West Jordan
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the West Jordan 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	5% 7% 2 6% 4 4 4 4 5% 7% 52%	104790
	Night	6% 9% 3 6% 4 4 4 3 5% 7% 50%	102960
Transparency	Day	30% 7% 10% 18% 20% 14%	104555
	Night	32% 7% 11% 19% 19% 12%	102784
Seeing	Day	10% 19% 33% 28% 9% 1	14826
	Night	10% 10% 25% 33% 18% 4	25375

By Month

Percentage Cloud Cover SW (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	9% 18% 6% 14% 5% 4 4 3 4 5% 27%	2858
	11th to 20th	Day	9% 22% 6% 12% 5% 4 4 3 4 6% 26%	2860
	21st to end	Day	8% 15% 5% 10% 5% 4 4 3 4 6% 35%	3146
February	1st to 10th	Day	9% 14% 4 9% 5% 5% 4 5% 5% 6% 35%	1710
	11th to 20th	Day	8% 15% 4 10% 5% 4 4 4 5% 7% 35%	1740
	21st to end	Day	5% 15% 6% 10% 6% 4 5% 5% 5% 7% 33%	1570
March	1st to 10th	Day	3 14% 6% 14% 5% 5% 4 4 5% 6% 34%	3348
	11th to 20th	Day	5% 11% 3 6% 4 4 4 3 6% 7% 47%	3490
	21st to end	Day	8% 17% 4 10% 6% 6% 6% 5% 6% 6% 26%	3825
April	1st to 10th	Day	9% 9% 4 6% 5% 4 5% 4 5% 7% 42%	2102
	11th to 20th	Day	8% 10% 3 7% 4 4 4 5% 5% 6% 43%	2405
	21st to end	Day	8% 8% 2 6% 4 4 4 3 5% 8% 47%	2470
May	1st to 10th	Day	8% 9% 2 6% 4 4 5% 5% 7% 8% 42%	4110
	11th to 20th	Day	4 3 1 4 3 3 3 4 6% 8% 60%	4071
	21st to end	Day	6% 5% 2 5% 4 4 5% 4 6% 7% 52%	4477
June	1st to 10th	Day	3 4 1 4 4 4 4 4 6% 9% 56%	2470
	11th to 20th	Day	4 3 1 4 3 3 3 3 5% 6% 64%	2547
	21st to end	Day	2 1 1 2 3 2 3 3 4 5% 73%	2470
July	1st to 10th	Day	1 1 1 2 2 2 3 2 4 5% 79%	4110
	11th to 20th	Day	2 2 1 3 3 3 5% 4 7% 8% 61%	4110
	21st to end	Day	2 2 1 3 3 4 4 4 6% 7% 66%	4454
August	1st to 10th	Day	2 1 1 4 3 3 4 3 6% 7% 65%	4092
	11th to 20th	Day	2 1 1 4 4 4 4 3 6% 6% 65%	4028
	21st to end	Day	2 2 1 3 3 2 3 3 5% 5% 71%	4495
September	1st to 10th	Day	3 2 3 2 2 3 3 5% 6% 71%	2137
	11th to 20th	Day	4 2 1 3 3 3 3 3 5% 7% 65%	2090
	21st to end	Day	6% 3 1 2 2 2 2 2 4 6% 70%	2090
October	1st to 10th	Day	4 3 1 3 2 2 3 2 3 4 70%	3339
	11th to 20th	Day	7% 5% 1 4 3 2 3 2 4 7% 62%	3150
	21st to end	Day	7% 7% 2 4 2 3 3 3 4 5% 60%	3415
November	1st to 10th	Day	8% 8% 2 6% 4 4 5% 4 5% 7% 48%	1710
	11th to 20th	Day	11% 8% 3 5% 5% 3 3 4 5% 7% 47%	1710
	21st to end	Day	7% 10% 4 7% 5% 5% 3 3 5% 6% 45%	1599
December	1st to 10th	Day	9% 12% 4 8% 3 4 4 3 5% 7% 42%	1520
	11th to 20th	Day	10% 12% 5% 9% 5% 5% 5% 4 7% 7% 32%	1926
	21st to end	Day	8% 13% 5% 10% 5% 4 3 4 5% 7% 34%	3146
January	1st to 10th	Night	8% 18% 6% 11% 5% 3 4 3 4 6% 31%	4097
	11th to 20th	Night	13% 21% 5% 11% 4 4 4 3 4 5% 26%	4110
	21st to end	Night	8% 15% 4 8% 5% 5% 5% 4 6% 6% 35%	4521
February	1st to 10th	Night	9% 12% 4 8% 4 5% 5% 4 5% 7% 36%	2470
	11th to 20th	Night	7% 13% 4 7% 5% 5% 4 3 4 7% 40%	2325
	21st to end	Night	6% 13% 5% 8% 6% 4 4 3 5% 7% 40%	1884
March	1st to 10th	Night	5% 11% 4 11% 5% 6% 6% 5% 6% 7% 35%	3524
	11th to 20th	Night	5% 10% 2 5% 4 4 4 4 6% 7% 50%	3490
	21st to end	Night	8% 18% 4 9% 5% 4 4 4 6% 5% 34%	3828
April	1st to 10th	Night	11% 10% 2 5% 4 3 4 3 4 7% 47%	2076
	11th to 20th	Night	6% 8% 2 6% 5% 4 4 5% 5% 7% 47%	1720
	21st to end	Night	10% 8% 2 5% 4 4 5% 4 5% 6% 49%	1710
May	1st to 10th	Night	7% 12% 2 6% 4 4 5% 4 6% 7% 42%	2860
	11th to 20th	Night	5% 3 1 4 3 3 3 4 6% 7% 60%	2834
	21st to end	Night	8% 5% 2 4 4 3 4 3 5% 7% 54%	3110
June	1st to 10th	Night	5% 4 2 4 4 3 4 4 5% 8% 57%	1706
	11th to 20th	Night	4 2 1 4 2 3 3 3 4 7% 66%	1576
	21st to end	Night	2 3 1 3 3 2 3 3 6% 7% 68%	1710
July	1st to 10th	Night	1 2 1 4 3 3 2 3 4 5% 73%	2860
	11th to 20th	Night	2 2 1 4 4 5% 5% 5% 7% 10% 55%	2860
	21st to end	Night	2 3 2 5% 4 4 4 4 6% 7% 61%	3109
August	1st to 10th	Night	2 2 1 3 3 3 5% 4 6% 9% 62%	2847
	11th to 20th	Night	2 2 2 4 4 4 5% 4 5% 5% 64%	2811
	21st to end	Night	2 2 1 4 2 3 3 3 5% 5% 71%	3172
September	1st to 10th	Night	3 3 1 3 3 3 3 3 4 5% 68%	2041
	11th to 20th	Night	4 3 1 2 2 3 3 2 5% 6% 68%	2090
	21st to end	Night	5% 3 1 3 2 2 2 2 4 4 72%	2090
October	1st to 10th	Night	4 3 1 3 3 2 3 2 3 5% 72%	3635
	11th to 20th	Night	7% 4 1 4 2 3 3 2 4 6% 63%	3778
	21st to end	Night	7% 6% 2 4 2 2 3 3 5% 7% 58%	4140
November	1st to 10th	Night	8% 10% 2 5% 4 3 4 3 5% 7% 51%	2469
	11th to 20th	Night	10% 7% 2 4 3 3 3 4 5% 8% 50%	2470
	21st to end	Night	8% 10% 2 5% 4 3 3 4 6% 6% 48%	2557
December	1st to 10th	Night	9% 11% 3 6% 4 3 3 3 5% 7% 44%	2660
	11th to 20th	Night	12% 13% 4 7% 4 4 4 3 5% 8% 36%	3271
	21st to end	Night	9% 12% 5% 10% 5% 5% 5% 4 5% 6% 33%	4549

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	59% 8% 11% 15% 7% 1	2859
	11th to 20th	Day	60% 8% 14% 13% 4 1	2860
	21st to end	Day	50% 9% 18% 14% 7% 1	3146
February	1st to 10th	Day	51% 9% 13% 15% 10% 1	1710
	11th to 20th	Day	48% 9% 13% 18% 11% 1	1749
	21st to end	Day	49% 10% 12% 18% 10% 1	1570
March	1st to 10th	Day	42% 13% 14% 19% 11% 1	3348
	11th to 20th	Day	35% 9% 12% 33% 10% 1	3490
	21st to end	Day	55% 12% 15% 12% 6% 1	3825
April	1st to 10th	Day	41% 10% 13% 17% 14% 5%	2102
	11th to 20th	Day	39% 9% 14% 20% 16% 2	2408
	21st to end	Day	35% 9% 12% 24% 20% 1	2470
May	1st to 10th	Day	36% 10% 11% 21% 18% 4	4110
	11th to 20th	Day	21% 7% 9% 29% 32% 4	4074
	21st to end	Day	27% 9% 11% 25% 25% 3	4477
June	1st to 10th	Day	23% 8% 10% 22% 29% 9%	2470
	11th to 20th	Day	21% 5% 8% 18% 29% 19%	2547
	21st to end	Day	14% 4 6% 11% 31% 35%	2470
July	1st to 10th	Day	9% 3 4 7% 15% 61%	4046
	11th to 20th	Day	15% 6% 7% 11% 24% 37%	4041
	21st to end	Day	15% 6% 7% 9% 23% 40%	4314
August	1st to 10th	Day	15% 5% 7% 17% 28% 28%	4078
	11th to 20th	Day	16% 5% 7% 13% 34% 25%	4067
	21st to end	Day	14% 4 6% 14% 29% 33%	4494
September	1st to 10th	Day	14% 7% 6% 15% 29% 29%	2137
	11th to 20th	Day	18% 8% 8% 18% 28% 21%	2090
	21st to end	Day	17% 5% 7% 21% 34% 17%	2090
October	1st to 10th	Day	19% 5% 5% 13% 37% 21%	3339
	11th to 20th	Day	23% 5% 8% 27% 28% 8%	3150
	21st to end	Day	26% 6% 11% 31% 22% 3	3415
November	1st to 10th	Day	35% 8% 14% 21% 18% 4	1710
	11th to 20th	Day	37% 8% 12% 28% 15% 1	1710
	21st to end	Day	41% 7% 13% 24% 14% 2	1599
December	1st to 10th	Day	44% 9% 17% 19% 9% 2	1520
	11th to 20th	Day	49% 9% 12% 19% 10%	1924
	21st to end	Day	46% 9% 15% 15% 14% 1	3146
January	1st to 10th	Night	52% 7% 13% 18% 9% 1	4097
	11th to 20th	Night	59% 10% 13% 12% 6% 1	4110
	21st to end	Night	45% 11% 19% 16% 7% 2	4521
February	1st to 10th	Night	46% 8% 16% 20% 9% 1	2470
	11th to 20th	Night	44% 7% 11% 20% 16% 2	2326
	21st to end	Night	42% 9% 13% 21% 13% 2	1884
March	1st to 10th	Night	42% 12% 10% 21% 14% 1	3524
	11th to 20th	Night	30% 9% 12% 32% 15% 2	3490
	21st to end	Night	47% 12% 11% 17% 12% 2	3828
April	1st to 10th	Night	37% 7% 13% 21% 15% 6%	2076
	11th to 20th	Night	33% 9% 12% 21% 22% 3	1720
	21st to end	Night	35% 8% 12% 22% 21% 2	1710
May	1st to 10th	Night	32% 12% 12% 21% 22% 2	2860
	11th to 20th	Night	20% 7% 9% 28% 29% 6%	2835
	21st to end	Night	25% 7% 12% 26% 27% 3	3110
June	1st to 10th	Night	25% 6% 9% 22% 28% 9%	1706
	11th to 20th	Night	18% 6% 9% 17% 30% 20%	1576
	21st to end	Night	16% 4 7% 9% 27% 37%	1710
July	1st to 10th	Night	13% 3 5% 8% 11% 59%	2815
	11th to 20th	Night	20% 5% 7% 11% 23% 34%	2806
	21st to end	Night	21% 5% 7% 10% 23% 34%	3011
August	1st to 10th	Night	15% 5% 8% 14% 28% 30%	2838
	11th to 20th	Night	18% 7% 8% 13% 29% 25%	2838
	21st to end	Night	15% 4 7% 10% 30% 35%	3172
September	1st to 10th	Night	18% 4 6% 15% 25% 32%	2041
	11th to 20th	Night	19% 4 8% 18% 27% 24%	2090
	21st to end	Night	18% 4 5% 15% 33% 24%	2090
October	1st to 10th	Night	16% 4 6% 14% 35% 24%	3635
	11th to 20th	Night	22% 5% 6% 28% 30% 10%	3778
	21st to end	Night	24% 5% 9% 34% 23% 4	4140
November	1st to 10th	Night	33% 6% 12% 23% 20% 6%	2469
	11th to 20th	Night	32% 7% 14% 26% 18% 3	2470
	21st to end	Night	36% 7% 11% 26% 16% 4	2557
December	1st to 10th	Night	39% 9% 14% 24% 11% 3	2660
	11th to 20th	Night	46% 7% 13% 20% 12% 1	3272
	21st to end	Night	50% 8% 15% 14% 13% 1	4549

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	24% 19% 26% 21% 10%	270
	11th to 20th	Day	14% 22% 33% 19% 10% 1	270
	21st to end	Day	12% 21% 32% 25% 8% 1	297
February	1st to 10th	Day	16% 28% 33% 16% 7%	270
	11th to 20th	Day	16% 24% 34% 19% 6% 1	345
	21st to end	Day	14% 29% 37% 17% 3	382
March	1st to 10th	Day	15% 26% 36% 17% 4 1	460
	11th to 20th	Day	11% 23% 40% 21% 4	460
	21st to end	Day	18% 29% 35% 17% 1	506
April	1st to 10th	Day	16% 25% 30% 23% 5% 1	460
	11th to 20th	Day	17% 30% 31% 17% 6%	452
	21st to end	Day	15% 29% 26% 22% 6% 1	460
May	1st to 10th	Day	12% 27% 36% 17% 6% 1	463
	11th to 20th	Day	10% 25% 31% 25% 8% 1	488
	21st to end	Day	9% 19% 34% 25% 10% 2	529
June	1st to 10th	Day	5% 17% 38% 32% 6% 3	490
	11th to 20th	Day	6% 20% 34% 28% 12% 1	567
	21st to end	Day	4 16% 39% 34% 7% 1	490
July	1st to 10th	Day	1 10% 36% 43% 8% 2	486
	11th to 20th	Day	3 9% 40% 34% 11% 3	484
	21st to end	Day	3 3 37% 42% 13% 2	531
August	1st to 10th	Day	5% 9% 36% 39% 11% 1	487
	11th to 20th	Day	3 9% 36% 39% 10% 2	477
	21st to end	Day	4 12% 33% 38% 11% 4	539
September	1st to 10th	Day	3 9% 33% 37% 14% 3	490
	11th to 20th	Day	5% 16% 33% 35% 10% 2	490
	21st to end	Day	7% 15% 25% 37% 14% 2	490
October	1st to 10th	Day	7% 22% 27% 27% 15% 2	404
	11th to 20th	Day	11% 17% 27% 29% 16% 1	300
	21st to end	Day	11% 19% 34% 26% 9%	330
November	1st to 10th	Day	16% 21% 27% 26% 8% 2	282
	11th to 20th	Day	13% 20% 34% 21% 10% 3	270
	21st to end	Day	15% 14% 28% 29% 12% 2	270
December	1st to 10th	Day	17% 16% 29% 26% 10% 2	270
	11th to 20th	Day	16% 18% 33% 26% 7%	270
	21st to end	Day	22% 21% 29% 25% 4	297
January	1st to 10th	Night	16% 11% 25% 28% 16% 4	760
	11th to 20th	Night	14% 12% 26% 29% 15% 5%	760
	21st to end	Night	14% 11% 23% 32% 16% 4	836
February	1st to 10th	Night	14% 10% 31% 30% 12% 3	760
	11th to 20th	Night	13% 13% 29% 30% 13% 3	744
	21st to end	Night	11% 15% 30% 29% 13% 2	628
March	1st to 10th	Night	13% 15% 30% 28% 10% 4	760
	11th to 20th	Night	10% 12% 28% 31% 16% 3	760
	21st to end	Night	12% 19% 26% 31% 10% 3	836
April	1st to 10th	Night	15% 15% 29% 28% 11% 2	746
	11th to 20th	Night	8% 16% 31% 32% 11% 2	563
	21st to end	Night	11% 12% 26% 31% 16% 3	570
May	1st to 10th	Night	9% 11% 32% 33% 14% 2	570
	11th to 20th	Night	7% 9% 26% 31% 22% 4	561
	21st to end	Night	9% 11% 24% 32% 20% 4	617
June	1st to 10th	Night	5% 11% 23% 38% 21% 2	570
	11th to 20th	Night	4 11% 27% 37% 19% 1	570
	21st to end	Night	3 6% 25% 38% 25% 4	570
July	1st to 10th	Night	2 5% 24% 35% 32% 2	555
	11th to 20th	Night	4 4 21% 44% 25% 3	552
	21st to end	Night	3 3 16% 38% 39% 2	624
August	1st to 10th	Night	4 4 22% 41% 28% 2	567
	11th to 20th	Night	3 4 20% 44% 26% 3	564
	21st to end	Night	3 5% 23% 41% 25% 4	627
September	1st to 10th	Night	5% 5% 18% 41% 27% 5%	711
	11th to 20th	Night	4 7% 19% 40% 23% 7%	760
	21st to end	Night	7% 6% 20% 31% 26% 9%	760
October	1st to 10th	Night	7% 8% 24% 35% 21% 5%	760
	11th to 20th	Night	8% 7% 23% 35% 22% 5%	760
	21st to end	Night	9% 11% 25% 31% 19% 5%	836
November	1st to 10th	Night	13% 11% 22% 29% 20% 4	760
	11th to 20th	Night	11% 11% 29% 29% 15% 5%	760
	21st to end	Night	12% 11% 23% 33% 16% 4	847
December	1st to 10th	Night	15% 11% 26% 32% 15% 1	950
	11th to 20th	Night	19% 10% 27% 31% 11% 2	950
	21st to end	Night	22% 13% 24% 31% 8% 1	851

Page generated at 2024-11-03 00:11:17. Version ac07

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