Laurel Bank
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Laurel Bank clear sky chart from 2005-11-06 to 2024-12-09.

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	13% 6% 2 6% 5% 5% 5% 4 6% 8% 39%	101075
	Night	14% 6% 2 6% 4 4 4 4 6% 7% 43%	98640
Transparency	Day	39% 9% 13% 21% 14% 4	104725
	Night	37% 8% 13% 23% 16% 3	103129
Seeing	Day	20% 14% 24% 23% 14% 5%	15193
	Night	18% 12% 22% 31% 16% 2	25509

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	15% 7% 2 6% 4 4 4 3 5% 7% 42%	2836
	11th to 20th	Day	13% 9% 4 6% 5% 4 5% 4 6% 6% 38%	2840
	21st to end	Day	18% 9% 3 7% 5% 4 4 3 4 5% 38%	3124
February	1st to 10th	Day	12% 7% 3 8% 5% 5% 5% 4 5% 6% 38%	1710
	11th to 20th	Day	15% 7% 2 7% 6% 5% 5% 4 5% 7% 38%	1696
	21st to end	Day	16% 8% 2 6% 4 4 5% 4 6% 7% 37%	1641
March	1st to 10th	Day	22% 8% 2 5% 4 4 4 4 6% 7% 34%	3435
	11th to 20th	Day	10% 6% 2 5% 5% 3 4 4 5% 7% 50%	3480
	21st to end	Day	16% 9% 2 7% 5% 5% 5% 3 5% 7% 37%	3815
April	1st to 10th	Day	10% 6% 2 6% 4 5% 4 4 5% 7% 46%	2163
	11th to 20th	Day	13% 5% 2 6% 5% 4 5% 4 6% 7% 44%	2254
	21st to end	Day	15% 6% 2 7% 5% 4 5% 4 5% 6% 40%	2415
May	1st to 10th	Day	16% 7% 3 8% 6% 6% 6% 5% 7% 8% 28%	4082
	11th to 20th	Day	20% 8% 3 7% 5% 4 5% 4 6% 7% 31%	4081
	21st to end	Day	9% 4 2 6% 5% 5% 6% 5% 7% 11% 40%	4476
June	1st to 10th	Day	11% 4 2 6% 6% 5% 6% 5% 7% 10% 39%	2470
	11th to 20th	Day	9% 5% 2 6% 5% 6% 6% 5% 7% 11% 37%	2470
	21st to end	Day	8% 5% 2 7% 5% 6% 5% 5% 8% 12% 38%	2470
July	1st to 10th	Day	6% 4 2 6% 6% 6% 6% 5% 9% 10% 40%	4120
	11th to 20th	Day	8% 6% 2 6% 5% 6% 6% 5% 8% 11% 37%	4120
	21st to end	Day	13% 9% 3 9% 7% 7% 6% 5% 7% 9% 25%	4466
August	1st to 10th	Day	13% 6% 2 7% 6% 6% 6% 5% 7% 11% 30%	4104
	11th to 20th	Day	9% 4 2 7% 6% 5% 7% 5% 8% 11% 36%	4044
	21st to end	Day	8% 4 2 5% 4 4 5% 5% 7% 10% 47%	4222
September	1st to 10th	Day	13% 5% 2 6% 3 4 5% 4 5% 7% 45%	2252
	11th to 20th	Day	17% 6% 3 7% 4 4 3 4 5% 8% 40%	2090
	21st to end	Day	25% 6% 2 6% 5% 4 3 3 5% 6% 36%	2090
October	1st to 10th	Day	18% 5% 1 4 4 4 4 3 4 6% 47%	1910
	11th to 20th	Day	14% 6% 2 5% 4 3 4 3 5% 6% 49%	1900
	21st to end	Day	14% 6% 2 5% 5% 4 3 3 4 5% 49%	2090
November	1st to 10th	Day	12% 5% 2 5% 4 3 4 3 4 7% 52%	1957
	11th to 20th	Day	14% 6% 2 3 3 3 4 3 6% 7% 48%	1830
	21st to end	Day	12% 6% 3 5% 4 4 4 3 5% 6% 47%	1700
December	1st to 10th	Day	15% 8% 2 7% 5% 5% 4 4 5% 7% 38%	1584
	11th to 20th	Day	14% 4 2 6% 4 3 3 3 5% 7% 49%	2014
	21st to end	Day	20% 6% 2 8% 4 5% 6% 5% 7% 6% 31%	3124
January	1st to 10th	Night	11% 7% 2 7% 5% 5% 5% 4 6% 6% 41%	4109
	11th to 20th	Night	15% 7% 3 7% 4 3 4 3 4 5% 45%	4120
	21st to end	Night	20% 10% 3 6% 4 3 3 3 4 5% 39%	4532
February	1st to 10th	Night	13% 8% 3 5% 4 4 4 4 6% 8% 41%	2470
	11th to 20th	Night	18% 7% 3 6% 5% 4 4 3 5% 6% 39%	2365
	21st to end	Night	15% 7% 2 6% 5% 4 5% 4 6% 7% 40%	1812
March	1st to 10th	Night	23% 10% 2 6% 4 4 4 4 6% 6% 32%	3418
	11th to 20th	Night	10% 4 2 5% 4 3 5% 4 6% 7% 49%	3480
	21st to end	Night	15% 6% 2 5% 3 3 4 3 5% 6% 48%	3817
April	1st to 10th	Night	13% 6% 2 5% 4 4 5% 4 6% 8% 43%	2015
	11th to 20th	Night	13% 5% 2 5% 4 4 4 4 5% 8% 48%	1875
	21st to end	Night	14% 6% 1 5% 4 4 5% 3 5% 6% 47%	1781
May	1st to 10th	Night	17% 7% 3 9% 5% 5% 4 4 6% 8% 34%	2813
	11th to 20th	Night	24% 7% 3 6% 4 3 4 3 4 6% 35%	2812
	21st to end	Night	10% 4 2 5% 4 5% 5% 4 7% 10% 45%	3079
June	1st to 10th	Night	10% 4 1 5% 4 4 5% 4 9% 11% 43%	1710
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 7% 10% 46%	1710
	21st to end	Night	8% 3 1 5% 4 5% 5% 4 6% 10% 48%	1710
July	1st to 10th	Night	6% 4 2 5% 4 6% 6% 4 8% 11% 43%	2840
	11th to 20th	Night	7% 5% 2 6% 4 4 5% 5% 7% 11% 44%	2840
	21st to end	Night	10% 8% 3 9% 6% 6% 5% 5% 7% 11% 32%	3087
August	1st to 10th	Night	17% 5% 2 7% 5% 4 4 4 6% 10% 36%	2825
	11th to 20th	Night	9% 5% 2 7% 4 6% 6% 5% 7% 9% 40%	2785
	21st to end	Night	8% 4 2 6% 4 4 4 3 7% 9% 49%	3401
September	1st to 10th	Night	11% 5% 2 6% 4 4 4 4 7% 7% 46%	1924
	11th to 20th	Night	17% 6% 2 6% 4 3 3 4 5% 7% 43%	2090
	21st to end	Night	22% 7% 2 5% 4 5% 3 3 5% 5% 39%	2090
October	1st to 10th	Night	17% 5% 2 4 3 4 4 3 5% 6% 47%	2270
	11th to 20th	Night	14% 6% 2 4 3 4 4 3 5% 6% 50%	2280
	21st to end	Night	14% 3 2 4 3 3 3 3 5% 6% 53%	2508
November	1st to 10th	Night	14% 6% 2 5% 4 3 3 3 4 5% 51%	2341
	11th to 20th	Night	13% 5% 2 5% 4 3 4 4 5% 7% 50%	2565
	21st to end	Night	12% 5% 2 6% 4 4 4 4 5% 6% 48%	2693
December	1st to 10th	Night	16% 8% 3 6% 4 3 4 4 5% 6% 42%	2779
	11th to 20th	Night	13% 7% 2 6% 4 4 4 4 6% 7% 42%	3162
	21st to end	Night	17% 5% 2 7% 5% 5% 6% 4 7% 7% 34%	4532

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	37% 10% 9% 25% 15% 4	2837
	11th to 20th	Day	41% 10% 9% 18% 19% 3	2840
	21st to end	Day	47% 7% 8% 21% 15% 2	3124
February	1st to 10th	Day	45% 7% 11% 20% 15% 2	1710
	11th to 20th	Day	45% 6% 10% 21% 15% 3	1705
	21st to end	Day	46% 8% 10% 15% 16% 5%	1641
March	1st to 10th	Day	45% 8% 12% 20% 11% 4	3435
	11th to 20th	Day	32% 8% 10% 24% 19% 7%	3480
	21st to end	Day	45% 8% 11% 20% 13% 3	3815
April	1st to 10th	Day	36% 9% 12% 21% 16% 6%	2163
	11th to 20th	Day	37% 8% 12% 22% 17% 4	2254
	21st to end	Day	42% 8% 12% 22% 12% 3	2415
May	1st to 10th	Day	48% 12% 12% 18% 9% 2	4120
	11th to 20th	Day	48% 11% 12% 19% 8% 1	4085
	21st to end	Day	33% 14% 17% 20% 14% 3	4489
June	1st to 10th	Day	37% 12% 16% 23% 13% 1	2470
	11th to 20th	Day	38% 13% 17% 18% 14% 1	2470
	21st to end	Day	36% 13% 15% 23% 12% 2	2470
July	1st to 10th	Day	33% 13% 21% 18% 9% 5%	4055
	11th to 20th	Day	36% 12% 18% 24% 9% 1	4051
	21st to end	Day	53% 10% 13% 17% 7% 1	4324
August	1st to 10th	Day	44% 10% 18% 22% 6%	4091
	11th to 20th	Day	37% 11% 15% 25% 12% 1	4083
	21st to end	Day	30% 9% 19% 28% 13% 1	4222
September	1st to 10th	Day	38% 8% 12% 19% 19% 4	2252
	11th to 20th	Day	42% 7% 11% 22% 17% 2	2090
	21st to end	Day	49% 7% 10% 18% 15% 2	2090
October	1st to 10th	Day	31% 5% 9% 21% 27% 8%	3170
	11th to 20th	Day	25% 5% 9% 23% 23% 14%	3140
	21st to end	Day	25% 4 12% 27% 20% 12%	3428
November	1st to 10th	Day	32% 6% 10% 22% 26% 4	1957
	11th to 20th	Day	34% 6% 10% 22% 23% 6%	1830
	21st to end	Day	37% 5% 12% 23% 20% 3	1700
December	1st to 10th	Day	44% 8% 12% 17% 15% 3	1584
	11th to 20th	Day	33% 8% 10% 23% 21% 5%	2011
	21st to end	Day	44% 12% 11% 20% 11% 2	3124
January	1st to 10th	Night	35% 12% 13% 20% 17% 3	4109
	11th to 20th	Night	39% 7% 9% 22% 18% 5%	4120
	21st to end	Night	46% 6% 7% 24% 13% 4	4532
February	1st to 10th	Night	40% 6% 13% 22% 17% 1	2470
	11th to 20th	Night	45% 6% 9% 19% 16% 5%	2367
	21st to end	Night	41% 8% 12% 22% 11% 5%	1812
March	1st to 10th	Night	47% 10% 12% 17% 12% 2	3418
	11th to 20th	Night	31% 8% 11% 24% 23% 4	3480
	21st to end	Night	36% 7% 12% 23% 17% 4	3817
April	1st to 10th	Night	37% 9% 13% 21% 16% 4	2015
	11th to 20th	Night	34% 8% 13% 20% 20% 5%	1875
	21st to end	Night	36% 8% 13% 25% 16% 2	1781
May	1st to 10th	Night	46% 10% 15% 18% 10% 1	2840
	11th to 20th	Night	47% 9% 14% 21% 9% 1	2813
	21st to end	Night	30% 13% 19% 25% 9% 4	3087
June	1st to 10th	Night	31% 13% 17% 24% 14% 1	1710
	11th to 20th	Night	32% 11% 18% 25% 13% 1	1710
	21st to end	Night	30% 12% 18% 23% 15% 2	1710
July	1st to 10th	Night	33% 13% 20% 20% 12% 3	2795
	11th to 20th	Night	34% 10% 21% 26% 8% 1	2786
	21st to end	Night	44% 11% 16% 21% 7%	2988
August	1st to 10th	Night	42% 9% 19% 23% 6%	2814
	11th to 20th	Night	36% 9% 18% 25% 11% 1	2812
	21st to end	Night	30% 8% 17% 31% 12% 1	3401
September	1st to 10th	Night	35% 9% 14% 19% 17% 5%	1924
	11th to 20th	Night	39% 7% 13% 22% 18% 2	2090
	21st to end	Night	46% 7% 10% 19% 16% 2	2090
October	1st to 10th	Night	35% 5% 9% 21% 25% 5%	3790
	11th to 20th	Night	23% 5% 11% 23% 28% 11%	3779
	21st to end	Night	19% 4 11% 30% 25% 11%	4120
November	1st to 10th	Night	35% 6% 9% 21% 24% 5%	2341
	11th to 20th	Night	33% 6% 9% 22% 23% 6%	2565
	21st to end	Night	34% 7% 11% 25% 19% 4	2693
December	1st to 10th	Night	42% 8% 10% 24% 14% 3	2779
	11th to 20th	Night	38% 8% 11% 22% 18% 2	3164
	21st to end	Night	41% 10% 16% 18% 14% 1	4532

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	33% 26% 25% 13% 3	270
	11th to 20th	Day	36% 24% 29% 11%	270
	21st to end	Day	32% 29% 27% 10% 2	297
February	1st to 10th	Day	27% 26% 31% 13% 3	270
	11th to 20th	Day	43% 27% 23% 7% 1	270
	21st to end	Day	32% 26% 28% 11% 2	296
March	1st to 10th	Day	27% 24% 24% 20% 5%	460
	11th to 20th	Day	28% 26% 24% 17% 4 1	460
	21st to end	Day	25% 22% 29% 18% 6%	506
April	1st to 10th	Day	24% 25% 24% 18% 9%	460
	11th to 20th	Day	20% 19% 29% 19% 9% 3	452
	21st to end	Day	24% 18% 27% 18% 10% 2	460
May	1st to 10th	Day	22% 19% 30% 16% 10% 3	463
	11th to 20th	Day	22% 10% 30% 20% 13% 5%	487
	21st to end	Day	16% 11% 23% 23% 19% 8%	529
June	1st to 10th	Day	13% 8% 28% 25% 18% 7%	490
	11th to 20th	Day	10% 10% 24% 29% 19% 8%	490
	21st to end	Day	9% 8% 28% 32% 15% 7%	490
July	1st to 10th	Day	11% 5% 19% 30% 25% 11%	485
	11th to 20th	Day	4 4 19% 36% 25% 11%	484
	21st to end	Day	12% 5% 23% 27% 23% 10%	532
August	1st to 10th	Day	15% 4 22% 23% 25% 10%	486
	11th to 20th	Day	13% 5% 20% 27% 24% 12%	479
	21st to end	Day	11% 3 14% 29% 26% 18%	539
September	1st to 10th	Day	17% 4 15% 26% 26% 12%	490
	11th to 20th	Day	19% 4 13% 27% 28% 9%	490
	21st to end	Day	30% 9% 17% 26% 15% 3	490
October	1st to 10th	Day	23% 7% 18% 29% 19% 4	490
	11th to 20th	Day	16% 18% 20% 26% 17% 3	490
	21st to end	Day	19% 15% 27% 24% 13% 2	539
November	1st to 10th	Day	18% 13% 28% 28% 12% 2	495
	11th to 20th	Day	24% 19% 25% 22% 8%	330
	21st to end	Day	25% 20% 27% 21% 6% 1	250
December	1st to 10th	Day	26% 30% 28% 13% 5%	196
	11th to 20th	Day	25% 26% 25% 18% 5% 1	211
	21st to end	Day	28% 22% 27% 16% 7%	297
January	1st to 10th	Night	22% 23% 30% 21% 4	760
	11th to 20th	Night	22% 21% 29% 26% 3	760
	21st to end	Night	21% 23% 33% 22% 2	836
February	1st to 10th	Night	20% 20% 28% 30% 2	760
	11th to 20th	Night	28% 25% 28% 18% 1	743
	21st to end	Night	22% 22% 33% 20% 2	628
March	1st to 10th	Night	20% 18% 31% 27% 4	760
	11th to 20th	Night	26% 18% 26% 23% 7%	760
	21st to end	Night	19% 16% 31% 27% 7%	836
April	1st to 10th	Night	21% 19% 28% 26% 6%	760
	11th to 20th	Night	17% 16% 27% 27% 11% 1	751
	21st to end	Night	17% 12% 25% 37% 9%	641
May	1st to 10th	Night	18% 9% 27% 31% 14% 1	570
	11th to 20th	Night	19% 8% 18% 37% 16% 1	561
	21st to end	Night	15% 3 12% 35% 29% 4	617
June	1st to 10th	Night	9% 2 15% 44% 28% 1	570
	11th to 20th	Night	9% 3 14% 36% 35% 3	570
	21st to end	Night	8% 3 12% 43% 29% 4	570
July	1st to 10th	Night	11% 2 10% 38% 34% 5%	555
	11th to 20th	Night	6% 1 9% 35% 45% 4	552
	21st to end	Night	8% 3 11% 39% 36% 4	624
August	1st to 10th	Night	15% 2 10% 35% 35% 3	567
	11th to 20th	Night	13% 2 7% 38% 37% 4	564
	21st to end	Night	12% 1 8% 34% 38% 7%	787
September	1st to 10th	Night	12% 3 12% 32% 35% 6%	760
	11th to 20th	Night	19% 3 11% 29% 33% 5%	760
	21st to end	Night	25% 6% 17% 28% 22% 2	760
October	1st to 10th	Night	18% 9% 16% 27% 26% 4	760
	11th to 20th	Night	18% 10% 25% 29% 17% 1	760
	21st to end	Night	17% 10% 22% 36% 13% 1	836
November	1st to 10th	Night	18% 9% 23% 35% 14% 1	780
	11th to 20th	Night	19% 15% 22% 34% 11% 1	800
	21st to end	Night	16% 17% 25% 32% 9% 1	800
December	1st to 10th	Night	22% 19% 28% 25% 6%	795
	11th to 20th	Night	17% 18% 28% 31% 6%	760
	21st to end	Night	22% 16% 27% 32% 3	836

Page generated at 2024-12-06 03:54:52. Version ac07

Copyright © 2024 Attilla Danko.