Dolan Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dolan Lake clear sky chart from 2005-11-06 to 2024-08-30.

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	12% 8% 3 7% 5% 4 4 4 6% 7% 41%	95706
	Night	14% 8% 3 6% 4 4 4 3 5% 6% 43%	93389
Transparency	Day	41% 6% 11% 24% 15% 2	95460
	Night	41% 5% 11% 24% 16% 3	93242
Seeing	Day	15% 8% 23% 26% 20% 9%	15290
	Night	16% 7% 26% 32% 16% 2	25071

By Month

Percentage Cloud Cover SE (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% 11% 4 9% 5% 4 4 3 5% 5% 36%	2527
	11th to 20th	Day	16% 8% 3 8% 6% 4 5% 4 5% 6% 34%	2534
	21st to end	Day	24% 17% 4 7% 4 3 3 2 4 5% 26%	3135
February	1st to 10th	Day	16% 11% 5% 7% 5% 3 4 4 5% 6% 36%	1861
	11th to 20th	Day	15% 10% 4 8% 5% 3 4 3 5% 6% 37%	1848
	21st to end	Day	14% 10% 3 9% 5% 5% 4 3 5% 5% 36%	1570
March	1st to 10th	Day	21% 13% 3 6% 4 4 3 2 3 5% 35%	3120
	11th to 20th	Day	13% 7% 2 5% 3 3 4 3 5% 6% 48%	3294
	21st to end	Day	13% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	4165
April	1st to 10th	Day	11% 6% 3 5% 4 5% 4 4 6% 8% 44%	2280
	11th to 20th	Day	14% 8% 2 7% 4 4 4 3 5% 7% 41%	2254
	21st to end	Day	18% 7% 2 6% 4 4 5% 3 5% 6% 40%	2280
May	1st to 10th	Day	14% 7% 3 7% 5% 5% 6% 5% 7% 9% 31%	4068
	11th to 20th	Day	18% 8% 3 6% 4 4 4 3 6% 8% 37%	4081
	21st to end	Day	9% 6% 3 7% 5% 5% 5% 4 6% 7% 42%	4748
June	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 45%	2660
	11th to 20th	Day	6% 5% 2 5% 5% 5% 5% 5% 7% 9% 48%	2660
	21st to end	Day	6% 5% 2 5% 5% 4 5% 4 7% 9% 46%	2660
July	1st to 10th	Day	12% 4 2 6% 4 5% 5% 4 6% 10% 43%	4440
	11th to 20th	Day	5% 4 2 5% 5% 5% 5% 4 7% 11% 48%	4440
	21st to end	Day	8% 7% 3 8% 6% 6% 7% 6% 8% 9% 32%	4813
August	1st to 10th	Day	7% 4 2 5% 5% 5% 5% 5% 6% 11% 46%	2299
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 5% 7% 9% 44%	2245
	21st to end	Day	6% 5% 1 5% 5% 4 5% 4 6% 9% 50%	2485
September	1st to 10th	Day	10% 6% 2 6% 4 4 4 5% 5% 7% 47%	2160
	11th to 20th	Day	7% 6% 2 7% 4 3 5% 4 6% 7% 49%	2044
	21st to end	Day	9% 4 2 6% 3 3 3 3 4 7% 55%	1980
October	1st to 10th	Day	10% 5% 1 5% 4 3 4 2 5% 6% 55%	1961
	11th to 20th	Day	14% 6% 2 5% 4 3 4 3 4 7% 49%	1800
	21st to end	Day	17% 7% 2 6% 4 3 3 3 4 6% 45%	1854
November	1st to 10th	Day	8% 5% 2 4 5% 4 4 4 5% 5% 54%	1672
	11th to 20th	Day	14% 7% 3 7% 4 4 4 3 5% 6% 45%	1710
	21st to end	Day	18% 9% 3 7% 4 3 3 3 4 5% 42%	1710
December	1st to 10th	Day	15% 13% 3 7% 4 3 3 3 4 6% 38%	1647
	11th to 20th	Day	15% 10% 3 8% 5% 4 5% 4 5% 6% 34%	1918
	21st to end	Day	22% 15% 4 8% 5% 4 4 2 4 5% 26%	2783
January	1st to 10th	Night	16% 11% 3 8% 4 4 4 3 5% 6% 36%	4428
	11th to 20th	Night	15% 11% 4 10% 5% 5% 6% 4 4 5% 32%	4433
	21st to end	Night	24% 13% 6% 8% 4 4 3 3 4 5% 27%	4532
February	1st to 10th	Night	18% 12% 4 7% 5% 4 3 5% 4 6% 32%	2318
	11th to 20th	Night	15% 9% 3 7% 5% 4 4 3 4 5% 41%	2218
	21st to end	Night	18% 10% 2 9% 4 5% 3 4 5% 5% 36%	1884
March	1st to 10th	Night	21% 10% 2 7% 4 4 4 3 4 5% 36%	3733
	11th to 20th	Night	12% 7% 2 5% 4 3 4 3 4 6% 50%	3694
	21st to end	Night	17% 7% 3 7% 5% 4 4 4 5% 6% 38%	3466
April	1st to 10th	Night	11% 7% 2 6% 5% 4 4 4 4 7% 46%	1900
	11th to 20th	Night	16% 7% 2 4 4 4 4 4 6% 6% 44%	1875
	21st to end	Night	18% 7% 2 6% 5% 4 4 3 5% 6% 38%	1900
May	1st to 10th	Night	15% 8% 2 7% 5% 4 4 4 6% 7% 38%	2827
	11th to 20th	Night	13% 8% 2 7% 4 4 4 3 5% 6% 43%	2812
	21st to end	Night	8% 5% 3 6% 5% 5% 5% 5% 7% 10% 41%	2813
June	1st to 10th	Night	9% 5% 2 6% 4 4 4 4 5% 8% 49%	1520
	11th to 20th	Night	5% 3 2 5% 4 4 4 4 6% 9% 55%	1520
	21st to end	Night	4 3 1 4 4 4 4 5% 8% 10% 53%	1520
July	1st to 10th	Night	10% 6% 2 5% 3 4 4 4 6% 8% 48%	2530
	11th to 20th	Night	5% 3 1 5% 3 4 3 4 5% 8% 59%	2530
	21st to end	Night	8% 7% 3 9% 6% 5% 6% 5% 8% 9% 35%	2750
August	1st to 10th	Night	6% 3 2 5% 3 4 4 4 6% 9% 54%	1853
	11th to 20th	Night	5% 5% 1 6% 4 5% 4 4 7% 9% 50%	1876
	21st to end	Night	5% 4 2 6% 3 4 4 3 6% 9% 54%	2080
September	1st to 10th	Night	10% 5% 2 6% 4 3 4 3 4 6% 54%	1800
	11th to 20th	Night	7% 4 2 6% 4 4 4 4 5% 8% 53%	1898
	21st to end	Night	11% 5% 2 4 3 3 3 4 5% 7% 54%	1980
October	1st to 10th	Night	7% 5% 2 5% 3 3 3 2 6% 6% 57%	1997
	11th to 20th	Night	14% 5% 2 6% 4 3 3 2 4 5% 54%	2160
	21st to end	Night	19% 7% 3 5% 4 3 3 2 4 5% 45%	2502
November	1st to 10th	Night	11% 6% 2 4 3 3 3 3 5% 5% 56%	2406
	11th to 20th	Night	13% 5% 2 6% 3 3 3 3 5% 6% 50%	2470
	21st to end	Night	18% 6% 2 5% 4 3 3 3 4 6% 46%	2470
December	1st to 10th	Night	18% 9% 3 6% 4 4 4 3 5% 6% 37%	2531
	11th to 20th	Night	17% 8% 3 6% 4 4 4 3 5% 5% 40%	3279
	21st to end	Night	20% 14% 5% 9% 5% 4 5% 3 4 5% 26%	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	49% 4 12% 25% 9% 1	2528
	11th to 20th	Day	51% 5% 10% 24% 10%	2534
	21st to end	Day	62% 4 8% 18% 8% 1	3135
February	1st to 10th	Day	49% 5% 11% 22% 12% 2	1861
	11th to 20th	Day	49% 4 9% 21% 14% 3	1858
	21st to end	Day	49% 4 9% 19% 13% 4	1570
March	1st to 10th	Day	53% 4 6% 19% 15% 5%	3120
	11th to 20th	Day	36% 4 11% 28% 15% 5%	3294
	21st to end	Day	44% 6% 14% 23% 13% 1	4165
April	1st to 10th	Day	37% 5% 13% 27% 16% 1	2280
	11th to 20th	Day	42% 6% 11% 23% 15% 3	2254
	21st to end	Day	43% 6% 10% 26% 12% 2	2280
May	1st to 10th	Day	45% 11% 13% 22% 9% 1	4106
	11th to 20th	Day	43% 8% 10% 25% 12% 1	4085
	21st to end	Day	38% 9% 10% 19% 23% 1	4761
June	1st to 10th	Day	34% 8% 12% 25% 18% 3	2660
	11th to 20th	Day	30% 8% 11% 26% 22% 3	2660
	21st to end	Day	32% 8% 15% 23% 16% 6%	2660
July	1st to 10th	Day	36% 6% 12% 26% 16% 3	4371
	11th to 20th	Day	29% 6% 12% 34% 17% 2	4365
	21st to end	Day	45% 6% 16% 22% 9% 1	4662
August	1st to 10th	Day	32% 8% 14% 30% 14% 1	2285
	11th to 20th	Day	34% 8% 15% 27% 15% 2	2245
	21st to end	Day	29% 7% 15% 25% 18% 6%	2485
September	1st to 10th	Day	35% 6% 9% 28% 17% 5%	2160
	11th to 20th	Day	33% 5% 10% 26% 23% 2	2044
	21st to end	Day	30% 5% 8% 26% 28% 4	1980
October	1st to 10th	Day	30% 5% 9% 26% 25% 5%	1961
	11th to 20th	Day	36% 4 8% 25% 22% 6%	1800
	21st to end	Day	41% 5% 7% 25% 19% 3	1854
November	1st to 10th	Day	31% 5% 10% 29% 18% 6%	1672
	11th to 20th	Day	40% 4 7% 25% 19% 5%	1710
	21st to end	Day	45% 3 9% 25% 15% 2	1710
December	1st to 10th	Day	47% 4 12% 23% 12% 1	1647
	11th to 20th	Day	49% 6% 8% 26% 10% 1	1915
	21st to end	Day	60% 4 11% 15% 10% 1	2783
January	1st to 10th	Night	49% 3 12% 25% 10% 1	4428
	11th to 20th	Night	53% 5% 9% 21% 10% 1	4433
	21st to end	Night	60% 3 9% 18% 9% 1	4532
February	1st to 10th	Night	54% 5% 9% 21% 11% 1	2318
	11th to 20th	Night	46% 5% 8% 23% 16% 2	2219
	21st to end	Night	49% 5% 10% 18% 14% 3	1884
March	1st to 10th	Night	51% 4 7% 18% 17% 3	3733
	11th to 20th	Night	35% 6% 12% 22% 19% 6%	3694
	21st to end	Night	45% 7% 11% 25% 11% 1	3466
April	1st to 10th	Night	37% 5% 12% 26% 17% 3	1900
	11th to 20th	Night	39% 6% 9% 23% 19% 5%	1875
	21st to end	Night	45% 6% 10% 22% 15% 3	1900
May	1st to 10th	Night	42% 9% 16% 24% 9% 1	2854
	11th to 20th	Night	41% 8% 11% 24% 15% 1	2813
	21st to end	Night	34% 9% 14% 25% 17% 2	2821
June	1st to 10th	Night	32% 6% 13% 25% 22% 3	1520
	11th to 20th	Night	25% 6% 13% 25% 25% 6%	1520
	21st to end	Night	24% 7% 17% 26% 19% 7%	1520
July	1st to 10th	Night	34% 6% 10% 27% 18% 5%	2490
	11th to 20th	Night	23% 6% 11% 38% 20% 3	2482
	21st to end	Night	44% 5% 16% 22% 12% 1	2662
August	1st to 10th	Night	26% 7% 17% 29% 20% 2	1843
	11th to 20th	Night	28% 7% 13% 28% 21% 3	1876
	21st to end	Night	26% 7% 14% 27% 21% 5%	2080
September	1st to 10th	Night	31% 6% 7% 28% 20% 6%	1800
	11th to 20th	Night	29% 6% 8% 28% 24% 5%	1898
	21st to end	Night	29% 4 9% 24% 26% 7%	1980
October	1st to 10th	Night	28% 5% 9% 23% 29% 6%	1997
	11th to 20th	Night	35% 3 7% 25% 23% 7%	2160
	21st to end	Night	42% 4 6% 26% 17% 6%	2502
November	1st to 10th	Night	30% 4 10% 25% 25% 6%	2406
	11th to 20th	Night	35% 3 8% 25% 24% 6%	2470
	21st to end	Night	41% 3 9% 25% 19% 2	2470
December	1st to 10th	Night	48% 5% 11% 22% 13% 1	2531
	11th to 20th	Night	45% 5% 9% 24% 15% 1	3281
	21st to end	Night	61% 4 9% 16% 8% 2	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% 14% 29% 23% 7% 1	270
	11th to 20th	Day	27% 17% 33% 19% 5%	270
	21st to end	Day	22% 17% 39% 16% 6%	297
February	1st to 10th	Day	24% 11% 43% 17% 4	270
	11th to 20th	Day	26% 18% 38% 14% 3 1	270
	21st to end	Day	29% 15% 34% 19% 4	225
March	1st to 10th	Day	20% 17% 38% 20% 4 1	270
	11th to 20th	Day	23% 20% 32% 20% 5%	279
	21st to end	Day	25% 14% 31% 20% 9% 1	506
April	1st to 10th	Day	16% 15% 33% 25% 10% 1	460
	11th to 20th	Day	19% 14% 27% 24% 14% 1	452
	21st to end	Day	21% 11% 32% 24% 10% 3	460
May	1st to 10th	Day	19% 11% 27% 29% 10% 4	463
	11th to 20th	Day	18% 6% 24% 27% 17% 7%	487
	21st to end	Day	12% 3 25% 29% 22% 10%	684
June	1st to 10th	Day	12% 5% 17% 28% 26% 13%	680
	11th to 20th	Day	7% 2 18% 33% 30% 10%	680
	21st to end	Day	9% 2 23% 33% 25% 9%	680
July	1st to 10th	Day	12% 2 11% 24% 26% 25%	671
	11th to 20th	Day	6% 3 14% 30% 32% 16%	668
	21st to end	Day	9% 2 11% 32% 31% 16%	739
August	1st to 10th	Day	9% 2 9% 29% 31% 20%	503
	11th to 20th	Day	13% 1 15% 27% 31% 12%	479
	21st to end	Day	7% 2 9% 23% 37% 21%	532
September	1st to 10th	Day	12% 2 12% 23% 35% 16%	450
	11th to 20th	Day	9% 3 8% 27% 34% 19%	450
	21st to end	Day	10% 5% 21% 26% 23% 14%	450
October	1st to 10th	Day	11% 3 19% 37% 19% 10%	431
	11th to 20th	Day	13% 11% 37% 24% 11% 3	270
	21st to end	Day	25% 9% 30% 26% 10%	297
November	1st to 10th	Day	10% 6% 34% 26% 20% 5%	270
	11th to 20th	Day	15% 16% 29% 25% 12% 3	270
	21st to end	Day	23% 11% 30% 23% 11% 1	270
December	1st to 10th	Day	17% 18% 33% 20% 9% 3	270
	11th to 20th	Day	22% 12% 36% 24% 7%	270
	21st to end	Day	27% 18% 33% 16% 6%	297
January	1st to 10th	Night	20% 14% 35% 27% 4	950
	11th to 20th	Night	24% 14% 36% 21% 4	950
	21st to end	Night	21% 10% 40% 27% 2	1045
February	1st to 10th	Night	23% 12% 36% 25% 3 1	798
	11th to 20th	Night	20% 14% 38% 26% 2	743
	21st to end	Night	22% 15% 39% 23% 2	628
March	1st to 10th	Night	21% 12% 34% 29% 4	760
	11th to 20th	Night	20% 10% 34% 28% 7% 1	717
	21st to end	Night	23% 10% 29% 30% 7% 1	627
April	1st to 10th	Night	14% 11% 35% 32% 8%	570
	11th to 20th	Night	19% 9% 29% 30% 13% 1	563
	21st to end	Night	21% 7% 32% 31% 8% 1	570
May	1st to 10th	Night	15% 8% 28% 37% 12%	570
	11th to 20th	Night	16% 4 23% 32% 22% 2	561
	21st to end	Night	8% 2 18% 43% 25% 4	617
June	1st to 10th	Night	11% 2 17% 41% 26% 3	570
	11th to 20th	Night	6% 3 15% 46% 29% 2	570
	21st to end	Night	5% 2 17% 41% 32% 3	570
July	1st to 10th	Night	11% 1 8% 31% 39% 9%	555
	11th to 20th	Night	6% 1 9% 36% 42% 5%	552
	21st to end	Night	8% 2 11% 37% 36% 6%	624
August	1st to 10th	Night	7% 1 5% 42% 38% 7%	567
	11th to 20th	Night	6% 1 10% 39% 38% 5%	564
	21st to end	Night	7% 1 6% 36% 44% 7%	624
September	1st to 10th	Night	13% 1 10% 33% 37% 6%	540
	11th to 20th	Night	9% 2 11% 31% 41% 7%	638
	21st to end	Night	13% 2 18% 32% 28% 6%	720
October	1st to 10th	Night	9% 3 19% 38% 26% 5%	720
	11th to 20th	Night	17% 6% 28% 31% 15% 3	720
	21st to end	Night	22% 7% 30% 30% 10% 1	792
November	1st to 10th	Night	14% 6% 28% 38% 14% 1	740
	11th to 20th	Night	15% 9% 30% 33% 12% 1	760
	21st to end	Night	22% 8% 29% 29% 10% 1	760
December	1st to 10th	Night	23% 8% 32% 30% 6%	821
	11th to 20th	Night	24% 8% 29% 33% 6% 1	950
	21st to end	Night	26% 12% 34% 23% 5%	1045

Page generated at 2024-08-27 08:49:39. Version ac07

Copyright © 2024 Attilla Danko.