Jasper Maligne Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jasper Maligne 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	10% 15% 7% 12% 8% 4 6% 5% 5% 6% 21%	77784
	Night	6% 14% 7% 12% 9% 5% 6% 6% 6% 7% 23%	81569
Transparency	Day	63% 7% 12% 13% 5% 1	77486
	Night	60% 8% 12% 13% 6% 1	81448
Seeing	Day	22% 19% 29% 20% 8% 2	14982
	Night	14% 17% 36% 23% 9% 1	23603

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	2 11% 9% 20% 12% 8% 8% 6% 6% 6% 11%	1899
	11th to 20th	Day	4 14% 8% 14% 10% 4 4 5% 5% 5% 27%	2258
	21st to end	Day	5% 25% 10% 11% 10% 3 5% 5% 5% 6% 14%	2794
February	1st to 10th	Day	4 14% 11% 15% 9% 4 6% 5% 6% 6% 18%	1520
	11th to 20th	Day	2 13% 8% 21% 11% 4 6% 6% 6% 5% 17%	1552
	21st to end	Day	2 10% 9% 18% 12% 8% 6% 5% 6% 6% 19%	1570
March	1st to 10th	Day	2 14% 8% 14% 11% 6% 8% 6% 7% 6% 18%	1801
	11th to 20th	Day	2 14% 10% 15% 8% 5% 6% 5% 6% 6% 22%	1836
	21st to end	Day	3 21% 11% 17% 10% 4 6% 5% 5% 5% 13%	2369
April	1st to 10th	Day	5% 19% 13% 17% 10% 6% 6% 5% 4 4 11%	2160
	11th to 20th	Day	5% 20% 9% 15% 10% 5% 5% 5% 5% 5% 17%	2261
	21st to end	Day	8% 24% 8% 12% 8% 4 4 4 5% 6% 18%	2456
May	1st to 10th	Day	10% 25% 8% 12% 7% 3 4 4 5% 5% 16%	2520
	11th to 20th	Day	10% 14% 6% 9% 7% 4 5% 5% 5% 9% 26%	2600
	21st to end	Day	17% 17% 5% 10% 7% 3 5% 4 6% 5% 22%	2917
June	1st to 10th	Day	20% 14% 5% 9% 7% 4 6% 5% 5% 6% 18%	2852
	11th to 20th	Day	23% 16% 6% 11% 9% 4 5% 5% 5% 5% 12%	2880
	21st to end	Day	18% 12% 6% 10% 8% 4 5% 4 4 6% 21%	2880
July	1st to 10th	Day	17% 11% 5% 8% 7% 4 6% 5% 6% 7% 24%	2880
	11th to 20th	Day	17% 10% 4 8% 8% 4 6% 5% 6% 6% 26%	2836
	21st to end	Day	14% 9% 4 8% 7% 5% 6% 5% 5% 6% 30%	2776
August	1st to 10th	Day	16% 9% 5% 9% 8% 5% 6% 6% 5% 6% 26%	2507
	11th to 20th	Day	15% 9% 3 7% 6% 4 6% 4 6% 7% 31%	2475
	21st to end	Day	18% 12% 5% 8% 6% 4 5% 5% 5% 6% 27%	2543
September	1st to 10th	Day	18% 13% 4 8% 7% 3 4 5% 4 4 29%	2160
	11th to 20th	Day	14% 15% 4 7% 6% 3 4 4 4 6% 33%	2088
	21st to end	Day	15% 18% 3 9% 6% 3 4 4 4 6% 27%	1980
October	1st to 10th	Day	11% 20% 4 8% 7% 4 4 5% 6% 5% 26%	1850
	11th to 20th	Day	9% 20% 5% 10% 7% 4 6% 5% 5% 7% 22%	1647
	21st to end	Day	6% 19% 8% 12% 8% 6% 6% 5% 5% 6% 20%	1782
November	1st to 10th	Day	6% 18% 8% 13% 10% 5% 7% 5% 5% 6% 16%	1556
	11th to 20th	Day	3 13% 8% 12% 9% 4 7% 6% 7% 7% 23%	1330
	21st to end	Day	4 17% 8% 12% 10% 6% 5% 6% 6% 8% 19%	1330
December	1st to 10th	Day	5% 13% 8% 17% 11% 5% 6% 5% 4 4 22%	1330
	11th to 20th	Day	4 15% 7% 14% 11% 6% 7% 6% 5% 7% 17%	1499
	21st to end	Day	1 19% 8% 11% 8% 4 5% 5% 6% 8% 25%	2090
January	1st to 10th	Night	2 14% 9% 21% 15% 6% 6% 6% 5% 5% 11%	5046
	11th to 20th	Night	3 12% 7% 12% 9% 4 7% 7% 6% 7% 26%	4670
	21st to end	Night	6% 25% 10% 13% 9% 5% 5% 4 4 4 14%	4862
February	1st to 10th	Night	4 17% 9% 15% 12% 4 6% 6% 5% 5% 17%	2660
	11th to 20th	Night	3 15% 8% 18% 10% 4 6% 6% 4 6% 19%	2509
	21st to end	Night	2 11% 8% 13% 11% 6% 8% 6% 6% 8% 21%	1884
March	1st to 10th	Night	2 12% 8% 13% 12% 6% 7% 7% 6% 7% 21%	2165
	11th to 20th	Night	2 13% 9% 14% 9% 4 7% 6% 7% 7% 22%	2123
	21st to end	Night	2 15% 7% 16% 10% 5% 6% 6% 6% 7% 19%	1985
April	1st to 10th	Night	3 15% 11% 16% 12% 4 6% 5% 6% 7% 15%	1800
	11th to 20th	Night	4 15% 6% 11% 9% 5% 7% 6% 6% 8% 24%	1650
	21st to end	Night	7% 18% 5% 10% 6% 4 6% 6% 6% 6% 26%	1502
May	1st to 10th	Night	9% 20% 5% 8% 7% 4 5% 5% 7% 8% 22%	1440
	11th to 20th	Night	6% 10% 3 8% 5% 3 5% 6% 7% 8% 37%	1293
	21st to end	Night	15% 13% 5% 7% 7% 4 5% 4 5% 8% 28%	1358
June	1st to 10th	Night	16% 12% 3 8% 9% 3 5% 6% 5% 7% 27%	1105
	11th to 20th	Night	20% 12% 4 8% 8% 5% 7% 6% 5% 8% 17%	1080
	21st to end	Night	13% 8% 5% 6% 8% 3 6% 8% 7% 6% 29%	1080
July	1st to 10th	Night	14% 9% 3 7% 5% 4 5% 4 5% 8% 37%	1080
	11th to 20th	Night	17% 8% 4 5% 5% 3 5% 5% 7% 7% 33%	1121
	21st to end	Night	10% 5% 3 6% 7% 3 4 6% 6% 8% 42%	1538
August	1st to 10th	Night	13% 7% 3 6% 6% 3 4 6% 6% 8% 37%	1432
	11th to 20th	Night	14% 6% 2 6% 5% 3 5% 5% 5% 8% 42%	1424
	21st to end	Night	17% 9% 3 5% 5% 3 5% 5% 7% 8% 32%	1810
September	1st to 10th	Night	15% 10% 3 7% 5% 4 4 5% 6% 7% 34%	1800
	11th to 20th	Night	15% 11% 4 7% 6% 3 4 4 4 6% 35%	1872
	21st to end	Night	11% 13% 3 7% 6% 5% 5% 5% 6% 8% 31%	1980
October	1st to 10th	Night	9% 16% 5% 8% 6% 4 6% 6% 7% 7% 27%	2107
	11th to 20th	Night	8% 17% 6% 9% 7% 4 6% 5% 6% 8% 24%	2312
	21st to end	Night	7% 18% 7% 13% 10% 3 6% 5% 4 7% 20%	2574
November	1st to 10th	Night	8% 17% 9% 13% 10% 6% 7% 5% 6% 6% 15%	2504
	11th to 20th	Night	3 14% 8% 13% 11% 6% 7% 6% 7% 7% 18%	2848
	21st to end	Night	3 15% 8% 13% 10% 6% 7% 6% 5% 6% 18%	2850
December	1st to 10th	Night	5% 13% 7% 15% 11% 5% 6% 6% 5% 6% 20%	2850
	11th to 20th	Night	3 16% 10% 15% 12% 5% 7% 5% 6% 7% 13%	3689
	21st to end	Night	2 15% 6% 12% 9% 4 6% 6% 7% 9% 24%	5566

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	71% 6% 9% 9% 2 1	1899
	11th to 20th	Day	59% 6% 6% 8% 12% 8%	2282
	21st to end	Day	70% 7% 12% 7% 4	2794
February	1st to 10th	Day	68% 6% 8% 7% 8% 2	1520
	11th to 20th	Day	69% 6% 8% 12% 5% 1	1560
	21st to end	Day	66% 6% 9% 12% 5% 2	1570
March	1st to 10th	Day	66% 8% 9% 11% 5% 1	1801
	11th to 20th	Day	63% 7% 11% 13% 6%	1836
	21st to end	Day	74% 7% 8% 8% 2	2369
April	1st to 10th	Day	77% 6% 8% 7% 1	2160
	11th to 20th	Day	70% 7% 10% 10% 2	2261
	21st to end	Day	69% 8% 9% 11% 2	2456
May	1st to 10th	Day	69% 7% 11% 10% 2	2520
	11th to 20th	Day	55% 7% 16% 15% 7%	2604
	21st to end	Day	63% 6% 15% 11% 4	2918
June	1st to 10th	Day	66% 7% 11% 12% 4 1	2852
	11th to 20th	Day	72% 6% 12% 8% 2	2880
	21st to end	Day	64% 6% 14% 12% 4 1	2880
July	1st to 10th	Day	56% 7% 14% 17% 5%	2801
	11th to 20th	Day	57% 7% 14% 15% 5%	2749
	21st to end	Day	53% 6% 14% 20% 6% 1	2622
August	1st to 10th	Day	57% 7% 14% 16% 5%	2490
	11th to 20th	Day	52% 6% 16% 19% 6% 1	2475
	21st to end	Day	57% 6% 12% 19% 6%	2543
September	1st to 10th	Day	58% 6% 13% 19% 4 1	2160
	11th to 20th	Day	54% 5% 15% 17% 9%	2088
	21st to end	Day	59% 6% 12% 15% 7% 1	1980
October	1st to 10th	Day	60% 6% 13% 17% 4	1850
	11th to 20th	Day	60% 10% 13% 15% 2	1647
	21st to end	Day	65% 8% 11% 11% 5% 1	1782
November	1st to 10th	Day	71% 7% 10% 8% 4 1	1556
	11th to 20th	Day	59% 10% 15% 9% 5% 1	1330
	21st to end	Day	62% 8% 14% 7% 4 4	1330
December	1st to 10th	Day	66% 7% 6% 13% 7% 1	1330
	11th to 20th	Day	67% 6% 9% 11% 5% 2	1501
	21st to end	Day	56% 6% 12% 14% 11%	2090
January	1st to 10th	Night	72% 9% 8% 6% 5% 2	5046
	11th to 20th	Night	56% 6% 6% 10% 17% 5%	4708
	21st to end	Night	74% 5% 7% 9% 4 1	4862
February	1st to 10th	Night	69% 6% 8% 7% 7% 3	2660
	11th to 20th	Night	66% 8% 9% 9% 6% 1	2511
	21st to end	Night	59% 7% 9% 16% 7% 2	1884
March	1st to 10th	Night	62% 7% 10% 13% 6% 1	2165
	11th to 20th	Night	60% 8% 13% 14% 5%	2124
	21st to end	Night	63% 8% 14% 10% 4	1985
April	1st to 10th	Night	68% 8% 11% 11% 2	1800
	11th to 20th	Night	58% 7% 16% 14% 5%	1650
	21st to end	Night	59% 8% 12% 15% 4 1	1502
May	1st to 10th	Night	60% 9% 12% 15% 4	1440
	11th to 20th	Night	44% 10% 16% 19% 10%	1293
	21st to end	Night	55% 8% 16% 16% 5%	1358
June	1st to 10th	Night	55% 8% 17% 12% 6% 1	1105
	11th to 20th	Night	66% 9% 13% 10% 3	1080
	21st to end	Night	52% 9% 20% 14% 5% 1	1080
July	1st to 10th	Night	46% 6% 18% 23% 6% 1	1050
	11th to 20th	Night	50% 8% 17% 18% 6%	1085
	21st to end	Night	38% 7% 20% 27% 8% 1	1453
August	1st to 10th	Night	42% 10% 22% 21% 4	1424
	11th to 20th	Night	40% 8% 24% 22% 6%	1424
	21st to end	Night	49% 8% 18% 18% 7%	1810
September	1st to 10th	Night	49% 6% 18% 21% 6% 1	1800
	11th to 20th	Night	51% 6% 16% 19% 8%	1872
	21st to end	Night	51% 10% 16% 17% 7% 1	1980
October	1st to 10th	Night	54% 8% 16% 18% 3	2107
	11th to 20th	Night	59% 9% 13% 16% 3	2312
	21st to end	Night	65% 7% 11% 11% 6% 1	2574
November	1st to 10th	Night	71% 7% 10% 7% 4 1	2504
	11th to 20th	Night	64% 11% 10% 8% 6% 1	2848
	21st to end	Night	65% 9% 10% 9% 5% 3	2850
December	1st to 10th	Night	64% 7% 8% 10% 9% 1	2850
	11th to 20th	Night	68% 8% 9% 9% 4 1	3686
	21st to end	Night	56% 9% 12% 14% 7% 1	5566

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	13% 22% 34% 22% 7% 1	180
	11th to 20th	Day	17% 22% 32% 23% 4 3	180
	21st to end	Day	19% 23% 38% 13% 4 2	198
February	1st to 10th	Day	24% 21% 36% 14% 5% 1	180
	11th to 20th	Day	15% 23% 34% 19% 7% 2	252
	21st to end	Day	15% 25% 35% 18% 7% 1	382
March	1st to 10th	Day	18% 25% 32% 14% 9% 2	421
	11th to 20th	Day	18% 28% 30% 16% 5% 2	420
	21st to end	Day	19% 26% 30% 17% 6% 2	462
April	1st to 10th	Day	25% 20% 31% 16% 6% 1	420
	11th to 20th	Day	17% 23% 30% 20% 8% 2	412
	21st to end	Day	23% 25% 24% 18% 8% 3	420
May	1st to 10th	Day	23% 16% 34% 18% 7% 2	423
	11th to 20th	Day	16% 12% 24% 31% 14% 3	571
	21st to end	Day	22% 11% 24% 26% 15% 3	679
June	1st to 10th	Day	24% 17% 30% 20% 7% 1	782
	11th to 20th	Day	29% 15% 28% 19% 8% 1	810
	21st to end	Day	23% 13% 26% 23% 13% 2	810
July	1st to 10th	Day	22% 13% 26% 25% 13% 1	796
	11th to 20th	Day	23% 14% 30% 24% 8% 1	748
	21st to end	Day	18% 13% 30% 25% 11% 3	522
August	1st to 10th	Day	21% 10% 32% 25% 10% 3	447
	11th to 20th	Day	20% 19% 34% 17% 8% 1	437
	21st to end	Day	26% 16% 32% 17% 7% 1	495
September	1st to 10th	Day	30% 17% 28% 17% 6% 1	450
	11th to 20th	Day	25% 21% 27% 22% 4 1	450
	21st to end	Day	34% 26% 20% 15% 4 1	450
October	1st to 10th	Day	28% 20% 26% 17% 8% 2	450
	11th to 20th	Day	28% 23% 27% 16% 5% 2	297
	21st to end	Day	25% 19% 33% 18% 5%	297
November	1st to 10th	Day	29% 24% 28% 12% 5% 2	223
	11th to 20th	Day	23% 26% 33% 13% 4 1	180
	21st to end	Day	21% 26% 25% 18% 7% 3	180
December	1st to 10th	Day	14% 26% 28% 21% 7% 4	180
	11th to 20th	Day	15% 28% 34% 17% 4 1	180
	21st to end	Day	10% 20% 37% 23% 9% 2	198
January	1st to 10th	Night	12% 21% 44% 17% 4 1	1040
	11th to 20th	Night	11% 22% 44% 17% 4 1	891
	21st to end	Night	13% 25% 40% 16% 5% 1	836
February	1st to 10th	Night	14% 20% 35% 24% 6% 1	760
	11th to 20th	Night	10% 19% 41% 23% 6% 1	744
	21st to end	Night	10% 14% 38% 27% 10% 1	628
March	1st to 10th	Night	7% 19% 42% 22% 9% 1	722
	11th to 20th	Night	8% 23% 42% 21% 7% 1	720
	21st to end	Night	8% 16% 33% 29% 12% 1	792
April	1st to 10th	Night	9% 18% 31% 31% 10% 1	720
	11th to 20th	Night	8% 15% 38% 24% 13% 1	582
	21st to end	Night	15% 14% 28% 33% 9% 1	422
May	1st to 10th	Night	17% 9% 23% 34% 15% 1	360
	11th to 20th	Night	9% 8% 24% 36% 20% 3	354
	21st to end	Night	20% 8% 23% 26% 22% 2	389
June	1st to 10th	Night	21% 5% 33% 25% 15% 1	360
	11th to 20th	Night	24% 9% 28% 25% 14%	360
	21st to end	Night	18% 7% 25% 30% 20% 1	360
July	1st to 10th	Night	20% 5% 23% 37% 14% 1	350
	11th to 20th	Night	21% 9% 22% 32% 16%	348
	21st to end	Night	13% 7% 20% 40% 20%	394
August	1st to 10th	Night	16% 4 18% 38% 23% 1	358
	11th to 20th	Night	15% 8% 21% 37% 19% 1	356
	21st to end	Night	21% 10% 28% 29% 11% 1	622
September	1st to 10th	Night	21% 10% 29% 25% 14% 1	720
	11th to 20th	Night	19% 12% 25% 27% 15% 2	720
	21st to end	Night	21% 15% 30% 23% 9% 2	720
October	1st to 10th	Night	17% 14% 34% 25% 10% 1	720
	11th to 20th	Night	17% 16% 37% 24% 6% 1	720
	21st to end	Night	16% 17% 42% 19% 5% 1	792
November	1st to 10th	Night	16% 23% 41% 14% 5%	740
	11th to 20th	Night	15% 24% 44% 14% 3 1	948
	21st to end	Night	15% 21% 43% 16% 4 2	950
December	1st to 10th	Night	12% 22% 41% 18% 6%	950
	11th to 20th	Night	10% 23% 44% 16% 6%	1011
	21st to end	Night	9% 19% 47% 19% 6% 1	1144

Page generated at 2024-02-27 04:30:16. Version ac07

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