Jasper Athabasca Glacier
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jasper Athabasca Glacier clear sky chart from 2005-11-06 to 2024-11-01.

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	5% 14% 6% 16% 8% 6% 5% 4 5% 6% 23%	102104
	Night	4 13% 7% 19% 10% 7% 6% 4 6% 6% 19%	96916
Transparency	Day	27% 50% 8% 9% 5% 1	101850
	Night	29% 51% 8% 8% 4 1	96816
Seeing	Day	15% 19% 28% 23% 12% 3	15904
	Night	11% 18% 34% 24% 11% 2	24254

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	9% 7% 28% 12% 15% 9% 5% 6% 3 7%	1938
	11th to 20th	Day	1 10% 5% 22% 10% 7% 6% 5% 6% 3 25%	2396
	21st to end	Day	16% 8% 36% 9% 6% 4 4 3 4 10%	2794
February	1st to 10th	Day	1 13% 8% 28% 10% 7% 5% 4 5% 5% 14%	1520
	11th to 20th	Day	1 12% 7% 22% 13% 9% 6% 5% 6% 7% 14%	1574
	21st to end	Day	1 9% 6% 20% 16% 11% 8% 5% 6% 5% 14%	1570
March	1st to 10th	Day	9% 6% 21% 15% 10% 8% 5% 5% 6% 14%	3138
	11th to 20th	Day	1 12% 7% 19% 9% 6% 6% 5% 5% 5% 25%	3268
	21st to end	Day	11% 9% 24% 12% 8% 6% 4 5% 6% 14%	4129
April	1st to 10th	Day	3 16% 9% 21% 12% 8% 7% 5% 6% 4 8%	2280
	11th to 20th	Day	2 19% 10% 17% 10% 8% 7% 4 4 6% 13%	2395
	21st to end	Day	4 21% 7% 18% 8% 6% 5% 4 6% 6% 14%	2560
May	1st to 10th	Day	5% 21% 7% 13% 7% 5% 5% 4 5% 7% 20%	4420
	11th to 20th	Day	6% 19% 7% 12% 6% 6% 6% 5% 6% 7% 20%	4590
	21st to end	Day	8% 22% 9% 15% 9% 6% 5% 4 5% 6% 12%	5161
June	1st to 10th	Day	14% 19% 6% 11% 7% 5% 6% 4 5% 6% 16%	2930
	11th to 20th	Day	14% 22% 6% 12% 6% 5% 5% 4 5% 7% 13%	3040
	21st to end	Day	11% 15% 5% 11% 7% 6% 5% 4 6% 6% 23%	3040
July	1st to 10th	Day	7% 9% 3 9% 6% 5% 4 4 5% 6% 42%	5060
	11th to 20th	Day	5% 5% 2 6% 4 4 4 4 6% 7% 51%	4848
	21st to end	Day	5% 10% 5% 11% 6% 5% 5% 3 6% 7% 37%	4832
August	1st to 10th	Day	7% 8% 3 8% 4 5% 5% 5% 7% 9% 39%	4401
	11th to 20th	Day	8% 8% 4 8% 6% 5% 5% 5% 7% 9% 34%	4313
	21st to end	Day	10% 12% 5% 11% 7% 6% 5% 4 5% 7% 28%	4441
September	1st to 10th	Day	8% 14% 4 11% 6% 6% 5% 4 5% 6% 30%	2280
	11th to 20th	Day	8% 17% 5% 11% 5% 4 4 4 6% 8% 29%	2190
	21st to end	Day	10% 22% 6% 11% 6% 5% 4 4 5% 6% 21%	2090
October	1st to 10th	Day	7% 16% 8% 14% 7% 5% 6% 3 5% 6% 23%	1976
	11th to 20th	Day	6% 18% 9% 14% 8% 6% 6% 4 6% 7% 16%	1729
	21st to end	Day	4 20% 8% 20% 10% 7% 5% 3 4 5% 14%	1881
November	1st to 10th	Day	4 22% 12% 20% 11% 6% 4 3 4 4 11%	1594
	11th to 20th	Day	2 16% 8% 22% 11% 7% 5% 4 5% 4 15%	1330
	21st to end	Day	1 14% 8% 22% 12% 7% 6% 4 4 5% 17%	1330
December	1st to 10th	Day	2 13% 6% 19% 13% 8% 7% 4 4 5% 20%	1330
	11th to 20th	Day	13% 9% 28% 12% 9% 5% 4 5% 4 12%	1646
	21st to end	Day	8% 7% 26% 11% 6% 5% 5% 6% 6% 21%	2090
January	1st to 10th	Night	1 10% 7% 30% 18% 8% 7% 4 5% 3 8%	5003
	11th to 20th	Night	8% 4 19% 11% 7% 7% 5% 8% 7% 23%	4533
	21st to end	Night	13% 13% 35% 10% 5% 4 3 4 4 8%	4862
February	1st to 10th	Night	1 11% 8% 25% 11% 8% 6% 5% 6% 5% 15%	2660
	11th to 20th	Night	1 10% 8% 24% 14% 8% 6% 4 5% 5% 16%	2489
	21st to end	Night	9% 7% 19% 14% 10% 7% 5% 6% 7% 16%	1884
March	1st to 10th	Night	7% 6% 22% 12% 11% 9% 7% 8% 6% 12%	3736
	11th to 20th	Night	1 11% 8% 20% 9% 7% 7% 5% 6% 7% 19%	3711
	21st to end	Night	1 13% 10% 25% 12% 8% 5% 4 4 5% 14%	3523
April	1st to 10th	Night	2 14% 10% 25% 11% 6% 5% 4 5% 6% 11%	1900
	11th to 20th	Night	1 18% 8% 17% 11% 7% 5% 5% 7% 5% 16%	1736
	21st to end	Night	5% 17% 7% 15% 8% 7% 5% 5% 6% 7% 19%	1617
May	1st to 10th	Night	4 21% 7% 13% 6% 6% 5% 4 6% 7% 20%	2540
	11th to 20th	Night	6% 17% 7% 15% 6% 6% 5% 5% 6% 8% 20%	2301
	21st to end	Night	8% 24% 10% 14% 7% 6% 5% 3 5% 5% 13%	2414
June	1st to 10th	Night	15% 19% 4 10% 5% 5% 6% 3 7% 8% 20%	1247
	11th to 20th	Night	16% 22% 6% 14% 6% 5% 5% 4 6% 6% 10%	1140
	21st to end	Night	12% 14% 5% 11% 7% 5% 5% 4 5% 7% 24%	1140
July	1st to 10th	Night	9% 12% 4 9% 5% 4 5% 3 5% 6% 39%	1900
	11th to 20th	Night	6% 6% 2 5% 5% 5% 4 3 5% 7% 53%	2110
	21st to end	Night	9% 13% 4 7% 5% 4 4 3 6% 8% 36%	2718
August	1st to 10th	Night	9% 9% 2 10% 6% 6% 6% 4 7% 9% 32%	2529
	11th to 20th	Night	8% 6% 3 7% 5% 5% 7% 6% 9% 12% 32%	2515
	21st to end	Night	9% 12% 5% 14% 6% 5% 5% 4 5% 6% 29%	3228
September	1st to 10th	Night	10% 15% 6% 9% 4 4 4 3 6% 7% 32%	1900
	11th to 20th	Night	9% 17% 5% 10% 5% 5% 3 3 4 7% 30%	1990
	21st to end	Night	9% 18% 7% 11% 5% 5% 6% 3 5% 7% 24%	2090
October	1st to 10th	Night	5% 17% 7% 13% 5% 5% 6% 4 7% 6% 25%	2203
	11th to 20th	Night	6% 17% 8% 17% 8% 5% 5% 4 6% 7% 17%	2451
	21st to end	Night	2 19% 11% 22% 10% 5% 4 3 4 6% 14%	2717
November	1st to 10th	Night	4 21% 10% 22% 11% 5% 4 3 4 6% 10%	2476
	11th to 20th	Night	1 16% 8% 25% 13% 8% 5% 3 4 4 14%	2845
	21st to end	Night	1 14% 8% 22% 13% 8% 6% 4 5% 6% 14%	2850
December	1st to 10th	Night	1 13% 8% 18% 13% 9% 7% 3 4 5% 18%	2850
	11th to 20th	Night	8% 10% 27% 13% 10% 7% 4 6% 4 10%	3542
	21st to end	Night	1 9% 7% 21% 12% 8% 6% 5% 8% 8% 15%	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	44% 43% 5% 4 2 2	1938
	11th to 20th	Day	32% 38% 8% 6% 10% 7%	2420
	21st to end	Day	44% 45% 5% 4 2	2794
February	1st to 10th	Day	23% 66% 3 3 5% 1	1520
	11th to 20th	Day	20% 66% 6% 3 3 1	1582
	21st to end	Day	21% 65% 3 6% 4 2	1570
March	1st to 10th	Day	35% 44% 9% 5% 7%	3138
	11th to 20th	Day	29% 43% 11% 13% 3	3268
	21st to end	Day	39% 43% 8% 5% 4 1	4129
April	1st to 10th	Day	27% 66% 4 3 1	2280
	11th to 20th	Day	24% 66% 7% 3 1	2395
	21st to end	Day	24% 65% 5% 5% 1	2560
May	1st to 10th	Day	36% 42% 8% 10% 3	4420
	11th to 20th	Day	37% 41% 11% 8% 3	4594
	21st to end	Day	45% 41% 8% 5% 1	5162
June	1st to 10th	Day	19% 66% 6% 7% 2	2930
	11th to 20th	Day	22% 66% 4 6% 2	3040
	21st to end	Day	18% 66% 4 9% 3	3040
July	1st to 10th	Day	19% 38% 6% 14% 21% 2	4981
	11th to 20th	Day	12% 37% 7% 23% 20% 1	4763
	21st to end	Day	24% 41% 10% 15% 9% 1	4679
August	1st to 10th	Day	23% 42% 8% 23% 4	4384
	11th to 20th	Day	23% 43% 14% 17% 3	4355
	21st to end	Day	30% 43% 12% 11% 3	4440
September	1st to 10th	Day	20% 61% 7% 8% 2 1	2280
	11th to 20th	Day	25% 60% 5% 7% 3	2190
	21st to end	Day	26% 62% 4 5% 3 1	2090
October	1st to 10th	Day	23% 63% 7% 6% 2	1976
	11th to 20th	Day	24% 63% 6% 6% 1	1729
	21st to end	Day	26% 60% 6% 4 3	1881
November	1st to 10th	Day	27% 61% 5% 5% 2	1594
	11th to 20th	Day	22% 62% 8% 4 3 1	1330
	21st to end	Day	21% 62% 8% 3 3 3	1330
December	1st to 10th	Day	22% 62% 4 6% 4 1	1330
	11th to 20th	Day	34% 51% 7% 5% 2	1648
	21st to end	Day	26% 44% 10% 10% 8% 2	2090
January	1st to 10th	Night	48% 39% 7% 2 2 2	5003
	11th to 20th	Night	28% 39% 6% 7% 15% 5%	4571
	21st to end	Night	46% 44% 4 3 2	4862
February	1st to 10th	Night	22% 65% 3 3 4 2	2660
	11th to 20th	Night	18% 66% 8% 3 4 1	2491
	21st to end	Night	19% 65% 5% 6% 3 2	1884
March	1st to 10th	Night	30% 45% 14% 5% 6% 1	3736
	11th to 20th	Night	30% 45% 9% 12% 2 1	3712
	21st to end	Night	42% 42% 7% 5% 3 1	3523
April	1st to 10th	Night	19% 69% 5% 5% 2	1900
	11th to 20th	Night	19% 66% 7% 6% 2	1736
	21st to end	Night	18% 66% 6% 6% 4	1617
May	1st to 10th	Night	36% 41% 9% 12% 2	2540
	11th to 20th	Night	41% 41% 7% 8% 3	2301
	21st to end	Night	42% 42% 8% 6% 2	2414
June	1st to 10th	Night	17% 66% 9% 6% 2	1247
	11th to 20th	Night	22% 66% 5% 4 3	1140
	21st to end	Night	15% 64% 7% 10% 3	1140
July	1st to 10th	Night	24% 37% 6% 14% 19% 1	1870
	11th to 20th	Night	11% 36% 7% 23% 22% 1	2072
	21st to end	Night	27% 38% 8% 18% 9% 1	2632
August	1st to 10th	Night	27% 41% 10% 19% 3	2521
	11th to 20th	Night	21% 41% 17% 19% 2	2539
	21st to end	Night	31% 40% 14% 12% 2	3228
September	1st to 10th	Night	20% 62% 7% 8% 4 1	1900
	11th to 20th	Night	23% 60% 5% 8% 4	1990
	21st to end	Night	24% 62% 6% 5% 3	2090
October	1st to 10th	Night	24% 62% 6% 5% 3	2203
	11th to 20th	Night	23% 62% 7% 6% 2	2451
	21st to end	Night	22% 61% 8% 6% 3 1	2717
November	1st to 10th	Night	30% 60% 3 5% 2 1	2476
	11th to 20th	Night	24% 63% 6% 3 4 1	2845
	21st to end	Night	21% 62% 8% 4 2 3	2850
December	1st to 10th	Night	23% 62% 4 5% 5% 1	2850
	11th to 20th	Night	34% 53% 5% 6% 2	3539
	21st to end	Night	31% 43% 10% 8% 6% 2	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	10% 23% 31% 22% 11% 3	180
	11th to 20th	Day	9% 27% 32% 19% 10% 2	180
	21st to end	Day	14% 26% 39% 14% 5% 4	198
February	1st to 10th	Day	17% 31% 31% 12% 7% 2	180
	11th to 20th	Day	12% 21% 37% 20% 8% 3	261
	21st to end	Day	12% 23% 35% 22% 7% 1	382
March	1st to 10th	Day	15% 26% 31% 16% 10% 2	460
	11th to 20th	Day	10% 28% 33% 20% 7% 2	460
	21st to end	Day	10% 29% 30% 21% 8% 2	506
April	1st to 10th	Day	18% 23% 33% 20% 5% 2	460
	11th to 20th	Day	13% 25% 30% 20% 10% 2	452
	21st to end	Day	13% 23% 33% 19% 9% 3	460
May	1st to 10th	Day	18% 18% 27% 23% 11% 2	463
	11th to 20th	Day	14% 10% 22% 31% 18% 5%	610
	21st to end	Day	17% 14% 20% 25% 20% 4	734
June	1st to 10th	Day	21% 14% 28% 24% 12% 1	760
	11th to 20th	Day	20% 15% 26% 26% 12% 2	870
	21st to end	Day	16% 9% 22% 28% 20% 5%	870
July	1st to 10th	Day	13% 9% 23% 32% 18% 5%	856
	11th to 20th	Day	12% 10% 26% 29% 18% 5%	733
	21st to end	Day	8% 12% 25% 29% 18% 7%	560
August	1st to 10th	Day	9% 10% 20% 36% 19% 6%	487
	11th to 20th	Day	12% 12% 29% 32% 12% 4	477
	21st to end	Day	14% 17% 31% 24% 11% 2	539
September	1st to 10th	Day	18% 21% 28% 22% 10% 1	490
	11th to 20th	Day	19% 18% 30% 23% 9% 1	490
	21st to end	Day	25% 26% 27% 15% 6% 1	490
October	1st to 10th	Day	21% 22% 28% 17% 9% 3	490
	11th to 20th	Day	20% 28% 25% 16% 9% 1	319
	21st to end	Day	17% 28% 28% 19% 7% 2	330
November	1st to 10th	Day	14% 33% 28% 16% 6% 3	239
	11th to 20th	Day	16% 26% 36% 17% 4 2	180
	21st to end	Day	17% 27% 29% 13% 8% 6%	180
December	1st to 10th	Day	11% 25% 28% 19% 11% 6%	180
	11th to 20th	Day	9% 28% 35% 21% 5% 2	180
	21st to end	Day	8% 16% 40% 23% 12% 1	198
January	1st to 10th	Night	8% 27% 40% 19% 5% 1	1025
	11th to 20th	Night	7% 24% 42% 19% 6% 1	846
	21st to end	Night	5% 25% 44% 19% 6% 1	836
February	1st to 10th	Night	8% 24% 36% 22% 8% 2	760
	11th to 20th	Night	6% 19% 42% 23% 8% 1	744
	21st to end	Night	7% 13% 37% 27% 13% 2	628
March	1st to 10th	Night	6% 22% 38% 24% 9% 1	760
	11th to 20th	Night	6% 19% 43% 24% 7% 1	760
	21st to end	Night	7% 16% 40% 23% 12% 2	836
April	1st to 10th	Night	9% 16% 36% 27% 11% 1	760
	11th to 20th	Night	8% 14% 39% 28% 11%	608
	21st to end	Night	12% 16% 33% 26% 12% 1	477
May	1st to 10th	Night	14% 11% 27% 31% 14% 2	380
	11th to 20th	Night	12% 7% 24% 35% 21% 1	374
	21st to end	Night	20% 11% 21% 25% 19% 4	411
June	1st to 10th	Night	23% 10% 28% 26% 11% 3	380
	11th to 20th	Night	24% 14% 22% 23% 13% 3	380
	21st to end	Night	17% 8% 19% 28% 24% 4	380
July	1st to 10th	Night	18% 3 21% 29% 24% 5%	370
	11th to 20th	Night	15% 9% 20% 30% 24% 3	368
	21st to end	Night	10% 9% 17% 37% 25% 2	416
August	1st to 10th	Night	13% 6% 13% 38% 26% 4	378
	11th to 20th	Night	13% 6% 18% 34% 26% 3	381
	21st to end	Night	16% 10% 26% 34% 13% 1	670
September	1st to 10th	Night	18% 10% 27% 27% 15% 2	760
	11th to 20th	Night	17% 11% 21% 30% 16% 4	760
	21st to end	Night	21% 19% 27% 21% 10% 2	760
October	1st to 10th	Night	18% 14% 31% 24% 10% 1	760
	11th to 20th	Night	17% 21% 32% 24% 6% 1	760
	21st to end	Night	15% 23% 38% 17% 6% 1	836
November	1st to 10th	Night	13% 29% 35% 17% 6%	742
	11th to 20th	Night	12% 26% 41% 18% 3	945
	21st to end	Night	11% 24% 41% 17% 5% 2	950
December	1st to 10th	Night	8% 22% 42% 17% 10% 1	950
	11th to 20th	Night	7% 24% 43% 19% 7%	959
	21st to end	Night	5% 22% 44% 20% 8% 1	1144

Page generated at 2024-10-29 09:20:45. Version ac07

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