Abraham Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Abraham Lake clear sky chart from 2005-11-06 to 2024-03-01.

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	7% 8% 4 9% 8% 5% 7% 7% 7% 9% 28%	78476
	Night	3 7% 4 9% 9% 5% 8% 7% 8% 10% 31%	80882
Transparency	Day	46% 11% 16% 18% 8% 1	78181
	Night	41% 13% 17% 19% 8% 1	80757
Seeing	Day	17% 20% 34% 20% 7% 2	14748
	Night	11% 17% 38% 24% 9% 1	23414

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	4 3 11% 14% 10% 11% 9% 10% 9% 18%	2219
	11th to 20th	Day	1 3 3 7% 12% 6% 7% 10% 8% 9% 34%	2339
	21st to end	Day	1 5% 4 8% 10% 6% 8% 10% 11% 12% 26%	2794
February	1st to 10th	Day	1 5% 6% 10% 10% 6% 11% 8% 10% 10% 24%	1520
	11th to 20th	Day	1 7% 5% 10% 10% 6% 7% 8% 7% 10% 28%	1574
	21st to end	Day	1 4 5% 9% 13% 6% 9% 11% 9% 10% 23%	1570
March	1st to 10th	Day	6% 4 12% 11% 7% 9% 8% 8% 9% 26%	1801
	11th to 20th	Day	1 5% 5% 10% 10% 5% 8% 9% 10% 9% 27%	1871
	21st to end	Day	2 12% 8% 15% 10% 5% 7% 8% 8% 8% 17%	2321
April	1st to 10th	Day	4 11% 8% 13% 11% 7% 9% 8% 8% 8% 15%	2160
	11th to 20th	Day	4 14% 6% 13% 11% 4 7% 7% 7% 9% 19%	2292
	21st to end	Day	6% 14% 7% 12% 8% 4 6% 5% 6% 7% 22%	2391
May	1st to 10th	Day	8% 18% 6% 10% 8% 5% 6% 5% 7% 8% 20%	2520
	11th to 20th	Day	8% 11% 4 7% 7% 4 5% 6% 6% 9% 31%	2626
	21st to end	Day	17% 14% 4 7% 6% 3 5% 6% 5% 8% 24%	2917
June	1st to 10th	Day	16% 11% 3 9% 7% 5% 7% 6% 7% 8% 21%	2704
	11th to 20th	Day	21% 11% 4 8% 7% 4 6% 5% 6% 7% 20%	2880
	21st to end	Day	11% 9% 4 7% 9% 4 7% 6% 7% 8% 28%	2880
July	1st to 10th	Day	11% 7% 3 7% 7% 4 6% 6% 6% 8% 35%	2876
	11th to 20th	Day	11% 6% 2 6% 7% 3 6% 6% 8% 10% 37%	2700
	21st to end	Day	8% 6% 3 5% 6% 4 6% 6% 7% 8% 41%	2804
August	1st to 10th	Day	10% 7% 3 7% 7% 5% 5% 7% 7% 7% 35%	2507
	11th to 20th	Day	9% 6% 3 6% 6% 4 6% 6% 7% 10% 37%	2442
	21st to end	Day	10% 7% 3 7% 7% 4 5% 6% 7% 8% 34%	2566
September	1st to 10th	Day	11% 10% 4 6% 5% 3 5% 5% 5% 8% 38%	2160
	11th to 20th	Day	9% 10% 3 7% 7% 3 6% 5% 6% 8% 37%	2052
	21st to end	Day	9% 9% 4 8% 7% 5% 6% 6% 5% 8% 33%	1980
October	1st to 10th	Day	6% 12% 6% 7% 6% 3 6% 6% 7% 8% 33%	1900
	11th to 20th	Day	5% 8% 5% 8% 7% 4 6% 7% 8% 10% 32%	1620
	21st to end	Day	2 9% 5% 9% 9% 6% 7% 7% 8% 9% 29%	1782
November	1st to 10th	Day	1 7% 5% 10% 10% 5% 7% 8% 8% 11% 28%	1594
	11th to 20th	Day	1 5% 4 8% 7% 6% 8% 8% 10% 11% 32%	1330
	21st to end	Day	1 5% 4 9% 10% 7% 7% 8% 7% 10% 31%	1330
December	1st to 10th	Day	2 4 3 11% 12% 5% 7% 9% 8% 10% 29%	1330
	11th to 20th	Day	1 5% 3 10% 9% 7% 11% 9% 9% 10% 26%	1682
	21st to end	Day	4 4 7% 8% 5% 7% 8% 9% 11% 35%	2442
January	1st to 10th	Night	4 5% 15% 12% 7% 9% 10% 10% 10% 17%	4726
	11th to 20th	Night	3 2 8% 10% 6% 9% 8% 12% 10% 31%	4590
	21st to end	Night	1 5% 4 9% 11% 7% 9% 10% 9% 9% 26%	4862
February	1st to 10th	Night	1 7% 4 9% 11% 7% 9% 9% 9% 10% 23%	2660
	11th to 20th	Night	1 5% 4 10% 8% 6% 9% 7% 9% 12% 28%	2488
	21st to end	Night	5% 4 8% 13% 6% 9% 9% 9% 10% 27%	1884
March	1st to 10th	Night	1 4 6% 9% 9% 6% 9% 9% 9% 10% 28%	2165
	11th to 20th	Night	1 6% 5% 9% 7% 4 7% 9% 8% 10% 34%	2088
	21st to end	Night	1 10% 6% 12% 9% 4 7% 8% 9% 9% 26%	2034
April	1st to 10th	Night	2 8% 7% 10% 11% 6% 7% 7% 8% 9% 25%	1800
	11th to 20th	Night	4 11% 5% 11% 8% 3 5% 6% 8% 8% 30%	1619
	21st to end	Night	3 12% 5% 10% 6% 4 6% 5% 6% 7% 34%	1566
May	1st to 10th	Night	6% 15% 5% 8% 6% 4 6% 6% 6% 9% 28%	1440
	11th to 20th	Night	7% 9% 2 5% 4 3 5% 6% 6% 10% 42%	1267
	21st to end	Night	16% 13% 4 6% 5% 3 4 5% 8% 8% 30%	1358
June	1st to 10th	Night	15% 10% 3 6% 4 4 6% 5% 5% 8% 33%	1252
	11th to 20th	Night	15% 11% 4 8% 7% 5% 6% 7% 5% 7% 24%	1080
	21st to end	Night	8% 6% 2 5% 6% 3 5% 5% 7% 11% 43%	1080
July	1st to 10th	Night	8% 6% 3 4 6% 3 6% 5% 6% 8% 45%	1080
	11th to 20th	Night	9% 6% 2 5% 5% 2 6% 6% 7% 8% 43%	1260
	21st to end	Night	5% 3 2 4 5% 3 5% 6% 8% 10% 50%	1510
August	1st to 10th	Night	8% 7% 2 5% 5% 3 4 6% 6% 9% 45%	1432
	11th to 20th	Night	9% 5% 3 5% 5% 2 4 5% 6% 9% 48%	1456
	21st to end	Night	8% 6% 2 5% 5% 3 5% 6% 7% 9% 42%	1788
September	1st to 10th	Night	8% 9% 2 5% 5% 3 6% 6% 6% 8% 43%	1800
	11th to 20th	Night	9% 9% 4 7% 6% 3 4 5% 5% 8% 40%	1908
	21st to end	Night	6% 8% 4 7% 6% 4 6% 6% 7% 9% 40%	1980
October	1st to 10th	Night	5% 10% 5% 9% 6% 4 5% 5% 6% 9% 36%	2057
	11th to 20th	Night	4 9% 4 9% 8% 5% 6% 7% 7% 9% 33%	2340
	21st to end	Night	2 9% 5% 12% 11% 6% 8% 7% 7% 8% 27%	2574
November	1st to 10th	Night	1 8% 5% 10% 11% 6% 9% 8% 9% 10% 24%	2464
	11th to 20th	Night	1 5% 3 9% 9% 6% 11% 8% 8% 11% 29%	2850
	21st to end	Night	1 6% 5% 10% 10% 6% 8% 8% 9% 9% 29%	2850
December	1st to 10th	Night	1 5% 4 10% 9% 5% 8% 9% 9% 12% 28%	2850
	11th to 20th	Night	4 4 13% 10% 8% 11% 8% 9% 10% 22%	3510
	21st to end	Night	3 3 9% 9% 6% 9% 9% 9% 12% 30%	5214

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% 14% 15% 17% 6% 1	2219
	11th to 20th	Day	37% 12% 14% 15% 17% 4	2361
	21st to end	Day	33% 19% 24% 18% 6% 1	2794
February	1st to 10th	Day	45% 12% 16% 14% 10% 3	1520
	11th to 20th	Day	46% 12% 13% 19% 9% 1	1582
	21st to end	Day	49% 13% 12% 16% 9% 1	1570
March	1st to 10th	Day	45% 15% 16% 15% 8% 1	1801
	11th to 20th	Day	42% 17% 17% 17% 7%	1872
	21st to end	Day	56% 13% 14% 12% 5%	2321
April	1st to 10th	Day	57% 15% 14% 11% 3	2160
	11th to 20th	Day	58% 11% 13% 15% 4 1	2292
	21st to end	Day	59% 10% 13% 14% 4	2391
May	1st to 10th	Day	59% 10% 14% 13% 4	2520
	11th to 20th	Day	46% 10% 19% 18% 7%	2630
	21st to end	Day	58% 8% 15% 14% 5%	2918
June	1st to 10th	Day	57% 10% 13% 14% 5% 1	2704
	11th to 20th	Day	60% 9% 13% 12% 5%	2880
	21st to end	Day	50% 9% 17% 16% 7% 1	2880
July	1st to 10th	Day	45% 8% 15% 22% 10% 1	2797
	11th to 20th	Day	41% 8% 17% 24% 9% 1	2619
	21st to end	Day	37% 8% 15% 27% 12% 1	2648
August	1st to 10th	Day	44% 10% 16% 21% 9% 1	2490
	11th to 20th	Day	40% 8% 19% 23% 10% 1	2442
	21st to end	Day	41% 10% 15% 23% 9% 1	2566
September	1st to 10th	Day	42% 8% 19% 22% 8% 1	2160
	11th to 20th	Day	42% 9% 14% 25% 9% 1	2052
	21st to end	Day	44% 12% 16% 19% 9% 1	1980
October	1st to 10th	Day	46% 11% 13% 23% 7%	1900
	11th to 20th	Day	41% 11% 17% 23% 6%	1620
	21st to end	Day	42% 15% 18% 17% 7% 1	1782
November	1st to 10th	Day	44% 15% 18% 15% 7% 1	1594
	11th to 20th	Day	36% 13% 26% 17% 6%	1330
	21st to end	Day	41% 13% 19% 18% 5% 3	1330
December	1st to 10th	Day	44% 12% 18% 16% 10% 1	1330
	11th to 20th	Day	39% 15% 20% 17% 8% 1	1684
	21st to end	Day	32% 14% 18% 21% 14% 1	2442
January	1st to 10th	Night	46% 19% 14% 14% 6% 1	4726
	11th to 20th	Night	37% 15% 13% 13% 17% 5%	4630
	21st to end	Night	39% 17% 21% 16% 6% 1	4862
February	1st to 10th	Night	49% 13% 13% 14% 9% 2	2660
	11th to 20th	Night	43% 12% 16% 17% 10% 1	2490
	21st to end	Night	45% 11% 13% 21% 9% 1	1884
March	1st to 10th	Night	42% 15% 17% 16% 10%	2165
	11th to 20th	Night	37% 13% 17% 23% 10%	2088
	21st to end	Night	45% 12% 17% 19% 7%	2034
April	1st to 10th	Night	46% 15% 16% 17% 6%	1800
	11th to 20th	Night	47% 9% 19% 16% 8%	1619
	21st to end	Night	45% 12% 18% 20% 5% 1	1566
May	1st to 10th	Night	50% 9% 18% 19% 5%	1440
	11th to 20th	Night	34% 10% 21% 27% 9%	1267
	21st to end	Night	49% 8% 15% 21% 7%	1358
June	1st to 10th	Night	48% 7% 16% 21% 6% 1	1252
	11th to 20th	Night	54% 10% 17% 15% 5%	1080
	21st to end	Night	32% 9% 26% 27% 6% 1	1080
July	1st to 10th	Night	34% 8% 19% 27% 10% 1	1050
	11th to 20th	Night	35% 10% 20% 27% 8% 1	1218
	21st to end	Night	26% 7% 21% 33% 12% 1	1426
August	1st to 10th	Night	33% 7% 23% 31% 6%	1424
	11th to 20th	Night	31% 8% 22% 29% 9%	1456
	21st to end	Night	33% 11% 19% 27% 10% 1	1788
September	1st to 10th	Night	36% 10% 20% 26% 8% 1	1800
	11th to 20th	Night	40% 9% 18% 22% 10% 1	1908
	21st to end	Night	35% 12% 20% 23% 9%	1980
October	1st to 10th	Night	42% 11% 17% 23% 6%	2057
	11th to 20th	Night	43% 12% 19% 20% 7%	2340
	21st to end	Night	47% 14% 15% 17% 6%	2574
November	1st to 10th	Night	48% 16% 13% 14% 8% 1	2464
	11th to 20th	Night	39% 17% 20% 15% 8% 1	2850
	21st to end	Night	43% 14% 17% 16% 7% 3	2850
December	1st to 10th	Night	43% 12% 13% 19% 11% 2	2850
	11th to 20th	Night	45% 16% 20% 13% 5% 1	3507
	21st to end	Night	37% 13% 21% 19% 9% 1	5214

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	12% 18% 35% 23% 10% 2	180
	11th to 20th	Day	14% 14% 44% 21% 5% 2	180
	21st to end	Day	11% 29% 41% 12% 6% 2	198
February	1st to 10th	Day	19% 23% 39% 11% 5% 2	180
	11th to 20th	Day	13% 18% 38% 24% 7%	245
	21st to end	Day	14% 23% 38% 17% 6% 1	382
March	1st to 10th	Day	14% 27% 33% 16% 7% 2	421
	11th to 20th	Day	15% 25% 33% 21% 4 2	420
	21st to end	Day	17% 24% 33% 20% 4 2	462
April	1st to 10th	Day	19% 23% 33% 18% 5% 1	420
	11th to 20th	Day	14% 26% 33% 18% 8% 2	412
	21st to end	Day	19% 25% 27% 19% 9% 1	420
May	1st to 10th	Day	18% 18% 37% 20% 6% 1	423
	11th to 20th	Day	15% 11% 31% 29% 13% 2	597
	21st to end	Day	24% 13% 28% 23% 11% 2	679
June	1st to 10th	Day	20% 22% 31% 21% 6% 1	634
	11th to 20th	Day	26% 20% 31% 17% 6% 1	810
	21st to end	Day	17% 16% 30% 24% 11% 3	810
July	1st to 10th	Day	15% 15% 32% 27% 9% 2	792
	11th to 20th	Day	17% 13% 36% 22% 10% 1	618
	21st to end	Day	11% 16% 35% 25% 11% 3	550
August	1st to 10th	Day	15% 14% 34% 26% 10% 2	447
	11th to 20th	Day	12% 21% 39% 21% 6% 2	437
	21st to end	Day	16% 21% 34% 21% 6% 2	495
September	1st to 10th	Day	20% 25% 28% 20% 6% 1	450
	11th to 20th	Day	21% 19% 36% 19% 5% 1	450
	21st to end	Day	19% 28% 30% 16% 6% 1	450
October	1st to 10th	Day	20% 22% 31% 19% 6% 2	446
	11th to 20th	Day	17% 23% 34% 20% 6%	270
	21st to end	Day	17% 22% 39% 16% 5% 1	297
November	1st to 10th	Day	13% 27% 39% 14% 5% 2	255
	11th to 20th	Day	18% 27% 41% 9% 5% 1	180
	21st to end	Day	16% 27% 29% 17% 7% 5%	180
December	1st to 10th	Day	11% 23% 37% 19% 6% 4	180
	11th to 20th	Day	11% 25% 40% 19% 4 1	180
	21st to end	Day	10% 13% 47% 23% 7% 1	198
January	1st to 10th	Night	9% 21% 49% 16% 5%	950
	11th to 20th	Night	8% 25% 45% 17% 4 1	879
	21st to end	Night	7% 27% 43% 16% 5%	836
February	1st to 10th	Night	10% 22% 38% 22% 8% 1	760
	11th to 20th	Night	7% 19% 43% 24% 7%	744
	21st to end	Night	7% 13% 42% 24% 13% 1	628
March	1st to 10th	Night	5% 20% 42% 23% 9% 1	722
	11th to 20th	Night	6% 19% 46% 21% 7% 1	720
	21st to end	Night	8% 16% 38% 27% 10% 1	792
April	1st to 10th	Night	8% 14% 36% 30% 12% 1	720
	11th to 20th	Night	10% 13% 42% 24% 11%	551
	21st to end	Night	13% 13% 38% 28% 8% 1	486
May	1st to 10th	Night	14% 8% 29% 35% 13% 1	360
	11th to 20th	Night	14% 3 27% 39% 17% 1	354
	21st to end	Night	21% 8% 24% 32% 14% 1	389
June	1st to 10th	Night	19% 7% 33% 29% 11% 1	360
	11th to 20th	Night	22% 10% 31% 27% 10%	360
	21st to end	Night	13% 8% 28% 32% 19% 1	360
July	1st to 10th	Night	13% 6% 31% 34% 16%	350
	11th to 20th	Night	13% 9% 30% 35% 13%	348
	21st to end	Night	6% 6% 23% 47% 18% 1	394
August	1st to 10th	Night	13% 4 19% 37% 25% 2	358
	11th to 20th	Night	12% 6% 25% 36% 20% 1	388
	21st to end	Night	13% 11% 30% 34% 12% 1	600
September	1st to 10th	Night	15% 12% 29% 30% 12% 2	720
	11th to 20th	Night	14% 10% 31% 30% 13% 2	720
	21st to end	Night	17% 19% 31% 22% 11% 1	720
October	1st to 10th	Night	13% 13% 36% 28% 11%	720
	11th to 20th	Night	15% 16% 40% 22% 6%	720
	21st to end	Night	12% 19% 42% 21% 5%	792
November	1st to 10th	Night	10% 24% 45% 15% 5%	768
	11th to 20th	Night	13% 24% 47% 13% 3	950
	21st to end	Night	10% 25% 41% 17% 6% 1	950
December	1st to 10th	Night	8% 25% 39% 20% 7%	950
	11th to 20th	Night	8% 23% 44% 18% 6% 1	950
	21st to end	Night	4 22% 47% 19% 6% 1	1045

Page generated at 2024-02-27 04:30:15. Version ac07

Copyright © 2024 Attilla Danko.