Long Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Long Lake clear sky chart from 2005-11-06 to 2024-01-31.

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	18% 12% 5% 8% 7% 3 5% 5% 5% 6% 27%	74899
	Night	17% 13% 6% 10% 7% 3 4 4 4 6% 26%	75225
Transparency	Day	57% 6% 10% 16% 9% 1	74604
	Night	60% 6% 10% 15% 8% 1	75054
Seeing	Day	27% 18% 28% 17% 8% 3	13587
	Night	26% 18% 25% 21% 8% 1	22802

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	11% 19% 9% 16% 10% 4 5% 4 3 3 15%	1517
	11th to 20th	Day	13% 18% 8% 12% 11% 4 4 4 3 4 18%	1520
	21st to end	Day	11% 13% 9% 15% 11% 4 6% 5% 4 5% 17%	1711
February	1st to 10th	Day	13% 15% 10% 12% 11% 5% 6% 4 4 4 14%	1620
	11th to 20th	Day	11% 15% 8% 15% 11% 4 4 4 4 4 19%	1665
	21st to end	Day	15% 17% 6% 15% 8% 5% 4 3 4 5% 18%	1480
March	1st to 10th	Day	14% 14% 8% 13% 9% 3 4 4 4 4 23%	1797
	11th to 20th	Day	15% 16% 7% 9% 7% 4 5% 5% 4 4 25%	1908
	21st to end	Day	19% 14% 6% 9% 6% 2 3 3 3 4 32%	2344
April	1st to 10th	Day	20% 16% 6% 7% 5% 2 3 4 4 5% 29%	2160
	11th to 20th	Day	18% 14% 4 6% 5% 3 4 4 4 4 33%	2134
	21st to end	Day	23% 14% 4 7% 5% 2 4 4 4 6% 27%	2237
May	1st to 10th	Day	22% 11% 4 6% 5% 4 4 4 3 6% 30%	2471
	11th to 20th	Day	19% 10% 3 6% 5% 3 3 4 4 7% 35%	2478
	21st to end	Day	18% 9% 4 6% 5% 3 5% 6% 6% 8% 32%	2725
June	1st to 10th	Day	23% 8% 3 6% 6% 3 5% 5% 6% 7% 27%	2520
	11th to 20th	Day	22% 7% 2 6% 6% 4 5% 6% 6% 8% 30%	2520
	21st to end	Day	22% 8% 4 6% 6% 4 6% 5% 6% 7% 28%	2520
July	1st to 10th	Day	16% 7% 3 6% 6% 3 6% 5% 6% 7% 35%	2520
	11th to 20th	Day	15% 7% 3 6% 7% 4 5% 7% 7% 8% 32%	2520
	21st to end	Day	16% 7% 2 6% 6% 4 7% 7% 7% 9% 28%	2744
August	1st to 10th	Day	17% 7% 3 6% 6% 4 5% 5% 7% 9% 31%	2504
	11th to 20th	Day	16% 8% 3 6% 6% 4 5% 6% 7% 8% 30%	2188
	21st to end	Day	16% 6% 3 6% 6% 4 6% 5% 7% 9% 32%	2376
September	1st to 10th	Day	19% 7% 2 5% 5% 3 5% 5% 4 9% 36%	2160
	11th to 20th	Day	18% 7% 2 5% 4 2 3 4 6% 7% 42%	2106
	21st to end	Day	19% 9% 3 5% 4 3 4 5% 5% 8% 35%	1980
October	1st to 10th	Day	26% 11% 3 6% 5% 3 4 4 4 5% 29%	1828
	11th to 20th	Day	20% 14% 3 6% 4 4 5% 3 6% 7% 27%	1800
	21st to end	Day	26% 17% 4 7% 5% 2 5% 4 4 4 22%	1800
November	1st to 10th	Day	14% 16% 6% 8% 7% 3 4 4 4 5% 27%	1671
	11th to 20th	Day	15% 18% 7% 9% 7% 3 4 3 5% 5% 25%	1657
	21st to end	Day	16% 20% 7% 10% 7% 4 4 4 4 5% 19%	1520
December	1st to 10th	Day	18% 23% 11% 12% 7% 3 3 4 3 4 12%	1520
	11th to 20th	Day	18% 15% 10% 16% 8% 3 4 3 4 4 15%	1906
	21st to end	Day	20% 19% 9% 11% 8% 3 4 4 4 4 15%	2772
January	1st to 10th	Night	13% 18% 10% 16% 11% 4 4 4 3 3 13%	2649
	11th to 20th	Night	14% 19% 8% 15% 11% 4 6% 3 4 4 14%	2660
	21st to end	Night	9% 15% 8% 15% 10% 5% 7% 5% 4 4 18%	2868
February	1st to 10th	Night	14% 16% 9% 15% 11% 6% 5% 4 4 4 13%	2340
	11th to 20th	Night	11% 14% 8% 15% 10% 6% 6% 4 4 5% 17%	2180
	21st to end	Night	13% 15% 7% 14% 10% 6% 4 4 4 5% 19%	1776
March	1st to 10th	Night	14% 14% 8% 12% 9% 4 5% 3 3 4 25%	2150
	11th to 20th	Night	14% 17% 7% 10% 7% 4 4 3 4 5% 27%	2047
	21st to end	Night	17% 15% 6% 8% 4 3 4 3 4 5% 32%	2012
April	1st to 10th	Night	19% 14% 7% 9% 5% 3 3 3 4 5% 28%	1800
	11th to 20th	Night	19% 15% 4 6% 5% 3 3 3 5% 5% 30%	1775
	21st to end	Night	21% 12% 4 7% 5% 2 4 5% 5% 5% 31%	1721
May	1st to 10th	Night	23% 11% 3 6% 6% 2 4 4 4 5% 31%	1504
	11th to 20th	Night	15% 11% 3 5% 5% 3 5% 4 5% 8% 35%	1415
	21st to end	Night	15% 7% 4 5% 5% 4 5% 5% 7% 8% 36%	1550
June	1st to 10th	Night	23% 6% 2 5% 5% 3 5% 6% 5% 7% 33%	1440
	11th to 20th	Night	21% 6% 3 5% 4 3 4 5% 4 8% 37%	1440
	21st to end	Night	19% 6% 3 6% 6% 3 5% 4 6% 9% 34%	1440
July	1st to 10th	Night	14% 4 3 5% 4 3 6% 5% 5% 9% 42%	1440
	11th to 20th	Night	12% 6% 2 5% 5% 3 5% 6% 6% 9% 41%	1440
	21st to end	Night	12% 7% 3 6% 5% 3 4 5% 6% 9% 41%	1574
August	1st to 10th	Night	14% 5% 2 5% 4 3 5% 4 6% 8% 42%	1432
	11th to 20th	Night	15% 8% 3 6% 5% 3 4 5% 5% 7% 39%	1695
	21st to end	Night	15% 7% 2 5% 4 3 5% 5% 5% 7% 41%	1980
September	1st to 10th	Night	16% 7% 2 5% 5% 3 4 3 5% 7% 41%	1800
	11th to 20th	Night	15% 8% 2 5% 4 2 3 4 5% 7% 46%	1853
	21st to end	Night	19% 8% 3 5% 3 2 3 4 6% 7% 39%	1980
October	1st to 10th	Night	25% 10% 3 5% 5% 3 5% 5% 5% 6% 29%	2128
	11th to 20th	Night	18% 13% 4 7% 5% 3 4 5% 6% 7% 28%	2160
	21st to end	Night	25% 18% 5% 6% 5% 3 4 4 4 5% 21%	2556
November	1st to 10th	Night	16% 16% 7% 8% 5% 3 5% 4 5% 5% 27%	2407
	11th to 20th	Night	17% 16% 7% 8% 6% 3 3 5% 4 6% 24%	2521
	21st to end	Night	16% 18% 8% 12% 7% 3 4 4 5% 5% 18%	2660
December	1st to 10th	Night	18% 21% 12% 14% 7% 3 3 3 4 4 12%	2660
	11th to 20th	Night	18% 18% 9% 13% 8% 3 4 4 3 4 17%	3288
	21st to end	Night	22% 19% 7% 17% 7% 3 3 3 3 4 13%	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	75% 4 7% 10% 5%	1518
	11th to 20th	Day	70% 4 6% 10% 7% 3	1520
	21st to end	Day	70% 5% 8% 9% 6% 2	1711
February	1st to 10th	Day	73% 5% 6% 10% 3 2	1620
	11th to 20th	Day	69% 5% 8% 9% 8% 1	1674
	21st to end	Day	70% 5% 7% 9% 9% 1	1480
March	1st to 10th	Day	65% 5% 9% 12% 8% 2	1800
	11th to 20th	Day	62% 5% 9% 10% 11% 3	1908
	21st to end	Day	59% 3 7% 14% 14% 4	2344
April	1st to 10th	Day	59% 4 9% 16% 10% 2	2160
	11th to 20th	Day	54% 5% 8% 18% 13% 1	2134
	21st to end	Day	59% 5% 9% 13% 10% 3	2237
May	1st to 10th	Day	57% 5% 8% 17% 11% 2	2471
	11th to 20th	Day	50% 6% 9% 22% 12% 1	2482
	21st to end	Day	50% 9% 13% 18% 10% 1	2725
June	1st to 10th	Day	55% 7% 12% 15% 10% 1	2520
	11th to 20th	Day	51% 8% 10% 21% 9% 1	2520
	21st to end	Day	55% 7% 12% 17% 8% 1	2520
July	1st to 10th	Day	46% 8% 12% 23% 11%	2450
	11th to 20th	Day	47% 9% 15% 23% 6%	2445
	21st to end	Day	49% 9% 13% 19% 9%	2591
August	1st to 10th	Day	48% 9% 16% 20% 8%	2490
	11th to 20th	Day	49% 8% 15% 21% 7%	2188
	21st to end	Day	46% 9% 12% 23% 9% 1	2376
September	1st to 10th	Day	46% 6% 11% 26% 11% 1	2160
	11th to 20th	Day	41% 6% 10% 26% 16% 1	2106
	21st to end	Day	47% 6% 13% 21% 12% 1	1980
October	1st to 10th	Day	59% 5% 10% 16% 10%	1828
	11th to 20th	Day	57% 6% 13% 17% 6% 1	1800
	21st to end	Day	67% 6% 8% 11% 8% 1	1800
November	1st to 10th	Day	58% 6% 12% 15% 8%	1671
	11th to 20th	Day	61% 6% 10% 12% 8% 3	1657
	21st to end	Day	67% 7% 11% 10% 5%	1520
December	1st to 10th	Day	77% 5% 8% 8% 2 1	1520
	11th to 20th	Day	74% 5% 8% 8% 5%	1906
	21st to end	Day	73% 6% 5% 6% 9%	2772
January	1st to 10th	Night	76% 6% 6% 6% 5%	2649
	11th to 20th	Night	75% 6% 5% 8% 5% 2	2660
	21st to end	Night	69% 5% 7% 10% 7% 2	2868
February	1st to 10th	Night	75% 5% 7% 7% 5% 1	2340
	11th to 20th	Night	69% 6% 8% 9% 7%	2182
	21st to end	Night	67% 6% 8% 11% 7% 1	1776
March	1st to 10th	Night	65% 4 9% 13% 7% 1	2160
	11th to 20th	Night	62% 5% 9% 15% 9% 2	2048
	21st to end	Night	56% 5% 7% 16% 14% 3	2012
April	1st to 10th	Night	60% 4 9% 16% 9% 1	1800
	11th to 20th	Night	55% 6% 10% 17% 11%	1775
	21st to end	Night	55% 6% 10% 16% 11% 2	1721
May	1st to 10th	Night	56% 7% 8% 13% 14% 2	1504
	11th to 20th	Night	47% 7% 11% 20% 14% 2	1416
	21st to end	Night	45% 8% 15% 19% 11% 2	1551
June	1st to 10th	Night	50% 8% 13% 20% 8% 1	1440
	11th to 20th	Night	46% 7% 13% 21% 11% 1	1440
	21st to end	Night	47% 9% 14% 21% 9%	1440
July	1st to 10th	Night	38% 8% 16% 24% 13% 1	1400
	11th to 20th	Night	38% 8% 17% 28% 8%	1392
	21st to end	Night	40% 9% 16% 25% 9% 1	1486
August	1st to 10th	Night	38% 8% 19% 27% 7%	1422
	11th to 20th	Night	44% 8% 14% 24% 10%	1695
	21st to end	Night	42% 8% 14% 27% 9%	1980
September	1st to 10th	Night	42% 7% 13% 27% 9% 1	1800
	11th to 20th	Night	38% 6% 13% 31% 12%	1853
	21st to end	Night	44% 7% 12% 24% 11% 2	1980
October	1st to 10th	Night	55% 6% 12% 16% 10% 1	2128
	11th to 20th	Night	55% 8% 14% 16% 6% 1	2160
	21st to end	Night	67% 5% 10% 10% 6% 1	2556
November	1st to 10th	Night	59% 6% 10% 13% 9% 2	2407
	11th to 20th	Night	62% 6% 10% 13% 7% 3	2521
	21st to end	Night	68% 7% 9% 11% 5% 1	2660
December	1st to 10th	Night	78% 6% 7% 7% 3	2660
	11th to 20th	Night	72% 6% 8% 9% 6% 1	3288
	21st to end	Night	77% 5% 6% 6% 6%	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% 34% 9% 7% 1	180
	11th to 20th	Day	32% 25% 33% 7% 1 1	180
	21st to end	Day	24% 24% 37% 12% 3	218
February	1st to 10th	Day	40% 34% 24% 2	240
	11th to 20th	Day	35% 25% 32% 7% 1	332
	21st to end	Day	35% 25% 27% 10% 3	346
March	1st to 10th	Day	31% 22% 30% 15% 2	420
	11th to 20th	Day	30% 24% 30% 10% 4 1	420
	21st to end	Day	34% 25% 21% 13% 6% 2	462
April	1st to 10th	Day	35% 23% 24% 13% 5% 1	420
	11th to 20th	Day	33% 20% 21% 17% 6% 2	412
	21st to end	Day	36% 18% 28% 10% 5% 2	420
May	1st to 10th	Day	32% 20% 25% 11% 7% 4	423
	11th to 20th	Day	25% 17% 30% 20% 6% 2	447
	21st to end	Day	24% 17% 30% 15% 12% 2	485
June	1st to 10th	Day	28% 18% 29% 18% 6% 2	450
	11th to 20th	Day	25% 14% 28% 21% 9% 3	450
	21st to end	Day	27% 17% 28% 18% 8% 2	450
July	1st to 10th	Day	18% 10% 30% 25% 13% 4	445
	11th to 20th	Day	16% 11% 33% 26% 11% 2	444
	21st to end	Day	17% 10% 37% 26% 8% 2	488
August	1st to 10th	Day	17% 10% 27% 26% 15% 5%	446
	11th to 20th	Day	18% 10% 29% 23% 13% 7%	439
	21st to end	Day	17% 16% 28% 23% 11% 6%	495
September	1st to 10th	Day	19% 12% 28% 18% 14% 8%	450
	11th to 20th	Day	18% 14% 24% 19% 15% 11%	450
	21st to end	Day	19% 15% 27% 20% 14% 5%	450
October	1st to 10th	Day	33% 14% 23% 12% 13% 6%	450
	11th to 20th	Day	28% 22% 24% 18% 7% 1	450
	21st to end	Day	34% 20% 24% 17% 4	405
November	1st to 10th	Day	32% 17% 25% 19% 7% 1	365
	11th to 20th	Day	33% 24% 24% 14% 5% 1	317
	21st to end	Day	33% 26% 27% 13% 1	180
December	1st to 10th	Day	34% 21% 31% 13% 2	180
	11th to 20th	Day	35% 26% 31% 7% 1 1	180
	21st to end	Day	35% 23% 31% 10% 1 1	198
January	1st to 10th	Night	28% 28% 29% 14% 2	760
	11th to 20th	Night	29% 25% 30% 13% 3	760
	21st to end	Night	20% 25% 33% 18% 4	835
February	1st to 10th	Night	28% 27% 31% 13% 2	720
	11th to 20th	Night	24% 30% 30% 14% 2	703
	21st to end	Night	27% 24% 33% 14% 3	592
March	1st to 10th	Night	28% 22% 30% 18% 2	720
	11th to 20th	Night	30% 24% 24% 16% 4 1	720
	21st to end	Night	28% 19% 28% 18% 6% 1	792
April	1st to 10th	Night	28% 22% 26% 20% 3	720
	11th to 20th	Night	30% 20% 25% 17% 8%	711
	21st to end	Night	30% 19% 23% 21% 7%	641
May	1st to 10th	Night	32% 12% 26% 19% 11%	424
	11th to 20th	Night	20% 13% 27% 32% 7%	354
	21st to end	Night	16% 12% 28% 30% 13% 1	389
June	1st to 10th	Night	24% 10% 24% 29% 11% 1	360
	11th to 20th	Night	24% 6% 20% 36% 14%	360
	21st to end	Night	21% 8% 28% 34% 9% 1	360
July	1st to 10th	Night	14% 4 25% 37% 18% 1	350
	11th to 20th	Night	14% 5% 25% 37% 17% 2	348
	21st to end	Night	12% 8% 23% 42% 12% 1	394
August	1st to 10th	Night	18% 7% 17% 40% 18% 1	358
	11th to 20th	Night	18% 7% 21% 30% 21% 3	631
	21st to end	Night	18% 8% 23% 33% 18% 1	792
September	1st to 10th	Night	18% 10% 22% 31% 17% 3	720
	11th to 20th	Night	19% 8% 20% 28% 21% 4	720
	21st to end	Night	25% 11% 23% 20% 19% 3	720
October	1st to 10th	Night	30% 15% 21% 18% 14% 2	720
	11th to 20th	Night	26% 17% 23% 25% 8% 1	720
	21st to end	Night	35% 19% 22% 19% 5%	792
November	1st to 10th	Night	29% 18% 26% 19% 7% 1	740
	11th to 20th	Night	30% 20% 26% 16% 8% 1	760
	21st to end	Night	31% 23% 25% 16% 5% 1	760
December	1st to 10th	Night	33% 26% 23% 14% 4	760
	11th to 20th	Night	29% 26% 24% 17% 3 1	760
	21st to end	Night	32% 27% 26% 13% 2	836

Page generated at 2024-01-28 05:26:34. Version ac07

Copyright 2024 Attilla Danko