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 2024-12-24.

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	17% 10% 3 7% 5% 4 4 4 5% 7% 34%	101243
	Night	18% 11% 4 7% 5% 4 4 3 5% 6% 34%	98776
Transparency	Day	49% 4 10% 22% 13% 2	104905
	Night	50% 4 9% 21% 13% 2	103253
Seeing	Day	24% 13% 25% 22% 12% 5%	14980
	Night	23% 10% 24% 28% 14% 1	25141

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	10% 5% 2 6% 5% 5% 5% 5% 7% 8% 41%	4120
	11th to 20th	Day	12% 6% 2 6% 5% 4 5% 4 6% 9% 41%	4120
	21st to end	Day	18% 9% 3 7% 5% 5% 4 4 5% 8% 31%	4466
August	1st to 10th	Day	12% 7% 3 8% 5% 5% 6% 5% 7% 10% 32%	4104
	11th to 20th	Day	12% 6% 2 7% 5% 4 6% 5% 7% 9% 38%	4044
	21st to end	Day	7% 4 2 5% 5% 5% 5% 4 7% 9% 48%	4340
September	1st to 10th	Day	15% 5% 2 4 3 3 4 4 6% 6% 48%	2214
	11th to 20th	Day	12% 6% 2 5% 4 5% 4 3 6% 8% 45%	2090
	21st to end	Day	19% 8% 3 6% 5% 4 3 4 5% 6% 38%	2090
October	1st to 10th	Day	17% 6% 2 5% 4 4 4 3 5% 8% 43%	1935
	11th to 20th	Day	18% 8% 2 6% 4 4 4 3 5% 6% 41%	1900
	21st to end	Day	23% 7% 2 6% 4 4 3 2 5% 5% 39%	2090
November	1st to 10th	Day	13% 8% 2 5% 4 4 4 4 4 6% 47%	1877
	11th to 20th	Day	16% 12% 3 7% 4 3 4 4 7% 6% 33%	1800
	21st to end	Day	19% 14% 5% 7% 4 3 4 3 5% 6% 32%	1637
December	1st to 10th	Day	25% 15% 6% 9% 5% 4 4 4 4 5% 21%	1600
	11th to 20th	Day	23% 17% 6% 8% 4 3 3 2 3 5% 26%	1990
	21st to end	Day	22% 20% 5% 8% 4 4 5% 3 5% 6% 17%	3100
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 7% 4 8% 9% 38%	2840
	11th to 20th	Night	11% 6% 2 7% 5% 5% 5% 4 6% 8% 40%	2840
	21st to end	Night	13% 9% 2 7% 5% 5% 5% 5% 6% 7% 37%	3087
August	1st to 10th	Night	13% 7% 3 7% 5% 5% 6% 4 7% 9% 33%	2825
	11th to 20th	Night	14% 7% 2 6% 5% 4 5% 3 5% 8% 40%	2785
	21st to end	Night	7% 5% 2 6% 4 4 6% 4 6% 9% 47%	3284
September	1st to 10th	Night	12% 5% 3 6% 4 4 4 3 5% 6% 47%	1962
	11th to 20th	Night	11% 4 1 5% 3 4 4 3 6% 7% 51%	2090
	21st to end	Night	17% 6% 3 5% 5% 4 4 3 4 7% 42%	2090
October	1st to 10th	Night	14% 5% 2 6% 3 3 4 3 5% 7% 46%	2244
	11th to 20th	Night	15% 6% 2 6% 4 5% 4 3 5% 7% 44%	2280
	21st to end	Night	23% 6% 2 5% 3 4 3 3 4 5% 42%	2508
November	1st to 10th	Night	13% 8% 2 6% 4 3 4 3 5% 5% 47%	2416
	11th to 20th	Night	20% 12% 3 5% 5% 3 4 4 4 7% 33%	2600
	21st to end	Night	19% 12% 3 8% 5% 4 4 3 4 5% 32%	2758
December	1st to 10th	Night	23% 16% 5% 10% 4 4 4 3 5% 4 23%	2800
	11th to 20th	Night	21% 17% 6% 8% 5% 4 3 3 3 5% 26%	3425
	21st to end	Night	22% 18% 6% 9% 5% 4 4 3 4 5% 21%	4610

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	38% 7% 13% 24% 14% 3	4055
	11th to 20th	Day	38% 6% 11% 30% 14% 1	4051
	21st to end	Day	51% 5% 9% 19% 15% 1	4324
August	1st to 10th	Day	45% 7% 13% 26% 8%	4091
	11th to 20th	Day	40% 6% 10% 30% 13%	4083
	21st to end	Day	31% 6% 14% 30% 17% 2	4340
September	1st to 10th	Day	36% 5% 10% 22% 23% 4	2214
	11th to 20th	Day	38% 5% 9% 27% 18% 3	2090
	21st to end	Day	48% 3 9% 20% 18% 1	2090
October	1st to 10th	Day	32% 3 7% 26% 28% 3	3208
	11th to 20th	Day	38% 4 11% 24% 16% 7%	3140
	21st to end	Day	33% 3 9% 31% 20% 4	3428
November	1st to 10th	Day	40% 3 9% 26% 18% 4	1877
	11th to 20th	Day	50% 4 9% 19% 16% 3	1800
	21st to end	Day	56% 3 9% 19% 13%	1637
December	1st to 10th	Day	67% 3 9% 16% 4 1	1600
	11th to 20th	Day	63% 2 9% 18% 7% 1	1986
	21st to end	Day	68% 3 12% 13% 5%	3100
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% 6% 11% 22% 15% 4	2795
	11th to 20th	Night	40% 7% 11% 28% 13% 1	2786
	21st to end	Night	44% 7% 10% 20% 17% 3	2988
August	1st to 10th	Night	45% 6% 16% 24% 8% 1	2814
	11th to 20th	Night	43% 6% 9% 22% 20% 1	2812
	21st to end	Night	33% 6% 11% 31% 16% 2	3284
September	1st to 10th	Night	38% 5% 12% 18% 22% 5%	1962
	11th to 20th	Night	32% 5% 12% 25% 23% 3	2090
	21st to end	Night	42% 5% 11% 21% 20% 1	2090
October	1st to 10th	Night	32% 3 9% 27% 23% 6%	3751
	11th to 20th	Night	35% 4 8% 23% 21% 9%	3779
	21st to end	Night	34% 3 5% 28% 26% 4	4120
November	1st to 10th	Night	39% 4 10% 21% 20% 6%	2416
	11th to 20th	Night	52% 3 7% 19% 15% 3	2600
	21st to end	Night	56% 3 9% 19% 12% 1	2758
December	1st to 10th	Night	65% 3 9% 17% 5% 1	2800
	11th to 20th	Night	63% 3 10% 16% 8%	3428
	21st to end	Night	66% 4 9% 15% 7%	4610

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	13% 5% 23% 32% 19% 8%	484
	21st to end	Day	20% 5% 21% 26% 21% 8%	532
August	1st to 10th	Day	13% 5% 22% 30% 19% 11%	486
	11th to 20th	Day	15% 6% 21% 28% 19% 10%	479
	21st to end	Day	12% 3 20% 30% 22% 12%	539
September	1st to 10th	Day	15% 6% 19% 28% 22% 10%	490
	11th to 20th	Day	12% 3 15% 32% 28% 11%	490
	21st to end	Day	24% 8% 22% 27% 14% 5%	490
October	1st to 10th	Day	18% 9% 25% 24% 19% 6%	490
	11th to 20th	Day	20% 14% 27% 24% 13% 2	490
	21st to end	Day	27% 15% 25% 21% 10% 1	539
November	1st to 10th	Day	20% 13% 30% 25% 10% 3	415
	11th to 20th	Day	29% 16% 31% 17% 5% 1	300
	21st to end	Day	31% 19% 35% 12% 2 1	217
December	1st to 10th	Day	32% 24% 29% 11% 5% 1	200
	11th to 20th	Day	39% 19% 22% 17% 5%	200
	21st to end	Day	37% 19% 26% 13% 5%	293
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% 39% 30% 5%	552
	21st to end	Night	14% 2 12% 36% 32% 4	624
August	1st to 10th	Night	10% 2 14% 38% 32% 3	567
	11th to 20th	Night	15% 2 12% 38% 28% 5%	564
	21st to end	Night	12% 2 12% 33% 33% 6%	722
September	1st to 10th	Night	14% 3 15% 35% 28% 5%	760
	11th to 20th	Night	13% 3 17% 30% 33% 4	760
	21st to end	Night	19% 5% 21% 32% 20% 3	760
October	1st to 10th	Night	17% 5% 19% 31% 24% 3	760
	11th to 20th	Night	18% 10% 26% 31% 13% 1	760
	21st to end	Night	26% 9% 23% 29% 12% 1	836
November	1st to 10th	Night	17% 9% 26% 32% 16%	780
	11th to 20th	Night	30% 11% 26% 24% 8% 1	800
	21st to end	Night	28% 12% 26% 27% 8% 1	800
December	1st to 10th	Night	33% 16% 27% 20% 5%	800
	11th to 20th	Night	29% 16% 27% 24% 5%	800
	21st to end	Night	31% 13% 27% 28% 2	851

Page generated at 2024-12-21 04:13:53. Version ac07

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