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 2024-01-16.

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	11% 4 2 3 3 2 3 3 4 6% 58%	74703
	Night	12% 5% 2 4 4 2 3 4 4 6% 54%	75121
Transparency	Day	28% 4 9% 21% 24% 15%	74424
	Night	30% 4 10% 19% 21% 15%	74922
Seeing	Day	13% 11% 24% 27% 19% 6%	14242
	Night	14% 6% 18% 30% 26% 6%	23562

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	24% 9% 3 5% 5% 3 4 4 5% 6% 32%	1642
	11th to 20th	Day	21% 6% 3 5% 5% 3 3 3 4 6% 42%	1669
	21st to end	Day	19% 7% 3 4 4 3 4 4 4 7% 40%	1782
February	1st to 10th	Day	20% 6% 2 5% 5% 3 4 4 4 5% 42%	1620
	11th to 20th	Day	17% 5% 2 5% 5% 3 5% 4 5% 8% 42%	1575
	21st to end	Day	21% 7% 2 4 3 2 4 4 4 7% 41%	1498
March	1st to 10th	Day	23% 11% 4 5% 5% 2 4 4 5% 5% 32%	1980
	11th to 20th	Day	22% 6% 3 5% 5% 4 4 5% 5% 8% 33%	1980
	21st to end	Day	19% 7% 2 5% 4 3 5% 4 5% 8% 39%	2178
April	1st to 10th	Day	19% 7% 2 5% 6% 3 4 4 6% 7% 38%	2146
	11th to 20th	Day	13% 5% 2 5% 5% 2 4 4 5% 7% 48%	2129
	21st to end	Day	8% 4 3 4 4 3 4 4 6% 10% 51%	2179
May	1st to 10th	Day	8% 4 2 4 3 1 3 4 4 8% 59%	2340
	11th to 20th	Day	8% 3 1 3 3 2 3 4 5% 9% 59%	2313
	21st to end	Day	7% 4 2 3 4 2 4 3 5% 8% 59%	2723
June	1st to 10th	Day	7% 4 2 3 3 2 4 4 6% 8% 58%	2520
	11th to 20th	Day	3 1 1 2 2 1 2 3 3 6% 76%	2520
	21st to end	Day	3 1 1 2 2 1 1 3 2 5% 80%	2520
July	1st to 10th	Day	2 1 1 1 1 2 2 2 5% 83%	2505
	11th to 20th	Day	1 1 1 1 2 2 2 2 2 5% 82%	2340
	21st to end	Day	1 1 1 1 2 1 2 3 3 5% 82%	2546
August	1st to 10th	Day	1 1 1 2 1 2 2 3 3 5% 80%	2328
	11th to 20th	Day	1 1 1 1 1 1 2 3 5% 84%	2276
	21st to end	Day	1 2 1 1 1 1 2 2 3 5% 82%	2376
September	1st to 10th	Day	1 1 1 1 1 1 2 2 3 5% 82%	2160
	11th to 20th	Day	4 2 1 3 3 2 3 2 4 7% 69%	2108
	21st to end	Day	3 1 1 2 2 1 2 3 3 5% 75%	1922
October	1st to 10th	Day	9% 3 1 2 2 2 3 3 3 5% 68%	1800
	11th to 20th	Day	9% 3 1 3 3 2 3 3 4 7% 63%	1800
	21st to end	Day	11% 3 1 4 3 2 4 3 5% 7% 56%	1980
November	1st to 10th	Day	12% 5% 2 4 4 2 4 4 5% 8% 48%	1859
	11th to 20th	Day	14% 7% 3 5% 5% 3 4 5% 5% 6% 44%	1627
	21st to end	Day	13% 5% 2 4 5% 2 4 5% 5% 7% 49%	1520
December	1st to 10th	Day	22% 7% 2 4 4 2 4 3 4 6% 42%	1520
	11th to 20th	Day	35% 8% 2 4 4 3 4 3 4 5% 27%	1928
	21st to end	Day	26% 9% 3 5% 5% 3 4 5% 5% 7% 30%	2794
January	1st to 10th	Night	22% 8% 2 5% 5% 3 4 5% 6% 8% 31%	2519
	11th to 20th	Night	21% 9% 2 5% 5% 3 4 4 4 6% 38%	2418
	21st to end	Night	18% 6% 2 4 5% 2 4 4 5% 8% 41%	2574
February	1st to 10th	Night	18% 6% 2 4 4 3 4 4 6% 6% 44%	2340
	11th to 20th	Night	16% 7% 2 5% 4 3 5% 5% 6% 8% 40%	2272
	21st to end	Night	17% 6% 2 3 4 3 4 3 5% 7% 47%	1754
March	1st to 10th	Night	21% 11% 3 6% 4 3 5% 5% 4 6% 33%	1980
	11th to 20th	Night	21% 7% 2 6% 4 3 4 4 4 7% 38%	1980
	21st to end	Night	17% 7% 3 4 4 2 4 4 5% 7% 45%	2178
April	1st to 10th	Night	14% 6% 2 6% 5% 3 4 4 5% 7% 43%	1814
	11th to 20th	Night	10% 5% 3 4 3 3 4 4 6% 7% 50%	1779
	21st to end	Night	7% 3 1 3 3 2 4 3 6% 8% 59%	1778
May	1st to 10th	Night	5% 5% 1 3 4 2 3 3 3 7% 63%	1620
	11th to 20th	Night	5% 3 1 4 4 2 3 4 5% 9% 60%	1576
	21st to end	Night	5% 3 1 2 3 2 3 4 6% 8% 62%	1552
June	1st to 10th	Night	4 5% 2 3 3 3 4 5% 5% 9% 58%	1440
	11th to 20th	Night	3 1 2 1 1 2 3 4 5% 77%	1440
	21st to end	Night	3 2 1 2 2 1 2 3 2 4 79%	1440
July	1st to 10th	Night	1 1 1 2 1 2 2 2 4 86%	1450
	11th to 20th	Night	1 1 1 1 2 1 2 1 2 4 84%	1620
	21st to end	Night	1 1 1 1 1 1 2 2 3 6% 83%	1773
August	1st to 10th	Night	1 1 1 2 2 1 2 2 4 4 82%	1611
	11th to 20th	Night	1 1 1 2 1 1 2 3 5% 84%	1624
	21st to end	Night	1 2 2 2 1 2 2 3 4 82%	1980
September	1st to 10th	Night	1 1 1 2 1 2 2 3 5% 84%	1800
	11th to 20th	Night	4 1 2 2 2 2 3 3 5% 7% 68%	1848
	21st to end	Night	3 2 1 2 3 1 2 2 4 6% 74%	2038
October	1st to 10th	Night	4 4 1 3 3 1 3 2 4 5% 69%	2160
	11th to 20th	Night	6% 3 1 3 3 2 4 4 4 7% 63%	2160
	21st to end	Night	10% 4 1 4 3 3 3 4 4 7% 58%	2376
November	1st to 10th	Night	13% 5% 2 4 3 2 5% 5% 6% 8% 46%	2220
	11th to 20th	Night	14% 6% 2 4 5% 4 4 6% 6% 8% 42%	2549
	21st to end	Night	13% 5% 2 5% 5% 2 4 4 4 7% 51%	2660
December	1st to 10th	Night	23% 6% 2 4 5% 2 3 3 4 7% 41%	2660
	11th to 20th	Night	35% 7% 2 4 4 2 4 3 5% 6% 28%	3276
	21st to end	Night	26% 9% 3 5% 5% 3 4 4 4 6% 31%	4862

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	52% 5% 12% 18% 8% 6%	1642
	11th to 20th	Day	45% 3 8% 15% 14% 14%	1669
	21st to end	Day	44% 4 8% 16% 20% 9%	1782
February	1st to 10th	Day	44% 4 8% 16% 20% 9%	1620
	11th to 20th	Day	39% 5% 10% 19% 21% 6%	1584
	21st to end	Day	42% 5% 11% 23% 13% 6%	1498
March	1st to 10th	Day	52% 6% 10% 13% 16% 2	1980
	11th to 20th	Day	47% 5% 9% 19% 14% 5%	1980
	21st to end	Day	43% 6% 13% 19% 16% 3	2178
April	1st to 10th	Day	44% 4 13% 22% 13% 3	2146
	11th to 20th	Day	34% 5% 16% 24% 17% 5%	2132
	21st to end	Day	27% 4 16% 29% 20% 5%	2179
May	1st to 10th	Day	23% 5% 12% 30% 24% 7%	2340
	11th to 20th	Day	22% 4 12% 30% 24% 8%	2316
	21st to end	Day	22% 6% 15% 36% 19% 3	2724
June	1st to 10th	Day	24% 5% 13% 26% 27% 5%	2520
	11th to 20th	Day	10% 3 11% 22% 37% 16%	2520
	21st to end	Day	10% 2 5% 17% 37% 29%	2520
July	1st to 10th	Day	8% 2 4 14% 34% 38%	2436
	11th to 20th	Day	9% 2 5% 15% 31% 39%	2271
	21st to end	Day	9% 2 3 11% 31% 44%	2405
August	1st to 10th	Day	9% 3 5% 22% 31% 30%	2312
	11th to 20th	Day	7% 2 4 17% 38% 32%	2276
	21st to end	Day	8% 3 6% 19% 37% 27%	2376
September	1st to 10th	Day	7% 2 4 14% 32% 41%	2160
	11th to 20th	Day	16% 3 8% 27% 35% 12%	2108
	21st to end	Day	12% 2 6% 24% 31% 24%	1922
October	1st to 10th	Day	21% 3 5% 20% 28% 23%	1800
	11th to 20th	Day	24% 4 8% 18% 25% 20%	1800
	21st to end	Day	27% 4 9% 21% 23% 16%	1980
November	1st to 10th	Day	32% 5% 10% 26% 17% 10%	1859
	11th to 20th	Day	38% 5% 12% 21% 15% 8%	1627
	21st to end	Day	34% 4 12% 17% 21% 12%	1520
December	1st to 10th	Day	43% 5% 8% 17% 17% 11%	1520
	11th to 20th	Day	60% 3 7% 13% 13% 5%	1928
	21st to end	Day	52% 5% 12% 19% 9% 3	2794
January	1st to 10th	Night	47% 6% 13% 17% 11% 5%	2519
	11th to 20th	Night	47% 4 10% 13% 13% 13%	2418
	21st to end	Night	41% 5% 11% 14% 19% 10%	2574
February	1st to 10th	Night	39% 4 9% 19% 19% 10%	2340
	11th to 20th	Night	39% 6% 9% 22% 17% 7%	2274
	21st to end	Night	35% 5% 14% 23% 18% 4	1754
March	1st to 10th	Night	51% 7% 9% 15% 16% 3	1980
	11th to 20th	Night	44% 4 10% 20% 16% 4	1980
	21st to end	Night	39% 5% 15% 22% 15% 4	2178
April	1st to 10th	Night	39% 6% 14% 21% 15% 5%	1814
	11th to 20th	Night	31% 5% 16% 22% 18% 7%	1779
	21st to end	Night	22% 5% 13% 33% 21% 5%	1778
May	1st to 10th	Night	22% 5% 9% 26% 32% 8%	1620
	11th to 20th	Night	21% 4 13% 28% 24% 9%	1577
	21st to end	Night	20% 7% 16% 34% 20% 4	1552
June	1st to 10th	Night	22% 6% 10% 25% 28% 8%	1440
	11th to 20th	Night	10% 3 10% 23% 36% 17%	1440
	21st to end	Night	12% 2 6% 14% 34% 32%	1440
July	1st to 10th	Night	6% 3 3 11% 35% 42%	1410
	11th to 20th	Night	6% 2 5% 14% 30% 43%	1566
	21st to end	Night	7% 3 3 10% 27% 50%	1674
August	1st to 10th	Night	9% 3 5% 16% 32% 36%	1602
	11th to 20th	Night	8% 3 5% 14% 30% 40%	1624
	21st to end	Night	10% 3 6% 15% 32% 35%	1980
September	1st to 10th	Night	5% 2 4 15% 30% 44%	1800
	11th to 20th	Night	15% 4 9% 19% 38% 16%	1848
	21st to end	Night	13% 2 7% 21% 26% 29%	2038
October	1st to 10th	Night	18% 3 8% 19% 27% 25%	2160
	11th to 20th	Night	21% 6% 8% 18% 26% 21%	2160
	21st to end	Night	25% 4 8% 20% 23% 19%	2376
November	1st to 10th	Night	33% 6% 12% 22% 16% 11%	2220
	11th to 20th	Night	38% 6% 14% 20% 16% 7%	2549
	21st to end	Night	34% 4 10% 20% 20% 13%	2660
December	1st to 10th	Night	42% 5% 7% 17% 18% 10%	2660
	11th to 20th	Night	56% 4 8% 14% 14% 4	3276
	21st to end	Night	53% 5% 14% 16% 10% 3	4862

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	26% 13% 23% 19% 17% 2	357
	21st to end	Day	22% 11% 21% 27% 16% 4	374
February	1st to 10th	Day	22% 14% 21% 21% 19% 3	340
	11th to 20th	Day	27% 15% 23% 20% 14% 1	335
	21st to end	Day	24% 19% 23% 22% 11% 2	344
March	1st to 10th	Day	30% 19% 24% 17% 9% 1	420
	11th to 20th	Day	26% 15% 29% 18% 8% 3	420
	21st to end	Day	22% 22% 31% 18% 6% 2	462
April	1st to 10th	Day	22% 20% 29% 19% 8% 2	420
	11th to 20th	Day	19% 20% 30% 18% 9% 3	412
	21st to end	Day	13% 20% 34% 19% 10% 5%	420
May	1st to 10th	Day	11% 20% 31% 23% 12% 3	423
	11th to 20th	Day	14% 18% 32% 19% 12% 5%	448
	21st to end	Day	12% 14% 27% 27% 15% 5%	485
June	1st to 10th	Day	10% 13% 29% 29% 16% 3	450
	11th to 20th	Day	7% 15% 33% 30% 14% 2	450
	21st to end	Day	2 6% 28% 35% 24% 6%	450
July	1st to 10th	Day	2 5% 25% 41% 22% 5%	446
	11th to 20th	Day	1 2 23% 41% 28% 7%	444
	21st to end	Day	1 1 14% 45% 30% 9%	487
August	1st to 10th	Day	2 4 25% 40% 23% 7%	447
	11th to 20th	Day	2 3 22% 36% 28% 9%	437
	21st to end	Day	1 3 20% 40% 28% 8%	495
September	1st to 10th	Day	2 6% 20% 38% 24% 9%	450
	11th to 20th	Day	4 8% 21% 35% 24% 7%	450
	21st to end	Day	6% 8% 24% 31% 23% 8%	450
October	1st to 10th	Day	9% 8% 24% 25% 25% 10%	450
	11th to 20th	Day	10% 10% 17% 26% 27% 11%	450
	21st to end	Day	13% 8% 21% 27% 23% 9%	495
November	1st to 10th	Day	14% 13% 18% 23% 25% 6%	455
	11th to 20th	Day	14% 9% 14% 24% 29% 11%	235
	21st to end	Day	17% 9% 20% 23% 20% 12%	180
December	1st to 10th	Day	26% 11% 18% 20% 16% 9%	180
	11th to 20th	Day	29% 11% 18% 19% 13% 9%	180
	21st to end	Day	26% 13% 17% 23% 17% 5%	198
January	1st to 10th	Night	26% 7% 16% 28% 19% 5%	760
	11th to 20th	Night	23% 7% 16% 29% 18% 6%	744
	21st to end	Night	21% 6% 16% 30% 23% 5%	792
February	1st to 10th	Night	21% 6% 16% 32% 21% 4	720
	11th to 20th	Night	21% 8% 21% 28% 16% 5%	704
	21st to end	Night	21% 9% 24% 28% 16% 2	592
March	1st to 10th	Night	26% 10% 18% 27% 15% 3	720
	11th to 20th	Night	23% 8% 18% 30% 17% 3	720
	21st to end	Night	22% 8% 27% 27% 14% 2	792
April	1st to 10th	Night	19% 11% 26% 25% 16% 4	720
	11th to 20th	Night	14% 13% 25% 28% 15% 5%	711
	21st to end	Night	10% 14% 28% 24% 20% 4	698
May	1st to 10th	Night	8% 9% 28% 28% 21% 5%	540
	11th to 20th	Night	5% 6% 27% 34% 24% 4	514
	21st to end	Night	9% 12% 21% 29% 25% 4	389
June	1st to 10th	Night	6% 10% 26% 33% 24% 1	360
	11th to 20th	Night	3 10% 28% 37% 21% 1	360
	21st to end	Night	4 1 20% 42% 31% 2	360
July	1st to 10th	Night	1 4 19% 35% 36% 5%	360
	11th to 20th	Night	1 15% 31% 42% 10%	522
	21st to end	Night	1 11% 30% 45% 13%	591
August	1st to 10th	Night	1 1 13% 35% 38% 12%	537
	11th to 20th	Night	1 13% 32% 42% 12%	556
	21st to end	Night	2 1 11% 31% 46% 9%	792
September	1st to 10th	Night	1 3 11% 33% 40% 12%	720
	11th to 20th	Night	5% 4 13% 38% 31% 9%	720
	21st to end	Night	4 5% 17% 29% 35% 10%	720
October	1st to 10th	Night	6% 5% 16% 33% 33% 8%	720
	11th to 20th	Night	8% 5% 13% 28% 38% 9%	720
	21st to end	Night	13% 4 13% 29% 30% 11%	792
November	1st to 10th	Night	14% 6% 17% 25% 29% 8%	740
	11th to 20th	Night	17% 5% 13% 34% 24% 6%	760
	21st to end	Night	15% 8% 14% 31% 23% 8%	760
December	1st to 10th	Night	26% 4 15% 28% 21% 6%	760
	11th to 20th	Night	30% 7% 13% 28% 18% 4	760
	21st to end	Night	25% 10% 19% 28% 16% 4	836

Page generated at 2024-01-13 16:28:32. Version ac07

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