Whitecourt
Clear Sky Chart
History

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

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	10% 9% 3 9% 6% 5% 5% 4 7% 8% 34%	105921
	Night	9% 10% 4 9% 6% 5% 5% 5% 6% 8% 33%	101801
Transparency	Day	45% 9% 17% 21% 8%	105653
	Night	47% 8% 16% 20% 8% 1	101715
Seeing	Day	15% 12% 29% 27% 13% 4	16241
	Night	14% 10% 29% 33% 14% 1	24534

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	4 15% 6% 13% 9% 5% 6% 6% 7% 7% 22%	1899
	11th to 20th	Day	5% 10% 4 8% 6% 6% 5% 7% 8% 9% 33%	2084
	21st to end	Day	5% 11% 3 9% 6% 5% 5% 5% 6% 9% 34%	2712
February	1st to 10th	Day	7% 11% 5% 12% 7% 7% 7% 4 8% 9% 24%	1520
	11th to 20th	Day	4 12% 6% 10% 6% 6% 6% 4 8% 8% 30%	1522
	21st to end	Day	5% 12% 5% 14% 8% 7% 5% 4 7% 7% 26%	1536
March	1st to 10th	Day	3 10% 6% 14% 8% 7% 5% 4 7% 10% 26%	3138
	11th to 20th	Day	6% 11% 4 8% 5% 5% 5% 4 6% 8% 40%	3349
	21st to end	Day	7% 15% 7% 17% 6% 5% 5% 4 5% 7% 23%	4031
April	1st to 10th	Day	8% 14% 4 11% 7% 5% 6% 4 7% 8% 26%	2313
	11th to 20th	Day	9% 13% 3 9% 6% 6% 6% 5% 7% 8% 28%	2440
	21st to end	Day	10% 11% 3 10% 6% 6% 6% 5% 8% 7% 29%	2552
May	1st to 10th	Day	14% 10% 3 8% 5% 5% 5% 5% 6% 7% 31%	4570
	11th to 20th	Day	10% 10% 4 9% 7% 6% 6% 5% 7% 7% 29%	4694
	21st to end	Day	12% 8% 3 11% 7% 7% 6% 5% 7% 8% 25%	5161
June	1st to 10th	Day	17% 8% 3 8% 6% 4 5% 5% 7% 7% 30%	3011
	11th to 20th	Day	16% 10% 3 9% 6% 6% 6% 5% 7% 8% 24%	3040
	21st to end	Day	10% 6% 3 7% 5% 6% 6% 5% 8% 10% 35%	3040
July	1st to 10th	Day	9% 5% 2 5% 4 4 5% 4 7% 8% 47%	5060
	11th to 20th	Day	8% 4 2 6% 5% 4 4 4 7% 10% 46%	4965
	21st to end	Day	12% 6% 2 5% 4 4 5% 4 8% 9% 40%	5138
August	1st to 10th	Day	14% 6% 2 6% 4 4 5% 3 6% 8% 43%	4403
	11th to 20th	Day	11% 6% 2 7% 4 4 5% 4 7% 9% 41%	4302
	21st to end	Day	13% 5% 2 6% 5% 5% 6% 5% 7% 9% 37%	4521
September	1st to 10th	Day	12% 6% 2 7% 4 5% 5% 5% 6% 8% 40%	2341
	11th to 20th	Day	13% 7% 3 6% 4 5% 5% 4 6% 8% 41%	2152
	21st to end	Day	10% 7% 2 7% 5% 5% 5% 5% 6% 8% 39%	2090
October	1st to 10th	Day	10% 9% 4 7% 4 5% 5% 4 7% 8% 38%	3285
	11th to 20th	Day	12% 12% 4 9% 5% 4 4 3 6% 7% 32%	2842
	21st to end	Day	6% 13% 5% 11% 6% 5% 5% 3 5% 7% 34%	3101
November	1st to 10th	Day	11% 14% 5% 11% 6% 4 5% 4 7% 7% 27%	1532
	11th to 20th	Day	7% 13% 4 10% 5% 5% 6% 4 5% 5% 34%	1337
	21st to end	Day	6% 12% 5% 10% 9% 5% 5% 5% 6% 9% 29%	1330
December	1st to 10th	Day	6% 13% 4 8% 7% 5% 6% 5% 6% 9% 31%	1330
	11th to 20th	Day	9% 12% 4 10% 7% 5% 6% 6% 6% 8% 27%	1490
	21st to end	Day	5% 9% 3 7% 5% 6% 4 3 6% 10% 41%	2090
January	1st to 10th	Night	4 12% 6% 15% 8% 5% 6% 4 6% 7% 27%	5046
	11th to 20th	Night	4 11% 4 9% 6% 7% 7% 7% 9% 8% 29%	4799
	21st to end	Night	7% 13% 4 9% 6% 5% 5% 4 7% 9% 30%	4958
February	1st to 10th	Night	6% 13% 5% 11% 8% 7% 6% 5% 5% 8% 26%	2660
	11th to 20th	Night	4 12% 5% 12% 7% 5% 6% 5% 6% 7% 32%	2544
	21st to end	Night	4 11% 5% 11% 6% 6% 6% 6% 7% 7% 30%	1917
March	1st to 10th	Night	3 7% 5% 14% 8% 8% 6% 5% 7% 9% 28%	3736
	11th to 20th	Night	6% 10% 3 7% 5% 6% 5% 4 7% 10% 37%	3630
	21st to end	Night	8% 18% 6% 16% 6% 4 4 3 5% 5% 24%	3619
April	1st to 10th	Night	8% 13% 4 10% 6% 6% 6% 4 7% 9% 29%	1867
	11th to 20th	Night	11% 12% 4 8% 6% 5% 6% 5% 6% 7% 30%	1691
	21st to end	Night	11% 12% 3 7% 6% 5% 5% 5% 7% 8% 30%	1625
May	1st to 10th	Night	16% 11% 5% 9% 5% 5% 4 4 5% 6% 30%	2388
	11th to 20th	Night	10% 9% 4 10% 7% 7% 6% 5% 7% 8% 27%	2199
	21st to end	Night	18% 8% 4 7% 5% 5% 6% 4 7% 9% 28%	2414
June	1st to 10th	Night	18% 8% 3 7% 5% 6% 5% 3 5% 7% 32%	1165
	11th to 20th	Night	17% 8% 3 7% 8% 7% 6% 6% 6% 8% 23%	1140
	21st to end	Night	11% 5% 2 8% 7% 6% 7% 5% 6% 8% 33%	1140
July	1st to 10th	Night	9% 5% 2 5% 4 4 5% 4 6% 8% 48%	1900
	11th to 20th	Night	9% 5% 2 7% 5% 5% 7% 6% 7% 10% 37%	1992
	21st to end	Night	13% 5% 2 6% 5% 5% 5% 5% 7% 9% 38%	2414
August	1st to 10th	Night	14% 6% 2 6% 4 4 5% 5% 6% 7% 42%	2524
	11th to 20th	Night	16% 6% 3 7% 5% 4 5% 4 7% 8% 35%	2525
	21st to end	Night	12% 6% 2 7% 5% 5% 5% 5% 7% 8% 39%	3146
September	1st to 10th	Night	11% 5% 3 7% 4 4 5% 4 7% 8% 42%	1837
	11th to 20th	Night	14% 6% 3 5% 3 3 4 4 6% 9% 43%	2028
	21st to end	Night	9% 6% 2 8% 5% 4 4 4 6% 10% 40%	2090
October	1st to 10th	Night	9% 9% 3 9% 6% 6% 7% 5% 7% 8% 32%	3689
	11th to 20th	Night	9% 10% 3 8% 5% 4 5% 4 7% 9% 37%	4086
	21st to end	Night	7% 9% 4 9% 5% 6% 5% 5% 7% 9% 33%	4457
November	1st to 10th	Night	13% 15% 5% 10% 6% 5% 4 4 6% 8% 26%	2746
	11th to 20th	Night	7% 13% 5% 11% 7% 7% 6% 5% 6% 6% 27%	2866
	21st to end	Night	6% 13% 4 10% 7% 5% 6% 5% 7% 8% 28%	2850
December	1st to 10th	Night	7% 12% 4 9% 7% 6% 5% 4 6% 8% 33%	2850
	11th to 20th	Night	9% 12% 4 10% 7% 7% 5% 4 6% 9% 28%	3697
	21st to end	Night	3 7% 3 8% 6% 5% 6% 5% 7% 8% 42%	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	55% 9% 15% 14% 6% 1	1899
	11th to 20th	Day	44% 8% 12% 13% 21% 2	2105
	21st to end	Day	44% 8% 24% 16% 7%	2712
February	1st to 10th	Day	55% 10% 14% 12% 9% 1	1520
	11th to 20th	Day	49% 9% 15% 19% 8%	1530
	21st to end	Day	54% 6% 13% 18% 8%	1536
March	1st to 10th	Day	51% 7% 16% 19% 7%	3138
	11th to 20th	Day	41% 7% 17% 23% 12% 1	3350
	21st to end	Day	60% 8% 14% 14% 5%	4031
April	1st to 10th	Day	53% 10% 15% 15% 7%	2313
	11th to 20th	Day	50% 7% 14% 19% 9%	2440
	21st to end	Day	50% 10% 13% 20% 7% 1	2552
May	1st to 10th	Day	48% 8% 12% 21% 10%	4570
	11th to 20th	Day	49% 9% 12% 22% 8%	4698
	21st to end	Day	52% 10% 15% 14% 9% 1	5162
June	1st to 10th	Day	50% 8% 17% 17% 7% 1	3011
	11th to 20th	Day	56% 9% 15% 17% 4	3040
	21st to end	Day	41% 11% 20% 21% 6%	3040
July	1st to 10th	Day	32% 8% 16% 30% 14% 1	4981
	11th to 20th	Day	32% 8% 17% 32% 10%	4878
	21st to end	Day	37% 10% 21% 23% 8%	4976
August	1st to 10th	Day	38% 10% 20% 31% 2	4385
	11th to 20th	Day	37% 9% 20% 24% 10%	4344
	21st to end	Day	41% 8% 26% 20% 4	4520
September	1st to 10th	Day	39% 10% 20% 25% 5% 1	2341
	11th to 20th	Day	40% 8% 21% 25% 6%	2152
	21st to end	Day	41% 9% 16% 24% 9% 1	2090
October	1st to 10th	Day	41% 8% 26% 20% 4	3285
	11th to 20th	Day	49% 7% 15% 24% 6%	2842
	21st to end	Day	49% 6% 18% 23% 4	3101
November	1st to 10th	Day	55% 8% 15% 17% 5%	1532
	11th to 20th	Day	50% 8% 18% 16% 8%	1337
	21st to end	Day	50% 10% 17% 15% 6% 2	1330
December	1st to 10th	Day	49% 9% 14% 18% 9% 1	1330
	11th to 20th	Day	51% 9% 16% 16% 8%	1492
	21st to end	Day	38% 8% 14% 22% 17% 1	2090
January	1st to 10th	Night	52% 9% 13% 18% 7% 1	5046
	11th to 20th	Night	48% 7% 13% 11% 17% 4	4840
	21st to end	Night	48% 10% 20% 14% 8%	4958
February	1st to 10th	Night	54% 7% 14% 16% 8% 1	2660
	11th to 20th	Night	50% 8% 15% 18% 9% 1	2546
	21st to end	Night	49% 8% 14% 19% 9% 1	1917
March	1st to 10th	Night	49% 8% 17% 19% 6%	3736
	11th to 20th	Night	40% 8% 20% 19% 12%	3630
	21st to end	Night	60% 7% 10% 18% 5%	3619
April	1st to 10th	Night	50% 7% 16% 17% 9% 1	1867
	11th to 20th	Night	51% 6% 13% 19% 10% 2	1691
	21st to end	Night	47% 9% 13% 21% 9% 1	1625
May	1st to 10th	Night	53% 7% 11% 19% 11%	2388
	11th to 20th	Night	47% 12% 13% 20% 8%	2199
	21st to end	Night	47% 12% 18% 13% 9%	2414
June	1st to 10th	Night	50% 8% 14% 18% 9%	1165
	11th to 20th	Night	55% 9% 15% 18% 1	1140
	21st to end	Night	46% 12% 18% 18% 6% 1	1140
July	1st to 10th	Night	33% 8% 14% 31% 13% 1	1870
	11th to 20th	Night	40% 10% 17% 26% 8%	1956
	21st to end	Night	40% 9% 20% 23% 7%	2337
August	1st to 10th	Night	39% 10% 21% 28% 2	2517
	11th to 20th	Night	43% 9% 16% 20% 12%	2549
	21st to end	Night	40% 10% 25% 21% 4	3146
September	1st to 10th	Night	37% 8% 20% 26% 6% 2	1837
	11th to 20th	Night	36% 8% 21% 27% 7% 1	2028
	21st to end	Night	38% 8% 18% 25% 10% 1	2090
October	1st to 10th	Night	47% 8% 21% 18% 6%	3689
	11th to 20th	Night	43% 7% 16% 27% 7%	4086
	21st to end	Night	44% 8% 21% 21% 5%	4457
November	1st to 10th	Night	56% 6% 14% 18% 5%	2746
	11th to 20th	Night	56% 9% 12% 16% 7% 1	2866
	21st to end	Night	51% 10% 16% 17% 5% 2	2850
December	1st to 10th	Night	50% 6% 13% 20% 10% 1	2850
	11th to 20th	Night	53% 7% 17% 18% 5%	3694
	21st to end	Night	37% 8% 15% 27% 10% 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	11% 13% 29% 33% 11% 4	180
	11th to 20th	Day	13% 12% 32% 28% 13% 2	180
	21st to end	Day	15% 13% 32% 27% 10% 4	198
February	1st to 10th	Day	14% 17% 37% 23% 8% 1	180
	11th to 20th	Day	11% 15% 35% 30% 8% 2	200
	21st to end	Day	10% 13% 35% 31% 7% 3	348
March	1st to 10th	Day	10% 17% 29% 32% 11%	460
	11th to 20th	Day	10% 16% 31% 28% 11% 3	460
	21st to end	Day	19% 15% 30% 27% 8% 2	506
April	1st to 10th	Day	18% 17% 37% 20% 6% 2	460
	11th to 20th	Day	15% 17% 29% 24% 12% 4	452
	21st to end	Day	16% 16% 35% 24% 9% 1	460
May	1st to 10th	Day	16% 18% 28% 23% 12% 3	548
	11th to 20th	Day	12% 10% 32% 27% 16% 4	675
	21st to end	Day	16% 10% 25% 29% 15% 5%	734
June	1st to 10th	Day	19% 13% 31% 24% 12% 2	841
	11th to 20th	Day	21% 10% 27% 24% 14% 3	870
	21st to end	Day	13% 9% 23% 29% 19% 6%	870
July	1st to 10th	Day	15% 7% 25% 32% 16% 5%	856
	11th to 20th	Day	13% 9% 27% 28% 18% 5%	796
	21st to end	Day	13% 7% 23% 31% 18% 8%	739
August	1st to 10th	Day	14% 8% 25% 28% 18% 7%	489
	11th to 20th	Day	11% 12% 32% 29% 14% 3	477
	21st to end	Day	16% 12% 26% 27% 16% 3	539
September	1st to 10th	Day	14% 14% 29% 24% 14% 5%	490
	11th to 20th	Day	19% 10% 25% 29% 14% 3	490
	21st to end	Day	14% 17% 29% 25% 11% 3	490
October	1st to 10th	Day	18% 13% 25% 26% 15% 3	440
	11th to 20th	Day	20% 10% 31% 25% 12% 2	300
	21st to end	Day	17% 20% 26% 28% 7% 2	330
November	1st to 10th	Day	17% 11% 28% 30% 11% 3	263
	11th to 20th	Day	12% 14% 37% 27% 8% 2	182
	21st to end	Day	9% 11% 39% 31% 5% 5%	180
December	1st to 10th	Day	12% 10% 29% 38% 8% 3	180
	11th to 20th	Day	12% 19% 29% 30% 8% 2	180
	21st to end	Day	13% 8% 29% 32% 13% 5%	198
January	1st to 10th	Night	12% 12% 32% 31% 11% 2	1040
	11th to 20th	Night	10% 14% 33% 32% 10% 1	979
	21st to end	Night	16% 16% 30% 28% 9% 1	893
February	1st to 10th	Night	12% 14% 28% 31% 14% 1	760
	11th to 20th	Night	10% 9% 35% 33% 12% 1	744
	21st to end	Night	9% 7% 32% 37% 12% 3	628
March	1st to 10th	Night	8% 11% 33% 33% 13% 1	760
	11th to 20th	Night	12% 8% 33% 34% 11% 2	760
	21st to end	Night	16% 9% 28% 33% 12% 1	836
April	1st to 10th	Night	13% 9% 30% 34% 11% 1	727
	11th to 20th	Night	16% 9% 30% 31% 13% 1	563
	21st to end	Night	14% 12% 27% 33% 13% 1	485
May	1st to 10th	Night	18% 13% 22% 32% 12% 2	380
	11th to 20th	Night	12% 9% 29% 32% 17% 1	374
	21st to end	Night	20% 8% 22% 30% 18% 2	411
June	1st to 10th	Night	19% 11% 24% 28% 17% 1	380
	11th to 20th	Night	19% 5% 24% 27% 22% 2	380
	21st to end	Night	13% 4 21% 34% 25% 2	380
July	1st to 10th	Night	16% 3 18% 37% 25%	370
	11th to 20th	Night	15% 5% 21% 34% 23% 2	368
	21st to end	Night	12% 5% 18% 39% 22% 3	416
August	1st to 10th	Night	13% 3 21% 29% 28% 5%	378
	11th to 20th	Night	13% 3 23% 35% 26% 1	391
	21st to end	Night	14% 4 23% 38% 20% 1	627
September	1st to 10th	Night	15% 5% 22% 37% 19% 2	697
	11th to 20th	Night	16% 6% 20% 38% 18% 1	760
	21st to end	Night	11% 9% 30% 33% 15% 2	760
October	1st to 10th	Night	17% 8% 28% 32% 14% 1	760
	11th to 20th	Night	13% 10% 28% 34% 14% 1	760
	21st to end	Night	15% 13% 32% 30% 9% 1	836
November	1st to 10th	Night	20% 10% 29% 30% 11% 1	916
	11th to 20th	Night	13% 14% 35% 29% 8% 1	956
	21st to end	Night	12% 11% 35% 32% 8% 1	950
December	1st to 10th	Night	12% 13% 32% 31% 10% 1	950
	11th to 20th	Night	12% 14% 31% 32% 10% 2	1015
	21st to end	Night	9% 9% 33% 35% 12% 2	1144

Page generated at 2024-11-08 20:45:34. Version ac07

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