Possum Poop Hollow Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Possum Poop Hollow Observatory clear sky chart from 2005-11-06 to 2024-07-16.

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	18% 10% 3 7% 5% 4 4 4 5% 7% 32%	89469
	Night	18% 11% 4 7% 5% 4 4 3 5% 6% 34%	89938
Transparency	Day	51% 4 10% 21% 12% 2	89241
	Night	52% 4 10% 20% 12% 2	89770
Seeing	Day	24% 13% 25% 22% 12% 5%	14414
	Night	23% 10% 24% 28% 14% 2	24539

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	20% 20% 9% 10% 5% 3 4 2 3 6% 19%	2836
	11th to 20th	Day	18% 21% 9% 11% 8% 4 3 2 3 3 18%	2840
	21st to end	Day	23% 22% 6% 9% 6% 3 3 3 3 4 17%	3124
February	1st to 10th	Day	22% 15% 4 9% 6% 3 3 2 4 5% 26%	1710
	11th to 20th	Day	20% 16% 3 11% 5% 4 3 3 5% 6% 24%	1706
	21st to end	Day	22% 15% 4 9% 4 3 3 2 4 5% 28%	1582
March	1st to 10th	Day	21% 16% 4 8% 4 3 3 3 4 6% 29%	3435
	11th to 20th	Day	16% 9% 3 6% 4 4 5% 3 5% 7% 39%	3480
	21st to end	Day	21% 10% 3 7% 5% 4 5% 3 6% 7% 30%	3815
April	1st to 10th	Day	17% 12% 3 7% 6% 5% 4 3 5% 6% 32%	2146
	11th to 20th	Day	17% 9% 2 6% 4 4 4 3 5% 7% 39%	2300
	21st to end	Day	21% 8% 3 6% 4 3 4 4 5% 8% 33%	2470
May	1st to 10th	Day	22% 10% 3 8% 5% 5% 5% 4 5% 7% 26%	4082
	11th to 20th	Day	20% 8% 3 7% 4 5% 5% 3 6% 7% 33%	4081
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 5% 7% 10% 38%	4476
June	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 5% 6% 9% 37%	2527
	11th to 20th	Day	13% 6% 2 6% 5% 5% 6% 5% 7% 8% 37%	2646
	21st to end	Day	14% 6% 2 5% 5% 5% 5% 5% 7% 9% 37%	2470
July	1st to 10th	Day	13% 6% 3 7% 6% 5% 5% 5% 7% 8% 36%	2470
	11th to 20th	Day	13% 6% 2 5% 5% 5% 5% 5% 7% 9% 38%	2407
	21st to end	Day	15% 7% 3 6% 6% 6% 5% 5% 6% 9% 34%	2547
August	1st to 10th	Day	12% 6% 2 7% 5% 5% 6% 5% 8% 11% 32%	2327
	11th to 20th	Day	14% 7% 2 7% 5% 4 5% 5% 7% 10% 34%	2303
	21st to end	Day	12% 6% 2 6% 5% 5% 4 4 6% 9% 41%	2466
September	1st to 10th	Day	16% 5% 2 4 3 3 4 4 6% 6% 46%	2098
	11th to 20th	Day	13% 6% 2 5% 4 5% 4 3 6% 8% 45%	1980
	21st to end	Day	19% 7% 3 6% 5% 4 3 3 5% 6% 39%	1980
October	1st to 10th	Day	17% 6% 2 5% 4 4 4 3 5% 8% 41%	1834
	11th to 20th	Day	19% 8% 2 6% 4 4 4 3 6% 5% 39%	1800
	21st to end	Day	24% 8% 2 6% 4 4 3 2 4 5% 38%	1980
November	1st to 10th	Day	13% 8% 2 5% 4 4 4 4 4 6% 46%	1781
	11th to 20th	Day	16% 12% 3 7% 4 3 4 4 6% 6% 34%	1710
	21st to end	Day	19% 13% 4 7% 4 4 4 3 5% 6% 33%	1556
December	1st to 10th	Day	25% 16% 6% 8% 5% 4 4 3 4 5% 21%	1520
	11th to 20th	Day	22% 17% 6% 8% 4 3 3 2 3 5% 26%	1910
	21st to end	Day	22% 20% 5% 8% 4 4 5% 3 5% 6% 17%	3074
January	1st to 10th	Night	18% 21% 7% 11% 5% 4 4 3 4 4 20%	4109
	11th to 20th	Night	20% 18% 6% 12% 6% 6% 3 3 3 4 19%	4120
	21st to end	Night	27% 17% 6% 10% 5% 3 3 2 3 3 21%	4532
February	1st to 10th	Night	21% 14% 4 9% 6% 3 4 3 4 5% 27%	2470
	11th to 20th	Night	22% 14% 4 9% 5% 5% 4 3 5% 4 25%	2356
	21st to end	Night	23% 15% 4 7% 4 3 4 3 5% 5% 27%	1870
March	1st to 10th	Night	23% 12% 3 6% 4 4 3 3 4 6% 32%	3418
	11th to 20th	Night	16% 12% 5% 8% 4 4 4 3 5% 6% 35%	3480
	21st to end	Night	18% 9% 3 6% 4 4 3 3 5% 5% 40%	3817
April	1st to 10th	Night	20% 12% 2 5% 5% 3 4 3 5% 8% 34%	2033
	11th to 20th	Night	18% 8% 3 5% 4 4 3 4 5% 8% 39%	1844
	21st to end	Night	17% 6% 3 7% 4 4 4 3 6% 6% 41%	1710
May	1st to 10th	Night	27% 11% 4 7% 4 5% 4 3 5% 6% 24%	2813
	11th to 20th	Night	18% 9% 3 7% 5% 3 4 3 5% 7% 37%	2812
	21st to end	Night	14% 8% 3 6% 4 5% 5% 4 5% 8% 39%	3079
June	1st to 10th	Night	12% 6% 2 4 4 5% 5% 4 6% 8% 43%	1639
	11th to 20th	Night	10% 5% 2 7% 5% 5% 5% 5% 7% 10% 40%	1521
	21st to end	Night	14% 5% 2 5% 4 5% 4 4 7% 10% 42%	1709
July	1st to 10th	Night	10% 7% 3 7% 5% 4 6% 4 8% 8% 38%	1710
	11th to 20th	Night	10% 5% 2 6% 5% 5% 5% 4 6% 10% 42%	1674
	21st to end	Night	12% 5% 1 6% 4 5% 5% 5% 8% 9% 40%	1771
August	1st to 10th	Night	9% 5% 2 7% 5% 4 6% 5% 7% 9% 39%	1611
	11th to 20th	Night	12% 7% 2 6% 5% 5% 5% 4 6% 8% 41%	1598
	21st to end	Night	11% 5% 2 5% 3 4 5% 3 5% 8% 48%	1872
September	1st to 10th	Night	12% 5% 3 6% 4 4 4 3 5% 6% 47%	1858
	11th to 20th	Night	11% 4 1 5% 3 4 4 3 6% 7% 51%	1980
	21st to end	Night	16% 6% 3 5% 5% 4 4 3 4 7% 44%	1980
October	1st to 10th	Night	15% 6% 2 6% 3 3 4 3 6% 7% 45%	2125
	11th to 20th	Night	16% 6% 2 6% 4 5% 4 3 5% 7% 43%	2160
	21st to end	Night	24% 7% 2 5% 4 4 3 3 4 5% 40%	2376
November	1st to 10th	Night	13% 8% 2 6% 3 3 4 3 5% 4 47%	2292
	11th to 20th	Night	19% 12% 3 5% 5% 3 4 4 4 7% 34%	2470
	21st to end	Night	19% 12% 3 8% 5% 4 4 3 4 5% 32%	2620
December	1st to 10th	Night	23% 17% 5% 9% 4 4 4 3 5% 4 23%	2660
	11th to 20th	Night	20% 16% 6% 8% 5% 4 3 3 4 5% 26%	3285
	21st to end	Night	22% 18% 6% 9% 5% 5% 4 3 4 5% 21%	4564

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	69% 3 10% 13% 5%	2837
	11th to 20th	Day	74% 3 6% 12% 5%	2840
	21st to end	Day	73% 2 6% 14% 4 1	3124
February	1st to 10th	Day	64% 3 8% 18% 7% 1	1710
	11th to 20th	Day	63% 4 8% 16% 8% 1	1715
	21st to end	Day	61% 3 8% 17% 10% 1	1582
March	1st to 10th	Day	58% 3 8% 21% 9% 1	3435
	11th to 20th	Day	45% 4 8% 30% 12% 1	3480
	21st to end	Day	53% 5% 7% 22% 12% 1	3815
April	1st to 10th	Day	53% 4 9% 18% 13% 3	2146
	11th to 20th	Day	46% 4 11% 18% 18% 3	2300
	21st to end	Day	50% 4 11% 21% 12% 2	2470
May	1st to 10th	Day	57% 4 10% 21% 8% 1	4120
	11th to 20th	Day	51% 5% 11% 21% 12% 1	4085
	21st to end	Day	39% 7% 16% 22% 13% 3	4489
June	1st to 10th	Day	43% 6% 13% 22% 15% 1	2527
	11th to 20th	Day	43% 7% 13% 22% 13% 1	2646
	21st to end	Day	42% 6% 14% 24% 13% 1	2470
July	1st to 10th	Day	43% 7% 14% 19% 14% 3	2405
	11th to 20th	Day	41% 7% 11% 24% 15% 2	2338
	21st to end	Day	46% 5% 11% 23% 13% 2	2405
August	1st to 10th	Day	44% 6% 15% 25% 10% 1	2314
	11th to 20th	Day	43% 6% 13% 26% 11% 1	2303
	21st to end	Day	40% 6% 13% 25% 13% 3	2466
September	1st to 10th	Day	37% 5% 11% 22% 22% 3	2098
	11th to 20th	Day	38% 5% 9% 27% 17% 3	1980
	21st to end	Day	46% 3 9% 21% 19% 1	1980
October	1st to 10th	Day	42% 4 12% 23% 17% 2	1834
	11th to 20th	Day	46% 4 9% 25% 15%	1800
	21st to end	Day	50% 3 7% 23% 15% 2	1980
November	1st to 10th	Day	40% 3 10% 26% 17% 4	1781
	11th to 20th	Day	49% 4 9% 19% 16% 3	1710
	21st to end	Day	54% 3 9% 20% 13%	1556
December	1st to 10th	Day	67% 3 8% 16% 4 1	1520
	11th to 20th	Day	63% 2 9% 18% 7% 1	1906
	21st to end	Day	68% 3 12% 13% 4	3074
January	1st to 10th	Night	70% 3 8% 13% 6% 1	4109
	11th to 20th	Night	71% 3 10% 13% 3	4120
	21st to end	Night	71% 2 6% 15% 5% 1	4532
February	1st to 10th	Night	61% 4 10% 16% 9%	2470
	11th to 20th	Night	63% 2 7% 17% 10%	2358
	21st to end	Night	60% 3 9% 15% 9% 3	1870
March	1st to 10th	Night	55% 4 7% 23% 11% 1	3418
	11th to 20th	Night	50% 5% 8% 26% 11% 1	3480
	21st to end	Night	46% 4 7% 25% 15% 2	3817
April	1st to 10th	Night	51% 4 8% 20% 14% 2	2033
	11th to 20th	Night	44% 4 12% 20% 16% 5%	1844
	21st to end	Night	44% 5% 11% 22% 16% 2	1710
May	1st to 10th	Night	61% 5% 8% 15% 10% 2	2840
	11th to 20th	Night	48% 7% 10% 22% 11% 1	2813
	21st to end	Night	42% 8% 13% 23% 11% 4	3087
June	1st to 10th	Night	37% 7% 11% 27% 16% 2	1639
	11th to 20th	Night	39% 8% 14% 23% 15% 2	1521
	21st to end	Night	37% 8% 15% 23% 16% 2	1709
July	1st to 10th	Night	41% 8% 13% 21% 14% 3	1665
	11th to 20th	Night	35% 8% 13% 25% 17% 2	1620
	21st to end	Night	37% 8% 14% 24% 17% 1	1672
August	1st to 10th	Night	39% 7% 16% 24% 13% 1	1600
	11th to 20th	Night	40% 7% 13% 23% 16% 1	1598
	21st to end	Night	34% 6% 13% 28% 16% 4	1872
September	1st to 10th	Night	38% 5% 13% 18% 21% 5%	1858
	11th to 20th	Night	32% 6% 12% 26% 22% 3	1980
	21st to end	Night	41% 5% 11% 21% 21% 1	1980
October	1st to 10th	Night	38% 4 12% 25% 17% 3	2125
	11th to 20th	Night	41% 4 9% 25% 19% 2	2160
	21st to end	Night	48% 3 6% 24% 17% 2	2376
November	1st to 10th	Night	40% 4 10% 20% 20% 6%	2292
	11th to 20th	Night	51% 3 7% 19% 16% 3	2470
	21st to end	Night	55% 3 9% 20% 12% 1	2620
December	1st to 10th	Night	65% 3 8% 17% 5% 1	2660
	11th to 20th	Night	63% 3 10% 17% 8%	3288
	21st to end	Night	66% 4 9% 15% 6%	4564

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	30% 30% 26% 10% 6%	270
	11th to 20th	Day	43% 21% 28% 7%	270
	21st to end	Day	37% 26% 26% 8% 2 1	297
February	1st to 10th	Day	34% 21% 33% 8% 3	270
	11th to 20th	Day	44% 25% 23% 7% 1	270
	21st to end	Day	38% 23% 31% 7%	237
March	1st to 10th	Day	34% 18% 27% 16% 5%	460
	11th to 20th	Day	31% 23% 27% 14% 5% 1	460
	21st to end	Day	32% 16% 32% 15% 5%	506
April	1st to 10th	Day	29% 22% 23% 19% 6% 1	460
	11th to 20th	Day	27% 18% 26% 16% 8% 4	452
	21st to end	Day	29% 17% 27% 19% 6% 2	460
May	1st to 10th	Day	26% 17% 27% 16% 9% 5%	463
	11th to 20th	Day	23% 12% 28% 23% 10% 4	487
	21st to end	Day	16% 9% 26% 26% 16% 7%	529
June	1st to 10th	Day	17% 9% 22% 30% 16% 6%	490
	11th to 20th	Day	18% 7% 24% 28% 18% 6%	490
	21st to end	Day	16% 8% 29% 29% 13% 4	490
July	1st to 10th	Day	16% 5% 19% 26% 20% 14%	485
	11th to 20th	Day	12% 4 23% 33% 20% 9%	465
	21st to end	Day	19% 5% 20% 26% 21% 9%	488
August	1st to 10th	Day	13% 4 21% 30% 20% 12%	446
	11th to 20th	Day	15% 6% 19% 28% 20% 11%	439
	21st to end	Day	13% 3 21% 31% 20% 12%	495
September	1st to 10th	Day	16% 6% 18% 28% 22% 10%	450
	11th to 20th	Day	12% 3 15% 31% 28% 11%	450
	21st to end	Day	22% 8% 22% 28% 14% 5%	450
October	1st to 10th	Day	18% 9% 25% 23% 19% 6%	450
	11th to 20th	Day	20% 14% 28% 24% 12% 1	450
	21st to end	Day	29% 16% 24% 20% 10% 1	495
November	1st to 10th	Day	20% 12% 29% 26% 10% 3	379
	11th to 20th	Day	30% 18% 28% 18% 6% 1	270
	21st to end	Day	28% 19% 35% 14% 3 1	196
December	1st to 10th	Day	33% 24% 26% 11% 5% 1	180
	11th to 20th	Day	38% 19% 22% 16% 5%	180
	21st to end	Day	38% 19% 26% 12% 5%	285
January	1st to 10th	Night	32% 18% 26% 19% 4	760
	11th to 20th	Night	34% 17% 28% 19% 2	760
	21st to end	Night	30% 18% 31% 19% 2	836
February	1st to 10th	Night	31% 13% 29% 25% 2	760
	11th to 20th	Night	34% 19% 30% 16% 2	743
	21st to end	Night	34% 16% 31% 17% 2	628
March	1st to 10th	Night	28% 14% 28% 26% 4	760
	11th to 20th	Night	31% 16% 28% 18% 6% 1	760
	21st to end	Night	28% 13% 33% 22% 4 1	836
April	1st to 10th	Night	28% 15% 28% 23% 6%	760
	11th to 20th	Night	21% 14% 31% 22% 11% 1	720
	21st to end	Night	18% 11% 31% 32% 8% 1	570
May	1st to 10th	Night	23% 9% 25% 31% 11% 1	570
	11th to 20th	Night	20% 6% 27% 31% 15% 1	561
	21st to end	Night	14% 3 23% 32% 23% 4	617
June	1st to 10th	Night	13% 3 24% 36% 23% 1	499
	11th to 20th	Night	12% 4 22% 38% 23% 1	381
	21st to end	Night	16% 3 18% 40% 22% 2	569
July	1st to 10th	Night	14% 2 17% 37% 27% 4	555
	11th to 20th	Night	10% 3 14% 38% 30% 5%	540
	21st to end	Night	14% 3 12% 36% 31% 4	591
August	1st to 10th	Night	10% 2 13% 39% 34% 3	537
	11th to 20th	Night	14% 3 11% 38% 29% 5%	534
	21st to end	Night	13% 3 13% 33% 33% 6%	684
September	1st to 10th	Night	14% 3 15% 34% 29% 5%	720
	11th to 20th	Night	13% 3 18% 30% 33% 4	720
	21st to end	Night	18% 6% 20% 33% 22% 3	720
October	1st to 10th	Night	18% 5% 20% 30% 23% 4	720
	11th to 20th	Night	19% 10% 26% 32% 12% 1	720
	21st to end	Night	27% 9% 23% 29% 11% 1	792
November	1st to 10th	Night	17% 9% 25% 32% 16%	740
	11th to 20th	Night	29% 11% 26% 24% 9% 1	760
	21st to end	Night	27% 11% 25% 28% 8% 1	760
December	1st to 10th	Night	33% 16% 27% 20% 4	760
	11th to 20th	Night	28% 17% 27% 24% 5%	760
	21st to end	Night	31% 13% 26% 28% 2	836

Page generated at 2024-07-13 10:19:50. Version ac07

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