Jasper House Viewpoint
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jasper House Viewpoint 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	8% 10% 4 10% 7% 6% 6% 5% 7% 8% 30%	102032
	Night	5% 9% 4 10% 6% 6% 6% 5% 7% 9% 33%	96967
Transparency	Day	50% 12% 14% 16% 7% 1	101770
	Night	46% 13% 16% 17% 7% 1	96875
Seeing	Day	19% 21% 31% 20% 7% 1	16167
	Night	13% 19% 35% 24% 9% 1	24360

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	1 5% 5% 15% 9% 8% 7% 6% 9% 10% 24%	1899
	11th to 20th	Day	1 7% 3 11% 5% 6% 6% 5% 10% 10% 36%	2124
	21st to end	Day	3 8% 4 10% 7% 7% 8% 6% 9% 11% 27%	2794
February	1st to 10th	Day	2 9% 5% 12% 8% 7% 7% 7% 9% 8% 26%	1520
	11th to 20th	Day	1 11% 5% 12% 7% 7% 6% 5% 7% 8% 29%	1555
	21st to end	Day	1 7% 5% 12% 10% 8% 7% 8% 7% 7% 27%	1551
March	1st to 10th	Day	5% 3 11% 10% 9% 9% 6% 8% 9% 29%	3138
	11th to 20th	Day	2 10% 3 6% 5% 5% 7% 6% 9% 11% 37%	3252
	21st to end	Day	2 12% 6% 22% 9% 5% 5% 5% 6% 9% 21%	4165
April	1st to 10th	Day	3 12% 6% 14% 10% 9% 8% 6% 7% 8% 17%	2280
	11th to 20th	Day	4 14% 7% 13% 9% 6% 5% 5% 7% 7% 22%	2384
	21st to end	Day	7% 14% 5% 12% 8% 6% 6% 5% 6% 8% 23%	2621
May	1st to 10th	Day	9% 18% 5% 11% 7% 6% 5% 4 5% 6% 25%	4420
	11th to 20th	Day	9% 15% 5% 10% 7% 6% 6% 4 7% 8% 24%	4615
	21st to end	Day	16% 16% 5% 12% 7% 7% 6% 4 5% 6% 16%	5216
June	1st to 10th	Day	18% 11% 3 9% 7% 7% 5% 5% 6% 7% 21%	3040
	11th to 20th	Day	21% 13% 4 10% 8% 7% 6% 5% 5% 6% 16%	3040
	21st to end	Day	13% 9% 4 9% 7% 7% 6% 5% 7% 6% 26%	3040
July	1st to 10th	Day	12% 7% 3 7% 6% 4 5% 4 5% 6% 41%	5060
	11th to 20th	Day	8% 5% 1 6% 5% 5% 5% 4 6% 8% 46%	5060
	21st to end	Day	9% 6% 3 8% 7% 6% 8% 6% 9% 8% 32%	4868
August	1st to 10th	Day	12% 6% 2 6% 5% 5% 6% 5% 6% 8% 40%	4401
	11th to 20th	Day	11% 7% 3 6% 5% 6% 6% 5% 7% 9% 35%	4330
	21st to end	Day	12% 7% 3 8% 5% 6% 6% 4 7% 8% 34%	4478
September	1st to 10th	Day	11% 9% 3 8% 5% 5% 5% 4 6% 6% 37%	2280
	11th to 20th	Day	10% 9% 3 8% 4 5% 5% 5% 7% 7% 37%	2218
	21st to end	Day	9% 10% 4 9% 6% 6% 5% 5% 7% 7% 35%	2090
October	1st to 10th	Day	5% 11% 4 9% 6% 7% 6% 5% 7% 8% 32%	1933
	11th to 20th	Day	5% 9% 3 8% 7% 7% 6% 6% 8% 10% 32%	1743
	21st to end	Day	4 10% 4 10% 6% 6% 6% 5% 6% 9% 33%	1881
November	1st to 10th	Day	2 10% 4 12% 7% 8% 7% 6% 7% 9% 27%	1528
	11th to 20th	Day	1 7% 4 8% 6% 7% 7% 6% 7% 11% 37%	1330
	21st to end	Day	2 10% 3 11% 7% 6% 5% 5% 9% 11% 31%	1330
December	1st to 10th	Day	3 8% 3 12% 10% 7% 6% 6% 7% 9% 29%	1316
	11th to 20th	Day	2 6% 3 10% 7% 8% 8% 6% 7% 10% 32%	1442
	21st to end	Day	1 6% 3 8% 7% 6% 6% 5% 8% 11% 39%	2090
January	1st to 10th	Night	1 8% 5% 15% 8% 7% 6% 5% 8% 10% 27%	5046
	11th to 20th	Night	1 6% 3 10% 6% 7% 8% 7% 8% 13% 32%	4801
	21st to end	Night	1 7% 4 11% 7% 8% 8% 6% 9% 11% 27%	4862
February	1st to 10th	Night	2 10% 4 12% 10% 7% 7% 8% 7% 8% 26%	2660
	11th to 20th	Night	1 9% 4 11% 8% 6% 8% 6% 8% 9% 29%	2510
	21st to end	Night	1 8% 5% 12% 8% 7% 7% 6% 8% 9% 29%	1902
March	1st to 10th	Night	5% 4 11% 11% 10% 9% 5% 8% 8% 29%	3736
	11th to 20th	Night	2 7% 3 7% 5% 5% 6% 6% 9% 10% 40%	3726
	21st to end	Night	1 12% 7% 20% 7% 4 5% 4 6% 6% 28%	3488
April	1st to 10th	Night	2 13% 5% 12% 7% 6% 6% 7% 8% 8% 26%	1900
	11th to 20th	Night	5% 13% 4 11% 8% 6% 5% 4 6% 9% 30%	1746
	21st to end	Night	8% 13% 5% 10% 5% 6% 5% 4 6% 7% 32%	1558
May	1st to 10th	Night	8% 17% 4 9% 6% 5% 5% 4 6% 8% 27%	2540
	11th to 20th	Night	9% 12% 4 10% 7% 6% 5% 4 6% 7% 30%	2277
	21st to end	Night	16% 15% 4 8% 5% 4 5% 5% 7% 7% 23%	2355
June	1st to 10th	Night	15% 10% 4 7% 5% 5% 5% 4 7% 6% 32%	1140
	11th to 20th	Night	18% 10% 3 9% 7% 6% 7% 5% 8% 7% 21%	1140
	21st to end	Night	10% 8% 2 7% 6% 6% 6% 5% 7% 6% 36%	1140
July	1st to 10th	Night	12% 5% 2 5% 4 4 4 4 6% 8% 45%	1900
	11th to 20th	Night	8% 5% 2 4 4 3 4 4 7% 7% 53%	1900
	21st to end	Night	10% 5% 2 6% 5% 5% 5% 5% 7% 8% 42%	2680
August	1st to 10th	Night	11% 8% 3 6% 4 5% 4 3 7% 8% 41%	2529
	11th to 20th	Night	14% 8% 2 7% 4 4 4 5% 7% 8% 36%	2497
	21st to end	Night	11% 6% 3 6% 5% 5% 6% 5% 7% 8% 38%	3175
September	1st to 10th	Night	11% 9% 2 7% 5% 4 5% 4 5% 8% 40%	1900
	11th to 20th	Night	10% 9% 3 7% 5% 5% 5% 4 5% 7% 40%	1962
	21st to end	Night	8% 8% 3 6% 4 5% 5% 6% 7% 8% 39%	2090
October	1st to 10th	Night	6% 13% 4 8% 5% 6% 5% 5% 6% 8% 34%	2243
	11th to 20th	Night	5% 9% 3 7% 6% 5% 6% 6% 9% 9% 36%	2437
	21st to end	Night	2 8% 5% 12% 8% 6% 7% 5% 8% 9% 31%	2717
November	1st to 10th	Night	3 11% 5% 11% 7% 6% 6% 6% 8% 8% 30%	2535
	11th to 20th	Night	2 9% 4 10% 6% 5% 6% 5% 9% 10% 35%	2850
	21st to end	Night	1 10% 3 10% 8% 7% 6% 5% 8% 11% 31%	2850
December	1st to 10th	Night	3 7% 4 11% 8% 6% 7% 5% 8% 8% 34%	2859
	11th to 20th	Night	1 8% 5% 11% 8% 7% 7% 5% 8% 10% 29%	3750
	21st to end	Night	6% 3 10% 6% 5% 7% 6% 9% 11% 37%	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	50% 16% 18% 12% 3 1	1899
	11th to 20th	Day	43% 13% 12% 13% 15% 4	2144
	21st to end	Day	42% 24% 18% 11% 4	2794
February	1st to 10th	Day	51% 15% 13% 10% 10% 2	1520
	11th to 20th	Day	55% 11% 12% 15% 7% 1	1563
	21st to end	Day	53% 12% 12% 15% 7% 2	1551
March	1st to 10th	Day	43% 19% 16% 13% 10%	3138
	11th to 20th	Day	37% 17% 16% 22% 7%	3252
	21st to end	Day	55% 15% 14% 9% 6% 1	4165
April	1st to 10th	Day	62% 14% 14% 8% 2	2280
	11th to 20th	Day	60% 10% 13% 13% 3	2384
	21st to end	Day	59% 12% 13% 12% 3	2621
May	1st to 10th	Day	58% 10% 13% 14% 5%	4420
	11th to 20th	Day	53% 15% 15% 12% 6%	4619
	21st to end	Day	65% 13% 11% 8% 3	5217
June	1st to 10th	Day	62% 11% 10% 12% 4 1	3040
	11th to 20th	Day	68% 10% 10% 9% 3	3040
	21st to end	Day	57% 13% 12% 12% 5% 1	3040
July	1st to 10th	Day	41% 8% 9% 18% 18% 6%	4981
	11th to 20th	Day	35% 10% 11% 24% 17% 3	4973
	21st to end	Day	46% 9% 16% 16% 12% 1	4713
August	1st to 10th	Day	42% 11% 12% 28% 7%	4384
	11th to 20th	Day	43% 12% 16% 22% 7%	4372
	21st to end	Day	47% 10% 16% 21% 5%	4477
September	1st to 10th	Day	46% 10% 16% 21% 5% 2	2280
	11th to 20th	Day	45% 11% 15% 19% 9% 1	2218
	21st to end	Day	49% 11% 16% 15% 8% 2	2090
October	1st to 10th	Day	48% 11% 17% 18% 5%	1933
	11th to 20th	Day	47% 14% 17% 18% 3	1743
	21st to end	Day	48% 12% 17% 17% 5%	1881
November	1st to 10th	Day	52% 12% 16% 14% 5% 1	1528
	11th to 20th	Day	42% 15% 22% 15% 6% 1	1330
	21st to end	Day	48% 16% 17% 11% 5% 4	1330
December	1st to 10th	Day	53% 12% 11% 15% 7% 1	1316
	11th to 20th	Day	46% 14% 16% 14% 8% 1	1444
	21st to end	Day	36% 15% 19% 18% 12% 1	2090
January	1st to 10th	Night	51% 12% 16% 13% 6% 1	5046
	11th to 20th	Night	44% 13% 11% 12% 17% 4	4843
	21st to end	Night	45% 23% 16% 12% 5% 1	4862
February	1st to 10th	Night	54% 12% 12% 12% 8% 1	2660
	11th to 20th	Night	50% 12% 15% 14% 6% 1	2512
	21st to end	Night	49% 11% 13% 18% 7% 2	1902
March	1st to 10th	Night	45% 19% 14% 12% 9% 1	3736
	11th to 20th	Night	33% 15% 21% 24% 6%	3727
	21st to end	Night	54% 11% 15% 14% 7%	3488
April	1st to 10th	Night	52% 15% 17% 13% 3	1900
	11th to 20th	Night	51% 11% 15% 16% 6%	1746
	21st to end	Night	50% 13% 15% 17% 5% 1	1558
May	1st to 10th	Night	52% 12% 16% 18% 2	2540
	11th to 20th	Night	49% 13% 15% 14% 8%	2277
	21st to end	Night	54% 18% 14% 12% 3	2355
June	1st to 10th	Night	51% 10% 15% 15% 7% 1	1140
	11th to 20th	Night	59% 14% 13% 10% 4	1140
	21st to end	Night	47% 12% 19% 15% 6% 1	1140
July	1st to 10th	Night	35% 10% 11% 24% 17% 3	1870
	11th to 20th	Night	30% 10% 16% 26% 18% 1	1864
	21st to end	Night	39% 9% 20% 21% 9% 3	2596
August	1st to 10th	Night	40% 9% 17% 32% 2	2521
	11th to 20th	Night	43% 12% 18% 23% 5%	2521
	21st to end	Night	43% 10% 23% 19% 4	3175
September	1st to 10th	Night	43% 10% 15% 23% 7% 2	1900
	11th to 20th	Night	43% 10% 18% 20% 8% 1	1962
	21st to end	Night	42% 13% 18% 18% 8%	2090
October	1st to 10th	Night	48% 12% 16% 19% 5%	2243
	11th to 20th	Night	43% 14% 17% 21% 4	2437
	21st to end	Night	50% 13% 15% 15% 6%	2717
November	1st to 10th	Night	51% 12% 17% 15% 4 1	2535
	11th to 20th	Night	46% 14% 19% 14% 6% 1	2850
	21st to end	Night	49% 14% 15% 14% 6% 2	2850
December	1st to 10th	Night	48% 11% 15% 17% 8% 1	2859
	11th to 20th	Night	50% 15% 15% 14% 5%	3747
	21st to end	Night	36% 17% 18% 20% 8% 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	10% 29% 34% 21% 4 2	180
	11th to 20th	Day	16% 23% 34% 20% 5% 3	180
	21st to end	Day	18% 30% 35% 11% 5% 1	198
February	1st to 10th	Day	19% 27% 34% 13% 5% 1	180
	11th to 20th	Day	15% 21% 42% 17% 4 1	255
	21st to end	Day	16% 25% 35% 18% 4 1	373
March	1st to 10th	Day	18% 28% 31% 16% 7% 1	460
	11th to 20th	Day	17% 27% 35% 15% 4 2	460
	21st to end	Day	15% 29% 31% 17% 7% 1	506
April	1st to 10th	Day	25% 21% 32% 17% 5%	460
	11th to 20th	Day	18% 20% 34% 18% 8% 2	452
	21st to end	Day	20% 26% 29% 15% 8% 2	460
May	1st to 10th	Day	19% 19% 33% 22% 6% 1	463
	11th to 20th	Day	18% 14% 31% 27% 9% 2	622
	21st to end	Day	24% 13% 25% 23% 12% 2	763
June	1st to 10th	Day	23% 21% 30% 20% 6%	870
	11th to 20th	Day	26% 19% 29% 19% 7% 1	870
	21st to end	Day	18% 16% 27% 24% 13% 2	870
July	1st to 10th	Day	21% 14% 29% 27% 8% 1	856
	11th to 20th	Day	17% 17% 31% 22% 11% 1	852
	21st to end	Day	15% 16% 31% 26% 9% 3	583
August	1st to 10th	Day	17% 13% 29% 27% 10% 4	487
	11th to 20th	Day	14% 21% 34% 22% 7% 2	477
	21st to end	Day	17% 21% 34% 20% 8% 1	539
September	1st to 10th	Day	19% 23% 31% 21% 6% 1	490
	11th to 20th	Day	18% 20% 34% 21% 6% 1	490
	21st to end	Day	28% 26% 26% 15% 4 1	490
October	1st to 10th	Day	22% 22% 31% 17% 7% 1	490
	11th to 20th	Day	20% 27% 31% 17% 5% 1	333
	21st to end	Day	16% 25% 35% 19% 4 1	330
November	1st to 10th	Day	23% 33% 27% 14% 3	210
	11th to 20th	Day	19% 32% 32% 14% 3 1	180
	21st to end	Day	24% 26% 26% 16% 6% 2	180
December	1st to 10th	Day	14% 29% 27% 15% 12% 3	180
	11th to 20th	Day	14% 28% 39% 13% 6% 1	180
	21st to end	Day	13% 23% 42% 14% 6% 3	198
January	1st to 10th	Night	12% 22% 46% 15% 4 1	1040
	11th to 20th	Night	11% 26% 41% 15% 5% 1	928
	21st to end	Night	13% 29% 36% 17% 6%	836
February	1st to 10th	Night	15% 22% 31% 25% 7%	760
	11th to 20th	Night	11% 18% 38% 28% 5%	744
	21st to end	Night	10% 16% 38% 24% 11% 1	628
March	1st to 10th	Night	9% 20% 37% 24% 8% 1	760
	11th to 20th	Night	8% 22% 40% 21% 7% 1	760
	21st to end	Night	10% 17% 35% 27% 10% 1	836
April	1st to 10th	Night	12% 18% 32% 29% 9% 1	760
	11th to 20th	Night	11% 16% 37% 26% 10%	618
	21st to end	Night	15% 18% 30% 28% 9% 1	418
May	1st to 10th	Night	17% 8% 25% 39% 11%	380
	11th to 20th	Night	12% 9% 29% 34% 16% 1	374
	21st to end	Night	21% 11% 25% 25% 17%	411
June	1st to 10th	Night	22% 11% 29% 26% 13% 1	380
	11th to 20th	Night	23% 9% 23% 29% 14% 1	380
	21st to end	Night	14% 11% 27% 29% 18% 1	380
July	1st to 10th	Night	18% 6% 22% 37% 16% 1	370
	11th to 20th	Night	18% 11% 18% 32% 20% 1	368
	21st to end	Night	12% 8% 21% 34% 25% 1	416
August	1st to 10th	Night	15% 6% 19% 34% 23% 3	378
	11th to 20th	Night	15% 7% 23% 32% 21% 2	376
	21st to end	Night	16% 10% 31% 31% 10% 1	643
September	1st to 10th	Night	18% 12% 27% 31% 11% 1	760
	11th to 20th	Night	18% 11% 27% 29% 14% 2	760
	21st to end	Night	17% 23% 29% 22% 9% 1	760
October	1st to 10th	Night	17% 16% 33% 25% 8% 1	760
	11th to 20th	Night	15% 17% 39% 24% 4 1	760
	21st to end	Night	14% 21% 38% 20% 6% 1	836
November	1st to 10th	Night	14% 25% 37% 20% 3	742
	11th to 20th	Night	14% 29% 39% 15% 3	950
	21st to end	Night	11% 28% 40% 15% 5% 1	950
December	1st to 10th	Night	12% 25% 37% 20% 6%	954
	11th to 20th	Night	9% 26% 43% 17% 5% 1	1040
	21st to end	Night	10% 23% 44% 16% 6% 1	1144

Page generated at 2024-10-29 09:20:44. Version ac07

Copyright © 2024 Attilla Danko.