Wapiticrossing Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wapiticrossing Ranch 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% 14% 5% 8% 6% 3 5% 4 5% 6% 34%	74589
	Night	8% 13% 5% 8% 7% 4 5% 5% 5% 6% 34%	75172
Transparency	Day	50% 5% 12% 19% 11% 2	74287
	Night	50% 6% 14% 19% 10% 2	74991
Seeing	Day	19% 17% 27% 22% 12% 3	13908
	Night	15% 11% 22% 30% 18% 2	23279

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% 27% 12% 13% 8% 4 5% 4 4 5% 13%	1462
	11th to 20th	Day	8% 24% 9% 13% 5% 4 4 4 3 6% 20%	1464
	21st to end	Day	7% 24% 9% 10% 7% 4 7% 4 4 5% 20%	1584
February	1st to 10th	Day	8% 26% 10% 13% 6% 3 4 4 4 4 17%	1466
	11th to 20th	Day	7% 28% 8% 12% 7% 3 4 3 4 5% 17%	1671
	21st to end	Day	8% 25% 11% 14% 8% 3 3 4 4 4 17%	1480
March	1st to 10th	Day	9% 22% 7% 13% 9% 4 5% 3 4 6% 19%	1800
	11th to 20th	Day	9% 22% 7% 8% 8% 5% 5% 5% 5% 5% 20%	1917
	21st to end	Day	12% 28% 7% 11% 8% 4 6% 4 4 4 13%	2254
April	1st to 10th	Day	12% 23% 8% 10% 7% 4 5% 5% 5% 5% 17%	2160
	11th to 20th	Day	12% 20% 6% 9% 7% 4 5% 4 4 5% 24%	2261
	21st to end	Day	14% 18% 4 8% 6% 4 6% 4 4 6% 25%	2340
May	1st to 10th	Day	11% 14% 4 8% 7% 4 5% 5% 5% 7% 31%	2352
	11th to 20th	Day	14% 11% 4 6% 7% 4 6% 6% 7% 8% 28%	2477
	21st to end	Day	19% 11% 4 8% 7% 4 5% 6% 5% 6% 25%	2873
June	1st to 10th	Day	20% 9% 4 7% 7% 4 5% 5% 4 7% 27%	2700
	11th to 20th	Day	19% 9% 4 8% 7% 4 6% 5% 7% 6% 26%	2700
	21st to end	Day	8% 5% 2 6% 5% 3 4 5% 5% 7% 50%	2700
July	1st to 10th	Day	4 3 1 3 4 3 4 5% 6% 6% 62%	2692
	11th to 20th	Day	4 3 1 3 3 2 3 4 4 5% 68%	2520
	21st to end	Day	2 2 1 2 2 2 3 2 4 6% 73%	2741
August	1st to 10th	Day	4 3 1 4 3 2 4 5% 5% 6% 64%	2490
	11th to 20th	Day	6% 4 1 3 3 2 3 3 4 7% 63%	2299
	21st to end	Day	6% 3 2 4 4 3 5% 5% 5% 7% 56%	2525
September	1st to 10th	Day	6% 4 2 5% 4 2 3 5% 5% 7% 57%	2160
	11th to 20th	Day	9% 7% 3 5% 5% 4 5% 4 6% 7% 45%	1990
	21st to end	Day	10% 7% 3 6% 5% 3 4 5% 5% 9% 42%	1980
October	1st to 10th	Day	12% 11% 3 8% 6% 4 4 4 4 6% 39%	1980
	11th to 20th	Day	12% 13% 4 7% 6% 3 5% 4 4 6% 35%	1657
	21st to end	Day	14% 16% 4 8% 7% 4 6% 5% 4 6% 27%	1782
November	1st to 10th	Day	16% 24% 5% 7% 6% 3 4 3 5% 6% 19%	1674
	11th to 20th	Day	9% 25% 8% 10% 6% 3 5% 3 5% 6% 19%	1634
	21st to end	Day	6% 21% 10% 10% 7% 5% 5% 4 5% 6% 20%	1350
December	1st to 10th	Day	7% 20% 10% 12% 7% 4 5% 5% 5% 6% 20%	1330
	11th to 20th	Day	9% 22% 12% 13% 9% 4 5% 4 4 6% 13%	1682
	21st to end	Day	5% 18% 9% 14% 9% 4 5% 5% 5% 7% 20%	2442
January	1st to 10th	Night	6% 23% 11% 13% 9% 4 6% 4 5% 5% 14%	2720
	11th to 20th	Night	8% 20% 8% 12% 8% 3 5% 4 4 5% 22%	2568
	21st to end	Night	6% 18% 7% 13% 9% 5% 6% 5% 5% 7% 19%	2772
February	1st to 10th	Night	9% 24% 9% 12% 7% 3 5% 3 4 5% 19%	2493
	11th to 20th	Night	7% 22% 8% 11% 6% 3 5% 4 4 6% 24%	2174
	21st to end	Night	6% 17% 9% 13% 10% 5% 5% 5% 4 4 21%	1776
March	1st to 10th	Night	7% 16% 6% 11% 7% 5% 6% 5% 5% 7% 26%	2160
	11th to 20th	Night	7% 14% 4 8% 8% 5% 6% 6% 6% 6% 28%	2041
	21st to end	Night	9% 16% 6% 9% 7% 5% 5% 6% 5% 7% 24%	2102
April	1st to 10th	Night	7% 13% 5% 8% 7% 4 6% 6% 7% 8% 28%	1800
	11th to 20th	Night	8% 14% 4 8% 8% 5% 7% 4 4 6% 32%	1648
	21st to end	Night	8% 11% 3 7% 6% 4 6% 6% 6% 7% 35%	1620
May	1st to 10th	Night	8% 11% 3 6% 5% 3 7% 4 6% 8% 40%	1605
	11th to 20th	Night	8% 7% 3 5% 6% 3 6% 6% 7% 8% 41%	1416
	21st to end	Night	15% 9% 3 6% 6% 4 5% 5% 5% 7% 33%	1402
June	1st to 10th	Night	13% 9% 4 8% 5% 3 5% 5% 7% 6% 35%	1260
	11th to 20th	Night	14% 7% 3 5% 6% 3 5% 5% 6% 7% 40%	1260
	21st to end	Night	6% 4 2 4 4 3 5% 5% 7% 6% 54%	1260
July	1st to 10th	Night	2 2 1 3 2 1 3 3 5% 8% 70%	1264
	11th to 20th	Night	3 1 1 2 3 1 3 4 4 6% 73%	1440
	21st to end	Night	2 1 1 2 3 1 3 4 4 6% 73%	1576
August	1st to 10th	Night	4 2 1 2 2 1 3 4 4 7% 69%	1449
	11th to 20th	Night	4 2 2 3 2 3 4 5% 8% 67%	1602
	21st to end	Night	5% 4 1 3 3 2 5% 4 4 7% 61%	1828
September	1st to 10th	Night	5% 3 1 3 4 2 4 3 5% 7% 61%	1800
	11th to 20th	Night	7% 6% 2 4 5% 3 5% 5% 5% 7% 53%	1970
	21st to end	Night	10% 7% 2 4 5% 3 3 3 5% 7% 50%	1980
October	1st to 10th	Night	8% 8% 3 6% 6% 3 5% 4 6% 7% 44%	1980
	11th to 20th	Night	12% 11% 3 6% 5% 4 4 4 4 6% 41%	2302
	21st to end	Night	12% 15% 4 8% 6% 3 4 4 5% 6% 34%	2574
November	1st to 10th	Night	13% 18% 6% 8% 7% 4 5% 5% 4 7% 23%	2405
	11th to 20th	Night	10% 20% 7% 10% 7% 3 4 4 5% 6% 24%	2525
	21st to end	Night	6% 16% 8% 9% 8% 5% 7% 4 4 7% 24%	2826
December	1st to 10th	Night	6% 18% 8% 12% 9% 4 5% 6% 5% 7% 21%	2850
	11th to 20th	Night	7% 20% 9% 14% 9% 4 5% 5% 5% 5% 16%	3510
	21st to end	Night	5% 18% 9% 13% 9% 5% 6% 5% 6% 6% 19%	5214

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	75% 6% 9% 8% 2	1462
	11th to 20th	Day	68% 6% 11% 10% 3 2	1464
	21st to end	Day	67% 5% 11% 12% 4 1	1584
February	1st to 10th	Day	72% 4 10% 10% 3 1	1466
	11th to 20th	Day	68% 7% 12% 9% 4	1680
	21st to end	Day	72% 5% 6% 12% 5% 1	1480
March	1st to 10th	Day	67% 6% 12% 11% 4	1800
	11th to 20th	Day	65% 6% 11% 16% 2	1918
	21st to end	Day	73% 5% 11% 9% 2	2254
April	1st to 10th	Day	68% 5% 13% 12% 2	2160
	11th to 20th	Day	62% 5% 11% 16% 6% 1	2261
	21st to end	Day	61% 6% 11% 17% 5% 1	2340
May	1st to 10th	Day	53% 5% 14% 22% 5%	2352
	11th to 20th	Day	50% 8% 17% 17% 7%	2480
	21st to end	Day	58% 7% 14% 17% 4	2874
June	1st to 10th	Day	56% 7% 13% 19% 5%	2700
	11th to 20th	Day	56% 6% 13% 18% 6% 2	2700
	21st to end	Day	33% 5% 16% 29% 16% 1	2700
July	1st to 10th	Day	22% 5% 10% 28% 27% 9%	2618
	11th to 20th	Day	19% 5% 9% 24% 32% 11%	2445
	21st to end	Day	14% 3 5% 25% 43% 11%	2589
August	1st to 10th	Day	20% 4 9% 32% 26% 9%	2473
	11th to 20th	Day	22% 4 10% 32% 27% 5%	2299
	21st to end	Day	26% 5% 11% 31% 22% 4	2525
September	1st to 10th	Day	27% 4 12% 31% 19% 8%	2160
	11th to 20th	Day	37% 4 12% 27% 17% 3	1990
	21st to end	Day	38% 7% 17% 24% 11% 2	1980
October	1st to 10th	Day	47% 4 13% 29% 7%	1980
	11th to 20th	Day	50% 5% 14% 24% 7% 1	1657
	21st to end	Day	58% 6% 13% 17% 6%	1782
November	1st to 10th	Day	65% 7% 12% 13% 3	1674
	11th to 20th	Day	66% 6% 14% 10% 4	1634
	21st to end	Day	64% 6% 14% 12% 5%	1350
December	1st to 10th	Day	64% 8% 12% 13% 2 1	1330
	11th to 20th	Day	73% 5% 12% 9% 1	1684
	21st to end	Day	64% 3 17% 11% 4 1	2442
January	1st to 10th	Night	72% 6% 11% 9% 2	2720
	11th to 20th	Night	65% 5% 12% 13% 3 2	2568
	21st to end	Night	63% 7% 12% 12% 5% 1	2772
February	1st to 10th	Night	68% 5% 11% 11% 4 1	2493
	11th to 20th	Night	63% 6% 14% 12% 5%	2175
	21st to end	Night	64% 6% 10% 14% 5% 1	1776
March	1st to 10th	Night	56% 7% 16% 15% 7%	2160
	11th to 20th	Night	53% 8% 16% 19% 5%	2041
	21st to end	Night	58% 8% 16% 14% 4	2102
April	1st to 10th	Night	49% 8% 18% 20% 4	1800
	11th to 20th	Night	51% 6% 14% 20% 7% 1	1648
	21st to end	Night	45% 7% 16% 23% 8%	1620
May	1st to 10th	Night	42% 5% 14% 28% 10%	1605
	11th to 20th	Night	37% 8% 19% 26% 10%	1416
	21st to end	Night	49% 6% 18% 21% 6%	1402
June	1st to 10th	Night	47% 6% 15% 24% 8%	1260
	11th to 20th	Night	42% 5% 17% 23% 11% 1	1260
	21st to end	Night	28% 7% 15% 31% 18% 2	1260
July	1st to 10th	Night	13% 4 8% 34% 26% 14%	1229
	11th to 20th	Night	13% 3 9% 28% 32% 15%	1392
	21st to end	Night	12% 3 5% 20% 42% 18%	1488
August	1st to 10th	Night	15% 3 10% 27% 34% 11%	1441
	11th to 20th	Night	16% 4 10% 33% 30% 7%	1602
	21st to end	Night	22% 5% 9% 31% 27% 6%	1828
September	1st to 10th	Night	22% 5% 11% 31% 22% 10%	1800
	11th to 20th	Night	30% 5% 11% 30% 20% 4	1970
	21st to end	Night	34% 5% 16% 28% 13% 4	1980
October	1st to 10th	Night	38% 6% 16% 29% 10%	1980
	11th to 20th	Night	45% 4 16% 23% 11% 1	2302
	21st to end	Night	50% 6% 14% 19% 9% 1	2574
November	1st to 10th	Night	60% 7% 14% 14% 3 1	2405
	11th to 20th	Night	61% 6% 16% 12% 4 1	2525
	21st to end	Night	58% 6% 15% 15% 6%	2826
December	1st to 10th	Night	63% 8% 12% 13% 4 1	2850
	11th to 20th	Night	69% 6% 13% 9% 2	3507
	21st to end	Night	64% 3 18% 9% 5%	5214

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	19% 21% 26% 21% 11% 2	180
	11th to 20th	Day	24% 18% 28% 12% 14% 4	166
	21st to end	Day	24% 24% 22% 22% 5% 2	176
February	1st to 10th	Day	29% 31% 25% 11% 3 1	172
	11th to 20th	Day	26% 24% 28% 15% 6%	336
	21st to end	Day	27% 19% 31% 17% 5% 1	346
March	1st to 10th	Day	27% 25% 25% 15% 7% 1	420
	11th to 20th	Day	26% 18% 26% 17% 11% 2	420
	21st to end	Day	33% 22% 26% 13% 5% 1	462
April	1st to 10th	Day	27% 22% 28% 15% 6% 1	420
	11th to 20th	Day	30% 24% 27% 12% 5% 2	412
	21st to end	Day	27% 21% 26% 19% 5% 3	420
May	1st to 10th	Day	18% 20% 27% 24% 9% 1	423
	11th to 20th	Day	25% 12% 29% 19% 11% 4	448
	21st to end	Day	23% 13% 23% 21% 15% 6%	635
June	1st to 10th	Day	21% 13% 24% 21% 16% 5%	630
	11th to 20th	Day	22% 19% 27% 18% 12% 3	630
	21st to end	Day	9% 12% 24% 29% 21% 4	630
July	1st to 10th	Day	6% 11% 28% 29% 21% 6%	613
	11th to 20th	Day	9% 14% 35% 28% 10% 5%	444
	21st to end	Day	4 11% 37% 30% 12% 6%	487
August	1st to 10th	Day	7% 11% 30% 31% 15% 6%	447
	11th to 20th	Day	7% 7% 29% 31% 19% 7%	437
	21st to end	Day	8% 15% 29% 25% 16% 6%	495
September	1st to 10th	Day	8% 14% 33% 24% 17% 4	450
	11th to 20th	Day	14% 16% 27% 25% 13% 5%	450
	21st to end	Day	20% 18% 24% 22% 12% 4	450
October	1st to 10th	Day	18% 11% 31% 26% 10% 4	450
	11th to 20th	Day	23% 15% 23% 22% 12% 5%	275
	21st to end	Day	30% 16% 27% 18% 7% 4	297
November	1st to 10th	Day	31% 17% 19% 25% 8%	270
	11th to 20th	Day	23% 21% 25% 17% 12% 3	270
	21st to end	Day	15% 21% 24% 29% 10% 1	189
December	1st to 10th	Day	23% 21% 23% 18% 12% 3	180
	11th to 20th	Day	23% 23% 26% 20% 8% 1	180
	21st to end	Day	22% 21% 26% 21% 8% 2	198
January	1st to 10th	Night	20% 18% 26% 25% 10% 1	834
	11th to 20th	Night	18% 14% 29% 25% 12% 2	734
	21st to end	Night	16% 13% 30% 29% 10% 2	792
February	1st to 10th	Night	20% 19% 29% 21% 9% 1	720
	11th to 20th	Night	21% 15% 28% 26% 9% 1	704
	21st to end	Night	18% 15% 26% 25% 13% 2	592
March	1st to 10th	Night	16% 13% 28% 29% 13% 2	720
	11th to 20th	Night	17% 15% 21% 30% 16% 1	720
	21st to end	Night	18% 11% 26% 32% 11% 2	792
April	1st to 10th	Night	16% 13% 21% 31% 16% 2	720
	11th to 20th	Night	17% 14% 28% 27% 13% 1	580
	21st to end	Night	14% 13% 25% 30% 15% 2	540
May	1st to 10th	Night	14% 8% 23% 33% 20% 2	525
	11th to 20th	Night	13% 5% 19% 30% 28% 5%	354
	21st to end	Night	19% 8% 13% 27% 29% 4	389
June	1st to 10th	Night	16% 7% 17% 29% 24% 6%	360
	11th to 20th	Night	19% 9% 20% 33% 17% 3	360
	21st to end	Night	7% 4 13% 40% 34% 2	360
July	1st to 10th	Night	1 3 14% 40% 41% 2	350
	11th to 20th	Night	4 4 14% 49% 27% 3	348
	21st to end	Night	2 2 10% 44% 39% 2	394
August	1st to 10th	Night	4 4 10% 37% 41% 4	375
	11th to 20th	Night	4 2 12% 39% 36% 7%	534
	21st to end	Night	7% 4 16% 38% 33% 3	640
September	1st to 10th	Night	7% 3 17% 37% 30% 6%	720
	11th to 20th	Night	10% 4 14% 32% 32% 7%	720
	21st to end	Night	14% 7% 15% 36% 23% 5%	720
October	1st to 10th	Night	12% 8% 18% 40% 21% 1	720
	11th to 20th	Night	19% 7% 16% 32% 22% 4	720
	21st to end	Night	20% 15% 20% 28% 15% 3	792
November	1st to 10th	Night	23% 12% 25% 28% 11%	740
	11th to 20th	Night	22% 17% 26% 24% 11% 1	815
	21st to end	Night	15% 16% 27% 27% 14% 1	950
December	1st to 10th	Night	17% 17% 25% 29% 11% 1	950
	11th to 20th	Night	19% 15% 31% 26% 8%	950
	21st to end	Night	20% 18% 30% 23% 8%	1045

Page generated at 2024-01-11 02:22:37. Version ac07

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