Soapstone Prairie Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Soapstone Prairie Natural Area clear sky chart from 2005-11-06 to 2024-11-08.

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% 6% 2 5% 4 4 5% 4 6% 7% 51%	105255
	Night	5% 6% 2 5% 4 3 4 3 5% 7% 55%	102555
Transparency	Day	29% 6% 11% 23% 21% 9%	104996
	Night	27% 6% 13% 26% 21% 8%	102403
Seeing	Day	12% 13% 29% 28% 14% 4	15694
	Night	9% 15% 27% 34% 13% 2	25692

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	1 7% 3 8% 5% 4 3 2 5% 6% 56%	2538
	11th to 20th	Day	1 5% 3 9% 5% 5% 5% 3 7% 9% 48%	2540
	21st to end	Day	1 5% 2 5% 4 3 4 4 6% 7% 60%	3128
February	1st to 10th	Day	2 7% 2 9% 5% 4 4 4 6% 7% 51%	1710
	11th to 20th	Day	1 6% 2 6% 5% 4 4 4 5% 8% 55%	1795
	21st to end	Day	2 8% 3 8% 4 3 3 3 5% 7% 55%	1570
March	1st to 10th	Day	2 11% 3 6% 3 3 3 3 6% 6% 52%	3130
	11th to 20th	Day	5% 9% 4 6% 5% 4 4 3 5% 6% 49%	3442
	21st to end	Day	5% 10% 3 6% 5% 4 5% 5% 6% 8% 43%	4063
April	1st to 10th	Day	6% 7% 2 5% 3 3 4 5% 6% 7% 51%	2280
	11th to 20th	Day	8% 12% 4 6% 4 4 5% 4 5% 7% 41%	2251
	21st to end	Day	10% 9% 2 6% 4 4 5% 4 7% 8% 40%	2280
May	1st to 10th	Day	12% 10% 4 7% 5% 5% 5% 4 6% 6% 37%	4154
	11th to 20th	Day	10% 7% 2 5% 4 6% 6% 5% 7% 9% 40%	4388
	21st to end	Day	8% 7% 2 5% 5% 4 5% 5% 7% 8% 44%	4825
June	1st to 10th	Day	6% 5% 1 5% 4 5% 5% 6% 8% 8% 46%	2660
	11th to 20th	Day	8% 4 1 4 4 4 6% 6% 6% 8% 48%	2660
	21st to end	Day	4 3 1 4 4 4 6% 6% 7% 8% 51%	2660
July	1st to 10th	Day	7% 4 1 5% 4 3 5% 4 7% 9% 51%	4430
	11th to 20th	Day	3 3 1 5% 4 5% 7% 6% 9% 9% 48%	4430
	21st to end	Day	4 4 2 5% 4 4 5% 5% 7% 9% 50%	4802
August	1st to 10th	Day	12% 4 2 5% 4 5% 6% 5% 8% 10% 41%	4102
	11th to 20th	Day	4 3 2 5% 5% 5% 6% 5% 7% 8% 51%	3771
	21st to end	Day	5% 4 2 5% 4 4 5% 4 8% 7% 53%	4180
September	1st to 10th	Day	7% 5% 1 4 3 4 4 3 5% 6% 58%	2280
	11th to 20th	Day	7% 4 1 3 3 4 4 4 6% 7% 57%	2261
	21st to end	Day	7% 4 1 3 2 3 3 3 4 6% 64%	2090
October	1st to 10th	Day	6% 4 1 2 2 2 2 2 3 4 73%	3177
	11th to 20th	Day	5% 5% 2 5% 3 3 4 3 5% 6% 59%	3150
	21st to end	Day	5% 6% 2 4 2 2 3 2 5% 6% 62%	3264
November	1st to 10th	Day	3 5% 1 4 2 3 4 3 5% 8% 61%	1736
	11th to 20th	Day	2 6% 2 3 3 3 3 3 5% 9% 61%	1710
	21st to end	Day	2 6% 3 4 3 3 3 4 6% 8% 57%	1558
December	1st to 10th	Day	2 5% 3 6% 4 4 3 3 5% 8% 57%	1520
	11th to 20th	Day	3 6% 2 7% 3 3 3 3 5% 7% 59%	1926
	21st to end	Day	2 6% 4 8% 5% 4 5% 4 5% 6% 51%	2794
January	1st to 10th	Night	2 6% 3 8% 5% 4 4 3 5% 6% 54%	4417
	11th to 20th	Night	1 4 3 7% 5% 4 4 4 5% 8% 56%	4430
	21st to end	Night	2 6% 2 7% 4 4 3 4 4 6% 58%	4553
February	1st to 10th	Night	2 7% 3 7% 3 4 4 4 5% 8% 54%	2470
	11th to 20th	Night	2 6% 2 6% 6% 4 3 3 4 7% 57%	2270
	21st to end	Night	2 10% 3 5% 4 3 3 3 4 6% 58%	1884
March	1st to 10th	Night	2 11% 3 7% 3 3 3 3 4 7% 54%	3734
	11th to 20th	Night	5% 11% 2 5% 3 3 3 3 4 7% 54%	3535
	21st to end	Night	5% 9% 2 7% 4 4 5% 3 6% 8% 48%	3581
April	1st to 10th	Night	6% 8% 2 4 3 4 4 4 6% 7% 53%	1900
	11th to 20th	Night	10% 8% 2 5% 4 3 3 3 5% 6% 50%	1877
	21st to end	Night	13% 9% 3 4 3 4 3 3 4 7% 46%	1900
May	1st to 10th	Night	12% 7% 2 7% 5% 5% 4 4 5% 6% 43%	2813
	11th to 20th	Night	11% 6% 2 5% 3 4 4 4 6% 9% 45%	2517
	21st to end	Night	9% 6% 2 5% 4 4 4 4 5% 7% 51%	2762
June	1st to 10th	Night	7% 4 2 3 3 4 4 3 7% 10% 54%	1520
	11th to 20th	Night	7% 3 1 3 3 3 4 3 7% 6% 60%	1520
	21st to end	Night	6% 3 4 2 3 4 3 6% 7% 61%	1520
July	1st to 10th	Night	5% 3 1 3 3 4 5% 4 6% 7% 57%	2540
	11th to 20th	Night	3 2 1 4 3 4 4 4 8% 10% 56%	2540
	21st to end	Night	4 3 1 4 3 4 5% 5% 7% 7% 57%	2761
August	1st to 10th	Night	12% 5% 1 4 3 4 5% 4 7% 9% 46%	2833
	11th to 20th	Night	5% 5% 2 5% 5% 4 5% 5% 7% 8% 48%	3055
	21st to end	Night	4 3 1 5% 3 4 5% 4 7% 10% 55%	3487
September	1st to 10th	Night	7% 4 1 4 3 3 3 3 5% 6% 59%	1900
	11th to 20th	Night	7% 3 1 3 2 3 3 3 4 6% 64%	1919
	21st to end	Night	7% 4 1 4 2 2 3 3 4 6% 63%	2090
October	1st to 10th	Night	6% 4 1 3 2 2 2 2 3 4 72%	3790
	11th to 20th	Night	7% 6% 2 5% 3 3 3 3 5% 6% 58%	3778
	21st to end	Night	5% 6% 2 4 2 3 3 3 4 7% 62%	4261
November	1st to 10th	Night	3 5% 2 4 3 3 3 3 5% 7% 62%	2503
	11th to 20th	Night	3 5% 1 5% 4 3 3 3 5% 7% 61%	2470
	21st to end	Night	2 7% 3 4 4 3 3 3 6% 7% 59%	2621
December	1st to 10th	Night	2 6% 3 6% 4 3 3 2 5% 7% 59%	2660
	11th to 20th	Night	3 7% 2 4 3 3 4 4 6% 10% 54%	3271
	21st to end	Night	3 6% 3 7% 4 4 4 4 5% 7% 52%	4873

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	29% 4 13% 27% 21% 7%	2539
	11th to 20th	Day	30% 8% 17% 22% 18% 4	2540
	21st to end	Day	22% 6% 15% 31% 21% 5%	3128
February	1st to 10th	Day	31% 6% 16% 25% 17% 5%	1710
	11th to 20th	Day	26% 5% 12% 29% 22% 6%	1805
	21st to end	Day	29% 4 11% 26% 21% 8%	1570
March	1st to 10th	Day	29% 4 11% 25% 24% 6%	3130
	11th to 20th	Day	34% 7% 14% 30% 12% 3	3442
	21st to end	Day	35% 8% 12% 32% 11% 2	4063
April	1st to 10th	Day	30% 7% 14% 24% 18% 8%	2280
	11th to 20th	Day	40% 6% 12% 20% 16% 6%	2254
	21st to end	Day	38% 8% 12% 26% 15% 1	2280
May	1st to 10th	Day	42% 8% 11% 21% 12% 6%	4154
	11th to 20th	Day	35% 10% 13% 23% 15% 4	4392
	21st to end	Day	32% 9% 12% 22% 20% 5%	4825
June	1st to 10th	Day	29% 11% 16% 22% 16% 5%	2660
	11th to 20th	Day	27% 9% 12% 20% 20% 12%	2660
	21st to end	Day	25% 8% 10% 23% 20% 13%	2660
July	1st to 10th	Day	27% 6% 8% 16% 25% 17%	4361
	11th to 20th	Day	27% 6% 10% 19% 20% 17%	4355
	21st to end	Day	27% 7% 9% 17% 23% 18%	4651
August	1st to 10th	Day	36% 7% 13% 20% 16% 8%	4087
	11th to 20th	Day	29% 5% 12% 17% 21% 16%	3807
	21st to end	Day	26% 5% 10% 18% 25% 16%	4179
September	1st to 10th	Day	24% 6% 7% 19% 28% 16%	2280
	11th to 20th	Day	23% 6% 9% 22% 27% 14%	2261
	21st to end	Day	22% 5% 7% 20% 35% 10%	2090
October	1st to 10th	Day	18% 3 4 17% 33% 24%	3177
	11th to 20th	Day	24% 4 10% 28% 26% 9%	3150
	21st to end	Day	24% 3 6% 29% 32% 6%	3264
November	1st to 10th	Day	22% 5% 13% 26% 26% 8%	1736
	11th to 20th	Day	21% 5% 10% 29% 28% 6%	1710
	21st to end	Day	25% 5% 11% 25% 26% 8%	1558
December	1st to 10th	Day	26% 6% 14% 30% 18% 7%	1520
	11th to 20th	Day	25% 4 12% 31% 26% 3	1924
	21st to end	Day	32% 6% 11% 23% 20% 8%	2794
January	1st to 10th	Night	28% 6% 11% 30% 20% 4	4417
	11th to 20th	Night	23% 10% 16% 22% 20% 8%	4430
	21st to end	Night	27% 6% 17% 30% 17% 4	4553
February	1st to 10th	Night	29% 4 16% 29% 19% 5%	2470
	11th to 20th	Night	30% 4 12% 28% 21% 4	2270
	21st to end	Night	29% 4 10% 24% 24% 9%	1884
March	1st to 10th	Night	30% 3 11% 24% 26% 6%	3734
	11th to 20th	Night	30% 5% 16% 22% 23% 3	3535
	21st to end	Night	32% 7% 16% 30% 12% 2	3581
April	1st to 10th	Night	29% 6% 13% 27% 19% 7%	1900
	11th to 20th	Night	34% 6% 13% 25% 17% 5%	1877
	21st to end	Night	38% 5% 10% 26% 19% 2	1900
May	1st to 10th	Night	38% 7% 11% 24% 13% 6%	2813
	11th to 20th	Night	31% 11% 17% 27% 12% 3	2518
	21st to end	Night	30% 10% 17% 24% 16% 4	2762
June	1st to 10th	Night	23% 10% 22% 26% 14% 5%	1520
	11th to 20th	Night	23% 7% 14% 22% 19% 15%	1520
	21st to end	Night	22% 5% 11% 27% 25% 10%	1520
July	1st to 10th	Night	25% 5% 9% 24% 25% 12%	2500
	11th to 20th	Night	22% 5% 14% 25% 24% 11%	2492
	21st to end	Night	24% 6% 12% 27% 19% 12%	2674
August	1st to 10th	Night	34% 6% 17% 21% 19% 4	2825
	11th to 20th	Night	33% 6% 12% 22% 16% 11%	3084
	21st to end	Night	25% 4 14% 23% 22% 12%	3487
September	1st to 10th	Night	26% 6% 9% 19% 24% 17%	1900
	11th to 20th	Night	21% 5% 11% 25% 24% 14%	1919
	21st to end	Night	23% 5% 7% 23% 32% 10%	2090
October	1st to 10th	Night	19% 3 6% 20% 29% 23%	3790
	11th to 20th	Night	29% 3 9% 28% 24% 7%	3778
	21st to end	Night	25% 3 7% 28% 27% 10%	4261
November	1st to 10th	Night	23% 5% 13% 24% 27% 9%	2503
	11th to 20th	Night	23% 4 11% 29% 25% 7%	2470
	21st to end	Night	24% 4 12% 25% 26% 8%	2621
December	1st to 10th	Night	26% 6% 15% 26% 20% 7%	2660
	11th to 20th	Night	24% 6% 13% 32% 22% 3	3272
	21st to end	Night	30% 6% 12% 26% 20% 7%	4873

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	12% 20% 31% 23% 13% 2	270
	11th to 20th	Day	13% 28% 33% 19% 7%	270
	21st to end	Day	6% 33% 36% 19% 5% 1	297
February	1st to 10th	Day	12% 31% 39% 16% 3	270
	11th to 20th	Day	12% 25% 38% 21% 3	270
	21st to end	Day	21% 20% 37% 20% 3	225
March	1st to 10th	Day	10% 23% 33% 28% 5%	270
	11th to 20th	Day	17% 18% 36% 22% 8%	425
	21st to end	Day	17% 20% 39% 18% 5%	506
April	1st to 10th	Day	15% 26% 32% 22% 5% 1	460
	11th to 20th	Day	22% 21% 38% 14% 4 1	452
	21st to end	Day	21% 17% 32% 20% 8% 2	460
May	1st to 10th	Day	21% 15% 30% 22% 10% 2	620
	11th to 20th	Day	22% 8% 25% 28% 14% 4	675
	21st to end	Day	13% 12% 26% 27% 19% 4	734
June	1st to 10th	Day	9% 7% 23% 34% 22% 6%	680
	11th to 20th	Day	10% 7% 34% 31% 16% 3	680
	21st to end	Day	6% 7% 29% 33% 19% 6%	680
July	1st to 10th	Day	9% 2 18% 37% 27% 7%	671
	11th to 20th	Day	5% 3 19% 39% 26% 7%	668
	21st to end	Day	7% 4 17% 33% 30% 8%	739
August	1st to 10th	Day	9% 3 22% 39% 21% 5%	497
	11th to 20th	Day	5% 6% 26% 36% 22% 6%	477
	21st to end	Day	7% 5% 29% 35% 19% 5%	539
September	1st to 10th	Day	10% 4 28% 36% 18% 5%	490
	11th to 20th	Day	8% 6% 34% 29% 18% 6%	471
	21st to end	Day	12% 6% 31% 27% 15% 9%	300
October	1st to 10th	Day	12% 5% 28% 30% 17% 7%	300
	11th to 20th	Day	9% 17% 35% 23% 12% 4	300
	21st to end	Day	12% 19% 35% 25% 7% 2	330
November	1st to 10th	Day	10% 18% 33% 27% 8% 4	291
	11th to 20th	Day	14% 23% 34% 20% 8% 1	270
	21st to end	Day	13% 28% 31% 20% 6% 1	270
December	1st to 10th	Day	12% 26% 33% 22% 7%	270
	11th to 20th	Day	15% 29% 31% 21% 4	270
	21st to end	Day	14% 30% 32% 20% 4 1	297
January	1st to 10th	Night	8% 27% 30% 25% 7% 3	950
	11th to 20th	Night	7% 35% 34% 18% 6% 1	950
	21st to end	Night	6% 27% 34% 26% 6% 1	855
February	1st to 10th	Night	7% 31% 35% 22% 5%	760
	11th to 20th	Night	8% 24% 38% 26% 4	744
	21st to end	Night	9% 25% 38% 25% 2	628
March	1st to 10th	Night	7% 20% 36% 32% 5%	760
	11th to 20th	Night	10% 15% 30% 34% 10% 1	760
	21st to end	Night	12% 15% 34% 31% 6% 1	692
April	1st to 10th	Night	11% 16% 35% 33% 5%	570
	11th to 20th	Night	15% 14% 32% 30% 7% 1	563
	21st to end	Night	19% 12% 23% 35% 9% 1	570
May	1st to 10th	Night	18% 11% 25% 33% 12% 2	570
	11th to 20th	Night	21% 5% 18% 38% 16% 2	561
	21st to end	Night	12% 6% 25% 34% 21% 2	617
June	1st to 10th	Night	8% 5% 18% 43% 24% 2	570
	11th to 20th	Night	9% 5% 21% 51% 14% 1	570
	21st to end	Night	7% 4 19% 46% 22% 3	570
July	1st to 10th	Night	9% 2 12% 43% 30% 4	555
	11th to 20th	Night	3 2 9% 50% 33% 2	552
	21st to end	Night	6% 1 6% 46% 37% 4	624
August	1st to 10th	Night	8% 3 10% 47% 30% 2	567
	11th to 20th	Night	6% 1 11% 52% 27% 3	564
	21st to end	Night	5% 3 14% 45% 31% 3	627
September	1st to 10th	Night	9% 4 14% 44% 25% 5%	570
	11th to 20th	Night	9% 4 17% 44% 22% 5%	570
	21st to end	Night	9% 5% 23% 43% 18% 2	570
October	1st to 10th	Night	12% 9% 22% 37% 17% 3	750
	11th to 20th	Night	8% 12% 30% 36% 11% 2	760
	21st to end	Night	11% 17% 31% 32% 8% 2	915
November	1st to 10th	Night	6% 14% 35% 34% 9% 2	963
	11th to 20th	Night	8% 21% 36% 30% 4 1	950
	21st to end	Night	7% 22% 32% 32% 7%	950
December	1st to 10th	Night	7% 28% 35% 26% 4	950
	11th to 20th	Night	10% 22% 37% 26% 5% 1	950
	21st to end	Night	8% 26% 35% 25% 5% 1	1045

Page generated at 2024-11-05 06:15:48. Version ac07

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