Pinawa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pinawa clear sky chart from 2005-11-06 to 2024-11-05.

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	12% 9% 4 9% 6% 5% 5% 4 6% 7% 33%	105596
	Night	10% 11% 4 10% 6% 5% 5% 4 6% 7% 32%	102053
Transparency	Day	48% 7% 15% 22% 7%	105337
	Night	50% 7% 14% 21% 7% 1	101959
Seeing	Day	15% 10% 31% 28% 13% 3	16269
	Night	16% 8% 31% 32% 12% 1	26174

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	6% 17% 6% 16% 6% 8% 8% 4 5% 4 18%	2219
	11th to 20th	Day	5% 9% 6% 17% 11% 12% 11% 6% 7% 5% 11%	2199
	21st to end	Day	7% 19% 10% 17% 7% 5% 5% 4 6% 4 14%	2669
February	1st to 10th	Day	8% 13% 5% 11% 7% 8% 7% 6% 8% 9% 18%	1680
	11th to 20th	Day	8% 10% 4 11% 7% 8% 7% 5% 7% 7% 25%	1664
	21st to end	Day	6% 12% 5% 13% 7% 7% 7% 5% 6% 6% 26%	1426
March	1st to 10th	Day	9% 12% 4 11% 10% 5% 5% 5% 5% 6% 27%	3277
	11th to 20th	Day	7% 10% 6% 15% 10% 5% 5% 4 5% 6% 26%	3478
	21st to end	Day	9% 16% 5% 10% 6% 4 4 3 5% 6% 32%	3814
April	1st to 10th	Day	11% 12% 4 8% 5% 4 4 4 6% 6% 36%	2306
	11th to 20th	Day	13% 9% 4 7% 5% 5% 5% 3 5% 7% 36%	2442
	21st to end	Day	15% 10% 3 6% 5% 4 5% 3 6% 7% 34%	2470
May	1st to 10th	Day	15% 10% 2 7% 4 4 4 4 5% 7% 38%	4370
	11th to 20th	Day	21% 9% 3 7% 5% 4 4 3 5% 6% 33%	4533
	21st to end	Day	21% 9% 3 8% 4 4 4 3 5% 5% 35%	5173
June	1st to 10th	Day	15% 7% 3 7% 6% 5% 5% 4 5% 8% 35%	2850
	11th to 20th	Day	17% 8% 2 6% 5% 4 5% 4 6% 8% 34%	2850
	21st to end	Day	14% 6% 2 7% 5% 6% 6% 5% 7% 8% 33%	2850
July	1st to 10th	Day	10% 6% 2 6% 5% 5% 6% 5% 7% 10% 39%	4750
	11th to 20th	Day	9% 4 2 5% 4 4 4 4 6% 10% 49%	4750
	21st to end	Day	8% 4 2 5% 4 4 5% 4 7% 9% 47%	5150
August	1st to 10th	Day	9% 6% 2 6% 5% 5% 6% 4 6% 9% 42%	4258
	11th to 20th	Day	11% 5% 2 6% 5% 5% 5% 4 6% 9% 43%	4041
	21st to end	Day	15% 7% 2 6% 4 4 5% 4 5% 8% 40%	4532
September	1st to 10th	Day	12% 5% 2 5% 5% 5% 4 4 6% 7% 45%	2340
	11th to 20th	Day	15% 7% 3 8% 5% 5% 4 5% 7% 8% 34%	2136
	21st to end	Day	17% 8% 3 7% 4 4 3 3 5% 7% 39%	2081
October	1st to 10th	Day	14% 10% 2 6% 5% 5% 4 4 6% 8% 36%	3160
	11th to 20th	Day	12% 11% 3 8% 4 4 4 3 6% 8% 38%	3140
	21st to end	Day	15% 13% 3 9% 6% 5% 4 4 6% 8% 28%	3044
November	1st to 10th	Day	16% 18% 6% 11% 4 5% 4 3 4 5% 23%	1519
	11th to 20th	Day	11% 17% 6% 14% 7% 5% 4 3 6% 6% 21%	1520
	21st to end	Day	12% 16% 6% 14% 10% 5% 4 4 5% 7% 18%	1454
December	1st to 10th	Day	8% 15% 6% 19% 10% 8% 6% 5% 5% 6% 13%	1330
	11th to 20th	Day	10% 14% 6% 15% 7% 5% 6% 5% 6% 7% 19%	1679
	21st to end	Day	11% 14% 4 13% 7% 7% 5% 5% 7% 7% 20%	2442
January	1st to 10th	Night	5% 15% 7% 15% 8% 9% 7% 5% 6% 6% 16%	4737
	11th to 20th	Night	5% 13% 5% 16% 12% 12% 9% 5% 7% 5% 10%	4709
	21st to end	Night	8% 20% 8% 13% 6% 6% 6% 4 6% 5% 16%	4997
February	1st to 10th	Night	8% 13% 5% 10% 7% 7% 6% 5% 6% 8% 26%	2499
	11th to 20th	Night	6% 12% 5% 8% 5% 6% 6% 6% 8% 8% 31%	2403
	21st to end	Night	6% 12% 4 13% 7% 6% 6% 5% 5% 6% 30%	2041
March	1st to 10th	Night	9% 13% 4 11% 8% 5% 6% 4 5% 6% 29%	3586
	11th to 20th	Night	6% 9% 4 9% 6% 5% 4 4 5% 7% 41%	3480
	21st to end	Night	12% 14% 5% 9% 5% 4 3 3 5% 6% 34%	3817
April	1st to 10th	Night	12% 10% 3 6% 5% 5% 5% 4 6% 6% 40%	1872
	11th to 20th	Night	14% 11% 3 8% 4 3 4 4 6% 6% 36%	1689
	21st to end	Night	11% 10% 3 8% 5% 5% 6% 4 5% 7% 36%	1710
May	1st to 10th	Night	18% 9% 3 6% 4 4 4 4 5% 6% 37%	2599
	11th to 20th	Night	18% 8% 2 5% 3 4 4 3 6% 7% 40%	2369
	21st to end	Night	19% 10% 2 5% 3 3 3 3 6% 6% 39%	2414
June	1st to 10th	Night	13% 7% 2 6% 4 4 5% 4 6% 9% 38%	1330
	11th to 20th	Night	15% 7% 2 7% 4 3 4 3 6% 7% 41%	1330
	21st to end	Night	12% 6% 2 5% 5% 5% 5% 4 6% 8% 42%	1330
July	1st to 10th	Night	9% 4 1 5% 4 3 4 4 6% 8% 52%	2220
	11th to 20th	Night	6% 3 1 4 3 3 4 4 7% 10% 54%	2220
	21st to end	Night	6% 3 1 4 4 3 5% 4 7% 10% 53%	2414
August	1st to 10th	Night	7% 4 2 7% 4 4 5% 4 8% 10% 46%	2679
	11th to 20th	Night	10% 4 2 5% 3 4 4 4 6% 9% 50%	2798
	21st to end	Night	11% 6% 2 6% 4 4 4 3 6% 9% 44%	3135
September	1st to 10th	Night	12% 5% 2 5% 4 3 4 3 5% 7% 50%	1839
	11th to 20th	Night	16% 6% 3 6% 4 4 3 4 5% 7% 41%	2042
	21st to end	Night	17% 8% 2 5% 4 3 4 3 5% 7% 41%	2090
October	1st to 10th	Night	16% 8% 2 6% 4 3 4 3 5% 8% 41%	3790
	11th to 20th	Night	12% 12% 3 7% 5% 4 5% 4 5% 8% 37%	3779
	21st to end	Night	12% 13% 4 8% 5% 5% 5% 4 5% 6% 33%	4498
November	1st to 10th	Night	15% 17% 4 11% 6% 5% 4 4 4 5% 25%	2660
	11th to 20th	Night	12% 17% 6% 15% 8% 5% 4 3 3 5% 22%	2660
	21st to end	Night	12% 16% 7% 15% 9% 7% 5% 4 4 4 18%	2724
December	1st to 10th	Night	7% 14% 5% 17% 10% 8% 6% 4 5% 6% 17%	2850
	11th to 20th	Night	9% 16% 6% 14% 7% 5% 5% 5% 6% 6% 20%	3518
	21st to end	Night	8% 12% 6% 13% 9% 7% 6% 5% 6% 5% 22%	5225

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% 11% 13% 3	2219
	11th to 20th	Day	70% 6% 12% 9% 3	2220
	21st to end	Day	70% 5% 9% 12% 4	2669
February	1st to 10th	Day	59% 7% 12% 14% 8% 1	1680
	11th to 20th	Day	53% 6% 13% 20% 8%	1673
	21st to end	Day	56% 7% 12% 15% 10%	1426
March	1st to 10th	Day	54% 7% 13% 20% 5%	3277
	11th to 20th	Day	55% 10% 12% 17% 6%	3480
	21st to end	Day	51% 7% 12% 22% 7% 1	3814
April	1st to 10th	Day	47% 6% 11% 23% 12% 1	2306
	11th to 20th	Day	47% 5% 11% 22% 13% 2	2442
	21st to end	Day	47% 6% 14% 23% 9% 1	2470
May	1st to 10th	Day	43% 8% 11% 26% 11% 1	4370
	11th to 20th	Day	49% 7% 11% 20% 12% 2	4537
	21st to end	Day	49% 7% 10% 23% 10% 1	5173
June	1st to 10th	Day	46% 7% 12% 21% 11% 1	2850
	11th to 20th	Day	46% 8% 15% 20% 11% 1	2850
	21st to end	Day	45% 9% 18% 21% 7%	2850
July	1st to 10th	Day	38% 9% 20% 26% 7%	4676
	11th to 20th	Day	29% 8% 21% 36% 7%	4669
	21st to end	Day	32% 7% 18% 34% 7%	4988
August	1st to 10th	Day	38% 7% 17% 29% 10%	4241
	11th to 20th	Day	35% 7% 24% 28% 6%	4080
	21st to end	Day	41% 7% 21% 26% 4	4531
September	1st to 10th	Day	37% 7% 18% 29% 9% 1	2340
	11th to 20th	Day	46% 8% 20% 22% 4	2136
	21st to end	Day	44% 5% 15% 29% 6%	2081
October	1st to 10th	Day	45% 6% 15% 27% 6%	3160
	11th to 20th	Day	44% 6% 15% 23% 13%	3140
	21st to end	Day	53% 6% 19% 19% 3	3044
November	1st to 10th	Day	64% 7% 12% 12% 4 1	1519
	11th to 20th	Day	64% 8% 12% 12% 3	1520
	21st to end	Day	66% 6% 16% 10% 2	1454
December	1st to 10th	Day	71% 7% 12% 8% 3	1330
	11th to 20th	Day	60% 6% 18% 12% 4	1680
	21st to end	Day	57% 9% 12% 18% 4	2442
January	1st to 10th	Night	66% 6% 12% 12% 3	4737
	11th to 20th	Night	71% 6% 9% 11% 2	4750
	21st to end	Night	67% 6% 12% 11% 3	4997
February	1st to 10th	Night	55% 6% 13% 18% 8% 1	2499
	11th to 20th	Night	46% 7% 17% 21% 8%	2404
	21st to end	Night	53% 6% 12% 18% 10%	2041
March	1st to 10th	Night	54% 7% 11% 18% 10% 1	3586
	11th to 20th	Night	40% 8% 19% 22% 11% 1	3480
	21st to end	Night	50% 7% 10% 23% 10% 1	3817
April	1st to 10th	Night	43% 5% 11% 23% 16% 3	1872
	11th to 20th	Night	47% 6% 9% 21% 16% 3	1689
	21st to end	Night	47% 5% 10% 24% 13% 1	1710
May	1st to 10th	Night	45% 7% 9% 26% 12%	2599
	11th to 20th	Night	42% 6% 13% 28% 8% 2	2369
	21st to end	Night	44% 7% 12% 24% 12% 1	2414
June	1st to 10th	Night	39% 10% 18% 20% 12% 1	1330
	11th to 20th	Night	41% 7% 14% 22% 14% 2	1330
	21st to end	Night	39% 8% 18% 26% 8% 1	1330
July	1st to 10th	Night	30% 8% 20% 33% 9% 1	2185
	11th to 20th	Night	22% 8% 23% 38% 7% 1	2178
	21st to end	Night	26% 7% 23% 35% 8% 1	2337
August	1st to 10th	Night	31% 6% 17% 35% 10%	2672
	11th to 20th	Night	30% 7% 26% 32% 6%	2825
	21st to end	Night	36% 6% 21% 30% 7%	3135
September	1st to 10th	Night	33% 6% 17% 32% 12%	1839
	11th to 20th	Night	42% 7% 17% 24% 8% 1	2042
	21st to end	Night	42% 6% 14% 29% 8% 1	2090
October	1st to 10th	Night	42% 5% 13% 31% 9%	3790
	11th to 20th	Night	45% 6% 16% 25% 8%	3779
	21st to end	Night	51% 6% 15% 23% 4	4498
November	1st to 10th	Night	61% 6% 15% 13% 5% 1	2660
	11th to 20th	Night	66% 6% 13% 11% 4	2660
	21st to end	Night	69% 6% 12% 9% 3	2724
December	1st to 10th	Night	68% 6% 15% 9% 2	2850
	11th to 20th	Night	61% 8% 14% 13% 5%	3516
	21st to end	Night	59% 7% 12% 16% 6%	5225

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% 8% 36% 29% 16% 2	270
	11th to 20th	Day	10% 10% 29% 36% 15% 1	270
	21st to end	Day	15% 8% 31% 30% 14% 2	297
February	1st to 10th	Day	13% 12% 29% 34% 9% 2	270
	11th to 20th	Day	12% 17% 29% 27% 13% 3	270
	21st to end	Day	10% 10% 39% 28% 12% 1	225
March	1st to 10th	Day	11% 10% 33% 31% 14% 1	270
	11th to 20th	Day	9% 16% 26% 32% 13% 3	270
	21st to end	Day	14% 9% 32% 30% 13% 2	297
April	1st to 10th	Day	16% 9% 32% 32% 9% 3	486
	11th to 20th	Day	19% 13% 30% 27% 10% 2	640
	21st to end	Day	17% 11% 33% 26% 11% 2	650
May	1st to 10th	Day	16% 14% 32% 25% 10% 2	653
	11th to 20th	Day	21% 11% 27% 26% 13% 2	675
	21st to end	Day	20% 11% 25% 27% 16% 2	734
June	1st to 10th	Day	16% 13% 30% 24% 14% 4	680
	11th to 20th	Day	17% 11% 35% 24% 11% 2	680
	21st to end	Day	14% 7% 27% 29% 17% 6%	680
July	1st to 10th	Day	11% 8% 29% 27% 17% 7%	671
	11th to 20th	Day	12% 10% 28% 28% 19% 4	668
	21st to end	Day	8% 7% 29% 29% 19% 8%	739
August	1st to 10th	Day	11% 8% 30% 28% 17% 6%	676
	11th to 20th	Day	10% 6% 26% 32% 17% 9%	665
	21st to end	Day	15% 9% 29% 26% 18% 3	748
September	1st to 10th	Day	12% 9% 31% 34% 13% 2	550
	11th to 20th	Day	18% 9% 36% 26% 10% 2	346
	21st to end	Day	21% 8% 38% 25% 7% 1	300
October	1st to 10th	Day	24% 11% 27% 28% 8% 3	300
	11th to 20th	Day	17% 15% 33% 28% 6% 1	300
	21st to end	Day	28% 12% 29% 24% 6% 1	330
November	1st to 10th	Day	24% 9% 31% 27% 8% 1	282
	11th to 20th	Day	17% 8% 44% 23% 7%	270
	21st to end	Day	18% 13% 40% 23% 6%	270
December	1st to 10th	Day	12% 7% 36% 29% 14% 3	270
	11th to 20th	Day	15% 7% 40% 30% 8%	270
	21st to end	Day	13% 7% 31% 32% 12% 5%	297
January	1st to 10th	Night	12% 9% 34% 30% 13% 2	950
	11th to 20th	Night	14% 7% 34% 34% 9% 2	950
	21st to end	Night	14% 7% 35% 32% 10% 1	1045
February	1st to 10th	Night	13% 7% 32% 36% 12% 1	950
	11th to 20th	Night	10% 7% 33% 34% 14% 2	929
	21st to end	Night	10% 8% 36% 31% 13% 2	785
March	1st to 10th	Night	13% 8% 32% 32% 14% 1	677
	11th to 20th	Night	13% 8% 39% 27% 11% 2	570
	21st to end	Night	18% 9% 26% 29% 14% 3	627
April	1st to 10th	Night	15% 7% 28% 39% 9% 2	570
	11th to 20th	Night	17% 7% 28% 34% 13%	563
	21st to end	Night	13% 8% 31% 37% 11%	570
May	1st to 10th	Night	18% 8% 34% 32% 8% 1	570
	11th to 20th	Night	20% 7% 29% 30% 13% 1	561
	21st to end	Night	20% 8% 30% 29% 13%	617
June	1st to 10th	Night	16% 5% 29% 32% 17% 1	570
	11th to 20th	Night	16% 7% 31% 31% 15%	570
	21st to end	Night	14% 6% 22% 38% 18% 2	570
July	1st to 10th	Night	6% 5% 25% 40% 22% 2	555
	11th to 20th	Night	8% 6% 26% 38% 20% 2	552
	21st to end	Night	8% 2 25% 39% 22% 3	624
August	1st to 10th	Night	9% 4 23% 42% 21% 2	567
	11th to 20th	Night	10% 5% 22% 37% 22% 4	564
	21st to end	Night	15% 5% 23% 37% 18% 2	627
September	1st to 10th	Night	15% 4 30% 35% 14% 2	570
	11th to 20th	Night	21% 6% 29% 33% 12%	570
	21st to end	Night	18% 8% 32% 30% 11% 1	570
October	1st to 10th	Night	23% 8% 32% 29% 7%	750
	11th to 20th	Night	22% 9% 32% 28% 8% 1	760
	21st to end	Night	25% 10% 30% 27% 7% 1	1026
November	1st to 10th	Night	21% 10% 34% 24% 9% 1	950
	11th to 20th	Night	19% 10% 35% 26% 8% 2	950
	21st to end	Night	20% 12% 39% 22% 6% 1	950
December	1st to 10th	Night	13% 8% 34% 33% 11% 2	950
	11th to 20th	Night	17% 10% 36% 29% 7% 1	950
	21st to end	Night	16% 9% 28% 31% 14% 1	1045

Page generated at 2024-11-03 01:11:24. Version ac07

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