Galbreath Wildlands Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Galbreath Wildlands Preserve 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	10% 4 1 4 3 3 3 2 4 6% 60%	105507
	Night	12% 6% 2 4 3 3 3 3 4 6% 55%	103366
Transparency	Day	25% 4 8% 20% 23% 20%	105268
	Night	30% 4 9% 18% 21% 18%	103195
Seeing	Day	13% 12% 25% 27% 18% 6%	15494
	Night	14% 7% 18% 30% 25% 6%	24769

By Month

Percentage Cloud Cover SW (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	21% 11% 2 5% 4 4 4 3 5% 6% 34%	2740
	11th to 20th	Day	29% 10% 3 8% 4 3 3 3 4 4 28%	2860
	21st to end	Day	26% 9% 3 6% 4 4 4 3 5% 6% 30%	3146
February	1st to 10th	Day	20% 7% 2 6% 4 4 3 3 3 5% 42%	1710
	11th to 20th	Day	17% 6% 2 6% 4 4 3 4 5% 8% 40%	1665
	21st to end	Day	20% 8% 2 5% 3 3 4 3 5% 7% 40%	1589
March	1st to 10th	Day	28% 15% 3 5% 4 3 3 2 4 4 28%	3442
	11th to 20th	Day	13% 5% 2 4 3 4 3 4 4 7% 50%	3490
	21st to end	Day	24% 9% 2 5% 4 4 4 4 6% 7% 30%	3825
April	1st to 10th	Day	17% 7% 2 6% 5% 4 3 3 6% 7% 39%	2266
	11th to 20th	Day	12% 5% 2 6% 4 3 3 4 6% 7% 47%	2249
	21st to end	Day	8% 5% 2 4 3 4 3 4 7% 9% 51%	2301
May	1st to 10th	Day	6% 4 1 3 2 2 3 2 4 6% 67%	4110
	11th to 20th	Day	4 2 1 2 2 2 2 2 4 6% 74%	4096
	21st to end	Day	4 2 1 2 2 2 2 2 4 6% 73%	4813
June	1st to 10th	Day	7% 4 2 3 3 3 3 3 6% 7% 59%	2660
	11th to 20th	Day	3 2 1 2 2 2 2 2 4 6% 76%	2660
	21st to end	Day	3 1 1 2 2 1 2 2 2 5% 80%	2660
July	1st to 10th	Day	1 1 1 1 1 1 1 1 3 90%	4392
	11th to 20th	Day	1 1 1 1 2 2 1 3 5% 83%	4110
	21st to end	Day	1 1 1 1 1 1 2 4 87%	4455
August	1st to 10th	Day	1 1 1 1 2 3 3 5% 7% 76%	4091
	11th to 20th	Day	1 1 1 1 1 1 1 2 5% 86%	3978
	21st to end	Day	1 1 1 2 1 2 2 1 3 5% 82%	4180
September	1st to 10th	Day	1 1 1 1 1 1 2 2 3 5% 83%	2280
	11th to 20th	Day	4 2 1 3 2 2 3 2 4 7% 69%	2225
	21st to end	Day	3 1 1 3 2 2 2 2 3 5% 76%	2028
October	1st to 10th	Day	5% 2 1 2 1 2 2 2 3 6% 73%	3180
	11th to 20th	Day	9% 3 1 3 2 2 2 2 4 7% 64%	3161
	21st to end	Day	8% 4 1 6% 3 4 5% 3 7% 8% 51%	3448
November	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 6% 8% 49%	1959
	11th to 20th	Day	15% 7% 2 5% 4 4 4 4 5% 7% 42%	1712
	21st to end	Day	14% 5% 2 5% 4 3 4 3 5% 7% 48%	1600
December	1st to 10th	Day	20% 7% 2 4 3 3 4 2 5% 6% 42%	1600
	11th to 20th	Day	35% 10% 2 5% 3 4 3 2 5% 5% 26%	2008
	21st to end	Day	26% 9% 3 6% 4 3 4 4 4 7% 29%	2818
January	1st to 10th	Night	19% 10% 2 6% 4 4 4 4 6% 8% 33%	4207
	11th to 20th	Night	25% 13% 3 9% 5% 4 3 2 3 5% 27%	4110
	21st to end	Night	28% 12% 3 7% 5% 4 3 3 4 5% 26%	4521
February	1st to 10th	Night	18% 6% 1 5% 3 4 4 3 6% 6% 43%	2470
	11th to 20th	Night	17% 8% 2 5% 4 4 4 4 6% 7% 38%	2402
	21st to end	Night	16% 7% 2 4 4 3 3 2 4 7% 48%	1861
March	1st to 10th	Night	25% 18% 3 5% 3 3 3 3 4 5% 28%	3432
	11th to 20th	Night	15% 5% 1 4 3 2 2 3 4 6% 55%	3490
	21st to end	Night	19% 16% 3 5% 4 4 4 4 5% 6% 32%	3828
April	1st to 10th	Night	13% 7% 2 6% 5% 4 4 3 4 7% 44%	1914
	11th to 20th	Night	10% 6% 2 4 3 4 4 3 5% 8% 50%	1879
	21st to end	Night	7% 4 1 3 3 3 3 2 7% 7% 59%	1876
May	1st to 10th	Night	5% 5% 1 3 2 2 2 2 3 5% 70%	2860
	11th to 20th	Night	2 2 1 3 2 3 2 1 3 5% 75%	2802
	21st to end	Night	3 2 1 2 2 1 2 2 3 5% 77%	2762
June	1st to 10th	Night	4 5% 2 3 3 5% 3 4 6% 8% 58%	1520
	11th to 20th	Night	3 1 2 1 2 2 2 4 5% 78%	1520
	21st to end	Night	3 2 1 2 2 1 2 2 2 3 80%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 1 2 92%	2564
	11th to 20th	Night	1 1 1 2 2 2 1 2 3 84%	2860
	21st to end	Night	1 1 1 1 1 2 5% 86%	3109
August	1st to 10th	Night	1 1 1 2 2 2 2 1 4 5% 79%	2848
	11th to 20th	Night	1 1 1 1 1 1 2 4 88%	2862
	21st to end	Night	1 2 1 2 1 2 2 1 2 3 83%	3498
September	1st to 10th	Night	1 1 2 1 2 1 3 5% 84%	1900
	11th to 20th	Night	4 2 2 3 2 3 3 2 5% 7% 68%	1951
	21st to end	Night	2 2 1 2 2 2 2 2 4 6% 76%	2152
October	1st to 10th	Night	3 3 1 3 2 2 2 2 3 4 76%	3800
	11th to 20th	Night	5% 6% 2 4 3 2 3 3 4 6% 62%	3777
	21st to end	Night	8% 5% 1 5% 3 4 4 3 5% 7% 55%	4121
November	1st to 10th	Night	12% 6% 2 4 3 4 5% 4 6% 7% 46%	2340
	11th to 20th	Night	14% 6% 2 5% 4 5% 4 4 6% 8% 41%	2684
	21st to end	Night	14% 5% 2 5% 4 3 3 3 4 6% 50%	2800
December	1st to 10th	Night	22% 6% 2 5% 4 3 3 3 4 7% 42%	2800
	11th to 20th	Night	34% 8% 2 5% 4 3 3 3 5% 6% 27%	3416
	21st to end	Night	26% 10% 3 6% 4 4 4 3 4 6% 30%	4910

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	47% 6% 15% 22% 7% 4	2740
	11th to 20th	Day	59% 4 9% 11% 8% 8%	2860
	21st to end	Day	54% 4 10% 15% 11% 5%	3146
February	1st to 10th	Day	44% 4 9% 16% 19% 8%	1710
	11th to 20th	Day	41% 5% 10% 18% 20% 6%	1674
	21st to end	Day	42% 5% 11% 23% 13% 6%	1589
March	1st to 10th	Day	58% 6% 8% 12% 14% 2	3442
	11th to 20th	Day	32% 5% 11% 26% 15% 11%	3490
	21st to end	Day	48% 8% 14% 18% 10% 2	3825
April	1st to 10th	Day	42% 4 14% 23% 13% 3	2266
	11th to 20th	Day	34% 5% 16% 24% 17% 4	2252
	21st to end	Day	26% 5% 16% 28% 20% 5%	2301
May	1st to 10th	Day	17% 5% 14% 30% 20% 15%	4110
	11th to 20th	Day	13% 3 8% 26% 35% 16%	4099
	21st to end	Day	13% 3 9% 43% 28% 3	4814
June	1st to 10th	Day	23% 5% 13% 27% 28% 5%	2660
	11th to 20th	Day	10% 3 11% 22% 38% 16%	2660
	21st to end	Day	10% 2 5% 16% 37% 30%	2660
July	1st to 10th	Day	5% 1 2 8% 19% 65%	4323
	11th to 20th	Day	7% 1 3 9% 21% 58%	4041
	21st to end	Day	5% 2 2 9% 31% 50%	4315
August	1st to 10th	Day	9% 3 4 13% 26% 46%	4076
	11th to 20th	Day	6% 2 2 17% 41% 32%	4017
	21st to end	Day	8% 3 5% 19% 36% 30%	4179
September	1st to 10th	Day	6% 2 4 13% 31% 44%	2280
	11th to 20th	Day	16% 3 8% 28% 35% 11%	2225
	21st to end	Day	12% 2 6% 23% 32% 24%	2028
October	1st to 10th	Day	15% 2 3 14% 23% 42%	3180
	11th to 20th	Day	22% 3 6% 23% 32% 14%	3161
	21st to end	Day	28% 5% 9% 23% 24% 11%	3448
November	1st to 10th	Day	31% 4 10% 27% 17% 11%	1959
	11th to 20th	Day	39% 5% 12% 21% 15% 8%	1712
	21st to end	Day	35% 4 11% 17% 20% 13%	1600
December	1st to 10th	Day	41% 5% 8% 17% 18% 11%	1600
	11th to 20th	Day	60% 3 7% 13% 12% 4	2008
	21st to end	Day	52% 5% 12% 19% 9% 3	2818
January	1st to 10th	Night	45% 7% 19% 18% 8% 3	4207
	11th to 20th	Night	59% 5% 10% 10% 8% 7%	4110
	21st to end	Night	58% 6% 9% 10% 11% 6%	4521
February	1st to 10th	Night	39% 5% 10% 19% 18% 10%	2470
	11th to 20th	Night	41% 6% 9% 21% 16% 6%	2404
	21st to end	Night	35% 5% 13% 25% 18% 4	1861
March	1st to 10th	Night	55% 8% 10% 12% 13% 2	3432
	11th to 20th	Night	31% 3 12% 23% 22% 9%	3490
	21st to end	Night	49% 8% 16% 17% 8% 2	3828
April	1st to 10th	Night	38% 6% 14% 22% 15% 5%	1914
	11th to 20th	Night	31% 5% 16% 24% 17% 6%	1879
	21st to end	Night	22% 5% 13% 33% 22% 5%	1876
May	1st to 10th	Night	17% 4 8% 31% 27% 14%	2860
	11th to 20th	Night	12% 5% 9% 18% 32% 23%	2803
	21st to end	Night	11% 4 9% 41% 31% 4	2762
June	1st to 10th	Night	22% 6% 10% 25% 28% 9%	1520
	11th to 20th	Night	10% 3 10% 23% 38% 18%	1520
	21st to end	Night	12% 2 6% 13% 34% 34%	1520
July	1st to 10th	Night	4 2 1 6% 20% 67%	2524
	11th to 20th	Night	8% 2 3 8% 20% 59%	2806
	21st to end	Night	5% 2 2 8% 25% 58%	3011
August	1st to 10th	Night	10% 2 3 9% 24% 52%	2839
	11th to 20th	Night	4 2 3 13% 42% 36%	2889
	21st to end	Night	10% 3 3 16% 32% 37%	3498
September	1st to 10th	Night	5% 2 4 14% 30% 46%	1900
	11th to 20th	Night	15% 4 8% 20% 38% 15%	1951
	21st to end	Night	13% 2 7% 21% 27% 30%	2152
October	1st to 10th	Night	15% 2 5% 12% 22% 45%	3800
	11th to 20th	Night	22% 5% 7% 20% 32% 15%	3777
	21st to end	Night	27% 5% 6% 23% 24% 15%	4121
November	1st to 10th	Night	32% 6% 12% 22% 16% 11%	2340
	11th to 20th	Night	38% 6% 15% 19% 16% 7%	2684
	21st to end	Night	35% 4 9% 19% 20% 13%	2800
December	1st to 10th	Night	41% 5% 7% 18% 19% 10%	2800
	11th to 20th	Night	56% 4 8% 14% 14% 4	3416
	21st to end	Night	53% 5% 13% 16% 9% 3	4910

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% 14% 22% 12% 13% 2	303
	11th to 20th	Day	27% 14% 23% 17% 17% 2	370
	21st to end	Day	23% 12% 22% 25% 14% 4	407
February	1st to 10th	Day	23% 15% 21% 20% 18% 3	370
	11th to 20th	Day	28% 15% 23% 20% 13% 1	365
	21st to end	Day	23% 18% 22% 24% 10% 2	379
March	1st to 10th	Day	32% 19% 24% 17% 8% 1	460
	11th to 20th	Day	25% 15% 29% 18% 9% 3	460
	21st to end	Day	23% 22% 30% 17% 5% 2	506
April	1st to 10th	Day	22% 19% 29% 19% 8% 3	460
	11th to 20th	Day	19% 19% 30% 19% 11% 3	452
	21st to end	Day	13% 20% 33% 19% 10% 4	460
May	1st to 10th	Day	11% 19% 32% 23% 11% 3	463
	11th to 20th	Day	13% 17% 31% 20% 14% 5%	488
	21st to end	Day	11% 13% 28% 27% 15% 6%	529
June	1st to 10th	Day	9% 14% 30% 29% 15% 3	490
	11th to 20th	Day	7% 16% 33% 29% 13% 2	490
	21st to end	Day	1 6% 30% 33% 23% 6%	490
July	1st to 10th	Day	2 5% 24% 40% 22% 6%	486
	11th to 20th	Day	1 2 24% 40% 26% 6%	484
	21st to end	Day	1 2 15% 44% 30% 9%	531
August	1st to 10th	Day	1 3 24% 41% 23% 7%	487
	11th to 20th	Day	2 5% 24% 34% 26% 8%	477
	21st to end	Day	1 4 20% 39% 27% 8%	539
September	1st to 10th	Day	2 5% 22% 37% 24% 9%	490
	11th to 20th	Day	5% 9% 21% 34% 24% 7%	490
	21st to end	Day	5% 7% 24% 31% 22% 10%	490
October	1st to 10th	Day	8% 7% 25% 26% 24% 10%	490
	11th to 20th	Day	11% 10% 18% 25% 26% 11%	490
	21st to end	Day	12% 8% 24% 26% 22% 8%	539
November	1st to 10th	Day	13% 14% 19% 23% 24% 6%	495
	11th to 20th	Day	18% 10% 14% 23% 26% 10%	260
	21st to end	Day	19% 9% 20% 21% 21% 11%	200
December	1st to 10th	Day	24% 10% 18% 21% 17% 11%	200
	11th to 20th	Day	31% 10% 18% 21% 13% 9%	200
	21st to end	Day	26% 14% 17% 22% 16% 4	204
January	1st to 10th	Night	26% 7% 16% 28% 19% 5%	760
	11th to 20th	Night	24% 7% 16% 29% 18% 6%	760
	21st to end	Night	22% 6% 16% 29% 21% 5%	836
February	1st to 10th	Night	22% 7% 16% 32% 20% 3	760
	11th to 20th	Night	22% 9% 20% 28% 16% 5%	744
	21st to end	Night	20% 9% 23% 29% 16% 2	628
March	1st to 10th	Night	26% 11% 18% 27% 15% 3	760
	11th to 20th	Night	23% 8% 19% 30% 17% 3	760
	21st to end	Night	22% 9% 27% 27% 13% 2	836
April	1st to 10th	Night	18% 11% 26% 24% 16% 4	760
	11th to 20th	Night	13% 13% 26% 28% 16% 5%	751
	21st to end	Night	10% 15% 29% 23% 20% 4	736
May	1st to 10th	Night	8% 9% 30% 28% 20% 4	570
	11th to 20th	Night	5% 6% 26% 32% 27% 4	543
	21st to end	Night	9% 11% 22% 29% 26% 4	411
June	1st to 10th	Night	6% 11% 27% 32% 23% 1	380
	11th to 20th	Night	3 11% 28% 36% 20% 1	380
	21st to end	Night	4 2 20% 42% 30% 2	380
July	1st to 10th	Night	1 4 19% 35% 36% 5%	381
	11th to 20th	Night	1 16% 33% 41% 10%	552
	21st to end	Night	1 11% 31% 45% 12%	624
August	1st to 10th	Night	2 1 12% 36% 38% 11%	567
	11th to 20th	Night	1 2 16% 31% 40% 11%	588
	21st to end	Night	3 2 12% 31% 45% 8%	836
September	1st to 10th	Night	1 3 12% 34% 40% 11%	760
	11th to 20th	Night	5% 4 14% 37% 31% 9%	760
	21st to end	Night	4 4 17% 29% 35% 10%	760
October	1st to 10th	Night	6% 5% 16% 33% 33% 8%	760
	11th to 20th	Night	8% 5% 13% 29% 37% 8%	760
	21st to end	Night	13% 4 13% 30% 29% 11%	836
November	1st to 10th	Night	14% 6% 18% 26% 29% 8%	780
	11th to 20th	Night	18% 6% 14% 34% 23% 6%	800
	21st to end	Night	16% 8% 14% 32% 23% 7%	800
December	1st to 10th	Night	24% 4 16% 28% 22% 6%	800
	11th to 20th	Night	30% 7% 13% 29% 18% 4	800
	21st to end	Night	26% 10% 18% 27% 15% 4	850

Page generated at 2024-12-21 01:13:48. Version ac07

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