Chickadee Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chickadee Ridge Observatory 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	16% 10% 3 8% 5% 5% 4 4 5% 7% 33%	101815
	Night	17% 11% 4 8% 5% 5% 4 3 5% 6% 32%	97831
Transparency	Day	49% 7% 12% 21% 10% 1	105337
	Night	50% 7% 12% 20% 10% 1	102398
Seeing	Day	23% 17% 31% 18% 8% 2	14549
	Night	22% 15% 31% 23% 8% 1	23729

By Month

Percentage Cloud Cover NE (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	14% 16% 6% 12% 6% 5% 5% 3 4 4 24%	2517
	11th to 20th	Day	13% 17% 7% 13% 7% 5% 5% 3 4 4 22%	2520
	21st to end	Day	18% 19% 7% 13% 6% 5% 3 3 3 3 18%	2996
February	1st to 10th	Day	15% 15% 4 12% 7% 5% 5% 4 5% 5% 23%	1710
	11th to 20th	Day	12% 15% 5% 10% 7% 5% 5% 3 4 5% 28%	1663
	21st to end	Day	20% 14% 5% 9% 7% 5% 5% 3 5% 4 24%	1551
March	1st to 10th	Day	21% 14% 4 9% 6% 4 3 3 3 5% 29%	3198
	11th to 20th	Day	11% 16% 5% 8% 6% 5% 5% 3 4 6% 30%	3480
	21st to end	Day	12% 11% 4 7% 4 4 4 3 4 6% 42%	3971
April	1st to 10th	Day	21% 13% 3 8% 4 4 3 3 4 6% 32%	2280
	11th to 20th	Day	22% 9% 3 7% 4 3 4 3 4 5% 37%	2254
	21st to end	Day	22% 11% 3 7% 5% 4 4 3 5% 5% 32%	2388
May	1st to 10th	Day	20% 8% 3 8% 5% 4 5% 3 5% 6% 33%	4426
	11th to 20th	Day	16% 9% 3 8% 5% 5% 4 3 5% 8% 33%	4398
	21st to end	Day	13% 6% 2 6% 5% 4 5% 4 6% 8% 40%	4837
June	1st to 10th	Day	20% 9% 3 7% 4 5% 5% 4 6% 6% 30%	2660
	11th to 20th	Day	14% 6% 3 6% 5% 5% 5% 4 7% 9% 36%	2660
	21st to end	Day	17% 8% 3 7% 6% 5% 6% 4 6% 7% 33%	2660
July	1st to 10th	Day	11% 6% 2 7% 5% 6% 5% 5% 7% 10% 35%	4440
	11th to 20th	Day	13% 5% 2 5% 4 5% 5% 4 7% 9% 40%	4440
	21st to end	Day	10% 6% 3 6% 4 5% 6% 4 7% 9% 40%	4814
August	1st to 10th	Day	17% 8% 3 7% 4 5% 4 4 5% 8% 35%	4238
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 7% 9% 35%	4025
	21st to end	Day	14% 6% 2 6% 4 4 4 4 7% 10% 38%	4180
September	1st to 10th	Day	13% 6% 2 6% 4 5% 5% 4 5% 8% 41%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 5% 7% 48%	2280
	21st to end	Day	18% 6% 2 7% 5% 4 4 4 5% 7% 39%	2014
October	1st to 10th	Day	20% 9% 2 7% 4 3 3 3 5% 6% 36%	1900
	11th to 20th	Day	20% 9% 3 7% 6% 5% 4 3 6% 7% 29%	1900
	21st to end	Day	25% 10% 4 9% 5% 5% 4 3 5% 6% 26%	1982
November	1st to 10th	Day	15% 10% 3 8% 4 5% 5% 4 6% 6% 34%	1747
	11th to 20th	Day	17% 13% 4 8% 6% 5% 4 3 4 6% 30%	1600
	21st to end	Day	20% 15% 5% 10% 6% 5% 5% 4 5% 4 22%	1600
December	1st to 10th	Day	22% 17% 4 12% 6% 5% 4 4 4 6% 17%	1528
	11th to 20th	Day	21% 13% 5% 9% 6% 4 4 3 5% 4 25%	1906
	21st to end	Day	28% 16% 6% 12% 4 3 3 2 2 3 20%	2772
January	1st to 10th	Night	17% 14% 7% 12% 6% 5% 5% 3 5% 5% 20%	4429
	11th to 20th	Night	13% 15% 5% 14% 8% 6% 5% 4 4 6% 20%	4440
	21st to end	Night	19% 18% 6% 12% 6% 6% 4 3 3 3 20%	4660
February	1st to 10th	Night	14% 17% 5% 9% 7% 5% 4 4 7% 6% 23%	2470
	11th to 20th	Night	12% 15% 6% 10% 5% 5% 4 3 5% 5% 30%	2403
	21st to end	Night	14% 14% 5% 8% 6% 4 5% 3 5% 6% 29%	1903
March	1st to 10th	Night	19% 12% 4 9% 5% 4 4 2 4 4 32%	3639
	11th to 20th	Night	17% 16% 4 8% 5% 4 4 4 5% 6% 26%	3479
	21st to end	Night	15% 10% 3 8% 4 4 3 3 4 6% 41%	3660
April	1st to 10th	Night	20% 10% 3 8% 4 4 4 3 4 5% 35%	1900
	11th to 20th	Night	20% 9% 2 7% 4 5% 4 3 5% 5% 37%	1875
	21st to end	Night	19% 11% 3 8% 4 4 4 3 5% 6% 33%	1809
May	1st to 10th	Night	21% 9% 3 7% 4 4 4 4 5% 6% 31%	2514
	11th to 20th	Night	19% 9% 2 6% 4 4 4 3 5% 6% 38%	2495
	21st to end	Night	13% 6% 3 6% 4 4 4 4 6% 7% 42%	2738
June	1st to 10th	Night	15% 8% 2 7% 6% 5% 5% 5% 6% 8% 33%	1520
	11th to 20th	Night	13% 6% 3 6% 4 5% 4 3 7% 7% 42%	1520
	21st to end	Night	17% 7% 2 7% 5% 5% 5% 4 6% 8% 35%	1520
July	1st to 10th	Night	10% 6% 3 8% 6% 6% 5% 5% 7% 8% 38%	2520
	11th to 20th	Night	13% 6% 2 6% 4 4 4 3 5% 7% 46%	2520
	21st to end	Night	9% 7% 2 6% 4 5% 5% 4 6% 7% 45%	2739
August	1st to 10th	Night	12% 7% 2 7% 4 5% 4 3 6% 7% 43%	2687
	11th to 20th	Night	12% 7% 3 7% 4 4 4 3 6% 8% 43%	2785
	21st to end	Night	10% 5% 2 6% 5% 4 5% 4 7% 9% 42%	3462
September	1st to 10th	Night	11% 6% 2 6% 4 4 4 3 5% 8% 47%	1900
	11th to 20th	Night	13% 4 2 4 3 3 4 4 5% 7% 51%	1900
	21st to end	Night	17% 6% 2 6% 4 4 4 3 5% 6% 43%	2165
October	1st to 10th	Night	18% 8% 3 6% 5% 5% 4 3 4 7% 38%	2280
	11th to 20th	Night	20% 9% 2 8% 5% 4 5% 3 5% 6% 32%	2280
	21st to end	Night	22% 11% 3 8% 5% 4 4 4 5% 5% 29%	2614
November	1st to 10th	Night	17% 10% 3 6% 5% 4 4 3 5% 6% 36%	2547
	11th to 20th	Night	17% 11% 3 8% 5% 5% 5% 3 5% 6% 32%	2800
	21st to end	Night	20% 13% 4 10% 5% 5% 5% 3 5% 6% 24%	2800
December	1st to 10th	Night	19% 16% 5% 11% 7% 5% 4 3 4 5% 19%	2686
	11th to 20th	Night	20% 16% 4 9% 5% 4 3 3 4 4 28%	3288
	21st to end	Night	29% 17% 4 11% 5% 4 4 3 3 4 16%	4884

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	59% 11% 13% 11% 6% 2	2518
	11th to 20th	Day	63% 8% 10% 11% 7%	2520
	21st to end	Day	72% 6% 8% 9% 5% 1	2996
February	1st to 10th	Day	61% 7% 10% 16% 5% 1	1710
	11th to 20th	Day	58% 6% 11% 15% 9% 1	1672
	21st to end	Day	62% 5% 10% 12% 10% 1	1551
March	1st to 10th	Day	58% 6% 10% 16% 9% 1	3201
	11th to 20th	Day	52% 9% 13% 15% 10% 2	3480
	21st to end	Day	41% 6% 8% 24% 16% 4	3971
April	1st to 10th	Day	54% 5% 8% 18% 12% 3	2280
	11th to 20th	Day	49% 6% 7% 21% 15% 2	2254
	21st to end	Day	54% 6% 9% 15% 14% 4	2388
May	1st to 10th	Day	49% 8% 10% 20% 11% 2	4440
	11th to 20th	Day	47% 9% 13% 20% 9% 1	4402
	21st to end	Day	39% 9% 12% 23% 15% 2	4837
June	1st to 10th	Day	51% 8% 10% 18% 12% 1	2660
	11th to 20th	Day	41% 8% 11% 25% 13% 2	2660
	21st to end	Day	48% 9% 12% 19% 11% 1	2660
July	1st to 10th	Day	42% 7% 14% 26% 12% 1	4370
	11th to 20th	Day	37% 8% 15% 30% 9%	4365
	21st to end	Day	38% 9% 13% 30% 11%	4661
August	1st to 10th	Day	47% 6% 13% 23% 11%	4224
	11th to 20th	Day	42% 8% 14% 26% 10% 1	4064
	21st to end	Day	39% 6% 14% 29% 10%	4180
September	1st to 10th	Day	39% 8% 15% 27% 12% 1	2280
	11th to 20th	Day	35% 8% 12% 31% 15%	2280
	21st to end	Day	44% 7% 14% 25% 10%	2014
October	1st to 10th	Day	43% 5% 11% 32% 8% 1	3160
	11th to 20th	Day	45% 6% 14% 24% 10%	3140
	21st to end	Day	50% 6% 15% 23% 6%	3246
November	1st to 10th	Day	47% 9% 16% 20% 8% 1	1747
	11th to 20th	Day	54% 7% 11% 16% 10% 1	1600
	21st to end	Day	63% 9% 11% 9% 7%	1600
December	1st to 10th	Day	67% 8% 11% 10% 4 1	1528
	11th to 20th	Day	62% 7% 14% 13% 4	1906
	21st to end	Day	71% 5% 7% 13% 4	2772
January	1st to 10th	Night	62% 9% 13% 11% 3	4429
	11th to 20th	Night	63% 10% 13% 10% 5% 1	4440
	21st to end	Night	68% 7% 9% 9% 6% 1	4660
February	1st to 10th	Night	59% 8% 12% 15% 6% 1	2470
	11th to 20th	Night	55% 6% 11% 20% 8% 1	2405
	21st to end	Night	55% 6% 11% 17% 10% 1	1903
March	1st to 10th	Night	54% 6% 9% 21% 9% 1	3649
	11th to 20th	Night	55% 8% 14% 14% 7% 1	3480
	21st to end	Night	42% 7% 9% 24% 16% 3	3660
April	1st to 10th	Night	51% 5% 8% 20% 14% 2	1900
	11th to 20th	Night	49% 6% 7% 19% 17% 1	1875
	21st to end	Night	52% 5% 9% 16% 15% 3	1809
May	1st to 10th	Night	50% 9% 11% 18% 10% 2	2520
	11th to 20th	Night	45% 8% 13% 23% 9% 2	2496
	21st to end	Night	37% 9% 15% 20% 18% 2	2739
June	1st to 10th	Night	46% 9% 13% 19% 11% 1	1520
	11th to 20th	Night	39% 8% 13% 21% 18% 2	1520
	21st to end	Night	45% 10% 13% 18% 12% 1	1520
July	1st to 10th	Night	41% 7% 15% 21% 15% 2	2480
	11th to 20th	Night	37% 7% 13% 34% 10%	2472
	21st to end	Night	37% 8% 15% 26% 14% 2	2651
August	1st to 10th	Night	39% 7% 14% 25% 13% 1	2677
	11th to 20th	Night	39% 6% 14% 31% 9%	2812
	21st to end	Night	36% 8% 16% 28% 11% 1	3462
September	1st to 10th	Night	36% 9% 12% 28% 14% 1	1900
	11th to 20th	Night	31% 8% 15% 32% 13% 1	1900
	21st to end	Night	41% 7% 11% 30% 11% 1	2165
October	1st to 10th	Night	40% 5% 11% 28% 15%	3800
	11th to 20th	Night	43% 5% 16% 26% 10%	3779
	21st to end	Night	49% 6% 13% 24% 8%	4300
November	1st to 10th	Night	47% 7% 14% 21% 10% 1	2547
	11th to 20th	Night	52% 7% 11% 19% 10% 2	2800
	21st to end	Night	60% 7% 12% 16% 5%	2800
December	1st to 10th	Night	66% 7% 10% 13% 4	2686
	11th to 20th	Night	61% 6% 10% 15% 7% 1	3288
	21st to end	Night	71% 7% 8% 12% 3	4884

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	26% 22% 36% 13% 3 1	180
	11th to 20th	Day	34% 18% 28% 17% 2 1	180
	21st to end	Day	28% 20% 33% 16% 4	261
February	1st to 10th	Day	31% 27% 32% 9% 1	270
	11th to 20th	Day	28% 29% 39% 4	270
	21st to end	Day	34% 23% 31% 10% 2	363
March	1st to 10th	Day	26% 23% 33% 14% 4	460
	11th to 20th	Day	28% 22% 32% 13% 4	460
	21st to end	Day	32% 22% 27% 12% 5% 1	506
April	1st to 10th	Day	30% 24% 29% 12% 5%	460
	11th to 20th	Day	33% 22% 22% 14% 7% 2	452
	21st to end	Day	29% 23% 28% 12% 5% 2	460
May	1st to 10th	Day	25% 17% 32% 18% 7% 2	463
	11th to 20th	Day	19% 16% 35% 20% 8% 2	487
	21st to end	Day	19% 15% 33% 22% 9% 3	529
June	1st to 10th	Day	22% 13% 36% 22% 6% 2	490
	11th to 20th	Day	15% 17% 34% 21% 11% 2	490
	21st to end	Day	20% 16% 30% 22% 9% 3	490
July	1st to 10th	Day	14% 10% 30% 29% 15% 3	485
	11th to 20th	Day	15% 13% 32% 22% 15% 3	484
	21st to end	Day	13% 9% 35% 28% 11% 4	532
August	1st to 10th	Day	14% 10% 32% 28% 13% 3	486
	11th to 20th	Day	15% 9% 28% 27% 15% 6%	479
	21st to end	Day	14% 11% 32% 25% 11% 6%	539
September	1st to 10th	Day	14% 16% 31% 22% 11% 7%	490
	11th to 20th	Day	12% 9% 25% 23% 18% 12%	490
	21st to end	Day	19% 12% 29% 23% 13% 4	490
October	1st to 10th	Day	26% 17% 25% 17% 11% 4	490
	11th to 20th	Day	28% 20% 30% 15% 6% 1	490
	21st to end	Day	28% 21% 28% 18% 4	482
November	1st to 10th	Day	27% 18% 28% 19% 7%	381
	11th to 20th	Day	28% 20% 34% 12% 6% 2	200
	21st to end	Day	32% 23% 28% 15% 3	200
December	1st to 10th	Day	32% 20% 35% 12% 2	182
	11th to 20th	Day	34% 23% 31% 9% 2 1	180
	21st to end	Day	33% 20% 32% 11% 3 1	198
January	1st to 10th	Night	28% 19% 31% 18% 4	760
	11th to 20th	Night	29% 18% 30% 18% 4 1	760
	21st to end	Night	20% 17% 37% 22% 5%	836
February	1st to 10th	Night	23% 22% 34% 19% 2	760
	11th to 20th	Night	22% 22% 36% 16% 3	743
	21st to end	Night	25% 20% 35% 18% 3	628
March	1st to 10th	Night	25% 16% 36% 20% 3	760
	11th to 20th	Night	27% 21% 27% 21% 4 1	760
	21st to end	Night	22% 17% 34% 19% 7%	836
April	1st to 10th	Night	27% 17% 33% 20% 3	760
	11th to 20th	Night	25% 21% 29% 18% 7% 1	751
	21st to end	Night	25% 15% 29% 22% 8% 1	669
May	1st to 10th	Night	23% 12% 27% 26% 9% 2	380
	11th to 20th	Night	16% 11% 38% 28% 7%	374
	21st to end	Night	13% 10% 38% 27% 11%	411
June	1st to 10th	Night	15% 6% 36% 35% 7% 1	380
	11th to 20th	Night	14% 11% 33% 28% 13% 1	380
	21st to end	Night	18% 8% 29% 33% 12% 1	380
July	1st to 10th	Night	10% 6% 32% 37% 14% 1	370
	11th to 20th	Night	12% 4 32% 36% 15% 1	368
	21st to end	Night	11% 4 31% 42% 12%	416
August	1st to 10th	Night	12% 6% 29% 35% 19%	481
	11th to 20th	Night	12% 5% 24% 34% 23% 2	564
	21st to end	Night	12% 7% 32% 33% 15% 2	822
September	1st to 10th	Night	13% 8% 34% 28% 16% 2	760
	11th to 20th	Night	14% 8% 23% 27% 23% 5%	760
	21st to end	Night	20% 10% 24% 27% 17% 2	760
October	1st to 10th	Night	22% 13% 28% 22% 13% 2	760
	11th to 20th	Night	26% 13% 31% 21% 8%	760
	21st to end	Night	29% 16% 28% 22% 5%	836
November	1st to 10th	Night	26% 15% 30% 21% 7%	780
	11th to 20th	Night	25% 17% 33% 16% 8% 1	800
	21st to end	Night	29% 19% 29% 18% 5%	800
December	1st to 10th	Night	29% 20% 31% 17% 3	768
	11th to 20th	Night	26% 19% 34% 17% 3 1	760
	21st to end	Night	34% 17% 30% 17% 1	836

Page generated at 2024-11-29 10:43:03. Version ac07

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