Trout Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Trout Lake clear sky chart from 2005-11-06 to 2024-12-09.

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	9% 10% 4 9% 6% 5% 5% 4 6% 8% 34%	106536
	Night	7% 12% 4 10% 6% 6% 6% 5% 7% 7% 30%	101763
Transparency	Day	47% 7% 16% 22% 8%	106237
	Night	50% 6% 14% 21% 8% 1	101708
Seeing	Day	14% 9% 24% 29% 20% 6%	17351
	Night	14% 9% 26% 31% 17% 3	24912

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	5% 14% 9% 16% 8% 7% 7% 6% 6% 4 16%	1524
	11th to 20th	Day	3 13% 5% 11% 8% 7% 7% 6% 7% 9% 24%	1692
	21st to end	Day	5% 16% 7% 15% 8% 9% 6% 4 5% 5% 20%	2195
February	1st to 10th	Day	4 13% 6% 13% 7% 8% 6% 4 7% 6% 26%	1330
	11th to 20th	Day	5% 13% 4 14% 7% 6% 6% 4 5% 6% 29%	1474
	21st to end	Day	4 13% 7% 14% 7% 5% 7% 5% 6% 7% 28%	1413
March	1st to 10th	Day	2 8% 4 14% 8% 7% 6% 5% 6% 6% 35%	3041
	11th to 20th	Day	6% 20% 7% 12% 6% 6% 6% 4 5% 6% 21%	3359
	21st to end	Day	3 10% 4 8% 6% 4 4 3 4 7% 47%	4086
April	1st to 10th	Day	7% 15% 5% 11% 7% 5% 4 5% 6% 6% 29%	2327
	11th to 20th	Day	5% 11% 3 8% 6% 6% 5% 5% 6% 7% 38%	2597
	21st to end	Day	9% 13% 4 10% 6% 6% 6% 5% 6% 7% 28%	2660
May	1st to 10th	Day	6% 7% 2 7% 5% 4 5% 5% 7% 8% 43%	4944
	11th to 20th	Day	7% 8% 3 8% 6% 6% 5% 5% 6% 8% 38%	5013
	21st to end	Day	12% 9% 3 7% 5% 4 5% 4 7% 8% 36%	5686
June	1st to 10th	Day	15% 10% 3 7% 5% 6% 5% 4 7% 8% 29%	3420
	11th to 20th	Day	16% 8% 3 7% 5% 6% 6% 5% 7% 8% 29%	3420
	21st to end	Day	12% 7% 2 7% 5% 5% 6% 5% 8% 9% 34%	3420
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 7% 6% 10% 12% 31%	5615
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 4 6% 8% 43%	5366
	21st to end	Day	9% 6% 2 5% 5% 5% 6% 5% 8% 10% 39%	5486
August	1st to 10th	Day	9% 5% 2 5% 4 4 4 4 5% 7% 50%	4864
	11th to 20th	Day	14% 7% 2 7% 5% 4 4 3 5% 7% 42%	4426
	21st to end	Day	16% 8% 3 9% 6% 6% 5% 4 5% 7% 31%	4814
September	1st to 10th	Day	14% 8% 3 8% 5% 4 4 4 6% 7% 36%	2332
	11th to 20th	Day	11% 11% 3 5% 5% 5% 5% 4 6% 10% 35%	2280
	21st to end	Day	15% 11% 3 9% 5% 5% 5% 4 5% 7% 32%	2015
October	1st to 10th	Day	7% 11% 5% 9% 6% 5% 5% 3 5% 7% 37%	3180
	11th to 20th	Day	10% 17% 7% 10% 5% 3 4 3 6% 7% 29%	2829
	21st to end	Day	8% 15% 6% 15% 5% 6% 5% 4 5% 5% 26%	2754
November	1st to 10th	Day	10% 15% 5% 12% 7% 6% 6% 4 5% 6% 24%	1381
	11th to 20th	Day	7% 18% 6% 14% 9% 8% 5% 4 5% 5% 21%	1200
	21st to end	Day	6% 14% 5% 13% 7% 7% 6% 4 6% 8% 24%	1160
December	1st to 10th	Day	4 15% 6% 15% 8% 6% 8% 4 5% 5% 22%	888
	11th to 20th	Day	4 11% 9% 15% 9% 9% 8% 5% 6% 4 21%	959
	21st to end	Day	6% 10% 4 11% 7% 6% 6% 4 6% 7% 31%	1386
January	1st to 10th	Night	3 15% 7% 16% 9% 8% 9% 6% 5% 5% 17%	5416
	11th to 20th	Night	4 9% 4 9% 8% 9% 8% 7% 10% 9% 24%	5206
	21st to end	Night	4 15% 6% 16% 7% 6% 5% 4 6% 7% 23%	5490
February	1st to 10th	Night	3 11% 6% 13% 8% 8% 7% 6% 7% 7% 26%	2850
	11th to 20th	Night	4 14% 4 12% 8% 5% 5% 4 7% 7% 29%	2589
	21st to end	Night	5% 14% 5% 12% 9% 6% 6% 5% 7% 5% 25%	2041
March	1st to 10th	Night	2 8% 3 12% 7% 5% 6% 5% 9% 9% 34%	3830
	11th to 20th	Night	7% 17% 8% 15% 7% 6% 6% 4 5% 7% 19%	3618
	21st to end	Night	3 7% 3 8% 6% 5% 5% 4 7% 8% 46%	3567
April	1st to 10th	Night	6% 16% 4 10% 6% 4 5% 5% 7% 7% 30%	1851
	11th to 20th	Night	5% 11% 3 9% 6% 6% 5% 5% 6% 8% 35%	1532
	21st to end	Night	9% 17% 4 10% 6% 7% 5% 4 6% 6% 25%	1520
May	1st to 10th	Night	5% 8% 3 7% 5% 5% 5% 4 5% 7% 49%	2013
	11th to 20th	Night	7% 7% 3 6% 4 6% 6% 5% 7% 9% 39%	1882
	21st to end	Night	12% 8% 2 8% 5% 5% 6% 5% 8% 10% 32%	1886
June	1st to 10th	Night	16% 10% 4 6% 5% 4 4 3 8% 9% 32%	760
	11th to 20th	Night	13% 8% 2 8% 4 4 6% 5% 6% 8% 35%	760
	21st to end	Night	11% 6% 2 6% 4 4 4 5% 9% 10% 38%	760
July	1st to 10th	Night	10% 6% 2 7% 5% 4 6% 5% 8% 11% 35%	1342
	11th to 20th	Night	9% 6% 3 6% 3 4 4 4 8% 10% 43%	1580
	21st to end	Night	8% 5% 2 5% 4 6% 6% 6% 8% 12% 39%	2066
August	1st to 10th	Night	7% 5% 2 5% 3 4 4 3 5% 6% 54%	2051
	11th to 20th	Night	12% 4 2 6% 4 4 4 4 7% 9% 43%	2400
	21st to end	Night	13% 8% 3 7% 5% 5% 6% 5% 8% 9% 31%	2844
September	1st to 10th	Night	13% 8% 3 7% 5% 4 5% 4 6% 7% 37%	1848
	11th to 20th	Night	12% 9% 2 7% 5% 4 5% 5% 8% 9% 33%	1900
	21st to end	Night	15% 11% 3 8% 4 5% 6% 4 6% 7% 31%	2162
October	1st to 10th	Night	9% 8% 4 9% 4 5% 5% 5% 7% 10% 35%	3800
	11th to 20th	Night	11% 16% 5% 8% 5% 3 4 3 5% 7% 33%	4095
	21st to end	Night	7% 17% 5% 11% 4 5% 5% 4 6% 6% 30%	4794
November	1st to 10th	Night	11% 17% 6% 13% 8% 5% 4 3 3 5% 25%	2896
	11th to 20th	Night	7% 19% 7% 14% 8% 7% 5% 3 4 5% 21%	3200
	21st to end	Night	6% 15% 5% 10% 8% 6% 5% 4 6% 7% 28%	3240
December	1st to 10th	Night	4 15% 7% 14% 9% 8% 6% 4 6% 7% 21%	3471
	11th to 20th	Night	4 12% 4 12% 8% 7% 6% 5% 7% 6% 28%	4233
	21st to end	Night	3 10% 4 10% 6% 6% 6% 5% 7% 8% 34%	6270

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	67% 6% 7% 15% 4 1	1524
	11th to 20th	Day	55% 5% 8% 13% 18% 1	1708
	21st to end	Day	65% 5% 10% 13% 6%	2195
February	1st to 10th	Day	57% 6% 9% 18% 10% 1	1330
	11th to 20th	Day	54% 6% 15% 18% 7%	1482
	21st to end	Day	54% 6% 15% 18% 7%	1413
March	1st to 10th	Day	48% 4 11% 23% 14%	3041
	11th to 20th	Day	62% 7% 11% 13% 7%	3359
	21st to end	Day	37% 5% 18% 30% 10% 1	4086
April	1st to 10th	Day	54% 5% 13% 19% 9%	2327
	11th to 20th	Day	44% 6% 12% 27% 11% 1	2597
	21st to end	Day	53% 6% 14% 18% 8%	2660
May	1st to 10th	Day	34% 8% 12% 27% 15% 5%	4944
	11th to 20th	Day	39% 8% 11% 23% 19% 1	5017
	21st to end	Day	43% 8% 12% 24% 12% 1	5687
June	1st to 10th	Day	50% 7% 13% 22% 7%	3420
	11th to 20th	Day	49% 8% 15% 21% 6%	3420
	21st to end	Day	43% 8% 20% 22% 7%	3420
July	1st to 10th	Day	40% 10% 25% 23% 2	5528
	11th to 20th	Day	36% 7% 25% 26% 6%	5273
	21st to end	Day	36% 8% 24% 28% 4	5313
August	1st to 10th	Day	33% 6% 17% 28% 15%	4845
	11th to 20th	Day	42% 6% 18% 21% 13%	4470
	21st to end	Day	52% 6% 22% 19% 2	4813
September	1st to 10th	Day	46% 8% 21% 20% 5%	2332
	11th to 20th	Day	44% 6% 25% 23% 2	2280
	21st to end	Day	52% 6% 18% 20% 4	2015
October	1st to 10th	Day	47% 4 15% 29% 4	3180
	11th to 20th	Day	56% 5% 15% 21% 3	2829
	21st to end	Day	59% 6% 14% 16% 4	2754
November	1st to 10th	Day	61% 5% 11% 19% 3	1381
	11th to 20th	Day	66% 5% 14% 11% 4	1200
	21st to end	Day	56% 7% 14% 18% 6%	1160
December	1st to 10th	Day	63% 7% 10% 16% 5% 1	888
	11th to 20th	Day	64% 6% 11% 13% 6%	960
	21st to end	Day	49% 6% 18% 17% 9%	1386
January	1st to 10th	Night	67% 5% 8% 12% 8%	5416
	11th to 20th	Night	51% 6% 9% 15% 16% 2	5252
	21st to end	Night	59% 6% 11% 18% 5%	5490
February	1st to 10th	Night	54% 5% 9% 20% 10%	2850
	11th to 20th	Night	52% 6% 13% 22% 7% 1	2591
	21st to end	Night	56% 6% 10% 21% 7%	2041
March	1st to 10th	Night	42% 6% 10% 32% 10% 1	3830
	11th to 20th	Night	63% 6% 8% 17% 5% 1	3619
	21st to end	Night	34% 7% 18% 32% 9%	3567
April	1st to 10th	Night	50% 6% 15% 21% 8%	1851
	11th to 20th	Night	46% 5% 10% 27% 12% 1	1532
	21st to end	Night	55% 7% 11% 18% 8% 1	1520
May	1st to 10th	Night	35% 6% 10% 24% 20% 6%	2013
	11th to 20th	Night	36% 7% 11% 27% 19%	1882
	21st to end	Night	40% 10% 16% 24% 10%	1886
June	1st to 10th	Night	47% 6% 14% 28% 5%	760
	11th to 20th	Night	44% 7% 19% 19% 10%	760
	21st to end	Night	37% 9% 22% 23% 9%	760
July	1st to 10th	Night	38% 11% 27% 22% 3	1320
	11th to 20th	Night	34% 7% 28% 26% 5%	1550
	21st to end	Night	34% 7% 25% 27% 6%	2000
August	1st to 10th	Night	31% 6% 16% 32% 15%	2045
	11th to 20th	Night	34% 8% 17% 27% 13%	2422
	21st to end	Night	47% 8% 21% 23% 2	2844
September	1st to 10th	Night	45% 6% 21% 22% 5%	1848
	11th to 20th	Night	45% 7% 21% 24% 4	1900
	21st to end	Night	52% 7% 14% 21% 6%	2162
October	1st to 10th	Night	43% 6% 18% 26% 8%	3800
	11th to 20th	Night	52% 4 14% 25% 5%	4095
	21st to end	Night	53% 5% 18% 20% 3	4794
November	1st to 10th	Night	63% 4 10% 17% 4	2896
	11th to 20th	Night	66% 4 11% 13% 4	3200
	21st to end	Night	54% 6% 14% 19% 6% 1	3240
December	1st to 10th	Night	62% 6% 12% 13% 6%	3471
	11th to 20th	Night	53% 6% 14% 18% 8% 1	4231
	21st to end	Night	45% 7% 14% 20% 13% 1	6270

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	8% 8% 26% 31% 25% 1	180
	11th to 20th	Day	14% 12% 29% 22% 18% 6%	180
	21st to end	Day	13% 14% 28% 25% 18% 2	198
February	1st to 10th	Day	11% 11% 33% 27% 16% 3	180
	11th to 20th	Day	8% 9% 34% 29% 15% 4	189
	21st to end	Day	11% 10% 29% 31% 16% 3	307
March	1st to 10th	Day	4 9% 27% 33% 19% 8%	431
	11th to 20th	Day	9% 12% 30% 27% 18% 3	460
	21st to end	Day	10% 10% 26% 34% 16% 4	506
April	1st to 10th	Day	12% 12% 28% 31% 13% 4	460
	11th to 20th	Day	10% 6% 25% 28% 21% 9%	452
	21st to end	Day	16% 14% 22% 28% 16% 5%	460
May	1st to 10th	Day	11% 11% 31% 29% 14% 4	766
	11th to 20th	Day	14% 9% 22% 32% 19% 4	862
	21st to end	Day	14% 7% 21% 31% 24% 4	940
June	1st to 10th	Day	19% 8% 21% 27% 20% 5%	870
	11th to 20th	Day	19% 7% 17% 31% 20% 6%	870
	21st to end	Day	13% 7% 17% 27% 26% 10%	870
July	1st to 10th	Day	15% 4 17% 29% 27% 9%	856
	11th to 20th	Day	13% 4 19% 24% 29% 11%	852
	21st to end	Day	15% 5% 13% 30% 28% 9%	947
August	1st to 10th	Day	11% 6% 14% 27% 30% 12%	769
	11th to 20th	Day	18% 9% 26% 26% 17% 4	537
	21st to end	Day	20% 7% 22% 31% 16% 4	539
September	1st to 10th	Day	19% 8% 25% 25% 18% 5%	490
	11th to 20th	Day	13% 8% 28% 31% 17% 3	490
	21st to end	Day	18% 16% 31% 21% 12% 3	490
October	1st to 10th	Day	17% 12% 35% 23% 9% 4	490
	11th to 20th	Day	18% 12% 30% 27% 10% 3	316
	21st to end	Day	15% 11% 30% 25% 12% 6%	220
November	1st to 10th	Day	11% 8% 37% 31% 11% 3	200
	11th to 20th	Day	13% 13% 25% 34% 14% 3	200
	21st to end	Day	16% 15% 28% 26% 13% 2	200
December	1st to 10th	Day	9% 15% 27% 28% 16% 5%	196
	11th to 20th	Day	8% 11% 32% 31% 13% 5%	180
	21st to end	Day	8% 7% 27% 35% 16% 7%	198
January	1st to 10th	Night	10% 10% 28% 34% 16% 3	1040
	11th to 20th	Night	14% 11% 27% 30% 15% 3	1040
	21st to end	Night	13% 13% 31% 29% 13% 1	1094
February	1st to 10th	Night	8% 10% 30% 35% 15% 3	850
	11th to 20th	Night	11% 11% 30% 33% 13% 2	751
	21st to end	Night	13% 8% 26% 33% 15% 4	628
March	1st to 10th	Night	7% 7% 29% 32% 21% 4	760
	11th to 20th	Night	12% 11% 25% 32% 18% 2	760
	21st to end	Night	10% 6% 23% 36% 20% 5%	836
April	1st to 10th	Night	13% 8% 24% 35% 19% 2	711
	11th to 20th	Night	11% 6% 21% 33% 24% 3	404
	21st to end	Night	19% 7% 23% 30% 18% 2	380
May	1st to 10th	Night	12% 8% 27% 34% 17% 1	380
	11th to 20th	Night	14% 9% 23% 31% 24% 1	374
	21st to end	Night	15% 4 19% 35% 26% 1	411
June	1st to 10th	Night	19% 4 22% 30% 23% 3	380
	11th to 20th	Night	17% 5% 16% 35% 25% 2	380
	21st to end	Night	12% 4 19% 28% 32% 5%	380
July	1st to 10th	Night	17% 4 17% 32% 25% 5%	370
	11th to 20th	Night	12% 3 17% 33% 30% 5%	368
	21st to end	Night	15% 4 17% 30% 28% 6%	416
August	1st to 10th	Night	9% 4 13% 33% 33% 8%	378
	11th to 20th	Night	18% 5% 25% 32% 16% 4	376
	21st to end	Night	20% 5% 19% 36% 17% 4	442
September	1st to 10th	Night	18% 7% 23% 28% 21% 3	708
	11th to 20th	Night	17% 7% 26% 33% 14% 3	760
	21st to end	Night	21% 10% 26% 30% 12% 1	760
October	1st to 10th	Night	19% 10% 31% 25% 12% 1	760
	11th to 20th	Night	21% 8% 33% 25% 11% 1	760
	21st to end	Night	18% 9% 27% 30% 13% 3	836
November	1st to 10th	Night	18% 11% 29% 28% 11% 3	944
	11th to 20th	Night	16% 9% 30% 28% 14% 2	1100
	21st to end	Night	13% 11% 28% 30% 14% 4	1100
December	1st to 10th	Night	11% 12% 31% 30% 14% 2	1091
	11th to 20th	Night	12% 10% 27% 33% 14% 3	1040
	21st to end	Night	10% 7% 27% 30% 20% 5%	1144

Page generated at 2024-12-06 01:54:49. Version ac07

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