Gabriel Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gabriel Lake clear sky chart from 2005-11-06 to 2024-02-15.

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	17% 8% 3 6% 6% 3 5% 5% 5% 7% 34%	78236
	Night	17% 8% 3 6% 5% 3 4 5% 5% 7% 36%	80829
Transparency	Day	48% 7% 12% 21% 12% 2	77941
	Night	46% 7% 12% 22% 12% 1	80658
Seeing	Day	24% 17% 27% 19% 10% 3	13821
	Night	23% 15% 27% 25% 9% 1	23152

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	14% 10% 3 8% 8% 3 5% 5% 5% 7% 32%	2517
	11th to 20th	Day	15% 11% 6% 10% 8% 3 5% 5% 6% 6% 25%	2520
	21st to end	Day	22% 13% 5% 8% 5% 4 4 4 4 6% 25%	3032
February	1st to 10th	Day	16% 10% 4 8% 6% 4 6% 6% 5% 8% 27%	1710
	11th to 20th	Day	14% 9% 4 7% 6% 4 5% 5% 5% 8% 33%	1731
	21st to end	Day	20% 9% 4 8% 6% 3 4 4 5% 6% 31%	1480
March	1st to 10th	Day	14% 8% 4 8% 7% 3 5% 4 5% 7% 36%	1797
	11th to 20th	Day	15% 11% 4 6% 7% 3 5% 4 5% 7% 32%	1941
	21st to end	Day	20% 8% 4 6% 6% 3 5% 4 5% 6% 33%	2326
April	1st to 10th	Day	18% 9% 3 7% 6% 3 6% 4 5% 6% 35%	2160
	11th to 20th	Day	17% 8% 3 6% 6% 3 4 5% 5% 6% 37%	2134
	21st to end	Day	19% 8% 3 6% 6% 3 5% 4 5% 6% 34%	2160
May	1st to 10th	Day	24% 8% 3 5% 6% 3 4 5% 4 6% 32%	2408
	11th to 20th	Day	20% 7% 3 5% 5% 3 5% 5% 5% 7% 35%	2478
	21st to end	Day	15% 7% 2 5% 5% 4 5% 6% 5% 9% 37%	2725
June	1st to 10th	Day	17% 5% 3 6% 6% 4 6% 6% 6% 9% 33%	2520
	11th to 20th	Day	17% 6% 3 7% 6% 3 6% 6% 7% 9% 30%	2520
	21st to end	Day	14% 7% 3 7% 5% 3 6% 5% 7% 9% 35%	2520
July	1st to 10th	Day	12% 6% 3 6% 5% 4 6% 6% 7% 10% 35%	2520
	11th to 20th	Day	10% 5% 2 5% 5% 3 6% 7% 8% 10% 39%	2520
	21st to end	Day	12% 6% 3 6% 5% 4 6% 5% 7% 8% 37%	2744
August	1st to 10th	Day	12% 6% 2 5% 5% 3 6% 7% 7% 11% 34%	2390
	11th to 20th	Day	12% 7% 3 6% 6% 5% 6% 6% 7% 8% 34%	2148
	21st to end	Day	15% 6% 2 5% 5% 4 5% 5% 7% 9% 39%	2376
September	1st to 10th	Day	17% 6% 3 5% 5% 3 5% 4 6% 7% 39%	2160
	11th to 20th	Day	15% 5% 2 4 4 3 4 4 5% 8% 45%	2116
	21st to end	Day	18% 6% 2 5% 5% 3 5% 5% 6% 7% 39%	1980
October	1st to 10th	Day	20% 6% 3 6% 5% 3 4 4 4 8% 37%	1821
	11th to 20th	Day	16% 8% 3 6% 5% 2 5% 5% 5% 7% 38%	1800
	21st to end	Day	24% 8% 3 6% 6% 3 5% 5% 6% 6% 29%	1859
November	1st to 10th	Day	15% 7% 2 5% 4 3 4 3 5% 7% 45%	1671
	11th to 20th	Day	18% 8% 3 7% 5% 3 4 4 5% 6% 36%	1710
	21st to end	Day	18% 10% 3 6% 7% 3 4 4 6% 7% 33%	1544
December	1st to 10th	Day	19% 9% 5% 7% 6% 3 5% 6% 5% 6% 28%	1520
	11th to 20th	Day	22% 9% 4 6% 6% 3 4 4 4 6% 32%	1906
	21st to end	Day	19% 13% 7% 10% 8% 3 5% 4 5% 5% 21%	2772
January	1st to 10th	Night	15% 8% 4 7% 6% 3 4 5% 5% 8% 35%	4429
	11th to 20th	Night	14% 9% 5% 11% 9% 4 5% 5% 5% 7% 28%	4440
	21st to end	Night	22% 12% 4 7% 7% 3 4 5% 5% 6% 26%	4619
February	1st to 10th	Night	16% 9% 4 6% 6% 3 5% 5% 6% 8% 33%	2470
	11th to 20th	Night	14% 8% 4 7% 6% 4 5% 6% 6% 8% 32%	2209
	21st to end	Night	18% 9% 3 6% 6% 3 4 5% 5% 7% 34%	1776
March	1st to 10th	Night	16% 8% 3 5% 5% 3 4 5% 6% 8% 37%	2150
	11th to 20th	Night	16% 8% 3 5% 5% 4 4 5% 6% 7% 35%	2015
	21st to end	Night	17% 7% 3 5% 6% 3 4 5% 5% 7% 39%	2030
April	1st to 10th	Night	17% 9% 4 7% 6% 4 5% 4 6% 6% 32%	1800
	11th to 20th	Night	18% 8% 4 6% 4 2 5% 5% 5% 7% 37%	1775
	21st to end	Night	19% 9% 4 5% 5% 2 3 4 6% 6% 38%	1797
May	1st to 10th	Night	23% 10% 4 6% 4 3 4 4 4 5% 34%	1566
	11th to 20th	Night	18% 7% 3 5% 6% 3 4 5% 6% 7% 37%	1415
	21st to end	Night	15% 6% 2 4 5% 3 4 5% 6% 9% 40%	1550
June	1st to 10th	Night	17% 6% 2 4 5% 3 5% 4 5% 8% 41%	1440
	11th to 20th	Night	16% 6% 3 5% 4 3 3 4 5% 8% 43%	1440
	21st to end	Night	11% 5% 2 4 4 3 5% 5% 6% 9% 46%	1440
July	1st to 10th	Night	12% 6% 3 5% 5% 3 4 4 6% 9% 44%	1440
	11th to 20th	Night	13% 6% 3 5% 3 3 4 5% 7% 10% 41%	1440
	21st to end	Night	11% 5% 2 5% 5% 3 5% 5% 6% 8% 44%	1574
August	1st to 10th	Night	12% 6% 2 4 5% 4 4 6% 7% 10% 41%	1545
	11th to 20th	Night	14% 5% 2 6% 5% 3 6% 5% 5% 9% 38%	1734
	21st to end	Night	16% 4 2 4 5% 3 4 5% 5% 8% 43%	1980
September	1st to 10th	Night	16% 6% 2 3 5% 3 4 5% 6% 7% 43%	1800
	11th to 20th	Night	15% 5% 2 4 4 2 3 3 5% 7% 51%	1843
	21st to end	Night	16% 8% 2 6% 4 2 4 3 5% 6% 44%	1980
October	1st to 10th	Night	22% 6% 2 4 4 2 4 5% 4 6% 40%	2135
	11th to 20th	Night	19% 7% 2 4 4 2 3 4 5% 6% 42%	2160
	21st to end	Night	22% 9% 3 5% 5% 3 3 5% 5% 7% 34%	2495
November	1st to 10th	Night	13% 7% 3 5% 4 3 4 4 5% 7% 44%	2407
	11th to 20th	Night	20% 6% 3 4 5% 3 4 4 5% 8% 38%	2470
	21st to end	Night	15% 9% 3 6% 5% 3 4 5% 5% 8% 37%	2633
December	1st to 10th	Night	20% 10% 4 7% 5% 3 4 5% 6% 7% 28%	2660
	11th to 20th	Night	20% 10% 4 7% 6% 3 5% 5% 5% 7% 29%	3288
	21st to end	Night	22% 11% 5% 7% 5% 3 4 5% 4 7% 25%	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	46% 10% 11% 25% 7% 2	2518
	11th to 20th	Day	56% 8% 10% 18% 6% 2	2520
	21st to end	Day	58% 6% 10% 18% 7% 1	3032
February	1st to 10th	Day	54% 7% 11% 17% 10% 1	1710
	11th to 20th	Day	48% 7% 10% 21% 13% 2	1740
	21st to end	Day	53% 5% 10% 20% 10% 1	1480
March	1st to 10th	Day	48% 5% 12% 21% 11% 3	1800
	11th to 20th	Day	51% 5% 11% 20% 11% 2	1941
	21st to end	Day	51% 5% 8% 17% 15% 4	2326
April	1st to 10th	Day	49% 6% 9% 21% 12% 3	2160
	11th to 20th	Day	46% 5% 11% 22% 14% 2	2134
	21st to end	Day	50% 6% 9% 20% 12% 4	2160
May	1st to 10th	Day	53% 5% 8% 19% 12% 2	2408
	11th to 20th	Day	47% 6% 11% 21% 13% 2	2482
	21st to end	Day	43% 8% 15% 20% 12% 2	2725
June	1st to 10th	Day	47% 7% 13% 19% 13%	2520
	11th to 20th	Day	48% 7% 12% 21% 10% 1	2520
	21st to end	Day	43% 8% 12% 26% 10%	2520
July	1st to 10th	Day	42% 8% 14% 21% 13% 2	2450
	11th to 20th	Day	38% 8% 17% 25% 12% 1	2445
	21st to end	Day	41% 8% 14% 20% 15% 2	2591
August	1st to 10th	Day	41% 9% 13% 24% 11% 1	2376
	11th to 20th	Day	44% 9% 15% 24% 9%	2148
	21st to end	Day	40% 7% 12% 25% 14% 2	2376
September	1st to 10th	Day	43% 7% 12% 22% 14% 1	2160
	11th to 20th	Day	38% 5% 10% 23% 22% 2	2116
	21st to end	Day	43% 5% 11% 20% 17% 2	1980
October	1st to 10th	Day	48% 5% 11% 21% 13% 2	1821
	11th to 20th	Day	44% 7% 13% 23% 12% 1	1800
	21st to end	Day	53% 6% 13% 17% 9% 2	1859
November	1st to 10th	Day	41% 4 12% 24% 17% 2	1671
	11th to 20th	Day	46% 7% 11% 21% 14% 3	1710
	21st to end	Day	49% 6% 14% 24% 6% 1	1544
December	1st to 10th	Day	56% 6% 14% 15% 9% 1	1520
	11th to 20th	Day	51% 8% 15% 19% 6% 1	1906
	21st to end	Day	64% 6% 9% 14% 6%	2772
January	1st to 10th	Night	46% 7% 13% 23% 9% 2	4429
	11th to 20th	Night	52% 9% 12% 19% 7% 1	4440
	21st to end	Night	58% 7% 9% 18% 7% 1	4619
February	1st to 10th	Night	48% 7% 15% 21% 9% 1	2470
	11th to 20th	Night	47% 8% 12% 18% 12% 2	2211
	21st to end	Night	49% 6% 8% 23% 12% 2	1776
March	1st to 10th	Night	42% 6% 14% 23% 12% 2	2160
	11th to 20th	Night	46% 6% 12% 22% 13% 2	2016
	21st to end	Night	44% 6% 9% 20% 17% 3	2030
April	1st to 10th	Night	51% 6% 10% 19% 13% 2	1800
	11th to 20th	Night	46% 6% 10% 21% 16% 1	1775
	21st to end	Night	46% 6% 10% 21% 14% 3	1797
May	1st to 10th	Night	52% 5% 10% 18% 13% 2	1566
	11th to 20th	Night	44% 6% 10% 22% 16% 2	1416
	21st to end	Night	40% 8% 15% 24% 10% 2	1551
June	1st to 10th	Night	42% 5% 11% 25% 15% 1	1440
	11th to 20th	Night	40% 6% 17% 26% 10% 1	1440
	21st to end	Night	33% 8% 17% 28% 14% 1	1440
July	1st to 10th	Night	36% 8% 16% 25% 13% 3	1400
	11th to 20th	Night	36% 8% 16% 29% 10% 1	1392
	21st to end	Night	36% 8% 17% 21% 17% 2	1486
August	1st to 10th	Night	36% 9% 15% 27% 12% 1	1535
	11th to 20th	Night	41% 7% 16% 24% 10%	1734
	21st to end	Night	38% 7% 13% 24% 17% 1	1980
September	1st to 10th	Night	38% 8% 13% 26% 14% 1	1800
	11th to 20th	Night	33% 5% 11% 25% 24% 1	1843
	21st to end	Night	41% 5% 9% 24% 20% 1	1980
October	1st to 10th	Night	45% 6% 11% 22% 15% 1	2135
	11th to 20th	Night	42% 7% 13% 26% 11% 1	2160
	21st to end	Night	49% 6% 12% 21% 11% 1	2495
November	1st to 10th	Night	39% 6% 11% 23% 19% 2	2407
	11th to 20th	Night	44% 6% 13% 21% 13% 3	2470
	21st to end	Night	42% 7% 17% 25% 9%	2633
December	1st to 10th	Night	52% 8% 13% 20% 8%	2660
	11th to 20th	Night	50% 9% 13% 18% 9% 1	3288
	21st to end	Night	57% 8% 12% 17% 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	31% 26% 29% 12% 2 1	180
	11th to 20th	Day	42% 23% 24% 9% 2 1	180
	21st to end	Day	29% 25% 32% 10% 3 1	272
February	1st to 10th	Day	34% 26% 31% 8% 1	270
	11th to 20th	Day	33% 28% 30% 7% 2	375
	21st to end	Day	34% 22% 29% 13% 2	346
March	1st to 10th	Day	29% 24% 29% 15% 3	420
	11th to 20th	Day	30% 26% 27% 13% 3 1	420
	21st to end	Day	30% 26% 27% 10% 5% 2	462
April	1st to 10th	Day	30% 23% 27% 13% 6% 1	420
	11th to 20th	Day	27% 23% 25% 14% 8% 3	412
	21st to end	Day	32% 18% 32% 12% 4 2	420
May	1st to 10th	Day	35% 17% 25% 13% 8% 3	423
	11th to 20th	Day	23% 19% 30% 18% 8% 2	447
	21st to end	Day	20% 11% 27% 24% 15% 4	485
June	1st to 10th	Day	19% 13% 32% 23% 10% 2	450
	11th to 20th	Day	21% 15% 26% 24% 13% 2	450
	21st to end	Day	16% 12% 32% 26% 12% 3	450
July	1st to 10th	Day	12% 9% 26% 29% 18% 6%	445
	11th to 20th	Day	13% 6% 28% 31% 20% 3	444
	21st to end	Day	15% 8% 33% 29% 11% 4	488
August	1st to 10th	Day	12% 9% 26% 25% 21% 6%	446
	11th to 20th	Day	17% 7% 24% 26% 18% 8%	439
	21st to end	Day	13% 11% 28% 24% 15% 8%	495
September	1st to 10th	Day	21% 10% 23% 21% 17% 8%	450
	11th to 20th	Day	16% 10% 24% 26% 14% 12%	450
	21st to end	Day	20% 10% 28% 23% 14% 4	450
October	1st to 10th	Day	28% 11% 23% 19% 15% 5%	450
	11th to 20th	Day	21% 17% 28% 22% 10% 2	450
	21st to end	Day	31% 15% 26% 20% 8%	435
November	1st to 10th	Day	22% 17% 22% 24% 12% 3	365
	11th to 20th	Day	28% 22% 25% 18% 6% 1	370
	21st to end	Day	26% 22% 31% 16% 3 1	204
December	1st to 10th	Day	31% 26% 26% 12% 4 1	180
	11th to 20th	Day	38% 23% 27% 9% 3	180
	21st to end	Day	28% 27% 26% 14% 5% 1	198
January	1st to 10th	Night	25% 24% 32% 17% 3	760
	11th to 20th	Night	29% 19% 30% 20% 2	760
	21st to end	Night	21% 25% 34% 17% 3	836
February	1st to 10th	Night	26% 19% 34% 19% 1	760
	11th to 20th	Night	26% 27% 32% 14% 1	722
	21st to end	Night	30% 23% 29% 16% 2	592
March	1st to 10th	Night	28% 20% 34% 15% 3	720
	11th to 20th	Night	26% 22% 30% 19% 4	720
	21st to end	Night	23% 21% 33% 17% 5%	792
April	1st to 10th	Night	25% 21% 32% 18% 3	720
	11th to 20th	Night	23% 18% 31% 21% 8%	711
	21st to end	Night	25% 18% 28% 23% 6%	717
May	1st to 10th	Night	29% 14% 26% 24% 6% 1	486
	11th to 20th	Night	21% 11% 31% 28% 8% 1	354
	21st to end	Night	19% 5% 22% 37% 16% 1	389
June	1st to 10th	Night	17% 8% 24% 34% 17%	360
	11th to 20th	Night	18% 7% 25% 34% 16%	360
	21st to end	Night	11% 3 28% 43% 15%	360
July	1st to 10th	Night	13% 5% 17% 41% 21% 3	350
	11th to 20th	Night	13% 3 20% 44% 19% 2	348
	21st to end	Night	14% 4 20% 43% 19% 1	394
August	1st to 10th	Night	13% 2 21% 38% 25% 2	471
	11th to 20th	Night	17% 3 14% 40% 23% 3	670
	21st to end	Night	16% 5% 18% 36% 23% 2	792
September	1st to 10th	Night	18% 5% 24% 31% 20% 3	720
	11th to 20th	Night	17% 7% 22% 29% 19% 5%	720
	21st to end	Night	19% 8% 23% 31% 17% 3	720
October	1st to 10th	Night	25% 10% 23% 24% 16% 2	720
	11th to 20th	Night	24% 11% 27% 29% 8%	720
	21st to end	Night	28% 16% 28% 21% 6%	792
November	1st to 10th	Night	18% 17% 28% 26% 10% 1	740
	11th to 20th	Night	26% 19% 25% 23% 7% 1	760
	21st to end	Night	20% 20% 31% 23% 6% 1	760
December	1st to 10th	Night	28% 21% 28% 18% 5%	760
	11th to 20th	Night	27% 22% 29% 19% 3	760
	21st to end	Night	28% 22% 32% 17% 2	836

Page generated at 2024-02-12 06:35:31. Version ac07

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