Powersville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Powersville 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	12% 8% 3 7% 4 4 4 4 6% 7% 40%	101331
	Night	12% 8% 3 7% 4 4 4 3 5% 6% 44%	97784
Transparency	Day	23% 46% 7% 14% 9% 1	104971
	Night	23% 46% 6% 13% 10% 1	102284
Seeing	Day	15% 10% 29% 27% 15% 4	15776
	Night	15% 10% 33% 30% 11% 1	25599

By Month

Percentage Cloud Cover SE (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	11% 13% 4 15% 6% 6% 5% 3 4 6% 28%	2595
	11th to 20th	Day	10% 13% 5% 10% 6% 6% 9% 3 4 6% 28%	2850
	21st to end	Day	14% 16% 8% 16% 6% 5% 4 3 4 5% 20%	3135
February	1st to 10th	Day	14% 11% 3 10% 7% 5% 4 4 5% 7% 30%	1710
	11th to 20th	Day	13% 11% 3 9% 5% 5% 3 4 5% 6% 36%	1664
	21st to end	Day	15% 9% 3 7% 4 4 4 4 5% 6% 38%	1547
March	1st to 10th	Day	17% 11% 3 7% 4 3 3 2 4 4 41%	3436
	11th to 20th	Day	9% 8% 3 6% 5% 4 4 4 5% 6% 45%	3480
	21st to end	Day	20% 15% 4 8% 5% 4 4 3 5% 7% 25%	3814
April	1st to 10th	Day	17% 9% 3 7% 5% 3 4 3 5% 7% 38%	2273
	11th to 20th	Day	16% 10% 2 6% 4 4 4 3 6% 6% 39%	2254
	21st to end	Day	21% 7% 2 7% 5% 4 4 3 4 6% 35%	2357
May	1st to 10th	Day	16% 8% 2 7% 5% 5% 4 4 7% 8% 34%	4082
	11th to 20th	Day	16% 8% 3 7% 4 4 5% 4 5% 8% 37%	4264
	21st to end	Day	13% 6% 2 6% 4 3 4 4 5% 7% 46%	4824
June	1st to 10th	Day	7% 5% 2 7% 5% 4 5% 5% 8% 8% 45%	2660
	11th to 20th	Day	8% 5% 2 5% 5% 4 5% 4 7% 9% 47%	2660
	21st to end	Day	10% 5% 2 6% 5% 4 5% 5% 7% 8% 44%	2660
July	1st to 10th	Day	10% 8% 3 7% 5% 5% 6% 5% 8% 9% 36%	4440
	11th to 20th	Day	7% 4 1 5% 4 4 4 3 6% 8% 53%	4295
	21st to end	Day	5% 3 2 5% 4 5% 5% 5% 8% 12% 45%	4465
August	1st to 10th	Day	6% 4 2 5% 4 5% 5% 5% 8% 10% 45%	4104
	11th to 20th	Day	14% 6% 2 5% 4 5% 4 4 7% 8% 42%	4041
	21st to end	Day	7% 4 2 5% 4 4 5% 3 6% 9% 51%	4193
September	1st to 10th	Day	13% 5% 2 4 4 3 2 2 5% 5% 54%	2280
	11th to 20th	Day	10% 4 2 5% 3 3 5% 4 6% 8% 50%	2233
	21st to end	Day	11% 5% 2 5% 3 4 3 3 5% 6% 52%	2008
October	1st to 10th	Day	13% 6% 2 5% 4 4 3 2 4 7% 49%	1900
	11th to 20th	Day	15% 8% 2 5% 3 3 3 2 5% 5% 50%	1900
	21st to end	Day	15% 8% 3 6% 3 3 4 3 5% 6% 43%	2090
November	1st to 10th	Day	10% 6% 2 6% 4 3 4 3 6% 7% 49%	1822
	11th to 20th	Day	13% 8% 3 8% 5% 3 3 3 5% 7% 44%	1554
	21st to end	Day	17% 12% 3 5% 4 3 2 3 5% 6% 40%	1520
December	1st to 10th	Day	12% 12% 4 9% 5% 5% 4 3 4 6% 37%	1520
	11th to 20th	Day	11% 10% 3 9% 5% 6% 4 4 6% 7% 36%	1918
	21st to end	Day	19% 15% 9% 13% 5% 4 5% 3 4 5% 20%	2783
January	1st to 10th	Night	10% 11% 4 18% 6% 5% 4 3 5% 5% 30%	4355
	11th to 20th	Night	11% 13% 5% 10% 5% 5% 6% 4 7% 5% 28%	4120
	21st to end	Night	15% 15% 7% 13% 5% 4 3 3 3 5% 26%	4532
February	1st to 10th	Night	13% 11% 5% 9% 5% 5% 4 3 5% 5% 34%	2470
	11th to 20th	Night	11% 11% 4 7% 5% 4 4 3 5% 5% 41%	2403
	21st to end	Night	14% 9% 4 7% 4 4 4 3 4 4 43%	1919
March	1st to 10th	Night	14% 9% 3 8% 4 3 3 2 4 4 46%	3419
	11th to 20th	Night	13% 8% 2 5% 3 3 3 3 4 6% 52%	3480
	21st to end	Night	19% 10% 5% 12% 6% 4 4 3 4 6% 27%	3817
April	1st to 10th	Night	12% 7% 2 7% 4 4 3 4 5% 7% 45%	1906
	11th to 20th	Night	14% 9% 3 6% 5% 4 4 3 5% 5% 42%	1875
	21st to end	Night	18% 8% 2 6% 3 4 4 3 5% 6% 41%	1819
May	1st to 10th	Night	15% 8% 3 7% 4 5% 5% 4 6% 7% 37%	2823
	11th to 20th	Night	13% 7% 2 5% 5% 5% 4 3 5% 6% 44%	2639
	21st to end	Night	9% 6% 1 6% 5% 4 4 4 6% 7% 49%	2743
June	1st to 10th	Night	6% 5% 1 4 3 3 4 4 8% 10% 51%	1520
	11th to 20th	Night	6% 4 1 5% 3 5% 4 3 7% 10% 51%	1520
	21st to end	Night	7% 4 2 6% 3 4 4 4 6% 10% 50%	1520
July	1st to 10th	Night	12% 5% 2 4 4 4 5% 4 5% 8% 48%	2530
	11th to 20th	Night	3 2 1 3 3 3 4 4 6% 9% 62%	2658
	21st to end	Night	6% 4 1 5% 4 4 4 4 7% 9% 51%	3098
August	1st to 10th	Night	3 2 2 4 4 3 4 4 6% 9% 58%	2836
	11th to 20th	Night	11% 6% 2 4 3 3 3 3 5% 7% 53%	2798
	21st to end	Night	5% 3 1 4 3 3 4 4 6% 8% 58%	3462
September	1st to 10th	Night	10% 4 2 4 3 3 3 3 4 6% 58%	1900
	11th to 20th	Night	10% 5% 1 5% 3 3 4 3 5% 7% 53%	1943
	21st to end	Night	8% 5% 2 4 4 3 4 3 5% 6% 57%	2152
October	1st to 10th	Night	13% 5% 3 5% 4 3 3 3 4 6% 53%	2280
	11th to 20th	Night	13% 6% 2 5% 4 3 3 2 4 6% 53%	2280
	21st to end	Night	17% 7% 3 6% 4 3 4 2 4 5% 47%	2508
November	1st to 10th	Night	8% 5% 1 4 3 3 3 4 6% 7% 56%	2354
	11th to 20th	Night	11% 7% 2 6% 4 3 3 3 5% 7% 48%	2622
	21st to end	Night	16% 11% 3 6% 3 3 3 2 4 4 43%	2660
December	1st to 10th	Night	11% 11% 4 8% 5% 4 4 3 4 7% 40%	2660
	11th to 20th	Night	12% 10% 4 9% 5% 3 4 3 4 5% 42%	3279
	21st to end	Night	19% 16% 8% 12% 5% 4 3 3 3 4 24%	4884

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	40% 36% 8% 12% 4 1	2596
	11th to 20th	Day	39% 36% 7% 13% 5%	2850
	21st to end	Day	46% 39% 5% 7% 3	3135
February	1st to 10th	Day	22% 64% 3 7% 4	1710
	11th to 20th	Day	18% 64% 4 7% 6%	1673
	21st to end	Day	16% 65% 3 7% 7% 2	1547
March	1st to 10th	Day	29% 40% 5% 13% 13% 1	3436
	11th to 20th	Day	20% 39% 7% 17% 16% 1	3480
	21st to end	Day	38% 39% 11% 9% 2	3814
April	1st to 10th	Day	19% 65% 3 9% 4	2273
	11th to 20th	Day	15% 66% 5% 8% 5%	2254
	21st to end	Day	19% 65% 3 8% 5%	2357
May	1st to 10th	Day	28% 40% 7% 14% 11%	4120
	11th to 20th	Day	29% 39% 7% 20% 5%	4268
	21st to end	Day	21% 39% 5% 20% 14% 1	4837
June	1st to 10th	Day	9% 65% 6% 11% 7% 2	2660
	11th to 20th	Day	13% 66% 5% 10% 6% 1	2660
	21st to end	Day	14% 65% 7% 10% 4	2660
July	1st to 10th	Day	32% 38% 8% 15% 6% 1	4371
	11th to 20th	Day	18% 37% 10% 23% 12% 1	4220
	21st to end	Day	18% 40% 13% 19% 9% 1	4325
August	1st to 10th	Day	20% 39% 10% 22% 9%	4090
	11th to 20th	Day	28% 39% 7% 16% 10%	4080
	21st to end	Day	21% 39% 13% 19% 6% 2	4192
September	1st to 10th	Day	12% 60% 7% 11% 10% 2	2280
	11th to 20th	Day	12% 60% 6% 13% 8% 1	2233
	21st to end	Day	15% 59% 4 14% 8%	2008
October	1st to 10th	Day	12% 36% 2 10% 38% 2	3160
	11th to 20th	Day	9% 36% 4 17% 27% 7%	3140
	21st to end	Day	22% 37% 5% 18% 15% 1	3428
November	1st to 10th	Day	17% 57% 7% 9% 9% 1	1822
	11th to 20th	Day	17% 59% 3 11% 10%	1554
	21st to end	Day	21% 59% 5% 9% 6%	1520
December	1st to 10th	Day	22% 60% 5% 8% 4 1	1520
	11th to 20th	Day	23% 48% 7% 17% 4 1	1915
	21st to end	Day	51% 36% 3 7% 3 1	2783
January	1st to 10th	Night	43% 35% 5% 11% 5%	4355
	11th to 20th	Night	39% 36% 6% 10% 9% 1	4120
	21st to end	Night	42% 38% 5% 9% 4 1	4532
February	1st to 10th	Night	19% 65% 5% 7% 4 1	2470
	11th to 20th	Night	17% 63% 3 10% 6%	2404
	21st to end	Night	16% 65% 2 7% 8% 3	1919
March	1st to 10th	Night	30% 40% 4 13% 13% 1	3419
	11th to 20th	Night	18% 39% 5% 22% 11% 5%	3480
	21st to end	Night	36% 39% 11% 11% 2	3817
April	1st to 10th	Night	15% 65% 5% 10% 5% 1	1906
	11th to 20th	Night	15% 66% 5% 8% 5% 1	1875
	21st to end	Night	16% 64% 4 8% 6% 1	1819
May	1st to 10th	Night	30% 40% 5% 13% 12%	2850
	11th to 20th	Night	26% 40% 7% 18% 8%	2640
	21st to end	Night	21% 39% 6% 14% 18% 1	2751
June	1st to 10th	Night	9% 65% 5% 10% 8% 2	1520
	11th to 20th	Night	10% 66% 4 12% 6% 1	1520
	21st to end	Night	10% 64% 7% 12% 5% 1	1520
July	1st to 10th	Night	26% 37% 7% 18% 9% 3	2490
	11th to 20th	Night	10% 37% 12% 24% 16% 1	2610
	21st to end	Night	19% 39% 15% 15% 12% 1	2999
August	1st to 10th	Night	13% 38% 11% 24% 13%	2826
	11th to 20th	Night	22% 38% 8% 18% 13% 1	2825
	21st to end	Night	17% 39% 12% 23% 7% 2	3462
September	1st to 10th	Night	12% 60% 4 11% 10% 3	1900
	11th to 20th	Night	10% 61% 5% 14% 8% 2	1943
	21st to end	Night	14% 60% 3 11% 11% 1	2152
October	1st to 10th	Night	14% 36% 2 10% 37% 1	3800
	11th to 20th	Night	12% 36% 4 15% 26% 7%	3779
	21st to end	Night	25% 37% 5% 15% 16% 2	4120
November	1st to 10th	Night	14% 57% 6% 12% 9% 2	2354
	11th to 20th	Night	14% 59% 3 13% 10% 2	2622
	21st to end	Night	20% 59% 3 11% 6%	2660
December	1st to 10th	Night	20% 59% 4 10% 7% 1	2660
	11th to 20th	Night	21% 48% 6% 16% 9% 1	3281
	21st to end	Night	48% 36% 2 8% 4 1	4884

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% 19% 31% 24% 6% 1	270
	11th to 20th	Day	21% 16% 41% 19% 3	270
	21st to end	Day	19% 14% 43% 20% 4	297
February	1st to 10th	Day	19% 19% 39% 19% 4	270
	11th to 20th	Day	19% 19% 36% 18% 8% 1	270
	21st to end	Day	19% 16% 46% 15% 4	225
March	1st to 10th	Day	20% 19% 41% 17% 3	270
	11th to 20th	Day	21% 15% 37% 21% 5%	270
	21st to end	Day	36% 17% 29% 14% 4	297
April	1st to 10th	Day	23% 17% 34% 19% 6% 1	453
	11th to 20th	Day	21% 16% 33% 22% 7% 1	452
	21st to end	Day	21% 18% 34% 19% 7% 1	537
May	1st to 10th	Day	20% 14% 34% 22% 8% 2	653
	11th to 20th	Day	21% 11% 29% 28% 10% 2	675
	21st to end	Day	18% 9% 26% 27% 17% 3	734
June	1st to 10th	Day	7% 5% 21% 36% 24% 7%	680
	11th to 20th	Day	9% 4 27% 37% 19% 4	680
	21st to end	Day	10% 9% 33% 30% 15% 3	680
July	1st to 10th	Day	8% 3 18% 32% 26% 12%	671
	11th to 20th	Day	7% 4 24% 35% 23% 6%	668
	21st to end	Day	6% 3 20% 40% 26% 5%	739
August	1st to 10th	Day	7% 3 20% 41% 24% 6%	676
	11th to 20th	Day	12% 4 20% 34% 25% 5%	665
	21st to end	Day	10% 2 17% 37% 27% 8%	552
September	1st to 10th	Day	14% 5% 21% 28% 27% 6%	490
	11th to 20th	Day	9% 3 23% 33% 24% 7%	443
	21st to end	Day	11% 9% 29% 25% 21% 4	300
October	1st to 10th	Day	18% 7% 30% 26% 13% 6%	300
	11th to 20th	Day	12% 24% 34% 21% 8% 1	300
	21st to end	Day	22% 18% 31% 19% 8% 2	330
November	1st to 10th	Day	15% 12% 44% 22% 5% 2	282
	11th to 20th	Day	18% 15% 35% 23% 7% 2	270
	21st to end	Day	24% 11% 35% 23% 6%	270
December	1st to 10th	Day	10% 17% 42% 19% 9% 3	270
	11th to 20th	Day	17% 17% 37% 22% 6% 1	270
	21st to end	Day	23% 24% 34% 18% 2	297
January	1st to 10th	Night	14% 14% 41% 24% 7%	950
	11th to 20th	Night	16% 16% 41% 21% 6% 1	950
	21st to end	Night	17% 14% 40% 26% 4	1045
February	1st to 10th	Night	19% 13% 39% 25% 3	950
	11th to 20th	Night	16% 14% 39% 27% 4	929
	21st to end	Night	19% 15% 42% 20% 4 1	663
March	1st to 10th	Night	16% 13% 42% 23% 6%	570
	11th to 20th	Night	19% 12% 36% 26% 6%	570
	21st to end	Night	26% 11% 37% 21% 4	627
April	1st to 10th	Night	15% 16% 42% 24% 3	570
	11th to 20th	Night	20% 12% 37% 24% 5%	563
	21st to end	Night	20% 9% 39% 23% 7% 1	570
May	1st to 10th	Night	15% 11% 34% 34% 5% 1	570
	11th to 20th	Night	15% 8% 32% 32% 12%	561
	21st to end	Night	12% 6% 29% 36% 16% 1	617
June	1st to 10th	Night	8% 3 26% 40% 21% 2	570
	11th to 20th	Night	7% 4 28% 44% 16% 1	570
	21st to end	Night	8% 4 30% 42% 16%	570
July	1st to 10th	Night	6% 3 16% 41% 32% 3	555
	11th to 20th	Night	5% 1 21% 46% 25% 3	552
	21st to end	Night	7% 1 16% 46% 29% 1	624
August	1st to 10th	Night	4 2 18% 49% 24% 2	567
	11th to 20th	Night	8% 2 15% 44% 28% 3	564
	21st to end	Night	7% 3 13% 44% 31% 2	627
September	1st to 10th	Night	12% 3 17% 38% 27% 3	570
	11th to 20th	Night	12% 3 21% 38% 24% 3	570
	21st to end	Night	9% 5% 27% 37% 20% 2	632
October	1st to 10th	Night	14% 6% 29% 31% 17% 2	760
	11th to 20th	Night	16% 10% 39% 27% 8%	760
	21st to end	Night	19% 12% 36% 26% 7%	836
November	1st to 10th	Night	10% 11% 39% 31% 9% 1	760
	11th to 20th	Night	14% 15% 41% 23% 7%	912
	21st to end	Night	20% 13% 36% 24% 6%	950
December	1st to 10th	Night	17% 13% 40% 25% 5% 1	950
	11th to 20th	Night	19% 10% 38% 27% 6%	950
	21st to end	Night	20% 17% 38% 23% 3	1045

Page generated at 2024-11-03 01:11:11. Version ac07

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