Tuscarora Shale Pit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tuscarora Shale Pit clear sky chart from 2005-11-06 to 2025-12-18.

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	15% 7% 3 7% 5% 5% 5% 4 6% 8% 36%	127228
	Night	15% 7% 3 7% 5% 5% 5% 4 6% 7% 38%	123801
Transparency	Day	44% 5% 12% 23% 14% 2	130823
	Night	43% 5% 12% 23% 15% 2	128275
Seeing	Day	25% 16% 27% 19% 10% 3	16236
	Night	22% 15% 25% 26% 11% 1	25734

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	12% 9% 3 12% 7% 5% 5% 4 4 5% 33%	3615
	11th to 20th	Day	12% 12% 5% 11% 7% 6% 6% 4 5% 7% 25%	4060
	21st to end	Day	15% 11% 4 9% 6% 5% 4 3 5% 6% 32%	4466
February	1st to 10th	Day	14% 13% 4 8% 7% 5% 4 3 6% 6% 31%	1800
	11th to 20th	Day	14% 9% 3 9% 6% 5% 4 4 5% 6% 34%	1759
	21st to end	Day	18% 10% 2 9% 5% 4 4 3 6% 6% 33%	1650
March	1st to 10th	Day	19% 7% 2 7% 4 5% 4 3 4 6% 38%	4881
	11th to 20th	Day	11% 6% 3 7% 5% 5% 5% 4 6% 8% 41%	4980
	21st to end	Day	13% 9% 2 6% 5% 5% 5% 4 5% 6% 40%	5528
April	1st to 10th	Day	16% 9% 3 8% 6% 4 5% 3 5% 6% 35%	2400
	11th to 20th	Day	15% 8% 2 8% 5% 4 4 4 6% 6% 38%	2374
	21st to end	Day	18% 6% 2 7% 4 5% 4 4 5% 6% 38%	2435
May	1st to 10th	Day	25% 6% 2 6% 4 5% 6% 4 6% 8% 28%	5862
	11th to 20th	Day	25% 6% 2 6% 5% 4 5% 4 5% 8% 29%	6226
	21st to end	Day	17% 6% 2 6% 4 5% 5% 5% 8% 9% 33%	6934
June	1st to 10th	Day	14% 5% 2 5% 5% 5% 6% 4 7% 8% 38%	2800
	11th to 20th	Day	14% 5% 2 7% 5% 4 5% 4 7% 9% 36%	2800
	21st to end	Day	10% 4 2 6% 5% 5% 5% 5% 7% 11% 41%	2800
July	1st to 10th	Day	5% 5% 2 7% 5% 6% 6% 5% 7% 9% 42%	6360
	11th to 20th	Day	7% 6% 3 7% 5% 7% 7% 6% 8% 11% 32%	6278
	21st to end	Day	10% 7% 3 7% 5% 4 5% 4 7% 9% 40%	6424
August	1st to 10th	Day	18% 6% 2 6% 5% 6% 6% 5% 7% 8% 32%	4234
	11th to 20th	Day	12% 5% 2 6% 4 6% 7% 5% 7% 8% 37%	4084
	21st to end	Day	15% 5% 2 5% 4 4 4 3 6% 8% 45%	4312
September	1st to 10th	Day	16% 6% 2 5% 4 4 4 3 5% 6% 45%	2400
	11th to 20th	Day	14% 5% 1 4 4 3 4 4 5% 8% 48%	2400
	21st to end	Day	21% 9% 2 6% 4 4 4 3 4 6% 37%	2090
October	1st to 10th	Day	16% 7% 2 5% 3 4 4 3 5% 6% 44%	2000
	11th to 20th	Day	17% 6% 2 5% 4 4 5% 4 6% 7% 41%	2000
	21st to end	Day	15% 6% 3 6% 5% 4 4 3 6% 7% 42%	2200
November	1st to 10th	Day	11% 5% 2 6% 4 3 4 3 6% 8% 48%	1929
	11th to 20th	Day	14% 7% 3 7% 5% 4 4 4 6% 8% 38%	1781
	21st to end	Day	15% 7% 2 8% 5% 5% 4 4 7% 7% 36%	1680
December	1st to 10th	Day	14% 6% 4 9% 7% 5% 5% 5% 8% 7% 31%	2680
	11th to 20th	Day	20% 12% 3 6% 4 4 5% 4 5% 6% 32%	3046
	21st to end	Day	17% 9% 4 10% 7% 6% 7% 4 6% 6% 23%	3960
January	1st to 10th	Night	11% 8% 3 11% 7% 6% 5% 4 6% 8% 33%	6329
	11th to 20th	Night	12% 8% 3 9% 6% 6% 6% 5% 6% 7% 32%	5900
	21st to end	Night	16% 8% 3 7% 5% 5% 5% 4 6% 7% 34%	6490
February	1st to 10th	Night	15% 9% 3 7% 6% 4 5% 4 5% 7% 35%	2600
	11th to 20th	Night	15% 9% 3 7% 5% 5% 4 4 6% 7% 35%	2525
	21st to end	Night	16% 9% 3 7% 4 6% 5% 4 5% 7% 34%	1980
March	1st to 10th	Night	17% 8% 2 7% 5% 5% 4 3 5% 6% 39%	4971
	11th to 20th	Night	10% 6% 3 7% 4 4 3 3 5% 6% 47%	4980
	21st to end	Night	12% 7% 3 6% 5% 4 5% 4 6% 7% 42%	5389
April	1st to 10th	Night	17% 10% 3 8% 6% 4 4 4 5% 7% 33%	2000
	11th to 20th	Night	15% 7% 3 6% 5% 4 4 3 7% 7% 40%	1975
	21st to end	Night	17% 5% 2 5% 4 4 4 4 6% 6% 42%	1982
May	1st to 10th	Night	27% 9% 3 6% 4 4 4 4 6% 6% 27%	4033
	11th to 20th	Night	25% 7% 2 4 4 3 4 3 6% 8% 33%	3667
	21st to end	Night	20% 6% 2 6% 4 4 4 4 6% 8% 35%	3920
June	1st to 10th	Night	13% 7% 2 4 4 4 5% 4 6% 7% 44%	1600
	11th to 20th	Night	13% 6% 3 6% 5% 4 5% 3 7% 8% 40%	1600
	21st to end	Night	10% 5% 2 5% 4 4 4 4 8% 10% 44%	1600
July	1st to 10th	Night	8% 6% 3 7% 5% 5% 5% 4 7% 10% 41%	3598
	11th to 20th	Night	9% 7% 3 7% 6% 6% 6% 6% 8% 10% 32%	3675
	21st to end	Night	10% 6% 2 6% 5% 4 4 4 6% 8% 45%	4427
August	1st to 10th	Night	18% 6% 2 6% 5% 4 4 4 6% 9% 35%	2915
	11th to 20th	Night	13% 7% 2 6% 4 4 4 3 6% 7% 42%	2931
	21st to end	Night	16% 4 1 5% 3 5% 4 3 5% 9% 45%	3586
September	1st to 10th	Night	14% 6% 2 5% 4 4 3 3 5% 7% 48%	2000
	11th to 20th	Night	12% 5% 1 5% 3 2 3 3 5% 7% 52%	2000
	21st to end	Night	21% 6% 3 6% 3 4 4 3 6% 7% 38%	2306
October	1st to 10th	Night	18% 6% 2 5% 3 4 3 3 5% 6% 46%	2400
	11th to 20th	Night	16% 6% 2 6% 4 4 4 3 5% 6% 46%	2400
	21st to end	Night	16% 6% 2 5% 4 3 5% 3 6% 6% 44%	2640
November	1st to 10th	Night	10% 7% 2 4 4 3 4 3 5% 6% 51%	2587
	11th to 20th	Night	14% 8% 2 6% 5% 4 4 4 6% 7% 41%	2835
	21st to end	Night	14% 7% 3 6% 5% 5% 5% 4 6% 8% 37%	2940
December	1st to 10th	Night	10% 6% 3 8% 6% 6% 6% 5% 6% 8% 37%	4720
	11th to 20th	Night	19% 9% 3 7% 5% 5% 5% 4 5% 6% 32%	5304
	21st to end	Night	17% 10% 3 10% 6% 6% 6% 4 5% 7% 26%	6996

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	50% 5% 11% 20% 12% 2	3616
	11th to 20th	Day	55% 6% 10% 14% 12% 3	4060
	21st to end	Day	53% 4 10% 21% 12% 1	4466
February	1st to 10th	Day	53% 4 11% 21% 10% 1	1800
	11th to 20th	Day	51% 5% 10% 23% 11% 1	1768
	21st to end	Day	52% 3 11% 22% 9% 4	1650
March	1st to 10th	Day	47% 4 9% 22% 13% 5%	4881
	11th to 20th	Day	39% 5% 13% 27% 11% 5%	4980
	21st to end	Day	44% 4 11% 19% 17% 4	5528
April	1st to 10th	Day	50% 3 10% 18% 15% 3	2400
	11th to 20th	Day	45% 4 9% 21% 17% 3	2374
	21st to end	Day	47% 4 7% 23% 16% 3	2435
May	1st to 10th	Day	53% 5% 12% 18% 11% 1	5897
	11th to 20th	Day	52% 5% 10% 22% 10% 1	6230
	21st to end	Day	44% 6% 13% 21% 14% 2	6949
June	1st to 10th	Day	41% 5% 12% 24% 16% 1	2800
	11th to 20th	Day	42% 6% 15% 21% 14% 2	2800
	21st to end	Day	36% 6% 12% 29% 15% 1	2800
July	1st to 10th	Day	37% 8% 12% 26% 15% 2	6290
	11th to 20th	Day	41% 9% 17% 21% 11% 1	6203
	21st to end	Day	38% 6% 11% 23% 21% 1	6240
August	1st to 10th	Day	47% 7% 13% 23% 9%	4221
	11th to 20th	Day	40% 8% 11% 26% 14% 1	4123
	21st to end	Day	37% 4 11% 29% 17% 2	4312
September	1st to 10th	Day	40% 4 11% 22% 20% 3	2400
	11th to 20th	Day	34% 4 10% 27% 22% 3	2400
	21st to end	Day	49% 3 9% 17% 20% 2	2090
October	1st to 10th	Day	36% 4 8% 26% 21% 5%	3260
	11th to 20th	Day	31% 6% 13% 27% 19% 5%	3240
	21st to end	Day	28% 3 12% 32% 24% 1	3538
November	1st to 10th	Day	35% 4 14% 22% 21% 4	1929
	11th to 20th	Day	44% 4 9% 23% 17% 3	1781
	21st to end	Day	45% 4 13% 26% 10% 1	1680
December	1st to 10th	Day	48% 6% 15% 23% 6% 2	2680
	11th to 20th	Day	52% 4 13% 22% 7% 1	3042
	21st to end	Day	57% 6% 14% 13% 8% 1	3960
January	1st to 10th	Night	45% 7% 12% 22% 12% 1	6329
	11th to 20th	Night	46% 7% 14% 18% 11% 4	5900
	21st to end	Night	46% 5% 12% 23% 12% 2	6490
February	1st to 10th	Night	49% 4 13% 24% 9% 1	2600
	11th to 20th	Night	48% 4 11% 20% 15% 2	2527
	21st to end	Night	49% 4 10% 21% 13% 3	1980
March	1st to 10th	Night	44% 5% 11% 23% 12% 5%	4971
	11th to 20th	Night	36% 4 14% 29% 11% 5%	4980
	21st to end	Night	40% 5% 12% 19% 22% 3	5389
April	1st to 10th	Night	51% 4 9% 18% 15% 3	2000
	11th to 20th	Night	42% 4 10% 22% 18% 3	1975
	21st to end	Night	41% 4 10% 25% 17% 4	1982
May	1st to 10th	Night	57% 4 10% 16% 10% 3	4060
	11th to 20th	Night	49% 5% 12% 23% 9% 1	3668
	21st to end	Night	47% 5% 13% 23% 11% 2	3927
June	1st to 10th	Night	38% 5% 12% 26% 17% 3	1600
	11th to 20th	Night	40% 5% 13% 24% 16% 2	1600
	21st to end	Night	34% 5% 16% 27% 18% 1	1600
July	1st to 10th	Night	37% 8% 15% 21% 15% 4	3560
	11th to 20th	Night	43% 8% 17% 20% 12% 1	3630
	21st to end	Night	36% 6% 12% 22% 23% 1	4297
August	1st to 10th	Night	45% 6% 15% 24% 10% 1	2904
	11th to 20th	Night	40% 6% 11% 27% 16% 1	2958
	21st to end	Night	35% 5% 12% 29% 16% 2	3586
September	1st to 10th	Night	38% 4 11% 24% 20% 4	2000
	11th to 20th	Night	32% 3 9% 31% 22% 3	2000
	21st to end	Night	46% 4 10% 20% 18% 2	2306
October	1st to 10th	Night	36% 3 10% 27% 22% 1	3920
	11th to 20th	Night	30% 4 10% 28% 22% 6%	3899
	21st to end	Night	28% 4 11% 31% 24% 3	4252
November	1st to 10th	Night	34% 3 11% 26% 22% 4	2587
	11th to 20th	Night	41% 4 9% 24% 17% 4	2835
	21st to end	Night	43% 5% 12% 26% 13% 1	2940
December	1st to 10th	Night	44% 6% 16% 27% 8%	4720
	11th to 20th	Night	50% 5% 13% 21% 10% 1	5307
	21st to end	Night	56% 5% 12% 17% 10%	6996

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	38% 26% 26% 7% 2	203
	11th to 20th	Day	39% 22% 31% 7% 2	300
	21st to end	Day	33% 33% 24% 8% 2	330
February	1st to 10th	Day	36% 28% 26% 9% 1	300
	11th to 20th	Day	46% 25% 26% 3	306
	21st to end	Day	38% 20% 27% 13% 2	414
March	1st to 10th	Day	35% 20% 28% 15% 2	500
	11th to 20th	Day	34% 24% 25% 12% 4 1	500
	21st to end	Day	31% 24% 28% 11% 4 1	550
April	1st to 10th	Day	32% 24% 27% 13% 4	500
	11th to 20th	Day	28% 22% 25% 15% 8% 3	492
	21st to end	Day	29% 19% 32% 13% 6% 1	500
May	1st to 10th	Day	34% 17% 28% 13% 7% 2	503
	11th to 20th	Day	26% 18% 27% 18% 9% 2	527
	21st to end	Day	23% 12% 26% 21% 13% 5%	573
June	1st to 10th	Day	21% 14% 28% 21% 13% 3	530
	11th to 20th	Day	23% 11% 28% 24% 11% 3	530
	21st to end	Day	13% 12% 33% 26% 13% 3	530
July	1st to 10th	Day	14% 6% 26% 30% 16% 8%	525
	11th to 20th	Day	9% 6% 30% 32% 17% 6%	524
	21st to end	Day	13% 9% 30% 29% 14% 4	576
August	1st to 10th	Day	15% 6% 23% 32% 17% 7%	526
	11th to 20th	Day	16% 5% 24% 32% 17% 6%	519
	21st to end	Day	15% 8% 25% 28% 15% 8%	583
September	1st to 10th	Day	21% 10% 21% 25% 15% 8%	530
	11th to 20th	Day	15% 5% 22% 33% 18% 7%	530
	21st to end	Day	32% 12% 24% 17% 12% 3	530
October	1st to 10th	Day	23% 10% 23% 24% 16% 4	530
	11th to 20th	Day	23% 20% 27% 20% 9% 2	530
	21st to end	Day	21% 20% 36% 16% 7% 1	583
November	1st to 10th	Day	19% 19% 30% 20% 9% 2	467
	11th to 20th	Day	29% 22% 26% 17% 5%	321
	21st to end	Day	30% 23% 36% 7% 3	220
December	1st to 10th	Day	33% 29% 24% 10% 4	220
	11th to 20th	Day	34% 25% 29% 11% 1	214
	21st to end	Day	29% 26% 25% 16% 4	220
January	1st to 10th	Night	24% 27% 31% 15% 3	800
	11th to 20th	Night	29% 21% 27% 20% 3	800
	21st to end	Night	22% 26% 30% 20% 2	880
February	1st to 10th	Night	24% 23% 27% 25% 2	800
	11th to 20th	Night	30% 28% 26% 15% 1	783
	21st to end	Night	28% 25% 27% 19% 2	660
March	1st to 10th	Night	26% 23% 29% 18% 4	800
	11th to 20th	Night	28% 21% 26% 19% 6% 1	800
	21st to end	Night	25% 21% 29% 19% 5% 1	880
April	1st to 10th	Night	29% 20% 27% 20% 4	800
	11th to 20th	Night	21% 20% 28% 24% 7% 1	791
	21st to end	Night	24% 14% 29% 26% 8%	782
May	1st to 10th	Night	26% 9% 25% 28% 12%	600
	11th to 20th	Night	22% 11% 30% 28% 9%	434
	21st to end	Night	19% 10% 22% 31% 18% 1	433
June	1st to 10th	Night	15% 5% 26% 35% 18% 1	400
	11th to 20th	Night	17% 7% 23% 35% 18% 1	400
	21st to end	Night	13% 5% 27% 39% 17%	400
July	1st to 10th	Night	13% 3 22% 37% 22% 3	390
	11th to 20th	Night	10% 3 21% 40% 24% 2	414
	21st to end	Night	11% 4 20% 40% 22% 3	657
August	1st to 10th	Night	12% 2 15% 41% 27% 3	597
	11th to 20th	Night	16% 4 14% 39% 25% 4	624
	21st to end	Night	14% 4 19% 34% 26% 3	880
September	1st to 10th	Night	18% 3 21% 32% 23% 3	800
	11th to 20th	Night	14% 6% 18% 30% 27% 5%	800
	21st to end	Night	25% 7% 19% 28% 20% 2	800
October	1st to 10th	Night	22% 8% 20% 28% 20% 3	800
	11th to 20th	Night	21% 15% 26% 27% 11% 1	800
	21st to end	Night	21% 17% 27% 26% 9%	880
November	1st to 10th	Night	17% 14% 30% 28% 10% 1	820
	11th to 20th	Night	23% 21% 25% 23% 7% 1	840
	21st to end	Night	22% 22% 28% 23% 6%	840
December	1st to 10th	Night	25% 24% 28% 18% 5% 1	840
	11th to 20th	Night	26% 20% 28% 22% 4	829
	21st to end	Night	23% 20% 28% 26% 3	880

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