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 2024-01-14.

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% 4 7% 7% 4 6% 6% 7% 8% 33%	74636
	Night	9% 10% 4 8% 7% 4 6% 6% 6% 8% 32%	75111
Transparency	Day	47% 9% 17% 19% 7%	74305
	Night	48% 8% 16% 20% 8% 1	74960
Seeing	Day	15% 12% 29% 27% 13% 4	15012
	Night	14% 10% 29% 33% 14% 2	23570

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% 12% 6% 12% 8% 5% 5% 6% 6% 7% 27%	1139
	11th to 20th	Day	7% 10% 5% 8% 9% 5% 5% 6% 7% 9% 30%	1219
	21st to end	Day	5% 13% 5% 8% 8% 4 7% 6% 6% 8% 30%	1544
February	1st to 10th	Day	8% 10% 5% 10% 9% 5% 8% 6% 7% 9% 24%	1440
	11th to 20th	Day	5% 11% 6% 10% 6% 4 7% 5% 8% 9% 29%	1440
	21st to end	Day	6% 10% 6% 12% 9% 5% 6% 6% 6% 7% 26%	1448
March	1st to 10th	Day	5% 12% 6% 11% 10% 5% 6% 5% 6% 8% 27%	1800
	11th to 20th	Day	8% 10% 5% 8% 7% 3 6% 5% 5% 9% 32%	1891
	21st to end	Day	10% 16% 6% 7% 6% 3 5% 6% 7% 9% 24%	2294
April	1st to 10th	Day	8% 11% 6% 10% 8% 4 6% 6% 7% 8% 25%	2191
	11th to 20th	Day	10% 13% 4 8% 7% 4 7% 6% 6% 9% 27%	2310
	21st to end	Day	11% 10% 3 8% 7% 4 6% 6% 7% 8% 29%	2417
May	1st to 10th	Day	12% 9% 4 8% 7% 5% 6% 7% 7% 8% 27%	2600
	11th to 20th	Day	11% 6% 2 6% 7% 4 6% 5% 7% 8% 38%	2654
	21st to end	Day	17% 7% 3 7% 6% 4 5% 4 6% 8% 33%	2917
June	1st to 10th	Day	17% 8% 3 7% 7% 3 6% 5% 7% 8% 30%	2852
	11th to 20th	Day	17% 9% 4 8% 7% 5% 6% 6% 7% 8% 24%	2880
	21st to end	Day	10% 5% 3 6% 6% 4 6% 6% 7% 10% 36%	2880
July	1st to 10th	Day	14% 6% 3 6% 5% 4 6% 6% 7% 8% 36%	2880
	11th to 20th	Day	12% 5% 3 6% 7% 4 5% 6% 8% 11% 34%	2827
	21st to end	Day	10% 5% 2 5% 5% 3 6% 7% 9% 9% 40%	2938
August	1st to 10th	Day	11% 6% 2 6% 6% 4 6% 6% 7% 9% 37%	2509
	11th to 20th	Day	8% 5% 3 6% 5% 3 5% 6% 8% 9% 42%	2460
	21st to end	Day	13% 5% 2 5% 7% 4 6% 6% 8% 8% 35%	2574
September	1st to 10th	Day	12% 6% 2 6% 5% 4 6% 6% 6% 8% 38%	2218
	11th to 20th	Day	13% 7% 3 5% 4 3 5% 5% 5% 8% 42%	2039
	21st to end	Day	10% 6% 3 6% 6% 4 4 6% 6% 8% 40%	1980
October	1st to 10th	Day	10% 10% 4 7% 7% 4 5% 5% 6% 7% 36%	1869
	11th to 20th	Day	11% 12% 3 6% 6% 3 4 4 6% 7% 37%	1620
	21st to end	Day	9% 13% 5% 9% 6% 3 5% 4 5% 7% 33%	1782
November	1st to 10th	Day	12% 12% 7% 9% 7% 3 5% 5% 6% 7% 27%	1454
	11th to 20th	Day	8% 12% 5% 9% 6% 4 6% 5% 6% 6% 34%	1330
	21st to end	Day	6% 11% 6% 9% 10% 4 5% 6% 6% 9% 29%	1330
December	1st to 10th	Day	7% 11% 6% 7% 7% 4 6% 6% 6% 9% 31%	1330
	11th to 20th	Day	9% 12% 4 9% 8% 4 6% 7% 5% 8% 27%	1490
	21st to end	Day	5% 9% 3 6% 6% 5% 5% 5% 6% 10% 41%	2090
January	1st to 10th	Night	6% 12% 6% 11% 9% 4 5% 6% 6% 8% 26%	3026
	11th to 20th	Night	6% 11% 5% 9% 8% 5% 6% 7% 8% 9% 27%	2813
	21st to end	Night	6% 14% 5% 8% 7% 3 5% 6% 7% 9% 29%	2826
February	1st to 10th	Night	7% 11% 5% 10% 9% 6% 5% 7% 5% 8% 27%	2520
	11th to 20th	Night	4 11% 5% 11% 8% 4 6% 6% 6% 8% 31%	2406
	21st to end	Night	5% 10% 6% 10% 7% 5% 6% 7% 7% 7% 31%	1807
March	1st to 10th	Night	6% 9% 7% 9% 8% 5% 7% 5% 6% 8% 29%	2160
	11th to 20th	Night	8% 10% 5% 8% 7% 4 6% 6% 7% 8% 30%	2068
	21st to end	Night	9% 17% 5% 8% 7% 4 6% 5% 5% 7% 26%	2059
April	1st to 10th	Night	8% 11% 5% 9% 7% 5% 6% 5% 6% 9% 29%	1769
	11th to 20th	Night	12% 11% 4 7% 6% 4 6% 7% 5% 8% 31%	1601
	21st to end	Night	12% 11% 4 6% 7% 3 5% 7% 6% 8% 31%	1540
May	1st to 10th	Night	13% 9% 5% 8% 7% 4 5% 6% 7% 8% 28%	1358
	11th to 20th	Night	12% 7% 3 6% 7% 4 5% 5% 7% 8% 36%	1239
	21st to end	Night	20% 8% 3 5% 5% 3 6% 5% 6% 7% 32%	1358
June	1st to 10th	Night	17% 8% 4 6% 6% 4 6% 4 5% 7% 33%	1104
	11th to 20th	Night	17% 8% 3 7% 8% 6% 6% 7% 6% 9% 23%	1080
	21st to end	Night	11% 5% 3 7% 8% 5% 8% 6% 6% 8% 33%	1080
July	1st to 10th	Night	14% 6% 3 6% 7% 3 5% 5% 8% 10% 36%	1080
	11th to 20th	Night	12% 6% 3 6% 7% 4 6% 8% 7% 9% 33%	1130
	21st to end	Night	11% 4 2 6% 5% 4 7% 6% 7% 9% 39%	1379
August	1st to 10th	Night	11% 6% 3 6% 5% 3 6% 7% 7% 9% 37%	1427
	11th to 20th	Night	9% 5% 2 5% 5% 4 5% 6% 8% 9% 41%	1438
	21st to end	Night	11% 6% 3 5% 6% 4 6% 6% 6% 9% 38%	1782
September	1st to 10th	Night	12% 6% 3 6% 5% 3 5% 5% 7% 8% 41%	1740
	11th to 20th	Night	14% 6% 3 5% 4 3 4 5% 6% 8% 43%	1921
	21st to end	Night	9% 6% 3 6% 6% 3 4 5% 6% 10% 41%	1980
October	1st to 10th	Night	10% 11% 3 7% 5% 4 6% 5% 6% 7% 36%	2088
	11th to 20th	Night	9% 9% 3 6% 6% 3 4 5% 6% 8% 40%	2340
	21st to end	Night	9% 12% 5% 8% 7% 4 5% 5% 6% 8% 32%	2574
November	1st to 10th	Night	14% 14% 5% 9% 7% 3 4 5% 5% 8% 26%	2605
	11th to 20th	Night	8% 11% 6% 10% 8% 5% 6% 6% 5% 7% 27%	2850
	21st to end	Night	7% 12% 5% 9% 8% 4 6% 6% 6% 8% 29%	2850
December	1st to 10th	Night	7% 10% 5% 8% 7% 5% 5% 5% 6% 8% 33%	2850
	11th to 20th	Night	10% 12% 5% 9% 8% 5% 5% 5% 5% 9% 28%	3697
	21st to end	Night	3 7% 3 8% 7% 4 6% 6% 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% 8% 14% 15% 8% 1	1139
	11th to 20th	Day	50% 9% 14% 16% 9% 2	1219
	21st to end	Day	51% 8% 15% 16% 9%	1544
February	1st to 10th	Day	54% 10% 14% 12% 9% 1	1440
	11th to 20th	Day	50% 9% 16% 19% 6%	1448
	21st to end	Day	55% 6% 13% 18% 7%	1448
March	1st to 10th	Day	55% 7% 16% 16% 7%	1800
	11th to 20th	Day	49% 6% 13% 22% 9% 1	1892
	21st to end	Day	56% 9% 16% 14% 5%	2294
April	1st to 10th	Day	53% 10% 16% 14% 7%	2191
	11th to 20th	Day	52% 7% 15% 18% 8%	2310
	21st to end	Day	50% 9% 13% 20% 7% 1	2417
May	1st to 10th	Day	51% 9% 14% 17% 8% 1	2600
	11th to 20th	Day	41% 8% 14% 25% 11%	2658
	21st to end	Day	49% 7% 15% 18% 10% 1	2918
June	1st to 10th	Day	50% 8% 18% 18% 6%	2852
	11th to 20th	Day	56% 9% 15% 16% 3	2880
	21st to end	Day	41% 11% 21% 21% 5%	2880
July	1st to 10th	Day	42% 11% 18% 23% 6% 1	2801
	11th to 20th	Day	43% 12% 24% 19% 2	2740
	21st to end	Day	35% 14% 26% 22% 3	2775
August	1st to 10th	Day	40% 12% 25% 19% 3	2491
	11th to 20th	Day	36% 10% 24% 24% 6%	2460
	21st to end	Day	43% 10% 23% 19% 6%	2574
September	1st to 10th	Day	41% 10% 20% 23% 5% 1	2218
	11th to 20th	Day	40% 9% 21% 25% 6%	2039
	21st to end	Day	40% 10% 16% 24% 9% 1	1980
October	1st to 10th	Day	45% 8% 19% 20% 7%	1869
	11th to 20th	Day	45% 9% 15% 24% 7%	1620
	21st to end	Day	50% 7% 15% 21% 7%	1782
November	1st to 10th	Day	55% 9% 14% 17% 5%	1454
	11th to 20th	Day	49% 8% 18% 16% 8%	1330
	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	54% 8% 13% 16% 6% 2	3026
	11th to 20th	Night	51% 9% 17% 15% 7% 2	2813
	21st to end	Night	50% 9% 16% 15% 11% 1	2826
February	1st to 10th	Night	54% 8% 14% 16% 8% 1	2520
	11th to 20th	Night	51% 8% 16% 17% 8% 1	2408
	21st to end	Night	49% 8% 14% 19% 9% 1	1807
March	1st to 10th	Night	52% 8% 14% 19% 6% 1	2160
	11th to 20th	Night	49% 8% 12% 20% 11%	2068
	21st to end	Night	56% 8% 13% 17% 6% 1	2059
April	1st to 10th	Night	51% 7% 16% 16% 9% 1	1769
	11th to 20th	Night	51% 7% 13% 19% 9% 2	1601
	21st to end	Night	47% 9% 13% 21% 9% 1	1540
May	1st to 10th	Night	51% 8% 15% 17% 8% 1	1358
	11th to 20th	Night	43% 9% 12% 22% 13%	1239
	21st to end	Night	50% 7% 15% 18% 10% 1	1358
June	1st to 10th	Night	50% 8% 15% 19% 8%	1104
	11th to 20th	Night	56% 10% 15% 18% 1	1080
	21st to end	Night	45% 12% 19% 18% 5% 1	1080
July	1st to 10th	Night	41% 10% 19% 22% 7% 1	1050
	11th to 20th	Night	45% 13% 22% 17% 3	1094
	21st to end	Night	38% 11% 25% 22% 3	1302
August	1st to 10th	Night	41% 12% 22% 22% 3	1420
	11th to 20th	Night	35% 12% 22% 24% 7%	1438
	21st to end	Night	40% 12% 20% 21% 7%	1782
September	1st to 10th	Night	38% 8% 21% 25% 6% 2	1740
	11th to 20th	Night	37% 8% 20% 27% 7% 1	1921
	21st to end	Night	37% 8% 18% 26% 10% 1	1980
October	1st to 10th	Night	47% 7% 14% 23% 8%	2088
	11th to 20th	Night	41% 8% 17% 25% 8%	2340
	21st to end	Night	49% 8% 14% 21% 7% 1	2574
November	1st to 10th	Night	56% 6% 14% 18% 5%	2605
	11th to 20th	Night	55% 9% 12% 16% 7% 1	2850
	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% 11% 32% 29% 11% 3	166
	21st to end	Day	14% 14% 34% 26% 9% 4	176
February	1st to 10th	Day	13% 18% 39% 21% 8% 1	160
	11th to 20th	Day	12% 16% 37% 29% 4 2	178
	21st to end	Day	8% 12% 33% 34% 8% 4	314
March	1st to 10th	Day	11% 18% 30% 30% 11%	420
	11th to 20th	Day	11% 14% 33% 28% 11% 4	420
	21st to end	Day	20% 15% 30% 26% 8% 2	462
April	1st to 10th	Day	16% 17% 36% 21% 6% 2	420
	11th to 20th	Day	16% 16% 29% 23% 12% 5%	412
	21st to end	Day	16% 16% 35% 23% 9% 1	420
May	1st to 10th	Day	16% 19% 28% 23% 12% 3	503
	11th to 20th	Day	11% 10% 32% 27% 17% 4	625
	21st to end	Day	16% 10% 24% 29% 15% 5%	679
June	1st to 10th	Day	18% 12% 31% 25% 12% 2	782
	11th to 20th	Day	21% 10% 27% 25% 14% 3	810
	21st to end	Day	13% 9% 25% 29% 19% 6%	810
July	1st to 10th	Day	16% 8% 25% 30% 16% 5%	796
	11th to 20th	Day	14% 9% 27% 28% 17% 4	739
	21st to end	Day	11% 7% 24% 31% 19% 8%	684
August	1st to 10th	Day	14% 8% 26% 28% 16% 8%	449
	11th to 20th	Day	11% 12% 33% 28% 14% 2	437
	21st to end	Day	16% 12% 26% 27% 16% 3	495
September	1st to 10th	Day	14% 15% 30% 25% 11% 4	450
	11th to 20th	Day	19% 10% 25% 28% 15% 3	450
	21st to end	Day	14% 17% 28% 26% 12% 3	450
October	1st to 10th	Day	18% 14% 23% 26% 16% 3	403
	11th to 20th	Day	20% 10% 32% 23% 13% 3	270
	21st to end	Day	17% 20% 26% 29% 7% 2	297
November	1st to 10th	Day	17% 11% 28% 30% 11% 3	237
	11th to 20th	Day	12% 14% 37% 27% 8% 2	180
	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	11% 14% 33% 31% 10% 1	947
	21st to end	Night	16% 17% 30% 27% 9% 1	846
February	1st to 10th	Night	12% 14% 29% 30% 14% 2	720
	11th to 20th	Night	11% 9% 36% 32% 11% 1	704
	21st to end	Night	9% 6% 33% 37% 13% 3	592
March	1st to 10th	Night	9% 10% 33% 33% 13% 1	720
	11th to 20th	Night	12% 8% 33% 34% 11% 2	720
	21st to end	Night	17% 9% 27% 33% 12% 2	792
April	1st to 10th	Night	13% 9% 31% 34% 11% 1	689
	11th to 20th	Night	17% 8% 31% 30% 13% 1	533
	21st to end	Night	15% 12% 27% 33% 12% 1	460
May	1st to 10th	Night	18% 13% 23% 32% 13% 2	360
	11th to 20th	Night	13% 7% 28% 32% 18% 1	354
	21st to end	Night	22% 7% 21% 31% 17% 2	389
June	1st to 10th	Night	19% 9% 24% 29% 18% 1	360
	11th to 20th	Night	19% 5% 24% 28% 22% 2	360
	21st to end	Night	12% 4 22% 34% 26% 3	360
July	1st to 10th	Night	16% 3 19% 38% 24%	350
	11th to 20th	Night	15% 5% 22% 34% 22% 2	348
	21st to end	Night	11% 5% 18% 41% 22% 3	394
August	1st to 10th	Night	13% 3 21% 28% 29% 5%	358
	11th to 20th	Night	12% 3 22% 36% 25% 1	370
	21st to end	Night	14% 4 22% 38% 21% 1	594
September	1st to 10th	Night	16% 5% 22% 37% 18% 2	660
	11th to 20th	Night	17% 6% 21% 38% 18% 1	720
	21st to end	Night	11% 9% 29% 33% 16% 2	720
October	1st to 10th	Night	17% 8% 28% 32% 15% 1	720
	11th to 20th	Night	14% 9% 27% 34% 15% 1	720
	21st to end	Night	15% 13% 31% 30% 9% 1	792
November	1st to 10th	Night	20% 10% 28% 30% 11% 1	869
	11th to 20th	Night	14% 14% 35% 28% 8% 1	950
	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 2024-01-11 02:22:42. Version ac07

Copyright 2024 Attilla Danko