Lake Lawrence
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Lawrence clear sky chart from 2005-11-06 to 2024-10-20.

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% 5% 4 5% 6% 33%	102130
	Night	16% 11% 3 8% 5% 5% 4 4 5% 6% 33%	96624
Transparency	Day	51% 9% 12% 16% 9% 2	101890
	Night	52% 10% 13% 16% 8% 2	96510
Seeing	Day	23% 14% 22% 25% 13% 3	15014
	Night	24% 10% 17% 27% 19% 2	23327

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	27% 17% 5% 11% 6% 5% 5% 3 4 5% 10%	2539
	11th to 20th	Day	26% 14% 4 8% 5% 4 4 3 4 5% 22%	2516
	21st to end	Day	22% 14% 5% 11% 7% 6% 6% 5% 7% 6% 12%	2936
February	1st to 10th	Day	24% 16% 5% 11% 6% 5% 4 3 5% 6% 15%	1710
	11th to 20th	Day	25% 16% 5% 11% 6% 5% 4 3 4 5% 16%	1665
	21st to end	Day	23% 20% 5% 9% 5% 5% 4 3 4 4 17%	1475
March	1st to 10th	Day	12% 13% 5% 12% 8% 7% 7% 6% 7% 6% 17%	3252
	11th to 20th	Day	15% 13% 4 8% 5% 5% 4 3 3 4 36%	3490
	21st to end	Day	16% 15% 5% 13% 9% 7% 6% 4 6% 5% 14%	3934
April	1st to 10th	Day	23% 16% 4 11% 7% 5% 5% 3 5% 6% 15%	2280
	11th to 20th	Day	19% 14% 4 10% 7% 5% 4 4 5% 5% 23%	2270
	21st to end	Day	20% 14% 5% 10% 6% 6% 4 4 5% 5% 22%	2479
May	1st to 10th	Day	19% 9% 3 7% 4 5% 5% 3 4 5% 35%	4420
	11th to 20th	Day	11% 9% 3 8% 6% 6% 6% 4 7% 8% 33%	4377
	21st to end	Day	23% 11% 4 10% 6% 6% 5% 4 7% 6% 18%	4813
June	1st to 10th	Day	23% 10% 3 8% 5% 5% 4 5% 5% 7% 24%	2660
	11th to 20th	Day	20% 11% 4 10% 6% 5% 6% 5% 6% 7% 21%	2829
	21st to end	Day	11% 7% 3 8% 6% 5% 4 4 6% 7% 38%	2850
July	1st to 10th	Day	6% 4 2 4 3 3 2 2 4 5% 65%	4740
	11th to 20th	Day	5% 3 1 3 3 2 2 3 4 5% 67%	4434
	21st to end	Day	9% 5% 2 4 3 3 3 3 5% 6% 56%	4790
August	1st to 10th	Day	5% 4 1 4 3 3 3 2 5% 7% 64%	4251
	11th to 20th	Day	7% 6% 2 6% 4 4 6% 5% 7% 9% 44%	4026
	21st to end	Day	13% 7% 2 6% 5% 4 4 3 5% 6% 45%	4322
September	1st to 10th	Day	9% 5% 2 6% 5% 4 4 4 6% 7% 49%	2280
	11th to 20th	Day	11% 8% 3 8% 5% 5% 5% 4 6% 7% 38%	2280
	21st to end	Day	14% 8% 3 7% 5% 4 4 3 6% 6% 39%	2004
October	1st to 10th	Day	17% 11% 4 8% 4 4 4 4 6% 6% 32%	1900
	11th to 20th	Day	19% 9% 4 9% 5% 4 4 4 6% 7% 29%	1891
	21st to end	Day	23% 10% 4 10% 5% 4 5% 4 5% 6% 25%	1900
November	1st to 10th	Day	23% 14% 4 10% 6% 5% 7% 3 6% 6% 16%	1538
	11th to 20th	Day	25% 13% 4 9% 7% 5% 5% 4 5% 6% 17%	1520
	21st to end	Day	23% 16% 4 7% 5% 5% 5% 4 5% 6% 19%	1520
December	1st to 10th	Day	18% 14% 5% 10% 7% 5% 4 4 4 5% 24%	1520
	11th to 20th	Day	20% 14% 4 11% 7% 6% 5% 4 6% 8% 15%	1925
	21st to end	Day	20% 16% 5% 12% 7% 6% 5% 4 6% 5% 14%	2794
January	1st to 10th	Night	25% 19% 6% 12% 7% 6% 4 3 4 3 10%	4406
	11th to 20th	Night	22% 15% 4 10% 5% 5% 4 3 5% 7% 21%	4382
	21st to end	Night	24% 14% 4 11% 7% 6% 5% 4 5% 6% 13%	4708
February	1st to 10th	Night	24% 14% 4 11% 6% 5% 5% 3 4 6% 19%	2470
	11th to 20th	Night	21% 15% 5% 11% 6% 4 4 3 4 4 23%	2402
	21st to end	Night	20% 17% 5% 9% 6% 5% 6% 4 4 5% 19%	1978
March	1st to 10th	Night	11% 14% 5% 11% 7% 7% 6% 6% 8% 7% 20%	3622
	11th to 20th	Night	12% 9% 3 8% 5% 5% 5% 4 5% 6% 40%	3489
	21st to end	Night	21% 17% 4 11% 7% 6% 5% 4 5% 5% 15%	3719
April	1st to 10th	Night	18% 15% 4 11% 7% 5% 5% 4 4 5% 21%	1900
	11th to 20th	Night	16% 13% 4 8% 6% 5% 5% 5% 6% 6% 27%	1856
	21st to end	Night	17% 11% 3 8% 5% 6% 6% 4 4 8% 27%	1701
May	1st to 10th	Night	17% 10% 4 8% 5% 4 3 3 4 4 40%	2540
	11th to 20th	Night	9% 7% 3 8% 5% 5% 5% 4 6% 6% 42%	2516
	21st to end	Night	12% 14% 3 8% 6% 5% 6% 4 6% 7% 30%	2762
June	1st to 10th	Night	15% 7% 3 7% 6% 5% 6% 4 5% 8% 34%	1520
	11th to 20th	Night	15% 10% 4 8% 4 4 4 4 7% 6% 33%	1345
	21st to end	Night	8% 6% 3 6% 4 3 4 4 6% 6% 51%	1330
July	1st to 10th	Night	3 3 1 3 2 2 2 2 4 5% 73%	2220
	11th to 20th	Night	4 2 1 3 2 2 2 2 3 5% 75%	2524
	21st to end	Night	4 3 1 4 2 3 2 2 4 6% 70%	2762
August	1st to 10th	Night	3 2 1 3 3 2 2 2 3 5% 74%	2680
	11th to 20th	Night	7% 4 1 4 4 4 3 4 6% 8% 55%	2812
	21st to end	Night	13% 6% 2 6% 3 3 4 3 4 5% 52%	3338
September	1st to 10th	Night	7% 4 2 4 3 3 4 3 5% 7% 58%	1900
	11th to 20th	Night	12% 8% 3 7% 5% 4 5% 3 5% 6% 44%	1900
	21st to end	Night	10% 7% 2 8% 5% 4 4 3 5% 6% 46%	2174
October	1st to 10th	Night	15% 9% 3 7% 5% 4 3 3 5% 6% 40%	2280
	11th to 20th	Night	20% 8% 3 9% 5% 5% 4 3 4 6% 34%	2273
	21st to end	Night	20% 8% 3 8% 5% 4 4 3 5% 7% 32%	2456
November	1st to 10th	Night	27% 10% 3 9% 5% 5% 6% 4 5% 6% 21%	2537
	11th to 20th	Night	24% 13% 3 10% 6% 5% 4 4 5% 5% 21%	2660
	21st to end	Night	20% 14% 4 9% 6% 5% 5% 4 4 6% 22%	2660
December	1st to 10th	Night	20% 13% 3 9% 6% 4 5% 4 5% 6% 24%	2660
	11th to 20th	Night	22% 14% 5% 10% 6% 5% 5% 4 5% 6% 19%	3280
	21st to end	Night	21% 13% 5% 12% 7% 6% 5% 4 5% 5% 17%	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	77% 10% 6% 5% 3 1	2539
	11th to 20th	Day	64% 7% 11% 13% 4 2	2540
	21st to end	Day	73% 9% 7% 7% 4 1	2936
February	1st to 10th	Day	69% 9% 8% 9% 4	1710
	11th to 20th	Day	69% 10% 8% 8% 5% 1	1674
	21st to end	Day	70% 7% 9% 9% 4	1475
March	1st to 10th	Day	61% 11% 14% 10% 3	3252
	11th to 20th	Day	54% 7% 10% 27% 2 1	3490
	21st to end	Day	69% 11% 11% 9%	3934
April	1st to 10th	Day	71% 9% 12% 8% 1	2280
	11th to 20th	Day	63% 8% 10% 11% 7% 1	2270
	21st to end	Day	65% 8% 11% 11% 4	2479
May	1st to 10th	Day	49% 10% 14% 18% 9%	4420
	11th to 20th	Day	46% 14% 20% 17% 3	4380
	21st to end	Day	64% 13% 14% 8% 1	4814
June	1st to 10th	Day	59% 8% 16% 11% 6%	2660
	11th to 20th	Day	62% 11% 14% 10% 3	2829
	21st to end	Day	44% 8% 18% 20% 8% 2	2850
July	1st to 10th	Day	23% 6% 9% 20% 22% 20%	4666
	11th to 20th	Day	20% 5% 7% 24% 37% 6%	4358
	21st to end	Day	26% 7% 13% 32% 20% 3	4639
August	1st to 10th	Day	21% 6% 11% 35% 23% 5%	4234
	11th to 20th	Day	33% 11% 20% 24% 9% 2	4065
	21st to end	Day	40% 7% 13% 26% 15% 1	4321
September	1st to 10th	Day	33% 7% 14% 25% 15% 5%	2280
	11th to 20th	Day	43% 11% 13% 16% 14% 3	2280
	21st to end	Day	44% 9% 16% 16% 13% 2	2004
October	1st to 10th	Day	50% 8% 10% 21% 10% 1	1900
	11th to 20th	Day	53% 8% 16% 15% 7% 1	1891
	21st to end	Day	59% 8% 9% 14% 10%	1900
November	1st to 10th	Day	68% 9% 9% 11% 3 1	1538
	11th to 20th	Day	67% 9% 9% 7% 6% 2	1520
	21st to end	Day	64% 8% 8% 10% 9% 1	1520
December	1st to 10th	Day	62% 9% 8% 11% 8% 2	1520
	11th to 20th	Day	66% 10% 11% 9% 3	1928
	21st to end	Day	69% 10% 10% 8% 3	2794
January	1st to 10th	Night	77% 9% 6% 5% 2 1	4406
	11th to 20th	Night	62% 8% 11% 15% 4 1	4420
	21st to end	Night	71% 10% 7% 7% 4 1	4708
February	1st to 10th	Night	67% 8% 10% 9% 5%	2470
	11th to 20th	Night	65% 8% 11% 9% 6% 1	2404
	21st to end	Night	67% 9% 10% 10% 5%	1978
March	1st to 10th	Night	60% 11% 13% 12% 4	3622
	11th to 20th	Night	44% 12% 17% 24% 2 1	3490
	21st to end	Night	71% 12% 9% 8%	3719
April	1st to 10th	Night	66% 9% 14% 10% 2	1900
	11th to 20th	Night	56% 10% 14% 11% 8% 1	1856
	21st to end	Night	58% 9% 15% 13% 5% 1	1701
May	1st to 10th	Night	47% 11% 13% 21% 8%	2540
	11th to 20th	Night	38% 17% 22% 17% 5% 1	2516
	21st to end	Night	53% 19% 17% 9% 2	2762
June	1st to 10th	Night	48% 10% 18% 19% 5%	1520
	11th to 20th	Night	50% 11% 20% 16% 3	1345
	21st to end	Night	35% 9% 23% 23% 8% 2	1330
July	1st to 10th	Night	17% 6% 11% 29% 15% 22%	2185
	11th to 20th	Night	16% 3 9% 27% 37% 7%	2477
	21st to end	Night	17% 6% 14% 35% 23% 5%	2674
August	1st to 10th	Night	16% 4 11% 36% 28% 4	2672
	11th to 20th	Night	25% 11% 30% 22% 9% 3	2839
	21st to end	Night	34% 8% 16% 30% 11% 1	3338
September	1st to 10th	Night	26% 9% 16% 27% 17% 5%	1900
	11th to 20th	Night	41% 10% 11% 19% 14% 4	1900
	21st to end	Night	39% 9% 15% 20% 15% 2	2174
October	1st to 10th	Night	44% 7% 14% 25% 9% 1	2280
	11th to 20th	Night	53% 7% 12% 19% 8% 1	2273
	21st to end	Night	52% 8% 11% 17% 11%	2456
November	1st to 10th	Night	64% 9% 11% 12% 4 1	2537
	11th to 20th	Night	66% 10% 9% 9% 5% 2	2660
	21st to end	Night	62% 8% 8% 11% 10% 1	2660
December	1st to 10th	Night	63% 8% 10% 12% 6% 1	2660
	11th to 20th	Night	65% 10% 12% 10% 3	3276
	21st to end	Night	67% 14% 8% 8% 2	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	37% 14% 18% 14% 11% 6%	180
	11th to 20th	Day	34% 17% 19% 18% 9% 3	180
	21st to end	Day	34% 18% 16% 17% 13% 2	288
February	1st to 10th	Day	39% 16% 19% 14% 10% 2	370
	11th to 20th	Day	39% 17% 21% 17% 5% 1	365
	21st to end	Day	39% 17% 23% 15% 7% 1	337
March	1st to 10th	Day	29% 23% 24% 17% 6% 1	460
	11th to 20th	Day	28% 16% 21% 20% 13% 2	460
	21st to end	Day	30% 20% 25% 17% 7% 1	506
April	1st to 10th	Day	32% 18% 22% 17% 9% 2	460
	11th to 20th	Day	27% 23% 24% 15% 6% 4	452
	21st to end	Day	28% 18% 25% 20% 8% 1	460
May	1st to 10th	Day	19% 17% 25% 24% 12% 2	463
	11th to 20th	Day	28% 13% 22% 22% 11% 4	488
	21st to end	Day	23% 13% 24% 25% 12% 3	529
June	1st to 10th	Day	24% 11% 23% 26% 13% 3	490
	11th to 20th	Day	20% 16% 32% 22% 10% 1	659
	21st to end	Day	12% 12% 23% 35% 15% 3	680
July	1st to 10th	Day	11% 8% 22% 39% 18% 3	671
	11th to 20th	Day	7% 7% 24% 39% 19% 3	497
	21st to end	Day	7% 6% 20% 39% 23% 5%	531
August	1st to 10th	Day	7% 8% 18% 40% 20% 6%	487
	11th to 20th	Day	8% 4 17% 41% 23% 7%	477
	21st to end	Day	12% 10% 24% 32% 16% 6%	539
September	1st to 10th	Day	12% 9% 25% 34% 15% 4	490
	11th to 20th	Day	15% 10% 21% 32% 18% 4	490
	21st to end	Day	17% 15% 22% 26% 18% 3	490
October	1st to 10th	Day	23% 15% 19% 22% 19% 3	490
	11th to 20th	Day	26% 15% 20% 19% 15% 6%	487
	21st to end	Day	33% 15% 17% 20% 11% 4	415
November	1st to 10th	Day	33% 23% 14% 15% 14% 1	205
	11th to 20th	Day	29% 19% 17% 14% 15% 7%	180
	21st to end	Day	29% 19% 18% 14% 9% 9%	180
December	1st to 10th	Day	34% 17% 13% 16% 13% 7%	180
	11th to 20th	Day	36% 17% 24% 13% 8% 2	180
	21st to end	Day	38% 17% 14% 19% 11% 1	198
January	1st to 10th	Night	41% 14% 15% 16% 12% 3	760
	11th to 20th	Night	31% 14% 15% 21% 16% 2	760
	21st to end	Night	32% 12% 16% 23% 15% 2	836
February	1st to 10th	Night	33% 13% 15% 26% 11% 1	760
	11th to 20th	Night	32% 12% 15% 27% 14% 1	744
	21st to end	Night	32% 14% 19% 24% 10% 1	628
March	1st to 10th	Night	27% 14% 19% 24% 13% 2	760
	11th to 20th	Night	27% 14% 19% 26% 13% 1	760
	21st to end	Night	30% 15% 23% 22% 9% 1	836
April	1st to 10th	Night	26% 13% 21% 23% 14% 2	760
	11th to 20th	Night	23% 14% 22% 25% 15% 2	728
	21st to end	Night	23% 12% 19% 30% 14% 1	561
May	1st to 10th	Night	17% 12% 21% 30% 20%	380
	11th to 20th	Night	16% 7% 17% 33% 25% 2	374
	21st to end	Night	20% 6% 19% 31% 22% 2	411
June	1st to 10th	Night	18% 6% 24% 28% 24% 1	380
	11th to 20th	Night	20% 8% 23% 30% 19% 1	380
	21st to end	Night	9% 4 19% 37% 28% 2	380
July	1st to 10th	Night	6% 4 13% 41% 33% 2	370
	11th to 20th	Night	7% 4 10% 46% 32% 2	368
	21st to end	Night	4 2 13% 37% 42% 4	416
August	1st to 10th	Night	8% 2 11% 31% 42% 6%	464
	11th to 20th	Night	7% 2 7% 33% 44% 7%	564
	21st to end	Night	10% 5% 12% 38% 32% 3	741
September	1st to 10th	Night	10% 4 14% 35% 31% 5%	760
	11th to 20th	Night	14% 6% 17% 22% 36% 6%	760
	21st to end	Night	15% 8% 16% 31% 27% 3	760
October	1st to 10th	Night	18% 9% 14% 29% 27% 3	760
	11th to 20th	Night	25% 11% 14% 26% 21% 5%	758
	21st to end	Night	26% 13% 16% 27% 16% 3	792
November	1st to 10th	Night	33% 11% 20% 25% 10% 1	740
	11th to 20th	Night	35% 12% 19% 19% 12% 2	760
	21st to end	Night	31% 12% 19% 21% 14% 4	760
December	1st to 10th	Night	29% 13% 16% 25% 16% 2	760
	11th to 20th	Night	36% 12% 20% 21% 9% 1	760
	21st to end	Night	42% 15% 17% 18% 8% 1	836

Page generated at 2024-10-17 10:09:41. Version ac07

Copyright © 2024 Attilla Danko.