% 7% 13% 19% 10% 1	1570
March	1st to 10th	Day	42% 7% 12% 23% 15% 1	3138
	11th to 20th	Day	33% 4 12% 40% 11%	3263
	21st to end	Day	45% 10% 18% 17% 8% 1	4165
April	1st to 10th	Day	47% 8% 13% 21% 10% 2	2280
	11th to 20th	Day	39% 6% 15% 22% 15% 3	2268
	21st to end	Day	38% 6% 13% 24% 16% 3	2476
May	1st to 10th	Day	30% 5% 9% 26% 26% 3	4420
	11th to 20th	Day	26% 6% 11% 29% 23% 4	4380
	21st to end	Day	39% 7% 15% 25% 11% 1	4814
June	1st to 10th	Day	40% 6% 9% 22% 18% 4	2660
	11th to 20th	Day	36% 5% 11% 25% 17% 5%	2660
	21st to end	Day	24% 4 9% 28% 26% 8%	2660
July	1st to 10th	Day	11% 2 5% 14% 27% 40%	4351
	11th to 20th	Day	10% 3 4 10% 24% 48%	4345
	21st to end	Day	11% 2 4 17% 36% 29%	4639
August	1st to 10th	Day	16% 2 5% 17% 38% 22%	4384
	11th to 20th	Day	15% 3 7% 36% 31% 7%	4233
	21st to end	Day	22% 4 8% 29% 30% 7%	4179
September	1st to 10th	Day	17% 4 10% 27% 29% 14%	2280
	11th to 20th	Day	26% 6% 12% 25% 23% 8%	2216
	21st to end	Day	28% 5% 16% 31% 14% 6%	2090
October	1st to 10th	Day	25% 4 12% 37% 22% 1	3256
	11th to 20th	Day	35% 6% 17% 24% 16% 1	3046
	21st to end	Day	39% 5% 15% 25% 12% 3	3101
November	1st to 10th	Day	50% 8% 15% 18% 8% 1	1764
	11th to 20th	Day	54% 9% 15% 16% 5% 2	1644
	21st to end	Day	59% 12% 12% 12% 5% 1	1600
December	1st to 10th	Day	61% 8% 12% 13% 6%	1367
	11th to 20th	Day	75% 7% 8% 8% 2	1720
	21st to end	Day	68% 6% 12% 9% 5%	2794
January	1st to 10th	Night	67% 7% 10% 12% 2 1	4406
	11th to 20th	Night	58% 9% 13% 14% 6% 1	4420
	21st to end	Night	70% 8% 11% 8% 2 1	4862
February	1st to 10th	Night	52% 7% 16% 15% 8% 1	2599
	11th to 20th	Night	48% 7% 17% 17% 10% 1	2337
	21st to end	Night	46% 8% 14% 20% 11% 1	1884
March	1st to 10th	Night	36% 7% 12% 26% 17% 2	3736
	11th to 20th	Night	30% 4 11% 38% 17% 1	3704
	21st to end	Night	47% 9% 15% 22% 6% 1	3488
April	1st to 10th	Night	43% 5% 13% 25% 12% 2	1900
	11th to 20th	Night	39% 5% 11% 23% 19% 4	1862
	21st to end	Night	36% 7% 11% 24% 18% 4	1701
May	1st to 10th	Night	33% 5% 8% 23% 27% 4	2540
	11th to 20th	Night	23% 5% 10% 32% 27% 2	2516
	21st to end	Night	30% 10% 16% 31% 12% 1	2762
June	1st to 10th	Night	33% 6% 10% 23% 23% 5%	1520
	11th to 20th	Night	33% 5% 8% 28% 19% 6%	1501
	21st to end	Night	23% 4 10% 25% 28% 9%	1520
July	1st to 10th	Night	10% 2 4 14% 29% 42%	2500
	11th to 20th	Night	8% 2 3 11% 20% 57%	2492
	21st to end	Night	8% 1 3 14% 35% 39%	2674
August	1st to 10th	Night	15% 2 5% 13% 39% 28%	2521
	11th to 20th	Night	21% 4 5% 25% 35% 10%	2662
	21st to end	Night	19% 4 7% 26% 31% 14%	3498
September	1st to 10th	Night	16% 4 7% 24% 31% 18%	1900
	11th to 20th	Night	25% 5% 11% 25% 24% 10%	1963
	21st to end	Night	26% 6% 12% 31% 18% 7%	2090
October	1st to 10th	Night	23% 3 8% 39% 27% 1	3721
	11th to 20th	Night	32% 5% 15% 24% 21% 3	3887
	21st to end	Night	39% 5% 10% 30% 14% 2	4457
November	1st to 10th	Night	49% 7% 16% 18% 9% 2	2535
	11th to 20th	Night	50% 8% 15% 17% 8% 2	2755
	21st to end	Night	56% 8% 13% 15% 7% 1	2800
December	1st to 10th	Night	56% 8% 12% 18% 5%	2823
	11th to 20th	Night	70% 8% 11% 8% 3	3494
	21st to end	Night	65% 7% 11% 11% 6%	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	22% 8% 31% 19% 16% 4	180
	11th to 20th	Day	27% 4 17% 29% 18% 5%	180
	21st to end	Day	25% 6% 20% 28% 19% 2	198
February	1st to 10th	Day	16% 8% 26% 33% 14% 3	237
	11th to 20th	Day	17% 11% 26% 28% 15% 5%	396
	21st to end	Day	13% 11% 29% 27% 15% 5%	382
March	1st to 10th	Day	15% 9% 31% 26% 13% 5%	460
	11th to 20th	Day	12% 9% 22% 28% 21% 7%	460
	21st to end	Day	14% 11% 29% 27% 15% 4	506
April	1st to 10th	Day	15% 10% 26% 30% 14% 6%	460
	11th to 20th	Day	11% 13% 29% 25% 14% 8%	452
	21st to end	Day	8% 10% 27% 28% 20% 8%	460
May	1st to 10th	Day	8% 6% 25% 33% 22% 7%	463
	11th to 20th	Day	12% 7% 18% 27% 25% 12%	488
	21st to end	Day	9% 5% 19% 29% 23% 16%	529
June	1st to 10th	Day	12% 7% 19% 26% 25% 11%	490
	11th to 20th	Day	8% 8% 30% 32% 18% 6%	490
	21st to end	Day	2 4 20% 29% 30% 14%	490
July	1st to 10th	Day	2 3 16% 36% 35% 9%	486
	11th to 20th	Day	2 3 18% 29% 34% 14%	484
	21st to end	Day	2 2 15% 29% 35% 18%	531
August	1st to 10th	Day	4 3 12% 30% 31% 20%	487
	11th to 20th	Day	2 2 12% 27% 34% 24%	477
	21st to end	Day	5% 4 19% 26% 28% 18%	539
September	1st to 10th	Day	6% 2 17% 28% 31% 15%	490
	11th to 20th	Day	7% 4 19% 28% 32% 11%	490
	21st to end	Day	7% 7% 22% 30% 26% 8%	490
October	1st to 10th	Day	10% 5% 24% 30% 23% 9%	490
	11th to 20th	Day	13% 6% 20% 29% 24% 9%	426
	21st to end	Day	16% 11% 25% 28% 14% 5%	330
November	1st to 10th	Day	21% 8% 19% 35% 16% 1	300
	11th to 20th	Day	22% 12% 23% 21% 17% 6%	222
	21st to end	Day	20% 6% 20% 31% 20% 4	200
December	1st to 10th	Day	21% 8% 21% 25% 18% 6%	182
	11th to 20th	Day	21% 8% 26% 27% 16% 3	180
	21st to end	Day	21% 9% 22% 34% 12% 3	198
January	1st to 10th	Night	27% 10% 22% 28% 11% 2	760
	11th to 20th	Night	24% 5% 21% 32% 16% 3	760
	21st to end	Night	21% 4 19% 36% 18% 2	836
February	1st to 10th	Night	19% 7% 27% 33% 12% 2	760
	11th to 20th	Night	16% 6% 27% 34% 17% 2	744
	21st to end	Night	15% 8% 27% 33% 14% 3	628
March	1st to 10th	Night	16% 6% 24% 34% 18% 3	760
	11th to 20th	Night	13% 8% 24% 34% 20% 2	760
	21st to end	Night	13% 6% 32% 34% 14% 2	836
April	1st to 10th	Night	12% 7% 25% 34% 19% 3	760
	11th to 20th	Night	10% 8% 28% 36% 15% 2	734
	21st to end	Night	7% 8% 28% 36% 19% 2	561
May	1st to 10th	Night	9% 6% 26% 33% 23% 3	380
	11th to 20th	Night	11% 6% 18% 29% 31% 5%	374
	21st to end	Night	8% 4 19% 38% 28% 4	411
June	1st to 10th	Night	8% 4 22% 41% 23% 3	380
	11th to 20th	Night	8% 5% 27% 38% 19% 2	380
	21st to end	Night	6% 2 21% 38% 28% 5%	380
July	1st to 10th	Night	4 2 11% 47% 32% 4	370
	11th to 20th	Night	3 1 19% 41% 33% 2	368
	21st to end	Night	1 2 12% 42% 40% 4	416
August	1st to 10th	Night	3 2 12% 37% 38% 8%	378
	11th to 20th	Night	2 1 11% 37% 39% 10%	452
	21st to end	Night	3 3 15% 37% 37% 5%	836
September	1st to 10th	Night	3 1 14% 44% 31% 6%	760
	11th to 20th	Night	6% 2 16% 33% 35% 9%	760
	21st to end	Night	8% 3 19% 37% 28% 6%	760
October	1st to 10th	Night	12% 4 17% 37% 28% 3	760
	11th to 20th	Night	13% 5% 20% 34% 26% 3	760
	21st to end	Night	15% 5% 24% 36% 16% 4	836
November	1st to 10th	Night	20% 7% 20% 41% 11% 1	780
	11th to 20th	Night	19% 8% 26% 31% 13% 3	800
	21st to end	Night	21% 5% 20% 31% 21% 2	800
December	1st to 10th	Night	18% 5% 19% 40% 16% 2	905
	11th to 20th	Night	24% 7% 19% 36% 12% 1	937
	21st to end	Night	26% 6% 21% 35% 10% 1	836

Page generated at 2024-11-29 07:43:06. Version ac07

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