Lost Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lost Lake clear sky chart from 2005-11-06 to 2024-04-03.

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% 15% 5% 9% 5% 3 4 4 4 5% 33%	78771
	Night	14% 16% 6% 10% 6% 3 4 4 4 5% 29%	81379
Transparency	Day	54% 5% 9% 16% 12% 3	78474
	Night	58% 6% 9% 14% 10% 3	81197
Seeing	Day	22% 21% 31% 19% 6% 1	13729
	Night	21% 18% 23% 24% 12% 2	22892

By Month

Percentage Cloud Cover SW (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% 31% 10% 14% 6% 3 3 3 3 4 9%	2539
	11th to 20th	Day	20% 20% 7% 10% 7% 4 4 4 4 4 17%	2540
	21st to end	Day	21% 23% 7% 12% 6% 2 3 3 3 5% 14%	2963
February	1st to 10th	Day	16% 20% 10% 13% 7% 2 4 4 4 4 17%	1710
	11th to 20th	Day	12% 22% 9% 14% 7% 3 4 4 3 4 17%	1665
	21st to end	Day	11% 27% 9% 13% 6% 3 4 3 3 4 18%	1529
March	1st to 10th	Day	12% 21% 9% 13% 7% 4 5% 4 4 5% 16%	1938
	11th to 20th	Day	13% 26% 8% 10% 6% 3 4 3 3 4 19%	2090
	21st to end	Day	16% 29% 8% 13% 6% 3 4 3 4 3 12%	2384
April	1st to 10th	Day	16% 25% 8% 12% 6% 3 3 3 3 3 17%	2185
	11th to 20th	Day	15% 22% 7% 12% 5% 3 3 3 3 4 21%	2129
	21st to end	Day	14% 22% 6% 10% 5% 3 5% 4 4 5% 22%	2287
May	1st to 10th	Day	13% 18% 5% 8% 5% 2 4 3 4 4 33%	2520
	11th to 20th	Day	15% 16% 4 8% 6% 4 4 5% 5% 6% 26%	2477
	21st to end	Day	20% 14% 5% 10% 6% 2 4 4 5% 6% 25%	2723
June	1st to 10th	Day	21% 13% 4 7% 4 3 4 4 4 5% 30%	2520
	11th to 20th	Day	17% 13% 6% 9% 5% 3 5% 5% 5% 7% 25%	2520
	21st to end	Day	9% 6% 2 5% 5% 3 4 3 5% 7% 50%	2520
July	1st to 10th	Day	4 5% 3 4 3 2 3 4 6% 7% 60%	2520
	11th to 20th	Day	6% 4 2 3 3 2 3 3 3 6% 66%	2520
	21st to end	Day	3 3 2 2 2 1 2 2 3 4 75%	2741
August	1st to 10th	Day	2 3 2 5% 4 2 3 2 4 6% 67%	2413
	11th to 20th	Day	5% 3 1 3 3 2 3 4 4 5% 68%	2298
	21st to end	Day	4 4 2 5% 4 2 4 3 6% 7% 57%	2412
September	1st to 10th	Day	6% 4 3 4 3 1 3 3 4 6% 62%	2160
	11th to 20th	Day	10% 7% 4 6% 5% 3 4 5% 4 6% 47%	2160
	21st to end	Day	12% 9% 3 7% 5% 3 4 4 4 5% 45%	1913
October	1st to 10th	Day	17% 11% 3 6% 5% 2 3 4 4 4 40%	1800
	11th to 20th	Day	14% 12% 6% 9% 5% 3 4 4 4 6% 34%	1800
	21st to end	Day	19% 13% 6% 9% 6% 3 3 3 3 4 30%	1894
November	1st to 10th	Day	19% 20% 7% 12% 6% 2 4 2 4 5% 17%	1619
	11th to 20th	Day	18% 22% 6% 12% 5% 3 5% 4 4 5% 16%	1520
	21st to end	Day	17% 17% 8% 10% 6% 3 3 4 3 5% 23%	1520
December	1st to 10th	Day	14% 18% 7% 12% 6% 3 3 4 4 5% 24%	1520
	11th to 20th	Day	17% 21% 7% 12% 6% 2 4 4 6% 7% 13%	1928
	21st to end	Day	16% 24% 7% 10% 7% 4 5% 4 4 4 16%	2794
January	1st to 10th	Night	17% 28% 9% 12% 6% 3 4 4 4 4 9%	4406
	11th to 20th	Night	21% 23% 7% 9% 6% 3 4 4 3 5% 17%	4420
	21st to end	Night	21% 19% 6% 14% 7% 3 4 4 4 5% 14%	4695
February	1st to 10th	Night	14% 18% 9% 15% 7% 3 5% 4 4 4 18%	2470
	11th to 20th	Night	13% 21% 8% 14% 6% 3 3 3 4 3 22%	2402
	21st to end	Night	13% 23% 11% 13% 7% 3 3 3 4 5% 17%	1924
March	1st to 10th	Night	10% 19% 8% 13% 7% 3 5% 4 4 6% 21%	2240
	11th to 20th	Night	10% 19% 7% 12% 8% 4 4 3 4 5% 23%	2090
	21st to end	Night	13% 25% 9% 14% 7% 3 5% 3 4 4 13%	2214
April	1st to 10th	Night	13% 24% 10% 11% 7% 3 4 4 3 4 19%	1820
	11th to 20th	Night	14% 17% 7% 11% 6% 3 3 4 4 6% 24%	1779
	21st to end	Night	14% 20% 5% 11% 6% 3 5% 3 5% 6% 23%	1667
May	1st to 10th	Night	13% 19% 6% 6% 6% 2 2 3 4 5% 33%	1440
	11th to 20th	Night	12% 13% 5% 10% 7% 4 6% 5% 6% 6% 26%	1416
	21st to end	Night	14% 14% 4 10% 6% 4 4 5% 6% 7% 27%	1552
June	1st to 10th	Night	21% 13% 4 8% 4 2 4 4 5% 5% 31%	1440
	11th to 20th	Night	13% 14% 6% 10% 5% 3 5% 4 4 6% 30%	1440
	21st to end	Night	9% 5% 3 5% 6% 3 4 4 4 7% 51%	1440
July	1st to 10th	Night	5% 6% 2 4 3 2 3 3 4 7% 63%	1440
	11th to 20th	Night	4 2 2 4 4 1 3 4 4 5% 66%	1440
	21st to end	Night	2 2 1 3 3 2 1 3 3 5% 75%	1576
August	1st to 10th	Night	4 3 2 4 4 2 2 3 5% 6% 66%	1523
	11th to 20th	Night	4 3 1 3 3 2 3 3 4 5% 69%	1602
	21st to end	Night	4 4 2 4 4 1 3 4 5% 6% 63%	1944
September	1st to 10th	Night	5% 4 2 5% 4 2 2 3 5% 7% 62%	1800
	11th to 20th	Night	9% 8% 4 8% 5% 3 4 4 4 5% 48%	1800
	21st to end	Night	11% 8% 3 7% 4 2 3 4 4 7% 45%	2043
October	1st to 10th	Night	15% 10% 4 7% 4 2 3 3 3 5% 44%	2160
	11th to 20th	Night	13% 12% 5% 8% 4 2 3 4 5% 5% 37%	2160
	21st to end	Night	16% 13% 5% 9% 5% 3 3 4 3 4 34%	2461
November	1st to 10th	Night	20% 17% 7% 11% 7% 2 4 4 3 5% 20%	2457
	11th to 20th	Night	19% 17% 7% 13% 6% 4 4 4 3 4 19%	2660
	21st to end	Night	13% 16% 7% 12% 5% 3 4 4 5% 5% 25%	2660
December	1st to 10th	Night	15% 17% 6% 13% 8% 3 4 4 4 4 23%	2660
	11th to 20th	Night	16% 19% 6% 12% 7% 4 4 4 5% 5% 17%	3276
	21st to end	Night	17% 21% 7% 13% 7% 3 4 4 4 5% 15%	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	83% 4 5% 6% 2	2539
	11th to 20th	Day	73% 5% 8% 9% 4 2	2540
	21st to end	Day	76% 5% 6% 8% 4 1	2963
February	1st to 10th	Day	71% 6% 10% 10% 3	1710
	11th to 20th	Day	71% 6% 7% 11% 4 1	1674
	21st to end	Day	71% 5% 8% 7% 7% 1	1529
March	1st to 10th	Day	70% 5% 9% 11% 3 1	1938
	11th to 20th	Day	69% 5% 7% 15% 4	2090
	21st to end	Day	79% 5% 7% 7% 1	2384
April	1st to 10th	Day	74% 5% 8% 11% 2	2185
	11th to 20th	Day	69% 4 9% 9% 7% 2	2132
	21st to end	Day	65% 7% 9% 11% 7% 2	2287
May	1st to 10th	Day	54% 5% 12% 21% 8%	2520
	11th to 20th	Day	58% 6% 13% 17% 6%	2480
	21st to end	Day	60% 6% 12% 18% 3	2724
June	1st to 10th	Day	57% 5% 12% 18% 7% 1	2520
	11th to 20th	Day	58% 7% 15% 15% 5% 1	2520
	21st to end	Day	33% 6% 15% 28% 14% 4	2520
July	1st to 10th	Day	23% 7% 13% 24% 24% 9%	2451
	11th to 20th	Day	21% 4 8% 20% 33% 13%	2445
	21st to end	Day	13% 3 7% 24% 41% 11%	2589
August	1st to 10th	Day	21% 4 12% 29% 27% 7%	2396
	11th to 20th	Day	19% 4 12% 30% 27% 8%	2298
	21st to end	Day	26% 5% 11% 28% 25% 5%	2412
September	1st to 10th	Day	23% 4 11% 26% 23% 12%	2160
	11th to 20th	Day	38% 6% 10% 20% 19% 7%	2160
	21st to end	Day	42% 5% 10% 21% 16% 6%	1913
October	1st to 10th	Day	48% 5% 7% 21% 15% 4	1800
	11th to 20th	Day	52% 5% 9% 15% 16% 2	1800
	21st to end	Day	59% 5% 5% 16% 14% 1	1894
November	1st to 10th	Day	72% 4 7% 12% 4	1619
	11th to 20th	Day	70% 7% 8% 10% 4 1	1520
	21st to end	Day	65% 6% 6% 11% 11% 1	1520
December	1st to 10th	Day	65% 6% 7% 14% 7% 1	1520
	11th to 20th	Day	70% 8% 10% 9% 2	1928
	21st to end	Day	73% 5% 9% 11% 2	2794
January	1st to 10th	Night	80% 7% 5% 5% 2	4406
	11th to 20th	Night	72% 5% 8% 10% 3 2	4420
	21st to end	Night	75% 6% 7% 7% 5% 1	4695
February	1st to 10th	Night	71% 6% 8% 11% 5%	2470
	11th to 20th	Night	68% 4 9% 12% 6% 1	2404
	21st to end	Night	71% 5% 6% 11% 6% 1	1924
March	1st to 10th	Night	65% 5% 11% 14% 3 1	2240
	11th to 20th	Night	64% 4 10% 17% 3 1	2090
	21st to end	Night	76% 6% 9% 7% 2	2214
April	1st to 10th	Night	71% 6% 9% 10% 4	1820
	11th to 20th	Night	64% 5% 11% 10% 7% 3	1779
	21st to end	Night	63% 6% 11% 11% 8% 1	1667
May	1st to 10th	Night	54% 5% 10% 21% 10%	1440
	11th to 20th	Night	56% 8% 11% 17% 6% 2	1416
	21st to end	Night	56% 8% 15% 16% 6%	1552
June	1st to 10th	Night	56% 5% 12% 20% 6%	1440
	11th to 20th	Night	54% 7% 15% 17% 6% 1	1440
	21st to end	Night	34% 6% 14% 26% 16% 4	1440
July	1st to 10th	Night	24% 6% 11% 23% 25% 11%	1400
	11th to 20th	Night	19% 5% 11% 19% 30% 16%	1392
	21st to end	Night	14% 2 8% 20% 40% 16%	1488
August	1st to 10th	Night	21% 5% 12% 25% 27% 10%	1515
	11th to 20th	Night	18% 3 13% 26% 30% 9%	1602
	21st to end	Night	22% 5% 11% 30% 25% 7%	1944
September	1st to 10th	Night	22% 4 13% 24% 23% 13%	1800
	11th to 20th	Night	39% 5% 9% 19% 16% 12%	1800
	21st to end	Night	40% 5% 12% 18% 17% 8%	2043
October	1st to 10th	Night	44% 4 8% 20% 19% 5%	2160
	11th to 20th	Night	50% 5% 8% 15% 19% 4	2160
	21st to end	Night	55% 6% 6% 14% 18% 2	2461
November	1st to 10th	Night	70% 4 6% 13% 6% 1	2457
	11th to 20th	Night	69% 6% 7% 10% 7%	2660
	21st to end	Night	63% 6% 6% 13% 11% 1	2660
December	1st to 10th	Night	66% 7% 7% 13% 8%	2660
	11th to 20th	Night	69% 9% 8% 9% 4	3276
	21st to end	Night	72% 8% 9% 7% 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	36% 30% 19% 11% 4	180
	11th to 20th	Day	32% 24% 29% 9% 4 1	180
	21st to end	Day	31% 24% 24% 17% 4	302
February	1st to 10th	Day	29% 32% 24% 12% 3	370
	11th to 20th	Day	32% 31% 25% 11% 1 1	365
	21st to end	Day	35% 27% 26% 11% 2	363
March	1st to 10th	Day	28% 31% 28% 8% 4	460
	11th to 20th	Day	29% 25% 27% 13% 5% 1	460
	21st to end	Day	36% 27% 23% 11% 3	506
April	1st to 10th	Day	34% 24% 24% 13% 4 1	429
	11th to 20th	Day	30% 30% 25% 10% 3 2	412
	21st to end	Day	29% 26% 30% 13% 2 1	420
May	1st to 10th	Day	26% 21% 31% 15% 6% 1	423
	11th to 20th	Day	26% 19% 27% 20% 6% 2	448
	21st to end	Day	24% 16% 29% 22% 6% 1	485
June	1st to 10th	Day	21% 21% 29% 20% 7% 2	450
	11th to 20th	Day	24% 24% 32% 13% 5% 1	450
	21st to end	Day	10% 15% 39% 25% 9% 1	450
July	1st to 10th	Day	6% 14% 46% 28% 4 1	446
	11th to 20th	Day	6% 16% 41% 26% 8% 2	444
	21st to end	Day	4 11% 42% 26% 13% 4	487
August	1st to 10th	Day	3 11% 41% 28% 11% 5%	447
	11th to 20th	Day	4 12% 36% 32% 12% 4	437
	21st to end	Day	7% 19% 38% 23% 9% 3	495
September	1st to 10th	Day	7% 18% 36% 27% 10% 2	450
	11th to 20th	Day	16% 16% 34% 26% 8% 1	450
	21st to end	Day	17% 19% 32% 24% 8% 1	450
October	1st to 10th	Day	21% 17% 31% 24% 7% 1	450
	11th to 20th	Day	24% 21% 24% 20% 9% 2	450
	21st to end	Day	32% 22% 24% 13% 6% 2	409
November	1st to 10th	Day	30% 24% 25% 18% 3	243
	11th to 20th	Day	29% 27% 24% 14% 4 2	180
	21st to end	Day	26% 25% 29% 16% 4	180
December	1st to 10th	Day	31% 20% 26% 17% 4 2	180
	11th to 20th	Day	33% 28% 28% 10% 2	180
	21st to end	Day	35% 28% 18% 15% 3 1	198
January	1st to 10th	Night	32% 24% 21% 16% 6%	760
	11th to 20th	Night	28% 21% 23% 21% 7% 1	760
	21st to end	Night	25% 19% 25% 22% 7% 1	836
February	1st to 10th	Night	24% 22% 25% 22% 7% 1	760
	11th to 20th	Night	28% 25% 18% 22% 6%	744
	21st to end	Night	29% 25% 22% 19% 4	628
March	1st to 10th	Night	23% 25% 21% 22% 9% 1	760
	11th to 20th	Night	22% 22% 24% 22% 8% 1	760
	21st to end	Night	28% 25% 22% 15% 8% 1	836
April	1st to 10th	Night	28% 20% 24% 19% 9% 1	728
	11th to 20th	Night	26% 21% 23% 17% 10% 3	711
	21st to end	Night	24% 18% 24% 21% 11% 2	587
May	1st to 10th	Night	24% 13% 22% 25% 15% 2	360
	11th to 20th	Night	18% 12% 21% 30% 17% 2	354
	21st to end	Night	16% 16% 22% 26% 17% 2	389
June	1st to 10th	Night	27% 13% 19% 25% 14% 3	360
	11th to 20th	Night	19% 18% 28% 25% 10%	360
	21st to end	Night	11% 10% 26% 34% 18% 1	360
July	1st to 10th	Night	9% 5% 30% 35% 20%	350
	11th to 20th	Night	4 7% 36% 35% 15% 3	348
	21st to end	Night	2 7% 26% 44% 19% 2	394
August	1st to 10th	Night	4 7% 23% 39% 21% 5%	449
	11th to 20th	Night	5% 5% 18% 34% 28% 10%	534
	21st to end	Night	6% 10% 30% 31% 20% 4	756
September	1st to 10th	Night	8% 9% 23% 35% 22% 3	720
	11th to 20th	Night	12% 11% 20% 30% 23% 5%	720
	21st to end	Night	15% 9% 24% 30% 18% 3	720
October	1st to 10th	Night	18% 13% 22% 28% 15% 4	720
	11th to 20th	Night	19% 14% 18% 27% 18% 3	720
	21st to end	Night	25% 21% 19% 21% 11% 4	792
November	1st to 10th	Night	29% 21% 19% 23% 7% 1	740
	11th to 20th	Night	29% 22% 24% 18% 5% 1	760
	21st to end	Night	20% 26% 24% 23% 7% 1	760
December	1st to 10th	Night	24% 21% 27% 20% 8% 1	760
	11th to 20th	Night	30% 22% 24% 19% 4	760
	21st to end	Night	33% 26% 23% 14% 4 1	836

Page generated at 2024-03-31 03:08:55. Version ac07

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