Sanders Preserve
Clear Sky Chart
History

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

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% 8% 3 8% 5% 5% 5% 4 6% 7% 34%	101423
	Night	17% 8% 3 7% 5% 5% 5% 4 5% 7% 34%	97651
Transparency	Day	47% 7% 13% 21% 11% 1	104917
	Night	48% 6% 13% 21% 11% 1	102246
Seeing	Day	21% 16% 29% 21% 10% 3	14800
	Night	20% 14% 30% 26% 8% 1	23850

By Month

Percentage Cloud Cover NE (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	13% 11% 4 11% 5% 5% 6% 5% 6% 7% 27%	2517
	11th to 20th	Day	16% 12% 6% 13% 7% 6% 5% 3 6% 6% 22%	2520
	21st to end	Day	20% 13% 4 11% 7% 5% 5% 4 6% 4 23%	2874
February	1st to 10th	Day	15% 12% 3 9% 7% 6% 7% 5% 6% 6% 25%	1710
	11th to 20th	Day	12% 11% 5% 9% 7% 6% 6% 4 6% 6% 27%	1805
	21st to end	Day	19% 11% 4 9% 6% 5% 4 4 5% 6% 29%	1570
March	1st to 10th	Day	22% 12% 4 8% 5% 4 4 3 4 5% 28%	3116
	11th to 20th	Day	13% 9% 3 9% 6% 6% 5% 5% 6% 7% 32%	3315
	21st to end	Day	19% 8% 3 9% 6% 4 4 3 4 5% 36%	4150
April	1st to 10th	Day	18% 9% 3 8% 5% 5% 4 3 4 7% 34%	2280
	11th to 20th	Day	17% 8% 2 7% 5% 5% 5% 4 5% 7% 36%	2254
	21st to end	Day	19% 7% 2 8% 5% 5% 5% 4 6% 6% 33%	2358
May	1st to 10th	Day	23% 9% 3 8% 4 4 4 4 5% 6% 31%	4224
	11th to 20th	Day	16% 7% 3 7% 5% 5% 6% 4 6% 8% 33%	4398
	21st to end	Day	11% 5% 2 7% 5% 5% 5% 5% 7% 9% 40%	4837
June	1st to 10th	Day	15% 6% 2 7% 6% 6% 6% 5% 7% 8% 33%	2660
	11th to 20th	Day	15% 5% 2 6% 5% 5% 6% 5% 8% 9% 34%	2660
	21st to end	Day	15% 6% 3 7% 5% 4 5% 4 7% 9% 35%	2660
July	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 5% 8% 9% 36%	4440
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 8% 10% 39%	4440
	21st to end	Day	13% 6% 2 7% 5% 5% 5% 5% 7% 9% 35%	4814
August	1st to 10th	Day	16% 5% 3 6% 5% 5% 5% 4 7% 8% 35%	4397
	11th to 20th	Day	13% 6% 3 7% 4 6% 6% 5% 7% 9% 34%	3743
	21st to end	Day	11% 5% 2 6% 5% 5% 6% 5% 7% 9% 40%	4180
September	1st to 10th	Day	12% 5% 2 5% 4 5% 6% 4 6% 7% 44%	2280
	11th to 20th	Day	13% 6% 2 4 3 3 4 3 6% 7% 48%	2203
	21st to end	Day	14% 6% 2 6% 4 4 5% 3 6% 8% 41%	2090
October	1st to 10th	Day	20% 7% 2 7% 5% 5% 5% 4 5% 6% 34%	1967
	11th to 20th	Day	15% 7% 2 7% 5% 5% 4 3 5% 7% 39%	1900
	21st to end	Day	22% 8% 2 7% 5% 4 5% 3 5% 6% 32%	1897
November	1st to 10th	Day	14% 7% 3 5% 4 4 3 4 6% 7% 42%	1717
	11th to 20th	Day	16% 7% 3 6% 5% 5% 5% 4 5% 7% 36%	1710
	21st to end	Day	17% 9% 3 7% 5% 5% 5% 5% 6% 8% 31%	1539
December	1st to 10th	Day	18% 13% 4 10% 6% 5% 5% 3 6% 6% 24%	1520
	11th to 20th	Day	22% 9% 3 7% 5% 4 4 4 4 6% 31%	1906
	21st to end	Day	25% 14% 5% 11% 6% 4 4 3 4 5% 20%	2772
January	1st to 10th	Night	16% 11% 3 9% 5% 5% 4 4 5% 7% 31%	4429
	11th to 20th	Night	14% 13% 5% 10% 6% 5% 5% 4 5% 6% 26%	4440
	21st to end	Night	22% 12% 4 9% 6% 5% 4 3 5% 5% 23%	4779
February	1st to 10th	Night	13% 11% 5% 9% 7% 6% 5% 5% 6% 7% 27%	2470
	11th to 20th	Night	11% 10% 4 10% 7% 5% 4 5% 6% 7% 31%	2260
	21st to end	Night	17% 9% 3 9% 6% 5% 4 4 6% 6% 32%	1884
March	1st to 10th	Night	23% 12% 3 9% 5% 4 4 4 5% 5% 27%	3724
	11th to 20th	Night	16% 10% 3 7% 5% 5% 5% 4 5% 6% 34%	3639
	21st to end	Night	15% 10% 4 11% 6% 5% 5% 3 4 4 33%	3481
April	1st to 10th	Night	20% 8% 3 7% 5% 5% 5% 3 5% 6% 33%	1900
	11th to 20th	Night	19% 8% 3 7% 5% 4 5% 4 5% 6% 35%	1875
	21st to end	Night	20% 6% 2 6% 4 4 4 4 5% 6% 38%	1819
May	1st to 10th	Night	22% 9% 3 7% 5% 4 5% 3 5% 6% 31%	2744
	11th to 20th	Night	17% 9% 3 9% 5% 5% 5% 4 6% 7% 31%	2495
	21st to end	Night	12% 5% 2 7% 5% 6% 6% 4 7% 9% 36%	2738
June	1st to 10th	Night	17% 6% 2 6% 5% 5% 5% 5% 5% 8% 39%	1520
	11th to 20th	Night	15% 5% 2 6% 4 4 5% 3 7% 8% 40%	1520
	21st to end	Night	13% 5% 2 6% 4 5% 5% 3 6% 8% 43%	1520
July	1st to 10th	Night	10% 5% 3 8% 6% 6% 5% 5% 6% 8% 39%	2520
	11th to 20th	Night	13% 6% 2 6% 4 5% 5% 4 6% 8% 42%	2520
	21st to end	Night	13% 6% 3 6% 4 5% 4 4 6% 7% 39%	2739
August	1st to 10th	Night	18% 6% 3 5% 4 5% 5% 4 6% 8% 36%	2529
	11th to 20th	Night	17% 7% 3 5% 4 5% 5% 4 6% 7% 38%	3054
	21st to end	Night	13% 5% 2 5% 4 3 3 4 6% 9% 46%	3476
September	1st to 10th	Night	13% 5% 2 6% 5% 4 4 4 5% 8% 45%	1900
	11th to 20th	Night	14% 5% 2 4 4 3 3 2 4 7% 51%	1976
	21st to end	Night	15% 5% 2 5% 4 4 4 4 5% 7% 44%	2090
October	1st to 10th	Night	20% 6% 3 7% 5% 5% 4 4 5% 6% 36%	2209
	11th to 20th	Night	15% 6% 2 7% 5% 5% 4 3 5% 7% 41%	2280
	21st to end	Night	23% 7% 2 6% 4 4 4 4 5% 8% 33%	2699
November	1st to 10th	Night	14% 7% 3 7% 5% 5% 4 3 5% 7% 41%	2483
	11th to 20th	Night	17% 6% 2 7% 5% 5% 5% 4 5% 7% 36%	2470
	21st to end	Night	15% 9% 2 6% 5% 5% 4 4 6% 7% 37%	2637
December	1st to 10th	Night	18% 12% 4 9% 4 4 5% 4 5% 7% 28%	2660
	11th to 20th	Night	20% 8% 3 7% 5% 5% 5% 5% 7% 6% 28%	3288
	21st to end	Night	27% 12% 5% 7% 4 5% 4 3 4 6% 23%	4884

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% 7% 14% 20% 6% 1	2518
	11th to 20th	Day	60% 8% 12% 14% 5% 1	2520
	21st to end	Day	61% 9% 12% 13% 5% 1	2874
February	1st to 10th	Day	56% 8% 13% 15% 7% 1	1710
	11th to 20th	Day	55% 7% 9% 18% 9% 2	1814
	21st to end	Day	55% 6% 11% 16% 10% 1	1570
March	1st to 10th	Day	58% 6% 12% 14% 8% 1	3119
	11th to 20th	Day	49% 8% 17% 15% 9% 2	3315
	21st to end	Day	51% 6% 6% 17% 17% 3	4150
April	1st to 10th	Day	51% 5% 8% 22% 12% 2	2280
	11th to 20th	Day	47% 7% 10% 21% 14% 2	2254
	21st to end	Day	50% 7% 9% 18% 13% 3	2358
May	1st to 10th	Day	53% 7% 10% 19% 10% 1	4238
	11th to 20th	Day	47% 9% 14% 20% 9% 1	4402
	21st to end	Day	36% 10% 14% 26% 12% 1	4837
June	1st to 10th	Day	46% 9% 13% 21% 10% 1	2660
	11th to 20th	Day	44% 8% 14% 20% 12% 1	2660
	21st to end	Day	45% 8% 14% 22% 11% 1	2660
July	1st to 10th	Day	42% 7% 13% 23% 13%	4370
	11th to 20th	Day	39% 6% 16% 28% 11% 1	4365
	21st to end	Day	44% 6% 16% 23% 11%	4661
August	1st to 10th	Day	45% 7% 16% 21% 10% 1	4383
	11th to 20th	Day	44% 6% 16% 26% 7%	3779
	21st to end	Day	38% 6% 14% 31% 11% 1	4180
September	1st to 10th	Day	37% 7% 13% 28% 13% 1	2280
	11th to 20th	Day	34% 6% 12% 27% 18% 1	2203
	21st to end	Day	40% 7% 12% 25% 13% 2	2090
October	1st to 10th	Day	45% 5% 7% 26% 17% 1	3266
	11th to 20th	Day	38% 4 12% 28% 17% 1	3140
	21st to end	Day	37% 5% 15% 28% 14% 1	3097
November	1st to 10th	Day	40% 7% 15% 24% 13% 1	1717
	11th to 20th	Day	47% 7% 12% 20% 13% 2	1710
	21st to end	Day	50% 7% 18% 17% 7% 1	1539
December	1st to 10th	Day	60% 7% 12% 14% 7% 1	1520
	11th to 20th	Day	55% 6% 16% 16% 7% 1	1906
	21st to end	Day	66% 6% 9% 13% 5%	2772
January	1st to 10th	Night	52% 8% 15% 16% 9% 1	4429
	11th to 20th	Night	56% 7% 12% 16% 9% 1	4440
	21st to end	Night	61% 7% 11% 14% 6% 1	4779
February	1st to 10th	Night	54% 8% 12% 18% 7% 1	2470
	11th to 20th	Night	51% 8% 12% 19% 9% 1	2262
	21st to end	Night	52% 6% 14% 18% 8% 2	1884
March	1st to 10th	Night	57% 6% 10% 17% 9% 1	3734
	11th to 20th	Night	50% 7% 12% 23% 7% 1	3640
	21st to end	Night	52% 7% 6% 17% 15% 3	3481
April	1st to 10th	Night	51% 6% 11% 20% 11% 1	1900
	11th to 20th	Night	49% 6% 9% 21% 13% 1	1875
	21st to end	Night	47% 6% 10% 18% 16% 3	1819
May	1st to 10th	Night	54% 6% 12% 15% 12% 2	2750
	11th to 20th	Night	50% 9% 12% 19% 8% 1	2496
	21st to end	Night	40% 11% 13% 19% 15% 1	2739
June	1st to 10th	Night	42% 7% 13% 24% 13% 1	1520
	11th to 20th	Night	39% 7% 17% 24% 12% 1	1520
	21st to end	Night	38% 8% 15% 25% 14%	1520
July	1st to 10th	Night	44% 5% 13% 21% 15% 1	2480
	11th to 20th	Night	39% 6% 15% 24% 15%	2472
	21st to end	Night	43% 5% 10% 29% 12% 1	2651
August	1st to 10th	Night	45% 7% 16% 24% 8%	2519
	11th to 20th	Night	45% 5% 18% 23% 9%	3084
	21st to end	Night	36% 4 13% 35% 11% 1	3476
September	1st to 10th	Night	38% 6% 12% 28% 15% 1	1900
	11th to 20th	Night	34% 5% 12% 27% 21% 1	1976
	21st to end	Night	39% 6% 13% 24% 17% 1	2090
October	1st to 10th	Night	48% 3 10% 24% 13% 1	3690
	11th to 20th	Night	33% 4 13% 27% 22% 1	3779
	21st to end	Night	41% 4 15% 29% 10%	4449
November	1st to 10th	Night	42% 6% 12% 22% 15% 2	2483
	11th to 20th	Night	46% 7% 12% 21% 11% 2	2470
	21st to end	Night	46% 6% 18% 21% 8% 1	2637
December	1st to 10th	Night	55% 7% 13% 18% 6%	2660
	11th to 20th	Night	53% 9% 15% 15% 8% 1	3288
	21st to end	Night	62% 7% 11% 15% 4	4884

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	28% 19% 30% 18% 4 1	180
	11th to 20th	Day	29% 23% 33% 12% 2 1	180
	21st to end	Day	20% 25% 35% 14% 6%	229
February	1st to 10th	Day	32% 27% 27% 11% 1	270
	11th to 20th	Day	27% 28% 31% 13% 1	413
	21st to end	Day	30% 19% 34% 15% 2	382
March	1st to 10th	Day	27% 21% 35% 14% 3	460
	11th to 20th	Day	27% 25% 30% 13% 4 1	460
	21st to end	Day	32% 23% 23% 16% 5% 1	506
April	1st to 10th	Day	30% 24% 24% 15% 7% 1	460
	11th to 20th	Day	27% 25% 25% 15% 6% 2	452
	21st to end	Day	27% 20% 31% 13% 6% 2	460
May	1st to 10th	Day	29% 17% 28% 16% 7% 2	463
	11th to 20th	Day	18% 16% 33% 24% 8% 1	487
	21st to end	Day	15% 13% 30% 25% 13% 4	529
June	1st to 10th	Day	16% 17% 31% 21% 12% 2	490
	11th to 20th	Day	15% 14% 29% 25% 14% 2	490
	21st to end	Day	16% 15% 32% 24% 11% 1	490
July	1st to 10th	Day	13% 9% 26% 31% 17% 5%	485
	11th to 20th	Day	12% 8% 28% 33% 16% 3	484
	21st to end	Day	14% 7% 35% 29% 12% 3	532
August	1st to 10th	Day	12% 8% 27% 29% 19% 5%	486
	11th to 20th	Day	14% 8% 27% 30% 16% 5%	479
	21st to end	Day	12% 13% 25% 28% 18% 4	539
September	1st to 10th	Day	16% 9% 25% 24% 17% 9%	490
	11th to 20th	Day	14% 10% 22% 21% 20% 13%	490
	21st to end	Day	17% 10% 26% 26% 14% 7%	490
October	1st to 10th	Day	25% 13% 26% 18% 15% 4	490
	11th to 20th	Day	17% 20% 27% 23% 11% 2	490
	21st to end	Day	28% 14% 28% 23% 7% 1	436
November	1st to 10th	Day	24% 12% 27% 23% 13% 2	381
	11th to 20th	Day	25% 22% 28% 19% 5% 1	370
	21st to end	Day	25% 24% 26% 21% 5%	199
December	1st to 10th	Day	27% 22% 31% 14% 6%	180
	11th to 20th	Day	28% 23% 36% 11% 3	180
	21st to end	Day	27% 24% 34% 12% 3 1	198
January	1st to 10th	Night	22% 21% 35% 21% 2	760
	11th to 20th	Night	24% 23% 31% 20% 2	760
	21st to end	Night	19% 21% 36% 22% 2	836
February	1st to 10th	Night	23% 17% 38% 21% 1	760
	11th to 20th	Night	20% 22% 38% 18% 1	743
	21st to end	Night	27% 19% 33% 20% 2	628
March	1st to 10th	Night	23% 20% 36% 18% 2	760
	11th to 20th	Night	24% 22% 33% 18% 3	760
	21st to end	Night	23% 21% 31% 20% 5%	836
April	1st to 10th	Night	24% 20% 32% 21% 3	760
	11th to 20th	Night	24% 17% 33% 20% 6%	751
	21st to end	Night	22% 19% 30% 23% 5%	679
May	1st to 10th	Night	24% 17% 29% 22% 6% 1	519
	11th to 20th	Night	18% 11% 35% 27% 7% 1	374
	21st to end	Night	14% 8% 29% 37% 12%	411
June	1st to 10th	Night	18% 8% 31% 33% 9% 1	380
	11th to 20th	Night	16% 6% 28% 39% 11%	380
	21st to end	Night	14% 6% 28% 40% 11%	380
July	1st to 10th	Night	12% 5% 25% 39% 18%	370
	11th to 20th	Night	13% 5% 22% 45% 15% 1	368
	21st to end	Night	13% 5% 25% 42% 14% 1	416
August	1st to 10th	Night	13% 3 23% 41% 18% 1	388
	11th to 20th	Night	15% 4 25% 34% 18% 4	719
	21st to end	Night	16% 6% 22% 36% 18% 2	836
September	1st to 10th	Night	13% 6% 24% 37% 18% 1	760
	11th to 20th	Night	16% 5% 24% 29% 22% 4	760
	21st to end	Night	18% 6% 27% 31% 16% 2	760
October	1st to 10th	Night	21% 10% 25% 29% 14% 1	760
	11th to 20th	Night	17% 13% 29% 32% 9%	760
	21st to end	Night	27% 12% 31% 26% 5%	836
November	1st to 10th	Night	18% 13% 30% 30% 9%	764
	11th to 20th	Night	21% 19% 29% 24% 7% 1	760
	21st to end	Night	21% 18% 30% 26% 6%	760
December	1st to 10th	Night	25% 18% 34% 20% 3	760
	11th to 20th	Night	23% 21% 32% 21% 3	760
	21st to end	Night	29% 20% 29% 20% 2	836

Page generated at 2024-11-03 13:19:02. Version ac07

Copyright © 2024 Attilla Danko.