Ghost Pine Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ghost Pine Observatory clear sky chart from 2005-11-06 to 2024-01-13.

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	6% 3 1 3 3 2 3 3 4 6% 66%	74706
	Night	7% 3 1 3 3 2 3 3 4 6% 63%	75044
Transparency	Day	21% 4 9% 19% 25% 21%	74421
	Night	23% 5% 9% 19% 24% 20%	74850
Seeing	Day	7% 8% 18% 26% 28% 12%	14120
	Night	8% 5% 18% 33% 31% 5%	23490

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	17% 8% 3 6% 4 3 3 4 4 8% 40%	1557
	11th to 20th	Day	11% 5% 3 5% 4 2 3 4 4 7% 51%	1639
	21st to end	Day	13% 6% 3 4 4 3 4 4 6% 8% 46%	1782
February	1st to 10th	Day	13% 5% 2 4 4 3 4 3 5% 6% 52%	1620
	11th to 20th	Day	10% 5% 2 5% 4 3 3 4 4 7% 52%	1626
	21st to end	Day	12% 4 2 4 5% 3 4 4 5% 6% 52%	1480
March	1st to 10th	Day	13% 6% 3 6% 5% 3 4 4 6% 9% 42%	1931
	11th to 20th	Day	12% 7% 2 6% 6% 2 5% 5% 6% 7% 43%	1980
	21st to end	Day	10% 5% 2 5% 5% 3 4 5% 5% 7% 50%	2210
April	1st to 10th	Day	10% 6% 3 6% 5% 3 5% 5% 5% 8% 46%	2160
	11th to 20th	Day	8% 3 2 4 4 2 3 4 5% 8% 60%	2129
	21st to end	Day	3 2 2 3 3 2 4 4 5% 8% 63%	2160
May	1st to 10th	Day	4 3 1 2 3 2 2 3 4 7% 68%	2282
	11th to 20th	Day	3 2 1 3 3 1 3 3 5% 8% 67%	2405
	21st to end	Day	3 2 1 3 3 2 3 4 6% 7% 66%	2723
June	1st to 10th	Day	4 2 1 2 3 2 3 4 5% 8% 66%	2520
	11th to 20th	Day	1 1 1 1 2 1 2 3 3 5% 80%	2520
	21st to end	Day	1 1 1 1 1 2 2 2 3 87%	2520
July	1st to 10th	Day	1 1 1 1 2 1 2 3 88%	2520
	11th to 20th	Day	1 1 1 1 1 2 3 89%	2433
	21st to end	Day	1 1 1 1 1 1 1 2 4 87%	2546
August	1st to 10th	Day	2 1 1 1 1 2 2 2 3 84%	2328
	11th to 20th	Day	1 1 1 1 1 2 2 4 86%	2221
	21st to end	Day	1 1 1 1 1 2 3 90%	2376
September	1st to 10th	Day	1 1 2 2 2 4 88%	2160
	11th to 20th	Day	2 1 1 1 2 1 2 2 3 4 80%	2160
	21st to end	Day	2 1 1 1 1 1 2 2 3 5% 80%	1906
October	1st to 10th	Day	3 2 2 2 2 1 2 2 3 5% 75%	1800
	11th to 20th	Day	5% 3 1 2 2 2 2 3 4 4 72%	1800
	21st to end	Day	7% 3 1 3 2 2 3 3 4 6% 67%	1980
November	1st to 10th	Day	7% 4 1 3 3 2 3 4 6% 8% 59%	1783
	11th to 20th	Day	9% 4 2 4 5% 3 3 5% 6% 7% 53%	1687
	21st to end	Day	7% 4 2 3 3 2 3 4 4 6% 59%	1520
December	1st to 10th	Day	11% 6% 2 3 4 3 4 4 4 8% 50%	1520
	11th to 20th	Day	24% 9% 4 6% 5% 3 3 3 5% 5% 33%	1928
	21st to end	Day	19% 8% 3 4 5% 2 3 4 5% 9% 38%	2794
January	1st to 10th	Night	14% 6% 3 5% 4 3 4 4 6% 9% 43%	2606
	11th to 20th	Night	11% 6% 2 5% 4 3 4 4 5% 7% 48%	2377
	21st to end	Night	13% 5% 2 4 3 2 4 5% 5% 7% 50%	2574
February	1st to 10th	Night	12% 4 2 4 4 2 4 4 5% 6% 53%	2340
	11th to 20th	Night	9% 4 2 3 4 3 4 4 6% 9% 52%	2219
	21st to end	Night	10% 4 2 3 3 1 4 4 5% 6% 57%	1776
March	1st to 10th	Night	12% 6% 2 4 5% 3 4 5% 5% 7% 46%	2026
	11th to 20th	Night	9% 7% 2 4 4 3 5% 5% 5% 7% 47%	1980
	21st to end	Night	11% 4 2 4 4 2 4 3 4 7% 55%	2144
April	1st to 10th	Night	6% 4 2 5% 5% 3 6% 5% 4 6% 54%	1800
	11th to 20th	Night	6% 3 1 3 3 2 3 3 5% 6% 65%	1779
	21st to end	Night	4 2 1 1 2 1 3 3 4 8% 70%	1800
May	1st to 10th	Night	4 2 2 3 1 3 3 3 6% 72%	1674
	11th to 20th	Night	3 1 1 1 2 1 3 4 5% 8% 71%	1488
	21st to end	Night	3 2 1 2 2 1 2 3 5% 6% 73%	1552
June	1st to 10th	Night	4 1 1 2 2 2 3 3 4 6% 71%	1440
	11th to 20th	Night	1 1 1 1 1 2 2 3 5% 83%	1440
	21st to end	Night	1 1 1 1 2 1 2 2 2 4 85%	1440
July	1st to 10th	Night	1 1 1 1 2 3 90%	1440
	11th to 20th	Night	1 1 1 1 1 1 1 2 3 88%	1522
	21st to end	Night	1 1 1 1 1 1 2 2 2 3 87%	1773
August	1st to 10th	Night	2 1 1 1 1 2 2 2 2 86%	1611
	11th to 20th	Night	1 1 1 1 1 2 2 2 86%	1678
	21st to end	Night	1 1 1 1 1 1 2 1 2 90%	1980
September	1st to 10th	Night	1 1 1 1 1 1 1 2 3 89%	1800
	11th to 20th	Night	1 2 1 2 2 1 2 1 3 5% 82%	1800
	21st to end	Night	1 1 1 1 1 2 2 3 5% 83%	2049
October	1st to 10th	Night	3 1 1 2 2 2 3 2 3 4 76%	2160
	11th to 20th	Night	3 1 1 2 2 1 3 3 4 6% 74%	2160
	21st to end	Night	6% 2 1 2 2 2 3 3 4 6% 69%	2376
November	1st to 10th	Night	6% 3 2 3 3 2 3 3 6% 8% 60%	2293
	11th to 20th	Night	8% 3 1 4 3 2 4 4 5% 8% 57%	2489
	21st to end	Night	7% 3 2 4 4 2 3 4 4 6% 60%	2660
December	1st to 10th	Night	13% 5% 2 4 4 3 4 4 4 7% 50%	2660
	11th to 20th	Night	21% 9% 3 4 4 2 4 4 5% 7% 36%	3276
	21st to end	Night	15% 8% 3 6% 5% 4 5% 5% 5% 6% 37%	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	45% 7% 13% 21% 9% 5%	1557
	11th to 20th	Day	34% 6% 11% 18% 18% 13%	1639
	21st to end	Day	38% 6% 10% 16% 22% 8%	1782
February	1st to 10th	Day	35% 4 10% 21% 20% 9%	1620
	11th to 20th	Day	33% 5% 11% 20% 22% 9%	1635
	21st to end	Day	34% 5% 9% 25% 20% 7%	1480
March	1st to 10th	Day	40% 7% 14% 17% 16% 5%	1931
	11th to 20th	Day	40% 5% 11% 21% 14% 8%	1980
	21st to end	Day	34% 7% 14% 19% 20% 6%	2210
April	1st to 10th	Day	36% 6% 13% 20% 18% 7%	2160
	11th to 20th	Day	24% 7% 13% 22% 25% 9%	2132
	21st to end	Day	18% 6% 15% 28% 25% 9%	2160
May	1st to 10th	Day	17% 4 11% 25% 32% 12%	2282
	11th to 20th	Day	16% 5% 10% 27% 29% 12%	2408
	21st to end	Day	16% 6% 15% 32% 22% 8%	2724
June	1st to 10th	Day	17% 5% 11% 27% 28% 13%	2520
	11th to 20th	Day	8% 4 9% 20% 34% 26%	2520
	21st to end	Day	6% 2 3 14% 36% 38%	2520
July	1st to 10th	Day	5% 2 3 11% 29% 50%	2451
	11th to 20th	Day	4 1 3 13% 30% 49%	2358
	21st to end	Day	4 2 3 10% 26% 54%	2405
August	1st to 10th	Day	8% 2 5% 14% 32% 39%	2312
	11th to 20th	Day	5% 1 3 12% 39% 40%	2221
	21st to end	Day	4 1 3 14% 36% 41%	2376
September	1st to 10th	Day	4 1 4 9% 30% 53%	2160
	11th to 20th	Day	10% 3 7% 23% 38% 19%	2160
	21st to end	Day	10% 3 5% 21% 30% 31%	1906
October	1st to 10th	Day	15% 3 6% 17% 33% 28%	1800
	11th to 20th	Day	17% 3 7% 21% 24% 28%	1800
	21st to end	Day	21% 4 7% 21% 28% 20%	1980
November	1st to 10th	Day	23% 6% 9% 26% 22% 12%	1783
	11th to 20th	Day	30% 6% 13% 23% 22% 7%	1687
	21st to end	Day	27% 5% 12% 22% 22% 12%	1520
December	1st to 10th	Day	34% 7% 9% 21% 19% 10%	1520
	11th to 20th	Day	55% 5% 7% 13% 16% 4	1928
	21st to end	Day	44% 7% 15% 18% 12% 4	2794
January	1st to 10th	Night	39% 7% 13% 23% 12% 6%	2606
	11th to 20th	Night	36% 6% 11% 19% 15% 13%	2377
	21st to end	Night	34% 6% 12% 14% 24% 9%	2574
February	1st to 10th	Night	33% 4 9% 20% 21% 13%	2340
	11th to 20th	Night	29% 5% 12% 21% 24% 10%	2221
	21st to end	Night	28% 4 13% 22% 25% 8%	1776
March	1st to 10th	Night	38% 7% 15% 15% 20% 5%	2026
	11th to 20th	Night	35% 5% 11% 21% 18% 9%	1980
	21st to end	Night	31% 6% 13% 22% 21% 7%	2144
April	1st to 10th	Night	31% 7% 13% 20% 20% 9%	1800
	11th to 20th	Night	21% 5% 14% 27% 20% 13%	1779
	21st to end	Night	14% 5% 14% 29% 30% 8%	1800
May	1st to 10th	Night	14% 4 10% 24% 33% 14%	1674
	11th to 20th	Night	12% 5% 11% 27% 32% 14%	1488
	21st to end	Night	12% 4 14% 34% 26% 10%	1552
June	1st to 10th	Night	15% 5% 10% 25% 31% 14%	1440
	11th to 20th	Night	7% 3 6% 22% 32% 29%	1440
	21st to end	Night	7% 2 4 12% 31% 44%	1440
July	1st to 10th	Night	4 1 2 9% 30% 54%	1400
	11th to 20th	Night	5% 2 4 10% 21% 59%	1474
	21st to end	Night	5% 1 3 7% 22% 62%	1674
August	1st to 10th	Night	8% 1 2 12% 30% 47%	1602
	11th to 20th	Night	6% 1 3 9% 32% 49%	1678
	21st to end	Night	5% 1 2 12% 31% 49%	1980
September	1st to 10th	Night	4 1 3 7% 30% 55%	1800
	11th to 20th	Night	9% 2 6% 18% 38% 27%	1800
	21st to end	Night	6% 2 5% 19% 30% 37%	2049
October	1st to 10th	Night	13% 3 7% 17% 29% 31%	2160
	11th to 20th	Night	13% 4 8% 17% 27% 30%	2160
	21st to end	Night	17% 4 7% 21% 26% 25%	2376
November	1st to 10th	Night	23% 6% 11% 24% 22% 15%	2293
	11th to 20th	Night	25% 5% 12% 24% 22% 10%	2489
	21st to end	Night	26% 5% 9% 21% 25% 14%	2660
December	1st to 10th	Night	35% 6% 9% 19% 19% 11%	2660
	11th to 20th	Night	48% 7% 10% 14% 18% 4	3276
	21st to end	Night	45% 9% 12% 17% 14% 4	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	29% 11% 24% 20% 15%	218
	11th to 20th	Day	15% 11% 27% 26% 16% 4	347
	21st to end	Day	14% 10% 27% 21% 21% 6%	374
February	1st to 10th	Day	16% 13% 21% 26% 18% 6%	340
	11th to 20th	Day	13% 18% 28% 23% 14% 4	358
	21st to end	Day	12% 15% 26% 31% 13% 3	346
March	1st to 10th	Day	15% 16% 28% 26% 10% 5%	420
	11th to 20th	Day	16% 12% 23% 27% 17% 5%	420
	21st to end	Day	12% 17% 26% 29% 13% 3	462
April	1st to 10th	Day	12% 14% 24% 29% 15% 6%	420
	11th to 20th	Day	10% 13% 27% 24% 17% 8%	412
	21st to end	Day	3 12% 23% 29% 23% 10%	420
May	1st to 10th	Day	6% 10% 26% 26% 24% 7%	423
	11th to 20th	Day	6% 6% 23% 28% 20% 16%	448
	21st to end	Day	4 7% 18% 25% 29% 16%	485
June	1st to 10th	Day	4 6% 19% 25% 31% 15%	450
	11th to 20th	Day	1 6% 17% 32% 35% 8%	450
	21st to end	Day	4 11% 28% 39% 17%	450
July	1st to 10th	Day	1 1 6% 29% 47% 16%	446
	11th to 20th	Day	1 7% 23% 45% 25%	444
	21st to end	Day	1 1 5% 24% 46% 24%	487
August	1st to 10th	Day	3 8% 25% 39% 25%	447
	11th to 20th	Day	2 1 7% 25% 40% 26%	437
	21st to end	Day	1 1 5% 23% 45% 26%	495
September	1st to 10th	Day	1 7% 29% 44% 19%	450
	11th to 20th	Day	3 4 10% 25% 40% 18%	450
	21st to end	Day	2 6% 19% 28% 31% 14%	450
October	1st to 10th	Day	3 10% 17% 26% 28% 16%	450
	11th to 20th	Day	5% 6% 17% 26% 33% 13%	450
	21st to end	Day	11% 7% 19% 27% 27% 9%	495
November	1st to 10th	Day	10% 8% 21% 22% 32% 8%	379
	11th to 20th	Day	9% 8% 17% 29% 28% 10%	259
	21st to end	Day	12% 7% 23% 33% 19% 6%	180
December	1st to 10th	Day	21% 11% 22% 24% 14% 8%	180
	11th to 20th	Day	17% 8% 30% 22% 16% 8%	180
	21st to end	Day	18% 15% 24% 20% 20% 3	198
January	1st to 10th	Night	17% 6% 22% 31% 19% 6%	760
	11th to 20th	Night	13% 8% 25% 35% 15% 4	732
	21st to end	Night	15% 6% 22% 32% 20% 4	792
February	1st to 10th	Night	14% 9% 19% 34% 21% 3	720
	11th to 20th	Night	12% 9% 23% 32% 19% 5%	704
	21st to end	Night	12% 11% 24% 35% 16% 2	592
March	1st to 10th	Night	15% 9% 22% 31% 19% 3	720
	11th to 20th	Night	14% 6% 22% 32% 24% 3	720
	21st to end	Night	13% 8% 28% 34% 17% 2	792
April	1st to 10th	Night	8% 8% 24% 38% 20% 3	720
	11th to 20th	Night	7% 9% 25% 34% 21% 4	711
	21st to end	Night	4 7% 25% 35% 23% 5%	720
May	1st to 10th	Night	5% 6% 26% 32% 26% 5%	594
	11th to 20th	Night	2 4 16% 36% 38% 4	426
	21st to end	Night	5% 5% 18% 32% 37% 3	389
June	1st to 10th	Night	5% 4 18% 36% 35% 2	360
	11th to 20th	Night	1 4 16% 40% 39% 1	360
	21st to end	Night	1 1 11% 43% 41% 3	360
July	1st to 10th	Night	1 5% 37% 54% 3	350
	11th to 20th	Night	3 36% 54% 7%	430
	21st to end	Night	1 3 27% 58% 10%	591
August	1st to 10th	Night	3 4 27% 58% 8%	537
	11th to 20th	Night	1 3 34% 51% 10%	610
	21st to end	Night	1 3 31% 57% 7%	792
September	1st to 10th	Night	1 1 6% 34% 51% 7%	720
	11th to 20th	Night	2 2 7% 34% 46% 9%	720
	21st to end	Night	1 3 12% 36% 37% 11%	720
October	1st to 10th	Night	4 6% 14% 34% 34% 8%	720
	11th to 20th	Night	4 5% 16% 33% 37% 6%	720
	21st to end	Night	8% 3 20% 30% 30% 10%	792
November	1st to 10th	Night	7% 6% 19% 30% 32% 7%	740
	11th to 20th	Night	9% 4 19% 35% 29% 3	760
	21st to end	Night	8% 7% 22% 39% 20% 5%	760
December	1st to 10th	Night	15% 8% 23% 29% 22% 4	760
	11th to 20th	Night	20% 6% 20% 32% 20% 3	760
	21st to end	Night	15% 11% 25% 30% 19% 1	836

Page generated at 2024-01-10 07:16:13. Version ac07

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