Lone Palm Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lone Palm Observatory clear sky chart from 2005-11-06 to 2024-11-08.

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	8% 5% 2 7% 6% 6% 6% 5% 8% 10% 37%	100833
	Night	8% 6% 2 7% 5% 5% 5% 5% 7% 10% 41%	98213
Transparency	Day	36% 12% 18% 19% 12% 3	104546
	Night	37% 10% 18% 20% 12% 4	102626
Seeing	Day	8% 4 18% 28% 24% 18%	15765
	Night	8% 4 18% 31% 30% 9%	25851

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	11% 7% 3 8% 5% 5% 5% 3 5% 6% 43%	2836
	11th to 20th	Day	17% 9% 4 7% 5% 4 4 4 6% 9% 32%	2840
	21st to end	Day	10% 7% 2 9% 4 6% 5% 4 5% 7% 40%	3124
February	1st to 10th	Day	11% 7% 2 6% 5% 4 5% 4 5% 8% 43%	1891
	11th to 20th	Day	6% 4 2 6% 5% 4 4 3 6% 7% 51%	1873
	21st to end	Day	8% 5% 2 5% 4 5% 4 4 6% 7% 49%	1727
March	1st to 10th	Day	7% 7% 3 9% 6% 6% 6% 5% 8% 10% 34%	3435
	11th to 20th	Day	4 3 1 4 4 4 5% 4 8% 11% 50%	3480
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 6% 9% 45%	3815
April	1st to 10th	Day	5% 4 1 5% 4 5% 5% 6% 8% 10% 48%	2090
	11th to 20th	Day	8% 4 3 7% 5% 6% 6% 6% 8% 9% 40%	2159
	21st to end	Day	5% 3 2 7% 5% 5% 5% 4 7% 9% 48%	2280
May	1st to 10th	Day	3 2 1 3 3 3 4 4 7% 11% 59%	3791
	11th to 20th	Day	7% 5% 3 8% 6% 6% 6% 5% 8% 9% 36%	4081
	21st to end	Day	4 4 2 5% 4 5% 5% 5% 7% 9% 50%	4476
June	1st to 10th	Day	13% 7% 3 8% 6% 7% 7% 5% 8% 11% 23%	2470
	11th to 20th	Day	6% 5% 2 8% 7% 8% 9% 7% 9% 11% 27%	2470
	21st to end	Day	8% 6% 3 8% 7% 8% 8% 6% 10% 11% 25%	2470
July	1st to 10th	Day	6% 6% 2 8% 6% 6% 7% 6% 9% 13% 31%	4120
	11th to 20th	Day	6% 6% 2 7% 6% 6% 7% 6% 10% 14% 30%	4120
	21st to end	Day	5% 5% 2 8% 7% 7% 8% 7% 9% 13% 27%	4466
August	1st to 10th	Day	4 4 2 8% 6% 8% 9% 7% 11% 15% 26%	4104
	11th to 20th	Day	4 4 2 7% 6% 6% 8% 7% 10% 14% 33%	3821
	21st to end	Day	6% 5% 2 7% 7% 7% 8% 7% 11% 14% 25%	3909
September	1st to 10th	Day	7% 7% 3 9% 8% 6% 10% 6% 10% 11% 23%	2090
	11th to 20th	Day	8% 7% 3 9% 7% 7% 8% 7% 9% 11% 24%	2090
	21st to end	Day	9% 7% 3 9% 7% 8% 7% 6% 9% 9% 26%	2090
October	1st to 10th	Day	12% 7% 3 9% 6% 7% 6% 6% 8% 10% 28%	2011
	11th to 20th	Day	7% 5% 3 6% 6% 5% 6% 5% 8% 9% 40%	1900
	21st to end	Day	9% 4 2 6% 5% 5% 5% 3 7% 9% 44%	2090
November	1st to 10th	Day	8% 5% 3 6% 6% 5% 5% 5% 8% 9% 39%	1927
	11th to 20th	Day	10% 7% 3 6% 5% 5% 5% 5% 8% 8% 39%	1900
	21st to end	Day	9% 6% 2 8% 5% 5% 6% 5% 6% 9% 39%	1900
December	1st to 10th	Day	8% 5% 2 7% 4 5% 5% 4 6% 8% 44%	1710
	11th to 20th	Day	11% 7% 2 7% 5% 5% 4 4 6% 8% 40%	2153
	21st to end	Day	11% 6% 3 8% 6% 7% 7% 5% 7% 8% 31%	3124
January	1st to 10th	Night	10% 6% 3 8% 5% 5% 5% 4 6% 7% 41%	4109
	11th to 20th	Night	16% 12% 4 8% 5% 5% 4 3 6% 7% 30%	4120
	21st to end	Night	10% 7% 2 7% 5% 5% 5% 5% 6% 7% 41%	4532
February	1st to 10th	Night	10% 7% 3 6% 4 4 4 3 6% 8% 46%	2285
	11th to 20th	Night	10% 4 2 4 4 3 4 4 6% 7% 52%	2190
	21st to end	Night	7% 5% 2 4 3 3 4 4 7% 7% 54%	1727
March	1st to 10th	Night	11% 8% 3 9% 6% 4 5% 4 6% 6% 38%	3418
	11th to 20th	Night	5% 3 1 4 3 3 4 4 8% 13% 53%	3480
	21st to end	Night	8% 6% 2 6% 5% 5% 5% 3 7% 7% 47%	3817
April	1st to 10th	Night	6% 3 2 5% 3 3 5% 3 7% 9% 55%	2090
	11th to 20th	Night	5% 4 3 6% 4 4 5% 5% 7% 9% 48%	1969
	21st to end	Night	5% 3 2 5% 5% 4 5% 4 6% 8% 53%	1900
May	1st to 10th	Night	4 3 1 3 3 3 4 3 6% 9% 62%	3130
	11th to 20th	Night	7% 5% 2 6% 5% 5% 4 5% 8% 11% 42%	2812
	21st to end	Night	5% 4 2 5% 3 4 4 4 6% 9% 53%	3079
June	1st to 10th	Night	10% 8% 3 7% 6% 5% 6% 7% 8% 10% 29%	1710
	11th to 20th	Night	7% 6% 2 8% 5% 6% 7% 6% 9% 13% 31%	1710
	21st to end	Night	6% 6% 2 9% 7% 5% 7% 5% 8% 12% 34%	1710
July	1st to 10th	Night	6% 6% 2 6% 5% 5% 6% 5% 8% 13% 38%	2840
	11th to 20th	Night	5% 5% 3 7% 5% 5% 7% 5% 9% 15% 35%	2840
	21st to end	Night	4 6% 3 8% 7% 7% 7% 6% 10% 13% 31%	3087
August	1st to 10th	Night	4 5% 2 9% 6% 5% 7% 5% 9% 12% 35%	2825
	11th to 20th	Night	4 5% 2 7% 6% 6% 7% 6% 9% 12% 36%	2971
	21st to end	Night	6% 6% 3 7% 6% 6% 7% 6% 9% 15% 29%	3727
September	1st to 10th	Night	6% 6% 3 9% 7% 6% 7% 6% 9% 12% 28%	2090
	11th to 20th	Night	8% 7% 3 10% 7% 7% 6% 6% 8% 11% 27%	2090
	21st to end	Night	10% 7% 3 9% 6% 7% 5% 6% 8% 9% 31%	2090
October	1st to 10th	Night	12% 7% 3 8% 4 5% 5% 4 7% 10% 34%	2166
	11th to 20th	Night	7% 5% 2 7% 5% 5% 5% 4 6% 9% 44%	2280
	21st to end	Night	8% 6% 2 7% 4 4 4 4 7% 9% 46%	2508
November	1st to 10th	Night	9% 5% 2 7% 5% 5% 5% 4 6% 7% 44%	2312
	11th to 20th	Night	8% 6% 2 7% 5% 6% 5% 4 7% 9% 42%	2280
	21st to end	Night	11% 6% 2 7% 5% 5% 5% 5% 7% 8% 39%	2280
December	1st to 10th	Night	5% 5% 2 5% 6% 5% 5% 5% 6% 9% 48%	2465
	11th to 20th	Night	14% 8% 2 6% 4 4 4 3 6% 7% 42%	3042
	21st to end	Night	12% 8% 3 9% 6% 5% 6% 4 6% 7% 34%	4532

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	41% 6% 8% 16% 23% 6%	2837
	11th to 20th	Day	49% 6% 6% 19% 16% 4	2840
	21st to end	Day	41% 7% 8% 17% 19% 7%	3124
February	1st to 10th	Day	38% 6% 11% 17% 21% 7%	1891
	11th to 20th	Day	29% 5% 13% 23% 21% 9%	1883
	21st to end	Day	32% 6% 13% 17% 26% 7%	1727
March	1st to 10th	Day	40% 12% 15% 17% 12% 4	3435
	11th to 20th	Day	25% 7% 16% 33% 16% 4	3480
	21st to end	Day	30% 9% 11% 28% 14% 7%	3815
April	1st to 10th	Day	28% 9% 16% 26% 16% 5%	2090
	11th to 20th	Day	36% 9% 13% 20% 18% 4	2159
	21st to end	Day	28% 8% 13% 22% 24% 6%	2280
May	1st to 10th	Day	16% 9% 16% 35% 19% 4	3826
	11th to 20th	Day	39% 11% 18% 20% 11% 1	4085
	21st to end	Day	26% 10% 14% 35% 15%	4489
June	1st to 10th	Day	48% 13% 20% 15% 4	2470
	11th to 20th	Day	42% 14% 22% 19% 2	2470
	21st to end	Day	44% 16% 25% 13% 3	2470
July	1st to 10th	Day	35% 15% 31% 15% 4	4055
	11th to 20th	Day	35% 17% 38% 10%	4051
	21st to end	Day	38% 20% 27% 14% 1	4324
August	1st to 10th	Day	36% 20% 32% 11% 1	4091
	11th to 20th	Day	31% 18% 29% 14% 8%	3860
	21st to end	Day	40% 18% 30% 11% 2	3909
September	1st to 10th	Day	45% 20% 21% 11% 3	2090
	11th to 20th	Day	45% 18% 22% 12% 3	2090
	21st to end	Day	47% 15% 15% 13% 10% 1	2090
October	1st to 10th	Day	51% 12% 17% 10% 7% 2	3336
	11th to 20th	Day	30% 9% 10% 23% 24% 4	3140
	21st to end	Day	28% 6% 11% 24% 26% 5%	3428
November	1st to 10th	Day	35% 8% 15% 17% 18% 7%	1927
	11th to 20th	Day	39% 8% 10% 21% 16% 6%	1900
	21st to end	Day	39% 8% 12% 19% 18% 5%	1900
December	1st to 10th	Day	35% 8% 14% 24% 14% 4	1710
	11th to 20th	Day	39% 7% 11% 17% 17% 8%	2150
	21st to end	Day	46% 8% 12% 15% 12% 6%	3124
January	1st to 10th	Night	40% 7% 11% 21% 17% 5%	4109
	11th to 20th	Night	52% 6% 8% 19% 11% 3	4120
	21st to end	Night	40% 7% 10% 19% 15% 9%	4532
February	1st to 10th	Night	36% 6% 13% 18% 18% 9%	2285
	11th to 20th	Night	30% 5% 13% 22% 21% 9%	2191
	21st to end	Night	26% 7% 15% 21% 24% 7%	1727
March	1st to 10th	Night	43% 10% 13% 18% 12% 4	3418
	11th to 20th	Night	20% 8% 27% 29% 13% 4	3480
	21st to end	Night	32% 8% 13% 23% 18% 5%	3817
April	1st to 10th	Night	24% 7% 19% 26% 16% 7%	2090
	11th to 20th	Night	30% 10% 14% 23% 19% 4	1969
	21st to end	Night	28% 6% 15% 23% 22% 6%	1900
May	1st to 10th	Night	17% 9% 19% 34% 16% 5%	3160
	11th to 20th	Night	31% 12% 20% 28% 8% 1	2813
	21st to end	Night	25% 9% 17% 34% 14%	3087
June	1st to 10th	Night	45% 12% 23% 16% 4	1710
	11th to 20th	Night	41% 13% 21% 22% 3	1710
	21st to end	Night	41% 14% 25% 16% 4	1710
July	1st to 10th	Night	34% 14% 30% 21% 1	2795
	11th to 20th	Night	34% 17% 40% 9%	2786
	21st to end	Night	38% 17% 31% 13% 1	2988
August	1st to 10th	Night	38% 15% 34% 12% 1	2814
	11th to 20th	Night	34% 16% 29% 14% 7%	2998
	21st to end	Night	41% 15% 33% 10% 1	3727
September	1st to 10th	Night	44% 19% 21% 14% 2	2090
	11th to 20th	Night	47% 17% 21% 14% 2	2090
	21st to end	Night	47% 13% 16% 15% 8% 2	2090
October	1st to 10th	Night	56% 11% 14% 12% 6% 2	3608
	11th to 20th	Night	33% 8% 11% 24% 20% 4	3779
	21st to end	Night	31% 7% 12% 22% 24% 5%	4120
November	1st to 10th	Night	38% 8% 12% 16% 19% 6%	2312
	11th to 20th	Night	37% 9% 12% 22% 13% 7%	2280
	21st to end	Night	39% 8% 12% 19% 18% 4	2280
December	1st to 10th	Night	32% 7% 15% 29% 11% 5%	2465
	11th to 20th	Night	41% 6% 13% 16% 14% 10%	3044
	21st to end	Night	46% 8% 13% 16% 12% 5%	4532

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	13% 7% 42% 24% 11% 3	270
	11th to 20th	Day	7% 10% 40% 26% 14% 3	270
	21st to end	Day	13% 13% 45% 22% 6%	297
February	1st to 10th	Day	11% 11% 34% 30% 12% 2	270
	11th to 20th	Day	7% 7% 33% 35% 13% 5%	295
	21st to end	Day	7% 7% 29% 36% 18% 3	382
March	1st to 10th	Day	7% 9% 34% 36% 13% 2	460
	11th to 20th	Day	8% 6% 30% 33% 19% 3	460
	21st to end	Day	6% 6% 29% 34% 21% 4	506
April	1st to 10th	Day	6% 7% 34% 33% 16% 4	460
	11th to 20th	Day	6% 9% 27% 32% 21% 5%	452
	21st to end	Day	6% 5% 23% 34% 24% 9%	460
May	1st to 10th	Day	5% 2 21% 36% 25% 11%	463
	11th to 20th	Day	9% 3 16% 30% 26% 15%	487
	21st to end	Day	7% 3 11% 26% 31% 21%	529
June	1st to 10th	Day	13% 2 9% 27% 28% 20%	490
	11th to 20th	Day	7% 1 8% 24% 30% 30%	490
	21st to end	Day	6% 1 5% 17% 30% 41%	490
July	1st to 10th	Day	6% 2 3 12% 30% 47%	485
	11th to 20th	Day	5% 1 3 11% 36% 44%	484
	21st to end	Day	6% 1 5% 19% 28% 41%	532
August	1st to 10th	Day	5% 2 6% 16% 33% 39%	486
	11th to 20th	Day	4 1 3 14% 32% 47%	479
	21st to end	Day	9% 1 5% 22% 29% 33%	539
September	1st to 10th	Day	8% 3 4 18% 30% 37%	490
	11th to 20th	Day	10% 1 8% 26% 27% 28%	490
	21st to end	Day	9% 2 9% 24% 33% 23%	490
October	1st to 10th	Day	16% 2 16% 33% 23% 9%	490
	11th to 20th	Day	7% 2 20% 35% 29% 7%	490
	21st to end	Day	7% 4 21% 37% 25% 7%	539
November	1st to 10th	Day	9% 7% 20% 36% 21% 7%	483
	11th to 20th	Day	10% 6% 27% 32% 22% 4	460
	21st to end	Day	8% 4 24% 40% 21% 3	460
December	1st to 10th	Day	5% 7% 28% 39% 16% 4	270
	11th to 20th	Day	8% 9% 27% 36% 16% 4	270
	21st to end	Day	8% 7% 26% 38% 18% 3	297
January	1st to 10th	Night	13% 7% 27% 35% 16% 2	760
	11th to 20th	Night	10% 7% 28% 37% 16% 2	760
	21st to end	Night	12% 8% 33% 36% 11%	836
February	1st to 10th	Night	11% 8% 25% 39% 16% 1	760
	11th to 20th	Night	10% 6% 29% 37% 15% 2	743
	21st to end	Night	9% 4 29% 43% 15%	628
March	1st to 10th	Night	5% 6% 33% 42% 14% 1	760
	11th to 20th	Night	6% 5% 27% 41% 19% 2	760
	21st to end	Night	6% 5% 29% 40% 20% 1	836
April	1st to 10th	Night	5% 6% 29% 41% 19% 1	760
	11th to 20th	Night	6% 5% 25% 42% 22% 1	751
	21st to end	Night	6% 2 23% 45% 22% 3	760
May	1st to 10th	Night	6% 2 16% 47% 27% 2	760
	11th to 20th	Night	8% 2 13% 34% 36% 6%	561
	21st to end	Night	7% 1 7% 29% 47% 10%	617
June	1st to 10th	Night	11% 1 7% 27% 44% 10%	570
	11th to 20th	Night	8% 1 6% 19% 44% 22%	570
	21st to end	Night	5% 1 4 15% 47% 28%	570
July	1st to 10th	Night	7% 2 3 13% 49% 27%	555
	11th to 20th	Night	7% 1 2 10% 45% 35%	552
	21st to end	Night	5% 1 2 10% 49% 33%	624
August	1st to 10th	Night	5% 3 12% 49% 31%	567
	11th to 20th	Night	4 1 3 10% 48% 34%	672
	21st to end	Night	11% 2 5% 18% 41% 24%	836
September	1st to 10th	Night	7% 2 6% 17% 45% 23%	760
	11th to 20th	Night	11% 2 5% 22% 43% 18%	760
	21st to end	Night	12% 3 6% 22% 41% 15%	760
October	1st to 10th	Night	15% 1 13% 30% 34% 6%	760
	11th to 20th	Night	8% 3 12% 32% 38% 7%	760
	21st to end	Night	10% 2 19% 34% 31% 5%	836
November	1st to 10th	Night	10% 3 21% 33% 28% 5%	771
	11th to 20th	Night	8% 4 24% 37% 24% 3	760
	21st to end	Night	12% 4 22% 42% 19% 2	760
December	1st to 10th	Night	5% 4 23% 38% 28% 3	760
	11th to 20th	Night	11% 6% 23% 34% 23% 3	760
	21st to end	Night	10% 5% 25% 37% 21% 2	836

Page generated at 2024-11-05 08:15:50. Version ac07

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