Jasper Marmot Meadows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jasper Marmot Meadows clear sky chart from 2005-11-06 to 2024-10-24.

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% 11% 5% 12% 7% 6% 6% 5% 7% 7% 26%	101934
	Night	4 10% 4 11% 7% 7% 7% 5% 8% 9% 28%	96889
Transparency	Day	56% 8% 14% 14% 6% 1	101675
	Night	52% 10% 17% 15% 6% 1	96794
Seeing	Day	19% 13% 28% 24% 12% 3	16084
	Night	11% 10% 35% 31% 11% 1	24292

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 7% 8% 16% 11% 10% 8% 6% 9% 10% 15%	1899
	11th to 20th	Day	1 7% 5% 16% 6% 5% 6% 6% 9% 8% 32%	2190
	21st to end	Day	1 15% 5% 14% 9% 7% 8% 6% 8% 9% 17%	2794
February	1st to 10th	Day	2 9% 6% 16% 9% 7% 8% 5% 8% 8% 22%	1520
	11th to 20th	Day	1 10% 5% 17% 9% 7% 7% 6% 8% 7% 22%	1564
	21st to end	Day	1 7% 4 17% 12% 9% 7% 6% 7% 7% 22%	1555
March	1st to 10th	Day	5% 3 12% 12% 11% 10% 7% 9% 10% 21%	3138
	11th to 20th	Day	2 10% 6% 14% 7% 6% 7% 5% 6% 8% 29%	3251
	21st to end	Day	1 13% 7% 21% 10% 6% 5% 5% 6% 7% 19%	4165
April	1st to 10th	Day	3 16% 8% 17% 11% 9% 8% 5% 6% 5% 13%	2280
	11th to 20th	Day	4 15% 7% 17% 10% 6% 6% 5% 5% 6% 19%	2376
	21st to end	Day	6% 18% 5% 15% 8% 6% 5% 4 6% 7% 19%	2615
May	1st to 10th	Day	8% 20% 6% 11% 6% 5% 5% 3 6% 6% 22%	4420
	11th to 20th	Day	10% 15% 4 12% 7% 7% 6% 5% 7% 7% 21%	4582
	21st to end	Day	14% 21% 6% 14% 8% 6% 5% 4 5% 4 12%	5183
June	1st to 10th	Day	17% 13% 4 12% 7% 6% 6% 5% 6% 6% 18%	3040
	11th to 20th	Day	19% 17% 6% 11% 8% 6% 6% 5% 5% 5% 13%	3040
	21st to end	Day	12% 12% 5% 11% 8% 7% 6% 5% 6% 7% 21%	3040
July	1st to 10th	Day	10% 7% 3 7% 5% 4 5% 4 5% 6% 43%	5060
	11th to 20th	Day	8% 6% 2 6% 5% 5% 5% 4 6% 7% 46%	5038
	21st to end	Day	9% 7% 3 8% 6% 6% 7% 6% 7% 8% 33%	4825
August	1st to 10th	Day	12% 7% 3 6% 6% 5% 6% 4 6% 7% 38%	4401
	11th to 20th	Day	12% 7% 3 7% 5% 6% 6% 5% 7% 8% 33%	4330
	21st to end	Day	13% 8% 3 7% 5% 5% 6% 5% 7% 9% 32%	4466
September	1st to 10th	Day	10% 11% 4 10% 5% 6% 5% 4 5% 6% 33%	2280
	11th to 20th	Day	10% 10% 4 8% 5% 6% 5% 5% 6% 6% 34%	2218
	21st to end	Day	8% 12% 5% 11% 7% 6% 5% 4 6% 6% 29%	2090
October	1st to 10th	Day	6% 14% 5% 10% 7% 6% 5% 5% 7% 8% 28%	1933
	11th to 20th	Day	4 12% 4 11% 6% 7% 8% 6% 7% 9% 26%	1750
	21st to end	Day	3 11% 5% 13% 8% 6% 7% 6% 6% 8% 25%	1809
November	1st to 10th	Day	3 13% 6% 15% 9% 8% 6% 5% 7% 7% 21%	1550
	11th to 20th	Day	2 7% 5% 10% 8% 7% 6% 7% 8% 10% 30%	1330
	21st to end	Day	1 11% 5% 12% 8% 8% 7% 5% 7% 9% 26%	1330
December	1st to 10th	Day	2 8% 5% 13% 9% 7% 7% 6% 9% 7% 25%	1330
	11th to 20th	Day	1 9% 4 11% 8% 9% 9% 7% 8% 10% 23%	1452
	21st to end	Day	8% 4 9% 7% 5% 7% 6% 8% 13% 33%	2090
January	1st to 10th	Night	1 7% 6% 18% 11% 8% 7% 5% 7% 9% 20%	5046
	11th to 20th	Night	1 8% 4 11% 7% 7% 8% 6% 10% 10% 28%	4735
	21st to end	Night	1 12% 5% 13% 9% 8% 8% 6% 8% 9% 20%	4862
February	1st to 10th	Night	3 11% 5% 13% 10% 8% 8% 6% 9% 8% 20%	2660
	11th to 20th	Night	1 9% 5% 13% 9% 8% 8% 5% 8% 10% 24%	2498
	21st to end	Night	1 10% 5% 13% 10% 8% 7% 6% 9% 9% 24%	1899
March	1st to 10th	Night	5% 3 13% 12% 11% 8% 7% 9% 9% 23%	3736
	11th to 20th	Night	2 9% 5% 9% 7% 6% 7% 6% 9% 10% 31%	3725
	21st to end	Night	1 13% 7% 20% 8% 6% 5% 4 6% 7% 22%	3488
April	1st to 10th	Night	1 14% 5% 14% 9% 8% 7% 5% 8% 8% 21%	1900
	11th to 20th	Night	3 12% 5% 13% 8% 6% 6% 5% 7% 9% 27%	1754
	21st to end	Night	5% 12% 5% 12% 6% 5% 6% 6% 6% 8% 28%	1563
May	1st to 10th	Night	5% 16% 5% 11% 7% 5% 7% 5% 7% 7% 26%	2540
	11th to 20th	Night	7% 13% 4 12% 6% 7% 6% 4 6% 7% 27%	2309
	21st to end	Night	10% 16% 6% 12% 7% 7% 5% 5% 6% 7% 19%	2388
June	1st to 10th	Night	14% 11% 4 10% 4 7% 6% 4 6% 7% 28%	1140
	11th to 20th	Night	16% 14% 4 10% 8% 6% 6% 5% 6% 7% 19%	1140
	21st to end	Night	9% 6% 3 8% 6% 7% 7% 5% 8% 9% 31%	1140
July	1st to 10th	Night	11% 6% 1 4 3 4 4 3 6% 6% 52%	1900
	11th to 20th	Night	6% 4 1 5% 4 4 5% 4 6% 7% 54%	1922
	21st to end	Night	9% 6% 2 6% 4 5% 5% 4 7% 10% 43%	2724
August	1st to 10th	Night	12% 8% 2 6% 4 4 5% 5% 7% 9% 38%	2529
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 5% 7% 10% 37%	2497
	21st to end	Night	12% 7% 3 6% 5% 5% 6% 5% 6% 8% 37%	3200
September	1st to 10th	Night	11% 8% 2 8% 5% 5% 5% 4 6% 8% 38%	1900
	11th to 20th	Night	9% 11% 3 8% 5% 5% 5% 4 6% 7% 37%	1962
	21st to end	Night	7% 9% 4 9% 5% 5% 6% 5% 7% 10% 33%	2090
October	1st to 10th	Night	4 13% 4 12% 6% 6% 5% 4 6% 8% 31%	2245
	11th to 20th	Night	5% 11% 3 9% 6% 6% 7% 5% 8% 10% 30%	2429
	21st to end	Night	3 11% 5% 12% 8% 7% 6% 5% 9% 8% 26%	2613
November	1st to 10th	Night	3 13% 5% 13% 8% 8% 7% 6% 8% 7% 23%	2522
	11th to 20th	Night	1 10% 4 10% 7% 7% 8% 6% 9% 11% 28%	2832
	21st to end	Night	1 10% 5% 12% 8% 8% 7% 5% 8% 10% 25%	2850
December	1st to 10th	Night	2 8% 4 13% 8% 7% 7% 6% 7% 9% 28%	2850
	11th to 20th	Night	1 8% 5% 14% 9% 8% 9% 6% 9% 9% 22%	3735
	21st to end	Night	1 7% 4 10% 7% 7% 6% 6% 8% 11% 33%	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	62% 11% 17% 8% 3	1899
	11th to 20th	Day	49% 10% 13% 10% 15% 3	2211
	21st to end	Day	60% 12% 17% 7% 3	2794
February	1st to 10th	Day	58% 9% 13% 10% 8% 2	1520
	11th to 20th	Day	61% 7% 12% 14% 5%	1572
	21st to end	Day	58% 8% 13% 14% 6% 1	1555
March	1st to 10th	Day	53% 12% 17% 12% 7%	3138
	11th to 20th	Day	53% 8% 17% 19% 3	3251
	21st to end	Day	63% 7% 14% 9% 7%	4165
April	1st to 10th	Day	72% 7% 13% 7% 1	2280
	11th to 20th	Day	64% 7% 15% 11% 2	2376
	21st to end	Day	64% 9% 13% 11% 2	2615
May	1st to 10th	Day	62% 7% 14% 13% 4	4420
	11th to 20th	Day	59% 7% 16% 13% 5%	4586
	21st to end	Day	72% 8% 10% 7% 3	5184
June	1st to 10th	Day	65% 7% 11% 11% 4 2	3040
	11th to 20th	Day	72% 7% 10% 8% 3	3040
	21st to end	Day	61% 8% 13% 11% 5% 1	3040
July	1st to 10th	Day	43% 7% 9% 18% 15% 7%	4981
	11th to 20th	Day	39% 6% 12% 22% 18% 2	4951
	21st to end	Day	53% 6% 11% 14% 11% 4	4672
August	1st to 10th	Day	43% 8% 12% 27% 10%	4384
	11th to 20th	Day	48% 9% 17% 20% 6% 1	4372
	21st to end	Day	54% 7% 13% 21% 4	4465
September	1st to 10th	Day	53% 5% 15% 21% 5% 1	2280
	11th to 20th	Day	50% 7% 17% 17% 8%	2218
	21st to end	Day	57% 8% 14% 14% 6% 1	2090
October	1st to 10th	Day	54% 9% 17% 16% 4	1933
	11th to 20th	Day	55% 11% 16% 16% 2	1750
	21st to end	Day	58% 9% 15% 14% 4	1809
November	1st to 10th	Day	61% 10% 15% 10% 3 1	1550
	11th to 20th	Day	49% 13% 22% 11% 5% 1	1330
	21st to end	Day	53% 12% 19% 9% 5% 2	1330
December	1st to 10th	Day	57% 9% 13% 14% 6% 1	1330
	11th to 20th	Day	57% 10% 16% 11% 5% 1	1454
	21st to end	Day	43% 10% 24% 14% 8%	2090
January	1st to 10th	Night	61% 9% 17% 9% 4 1	5046
	11th to 20th	Night	49% 10% 10% 13% 16% 2	4776
	21st to end	Night	62% 12% 13% 10% 3	4862
February	1st to 10th	Night	61% 9% 12% 9% 7% 1	2660
	11th to 20th	Night	56% 9% 17% 12% 5% 1	2500
	21st to end	Night	53% 7% 15% 17% 7% 1	1899
March	1st to 10th	Night	51% 14% 16% 13% 6% 1	3736
	11th to 20th	Night	46% 8% 24% 19% 3	3726
	21st to end	Night	58% 10% 15% 12% 5%	3488
April	1st to 10th	Night	60% 9% 18% 11% 2	1900
	11th to 20th	Night	52% 9% 19% 16% 4	1754
	21st to end	Night	52% 11% 15% 17% 4	1563
May	1st to 10th	Night	54% 10% 18% 17% 2	2540
	11th to 20th	Night	53% 10% 17% 14% 7%	2309
	21st to end	Night	63% 11% 14% 10% 2	2388
June	1st to 10th	Night	54% 7% 17% 14% 6% 1	1140
	11th to 20th	Night	62% 8% 16% 10% 3	1140
	21st to end	Night	46% 10% 21% 17% 5% 1	1140
July	1st to 10th	Night	34% 8% 13% 23% 21% 2	1870
	11th to 20th	Night	30% 6% 15% 28% 20% 1	1886
	21st to end	Night	41% 8% 16% 21% 9% 6%	2638
August	1st to 10th	Night	42% 9% 19% 28% 3	2521
	11th to 20th	Night	43% 11% 22% 19% 5%	2521
	21st to end	Night	46% 9% 23% 18% 4	3200
September	1st to 10th	Night	43% 7% 20% 22% 7% 1	1900
	11th to 20th	Night	46% 7% 20% 19% 8% 1	1962
	21st to end	Night	47% 11% 20% 17% 5% 1	2090
October	1st to 10th	Night	52% 10% 18% 17% 3	2245
	11th to 20th	Night	51% 11% 19% 17% 2	2429
	21st to end	Night	55% 10% 17% 13% 5%	2613
November	1st to 10th	Night	61% 10% 17% 10% 3	2522
	11th to 20th	Night	52% 13% 19% 9% 5%	2832
	21st to end	Night	54% 12% 17% 10% 5% 2	2850
December	1st to 10th	Night	54% 9% 17% 13% 7% 1	2850
	11th to 20th	Night	58% 12% 16% 10% 4	3732
	21st to end	Night	46% 9% 23% 17% 4 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	9% 7% 19% 44% 17% 3	180
	11th to 20th	Day	9% 7% 26% 38% 16% 4	180
	21st to end	Day	16% 6% 32% 30% 12% 5%	198
February	1st to 10th	Day	18% 11% 29% 29% 11% 3	180
	11th to 20th	Day	16% 13% 28% 25% 14% 5%	264
	21st to end	Day	10% 18% 38% 19% 12% 2	375
March	1st to 10th	Day	13% 22% 31% 19% 11% 3	460
	11th to 20th	Day	14% 20% 34% 19% 10% 3	460
	21st to end	Day	15% 20% 29% 21% 10% 5%	506
April	1st to 10th	Day	20% 20% 31% 21% 7% 1	460
	11th to 20th	Day	16% 15% 31% 23% 10% 5%	452
	21st to end	Day	20% 18% 25% 22% 10% 4	460
May	1st to 10th	Day	24% 13% 29% 22% 10% 2	463
	11th to 20th	Day	18% 11% 24% 29% 14% 3	602
	21st to end	Day	23% 10% 21% 24% 19% 3	743
June	1st to 10th	Day	25% 13% 30% 22% 9% 1	870
	11th to 20th	Day	29% 13% 26% 22% 9% 2	870
	21st to end	Day	19% 12% 24% 25% 15% 4	870
July	1st to 10th	Day	20% 10% 27% 29% 12% 2	856
	11th to 20th	Day	19% 11% 28% 27% 12% 3	843
	21st to end	Day	16% 13% 26% 25% 16% 4	553
August	1st to 10th	Day	18% 9% 25% 27% 16% 5%	487
	11th to 20th	Day	16% 14% 33% 22% 12% 4	477
	21st to end	Day	21% 12% 30% 22% 12% 3	539
September	1st to 10th	Day	25% 14% 27% 19% 13% 3	490
	11th to 20th	Day	18% 14% 27% 26% 13% 3	490
	21st to end	Day	27% 21% 26% 15% 8% 2	490
October	1st to 10th	Day	21% 16% 29% 19% 10% 5%	490
	11th to 20th	Day	20% 16% 27% 22% 12% 3	340
	21st to end	Day	18% 10% 28% 34% 8% 2	306
November	1st to 10th	Day	20% 13% 31% 25% 8% 3	212
	11th to 20th	Day	17% 9% 31% 30% 9% 4	180
	21st to end	Day	18% 14% 23% 28% 11% 7%	180
December	1st to 10th	Day	12% 6% 26% 31% 18% 8%	180
	11th to 20th	Day	10% 6% 24% 40% 14% 6%	180
	21st to end	Day	8% 7% 21% 40% 17% 8%	198
January	1st to 10th	Night	9% 13% 38% 32% 6% 1	1040
	11th to 20th	Night	7% 14% 41% 29% 7% 2	898
	21st to end	Night	9% 15% 44% 24% 7% 1	836
February	1st to 10th	Night	12% 11% 38% 28% 11% 1	760
	11th to 20th	Night	8% 10% 39% 33% 9% 1	744
	21st to end	Night	8% 10% 39% 29% 11% 3	628
March	1st to 10th	Night	6% 13% 41% 28% 11% 1	760
	11th to 20th	Night	5% 13% 43% 28% 10% 1	760
	21st to end	Night	7% 11% 36% 32% 12% 2	836
April	1st to 10th	Night	9% 12% 32% 35% 12% 1	760
	11th to 20th	Night	9% 12% 34% 30% 15% 1	626
	21st to end	Night	15% 8% 31% 33% 13%	423
May	1st to 10th	Night	14% 6% 23% 45% 13%	380
	11th to 20th	Night	11% 3 28% 41% 16% 1	374
	21st to end	Night	20% 5% 23% 29% 21% 1	411
June	1st to 10th	Night	20% 3 31% 31% 13% 1	380
	11th to 20th	Night	22% 6% 23% 33% 14% 2	380
	21st to end	Night	15% 6% 23% 34% 21% 2	380
July	1st to 10th	Night	16% 5% 19% 41% 18% 1	370
	11th to 20th	Night	16% 6% 21% 33% 22% 1	368
	21st to end	Night	12% 3 19% 43% 22%	416
August	1st to 10th	Night	16% 2 15% 39% 28% 2	378
	11th to 20th	Night	15% 4 20% 38% 21% 2	376
	21st to end	Night	17% 6% 25% 39% 12% 1	655
September	1st to 10th	Night	17% 6% 24% 37% 15% 1	760
	11th to 20th	Night	17% 5% 25% 33% 18% 1	760
	21st to end	Night	18% 12% 32% 27% 11% 1	760
October	1st to 10th	Night	15% 10% 31% 34% 9% 1	760
	11th to 20th	Night	13% 11% 38% 29% 8% 1	760
	21st to end	Night	13% 13% 40% 27% 7%	804
November	1st to 10th	Night	12% 13% 41% 28% 5% 1	740
	11th to 20th	Night	11% 16% 41% 27% 4 1	932
	21st to end	Night	9% 13% 45% 24% 7% 1	950
December	1st to 10th	Night	8% 12% 41% 29% 9% 1	950
	11th to 20th	Night	8% 10% 44% 28% 8% 1	1033
	21st to end	Night	5% 10% 43% 30% 10% 1	1144

Page generated at 2024-10-21 00:19:59. Version ac07

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