Aliquippa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Aliquippa clear sky chart from 2005-11-06 to 2024-11-04.

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	16% 10% 4 8% 5% 5% 5% 4 6% 7% 31%	101112
	Night	17% 11% 4 8% 5% 4 4 3 5% 6% 33%	97851
Transparency	Day	51% 4 11% 22% 11% 1	104761
	Night	51% 3 10% 22% 12% 2	102341
Seeing	Day	22% 12% 28% 22% 12% 4	14694
	Night	22% 10% 25% 28% 13% 2	24388

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	19% 20% 9% 11% 4 4 4 2 4 5% 18%	2836
	11th to 20th	Day	14% 23% 9% 14% 7% 4 3 3 3 4 18%	2840
	21st to end	Day	25% 19% 8% 14% 6% 4 3 3 3 4 11%	3124
February	1st to 10th	Day	20% 17% 5% 12% 7% 5% 4 2 3 5% 22%	1710
	11th to 20th	Day	16% 15% 5% 13% 6% 5% 4 4 4 5% 22%	1663
	21st to end	Day	20% 14% 5% 10% 5% 4 3 4 4 5% 25%	1573
March	1st to 10th	Day	21% 12% 4 9% 5% 5% 3 3 4 7% 27%	3435
	11th to 20th	Day	13% 10% 4 11% 6% 5% 5% 4 4 6% 33%	3480
	21st to end	Day	19% 10% 3 8% 5% 4 4 4 6% 7% 31%	3815
April	1st to 10th	Day	15% 14% 3 8% 5% 5% 4 4 5% 7% 30%	2182
	11th to 20th	Day	18% 9% 3 7% 5% 5% 4 3 5% 5% 34%	2302
	21st to end	Day	21% 9% 3 7% 4 4 5% 3 4 7% 32%	2470
May	1st to 10th	Day	23% 9% 3 8% 4 4 5% 4 6% 6% 28%	4082
	11th to 20th	Day	18% 9% 3 8% 5% 5% 5% 4 6% 7% 31%	4081
	21st to end	Day	12% 6% 2 6% 4 5% 5% 4 7% 9% 38%	4715
June	1st to 10th	Day	14% 7% 3 6% 5% 5% 6% 5% 7% 9% 33%	2660
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 5% 7% 9% 35%	2660
	21st to end	Day	13% 6% 2 7% 5% 4 5% 4 7% 9% 38%	2660
July	1st to 10th	Day	8% 6% 3 7% 5% 5% 5% 5% 6% 9% 40%	4283
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 4 7% 10% 40%	4120
	21st to end	Day	11% 6% 3 8% 6% 6% 5% 5% 7% 8% 36%	4466
August	1st to 10th	Day	13% 7% 4 8% 6% 6% 6% 5% 6% 9% 31%	4104
	11th to 20th	Day	11% 7% 3 7% 6% 5% 6% 5% 7% 9% 35%	4044
	21st to end	Day	8% 5% 2 7% 5% 6% 5% 5% 7% 9% 40%	4340
September	1st to 10th	Day	15% 7% 2 5% 3 3 5% 3 5% 7% 44%	2271
	11th to 20th	Day	11% 6% 3 5% 4 4 5% 4 6% 9% 43%	2090
	21st to end	Day	19% 8% 4 7% 4 4 4 3 5% 6% 36%	2090
October	1st to 10th	Day	15% 6% 3 6% 4 4 5% 4 7% 8% 39%	1907
	11th to 20th	Day	19% 8% 2 8% 5% 5% 5% 3 5% 5% 35%	1900
	21st to end	Day	22% 11% 2 7% 4 4 4 3 4 7% 32%	2090
November	1st to 10th	Day	11% 8% 3 7% 5% 5% 5% 4 4 5% 42%	1794
	11th to 20th	Day	17% 14% 3 8% 5% 4 4 3 5% 6% 32%	1596
	21st to end	Day	17% 14% 5% 10% 6% 4 4 3 5% 6% 26%	1520
December	1st to 10th	Day	21% 18% 6% 12% 6% 4 3 3 3 5% 18%	1520
	11th to 20th	Day	20% 17% 7% 11% 5% 4 3 3 5% 6% 20%	1910
	21st to end	Day	25% 22% 7% 11% 4 4 4 3 3 5% 12%	2779
January	1st to 10th	Night	16% 20% 8% 13% 5% 5% 4 3 4 4 18%	4109
	11th to 20th	Night	17% 17% 7% 15% 6% 6% 5% 3 4 4 16%	4120
	21st to end	Night	28% 16% 7% 12% 6% 3 3 2 3 3 16%	4532
February	1st to 10th	Night	21% 14% 4 10% 6% 4 4 3 4 5% 24%	2470
	11th to 20th	Night	19% 14% 4 11% 6% 5% 4 3 4 5% 25%	2403
	21st to end	Night	20% 13% 5% 10% 6% 4 5% 3 5% 5% 24%	1880
March	1st to 10th	Night	24% 12% 3 6% 4 3 3 2 4 6% 32%	3418
	11th to 20th	Night	17% 12% 6% 8% 4 3 3 3 4 6% 34%	3480
	21st to end	Night	18% 10% 3 7% 4 4 3 3 4 6% 38%	3817
April	1st to 10th	Night	17% 12% 3 7% 6% 4 4 3 4 6% 35%	1997
	11th to 20th	Night	17% 9% 3 6% 5% 5% 4 4 5% 7% 36%	1843
	21st to end	Night	15% 10% 3 7% 4 4 4 4 6% 8% 36%	1710
May	1st to 10th	Night	25% 11% 3 7% 4 4 4 3 4 8% 27%	2813
	11th to 20th	Night	17% 9% 3 7% 5% 4 4 4 5% 8% 35%	2812
	21st to end	Night	11% 6% 2 6% 4 4 5% 4 7% 11% 41%	2836
June	1st to 10th	Night	9% 6% 2 6% 4 5% 4 4 7% 8% 44%	1520
	11th to 20th	Night	11% 6% 3 5% 4 5% 5% 5% 6% 9% 42%	1520
	21st to end	Night	9% 4 2 6% 4 5% 5% 4 7% 8% 44%	1520
July	1st to 10th	Night	9% 8% 3 7% 5% 4 4 4 6% 8% 41%	2671
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 4 7% 8% 44%	2840
	21st to end	Night	9% 7% 3 8% 5% 5% 5% 4 6% 7% 41%	3087
August	1st to 10th	Night	11% 9% 4 8% 5% 5% 6% 4 7% 7% 35%	2825
	11th to 20th	Night	11% 9% 3 7% 4 4 5% 3 5% 7% 42%	2785
	21st to end	Night	8% 5% 2 6% 5% 5% 5% 5% 6% 9% 44%	3284
September	1st to 10th	Night	13% 5% 2 4 3 3 5% 4 5% 7% 49%	1905
	11th to 20th	Night	10% 4 2 4 3 3 5% 4 6% 8% 52%	2090
	21st to end	Night	16% 8% 3 6% 4 4 4 3 5% 7% 40%	2090
October	1st to 10th	Night	14% 6% 2 6% 4 3 5% 3 4 7% 45%	2272
	11th to 20th	Night	18% 7% 3 6% 4 5% 4 3 5% 5% 40%	2280
	21st to end	Night	23% 9% 2 6% 4 4 4 3 4 6% 36%	2508
November	1st to 10th	Night	14% 8% 2 6% 4 4 4 3 5% 7% 44%	2354
	11th to 20th	Night	19% 11% 3 7% 4 4 4 3 5% 6% 32%	2582
	21st to end	Night	20% 12% 4 8% 5% 4 3 4 5% 5% 29%	2660
December	1st to 10th	Night	23% 16% 7% 9% 5% 4 4 3 4 5% 19%	2660
	11th to 20th	Night	19% 17% 5% 10% 5% 4 4 3 4 5% 23%	3285
	21st to end	Night	25% 19% 6% 10% 6% 5% 4 3 4 5% 14%	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	71% 2 9% 13% 5%	2837
	11th to 20th	Day	73% 1 7% 13% 4 1	2840
	21st to end	Day	78% 2 8% 9% 2	3124
February	1st to 10th	Day	67% 2 9% 14% 7% 1	1710
	11th to 20th	Day	64% 4 8% 16% 8%	1672
	21st to end	Day	61% 3 10% 16% 8% 1	1573
March	1st to 10th	Day	59% 2 9% 24% 6%	3435
	11th to 20th	Day	53% 3 12% 23% 8% 1	3480
	21st to end	Day	53% 2 10% 21% 12% 1	3815
April	1st to 10th	Day	53% 3 11% 20% 12% 2	2182
	11th to 20th	Day	52% 4 10% 18% 14% 2	2302
	21st to end	Day	53% 4 9% 23% 10% 2	2470
May	1st to 10th	Day	57% 3 10% 21% 8% 1	4120
	11th to 20th	Day	53% 3 11% 24% 9% 1	4085
	21st to end	Day	41% 4 14% 25% 12% 3	4729
June	1st to 10th	Day	46% 5% 14% 23% 11% 1	2660
	11th to 20th	Day	44% 5% 13% 25% 13% 1	2660
	21st to end	Day	41% 5% 13% 26% 13% 1	2660
July	1st to 10th	Day	41% 5% 12% 24% 15% 3	4217
	11th to 20th	Day	38% 4 12% 29% 16% 1	4051
	21st to end	Day	43% 6% 11% 22% 17% 1	4324
August	1st to 10th	Day	49% 6% 12% 24% 9%	4091
	11th to 20th	Day	42% 5% 11% 31% 10% 1	4083
	21st to end	Day	38% 6% 11% 29% 14% 2	4340
September	1st to 10th	Day	39% 4 10% 24% 20% 4	2271
	11th to 20th	Day	37% 3 13% 29% 16% 2	2090
	21st to end	Day	50% 3 9% 24% 14%	2090
October	1st to 10th	Day	32% 3 10% 33% 20% 1	3167
	11th to 20th	Day	46% 5% 9% 23% 14% 4	3140
	21st to end	Day	39% 3 12% 28% 18%	3428
November	1st to 10th	Day	43% 4 10% 23% 17% 2	1794
	11th to 20th	Day	55% 2 9% 21% 11% 2	1596
	21st to end	Day	59% 3 11% 18% 7% 1	1520
December	1st to 10th	Day	71% 3 9% 13% 4	1520
	11th to 20th	Day	67% 3 9% 17% 3	1906
	21st to end	Day	77% 2 9% 9% 3	2779
January	1st to 10th	Night	71% 3 8% 15% 4	4109
	11th to 20th	Night	73% 2 9% 12% 3	4120
	21st to end	Night	76% 1 6% 13% 3	4532
February	1st to 10th	Night	63% 3 9% 19% 7%	2470
	11th to 20th	Night	62% 3 9% 18% 8%	2405
	21st to end	Night	63% 3 8% 15% 10% 1	1880
March	1st to 10th	Night	56% 2 9% 24% 9%	3418
	11th to 20th	Night	53% 2 11% 26% 7% 1	3480
	21st to end	Night	49% 2 8% 25% 14% 2	3817
April	1st to 10th	Night	52% 3 9% 20% 14% 2	1997
	11th to 20th	Night	48% 3 11% 19% 15% 4	1843
	21st to end	Night	46% 3 10% 25% 13% 3	1710
May	1st to 10th	Night	57% 3 7% 20% 10% 2	2840
	11th to 20th	Night	48% 4 10% 26% 10% 1	2813
	21st to end	Night	37% 4 14% 27% 14% 4	2843
June	1st to 10th	Night	37% 4 14% 25% 17% 2	1520
	11th to 20th	Night	38% 5% 15% 25% 15% 2	1520
	21st to end	Night	36% 6% 13% 25% 17% 2	1520
July	1st to 10th	Night	41% 5% 10% 24% 18% 3	2627
	11th to 20th	Night	35% 6% 13% 29% 16% 1	2786
	21st to end	Night	42% 5% 10% 19% 22% 3	2988
August	1st to 10th	Night	45% 7% 12% 24% 11% 1	2814
	11th to 20th	Night	41% 4 10% 29% 15% 1	2812
	21st to end	Night	35% 6% 13% 31% 13% 2	3284
September	1st to 10th	Night	34% 5% 10% 25% 21% 5%	1905
	11th to 20th	Night	30% 4 13% 28% 23% 1	2090
	21st to end	Night	44% 3 11% 23% 18% 1	2090
October	1st to 10th	Night	36% 3 8% 27% 24% 2	3792
	11th to 20th	Night	39% 4 10% 24% 15% 7%	3779
	21st to end	Night	36% 2 8% 31% 21% 2	4120
November	1st to 10th	Night	41% 2 11% 25% 17% 4	2354
	11th to 20th	Night	52% 3 9% 22% 11% 2	2582
	21st to end	Night	57% 2 10% 23% 7% 1	2660
December	1st to 10th	Night	67% 3 10% 15% 5%	2660
	11th to 20th	Night	65% 2 10% 18% 4	3288
	21st to end	Night	74% 3 9% 11% 2	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	31% 25% 29% 10% 3 2	270
	11th to 20th	Day	31% 25% 32% 9% 2 1	270
	21st to end	Day	30% 25% 34% 7% 3 1	297
February	1st to 10th	Day	35% 16% 37% 10% 1	270
	11th to 20th	Day	34% 27% 30% 8%	270
	21st to end	Day	39% 22% 28% 10%	244
March	1st to 10th	Day	29% 19% 29% 18% 4	460
	11th to 20th	Day	30% 18% 32% 13% 5% 1	460
	21st to end	Day	32% 17% 29% 16% 5% 1	506
April	1st to 10th	Day	30% 18% 26% 17% 8% 1	460
	11th to 20th	Day	23% 20% 28% 18% 8% 4	452
	21st to end	Day	28% 14% 32% 18% 6% 2	460
May	1st to 10th	Day	31% 13% 28% 18% 8% 3	463
	11th to 20th	Day	23% 11% 31% 22% 10% 4	487
	21st to end	Day	15% 6% 27% 26% 20% 5%	529
June	1st to 10th	Day	15% 11% 28% 27% 14% 5%	490
	11th to 20th	Day	18% 8% 25% 28% 16% 5%	490
	21st to end	Day	15% 8% 32% 29% 13% 3	490
July	1st to 10th	Day	13% 3 20% 31% 21% 11%	485
	11th to 20th	Day	13% 4 26% 29% 19% 8%	484
	21st to end	Day	14% 4 23% 31% 18% 10%	532
August	1st to 10th	Day	12% 6% 21% 30% 21% 10%	486
	11th to 20th	Day	16% 4 22% 30% 18% 10%	479
	21st to end	Day	12% 3 24% 27% 22% 12%	539
September	1st to 10th	Day	19% 5% 21% 27% 20% 8%	490
	11th to 20th	Day	12% 4 17% 31% 23% 12%	490
	21st to end	Day	24% 10% 23% 23% 14% 5%	490
October	1st to 10th	Day	16% 7% 28% 25% 19% 5%	490
	11th to 20th	Day	23% 14% 28% 25% 9% 2	490
	21st to end	Day	29% 13% 32% 19% 7%	539
November	1st to 10th	Day	18% 16% 34% 17% 11% 3	374
	11th to 20th	Day	29% 19% 28% 14% 9%	216
	21st to end	Day	25% 18% 43% 13% 1	180
December	1st to 10th	Day	30% 25% 29% 11% 3 2	180
	11th to 20th	Day	30% 21% 33% 14% 2	180
	21st to end	Day	36% 21% 28% 12% 2	202
January	1st to 10th	Night	29% 18% 33% 17% 3	760
	11th to 20th	Night	31% 15% 30% 20% 4	760
	21st to end	Night	27% 17% 31% 22% 4	836
February	1st to 10th	Night	28% 17% 28% 25% 3	760
	11th to 20th	Night	29% 19% 34% 17% 1	743
	21st to end	Night	29% 16% 31% 21% 3	628
March	1st to 10th	Night	26% 16% 29% 25% 4	760
	11th to 20th	Night	27% 16% 26% 23% 6% 1	760
	21st to end	Night	25% 14% 31% 24% 6% 1	836
April	1st to 10th	Night	25% 14% 30% 25% 6%	760
	11th to 20th	Night	22% 12% 31% 25% 9% 1	719
	21st to end	Night	21% 8% 34% 31% 6%	570
May	1st to 10th	Night	21% 8% 23% 36% 10% 2	570
	11th to 20th	Night	21% 6% 25% 33% 14% 1	561
	21st to end	Night	11% 3 22% 37% 24% 3	477
June	1st to 10th	Night	12% 3 24% 40% 20% 1	380
	11th to 20th	Night	14% 3 22% 38% 21% 1	380
	21st to end	Night	10% 2 27% 36% 24% 1	380
July	1st to 10th	Night	9% 2 16% 43% 23% 7%	452
	11th to 20th	Night	9% 1 18% 38% 30% 5%	552
	21st to end	Night	12% 2 13% 43% 28% 3	624
August	1st to 10th	Night	9% 1 15% 43% 28% 3	567
	11th to 20th	Night	11% 2 11% 40% 30% 5%	564
	21st to end	Night	14% 2 17% 34% 28% 6%	722
September	1st to 10th	Night	17% 2 16% 35% 26% 4	760
	11th to 20th	Night	11% 3 14% 35% 33% 4	760
	21st to end	Night	19% 6% 23% 27% 21% 4	760
October	1st to 10th	Night	17% 6% 22% 31% 23% 2	760
	11th to 20th	Night	23% 10% 28% 25% 12% 2	760
	21st to end	Night	28% 10% 26% 28% 8%	836
November	1st to 10th	Night	18% 10% 27% 31% 14%	755
	11th to 20th	Night	28% 12% 27% 24% 8% 2	760
	21st to end	Night	29% 13% 28% 23% 7%	760
December	1st to 10th	Night	34% 14% 27% 20% 5%	760
	11th to 20th	Night	27% 17% 30% 22% 4	760
	21st to end	Night	29% 14% 30% 24% 2	836

Page generated at 2024-11-01 22:47:53. Version ac07

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