Pompeys Pillar National Monument
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pompeys Pillar National Monument clear sky chart from 2005-11-06 to 2024-11-28.

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% 6% 2 6% 4 4 4 4 6% 8% 48%	106194
	Night	8% 8% 3 7% 5% 4 5% 4 6% 7% 44%	102029
Transparency	Day	33% 6% 12% 25% 18% 6%	105934
	Night	38% 6% 13% 24% 15% 4	101879
Seeing	Day	12% 8% 25% 31% 19% 5%	16029
	Night	13% 6% 28% 39% 14% 1	25656

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	5% 11% 4 11% 6% 6% 7% 5% 5% 6% 35%	2538
	11th to 20th	Day	6% 9% 3 8% 6% 7% 7% 6% 8% 7% 32%	2540
	21st to end	Day	3 7% 3 7% 4 4 5% 4 6% 8% 51%	3064
February	1st to 10th	Day	9% 12% 5% 9% 7% 6% 5% 4 6% 7% 30%	1710
	11th to 20th	Day	7% 12% 3 11% 5% 6% 5% 4 5% 7% 32%	1665
	21st to end	Day	5% 10% 3 10% 6% 4 5% 5% 7% 8% 37%	1469
March	1st to 10th	Day	5% 7% 3 7% 6% 5% 4 4 7% 9% 44%	3304
	11th to 20th	Day	6% 8% 3 8% 4 5% 4 4 6% 7% 46%	3490
	21st to end	Day	14% 16% 4 10% 5% 5% 4 4 5% 7% 26%	3900
April	1st to 10th	Day	12% 10% 3 6% 5% 4 4 5% 7% 9% 36%	2280
	11th to 20th	Day	11% 11% 4 7% 5% 5% 5% 4 6% 8% 33%	2272
	21st to end	Day	15% 9% 3 7% 5% 4 4 4 5% 7% 37%	2470
May	1st to 10th	Day	19% 9% 3 7% 4 5% 5% 4 6% 6% 33%	4366
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 8% 10% 40%	4388
	21st to end	Day	15% 5% 2 5% 5% 4 5% 5% 7% 9% 39%	4825
June	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 4 7% 10% 44%	2660
	11th to 20th	Day	8% 5% 2 6% 6% 5% 6% 4 7% 8% 44%	2762
	21st to end	Day	4 3 1 3 3 4 4 4 8% 8% 58%	2850
July	1st to 10th	Day	4 3 1 4 3 4 5% 4 7% 9% 57%	4661
	11th to 20th	Day	1 1 1 2 2 2 3 3 5% 9% 69%	4430
	21st to end	Day	2 2 1 4 3 3 4 4 6% 9% 63%	4802
August	1st to 10th	Day	4 3 1 4 4 4 4 4 8% 10% 54%	4140
	11th to 20th	Day	5% 2 1 4 3 4 4 4 7% 9% 58%	4028
	21st to end	Day	6% 3 1 3 3 3 3 3 5% 7% 64%	4338
September	1st to 10th	Day	7% 4 1 3 3 3 3 3 5% 8% 61%	2280
	11th to 20th	Day	9% 5% 2 5% 3 3 3 3 6% 7% 54%	2271
	21st to end	Day	12% 4 1 4 2 2 3 2 4 7% 59%	2005
October	1st to 10th	Day	7% 5% 1 4 3 3 3 2 3 6% 63%	3170
	11th to 20th	Day	10% 6% 2 5% 3 2 3 3 4 4 58%	3150
	21st to end	Day	7% 6% 2 6% 3 4 4 4 7% 10% 47%	3325
November	1st to 10th	Day	10% 11% 3 5% 3 4 3 3 5% 7% 44%	1625
	11th to 20th	Day	8% 10% 3 8% 5% 5% 4 5% 6% 6% 41%	1600
	21st to end	Day	7% 9% 3 8% 5% 5% 5% 3 6% 7% 41%	1576
December	1st to 10th	Day	6% 11% 3 10% 5% 5% 6% 3 7% 6% 38%	1520
	11th to 20th	Day	6% 8% 3 8% 6% 6% 4 4 6% 9% 40%	1926
	21st to end	Day	6% 10% 3 7% 5% 4 4 3 5% 6% 46%	2794
January	1st to 10th	Night	5% 10% 4 9% 6% 5% 5% 4 5% 7% 40%	4417
	11th to 20th	Night	6% 13% 5% 12% 7% 5% 4 3 5% 7% 33%	4430
	21st to end	Night	5% 8% 3 8% 5% 6% 5% 5% 8% 9% 39%	4620
February	1st to 10th	Night	9% 14% 5% 11% 6% 5% 6% 4 5% 6% 28%	2470
	11th to 20th	Night	7% 14% 5% 9% 6% 5% 5% 4 5% 7% 31%	2402
	21st to end	Night	6% 13% 4 11% 5% 4 6% 4 5% 6% 34%	1984
March	1st to 10th	Night	5% 10% 5% 9% 6% 4 5% 5% 6% 7% 38%	3562
	11th to 20th	Night	6% 7% 2 5% 4 5% 5% 4 6% 9% 48%	3490
	21st to end	Night	14% 15% 5% 11% 6% 5% 5% 4 5% 7% 22%	3749
April	1st to 10th	Night	13% 11% 3 7% 5% 5% 4 4 6% 7% 36%	1900
	11th to 20th	Night	12% 11% 5% 8% 6% 5% 5% 4 7% 7% 31%	1854
	21st to end	Night	15% 10% 3 7% 6% 4 4 4 5% 6% 35%	1710
May	1st to 10th	Night	18% 11% 3 6% 5% 4 4 4 6% 8% 33%	2604
	11th to 20th	Night	9% 7% 2 7% 5% 5% 6% 5% 7% 8% 39%	2517
	21st to end	Night	12% 5% 2 6% 6% 5% 6% 4 6% 9% 38%	2762
June	1st to 10th	Night	10% 5% 2 6% 6% 4 7% 4 7% 9% 39%	1520
	11th to 20th	Night	10% 5% 2 6% 5% 5% 4 5% 6% 10% 42%	1411
	21st to end	Night	7% 4 1 5% 4 5% 4 3 6% 8% 54%	1330
July	1st to 10th	Night	3 3 2 3 3 4 4 5% 7% 10% 57%	2284
	11th to 20th	Night	3 2 2 4 4 5% 5% 4 5% 7% 58%	2540
	21st to end	Night	3 3 2 5% 4 4 6% 5% 8% 10% 51%	2761
August	1st to 10th	Night	4 4 2 6% 5% 5% 5% 5% 6% 8% 52%	2783
	11th to 20th	Night	5% 4 1 5% 4 4 5% 5% 9% 9% 48%	2811
	21st to end	Night	7% 4 2 4 3 3 3 3 5% 7% 60%	3327
September	1st to 10th	Night	6% 5% 2 5% 3 3 4 3 5% 6% 59%	1900
	11th to 20th	Night	11% 4 1 4 4 4 4 3 6% 8% 51%	1905
	21st to end	Night	11% 5% 2 4 3 3 3 2 4 7% 55%	2175
October	1st to 10th	Night	9% 4 2 4 2 3 3 3 5% 7% 59%	3800
	11th to 20th	Night	10% 6% 2 5% 3 2 3 2 4 5% 56%	3778
	21st to end	Night	10% 6% 2 6% 4 3 3 3 5% 7% 50%	4200
November	1st to 10th	Night	10% 10% 3 7% 5% 4 3 4 5% 8% 42%	2670
	11th to 20th	Night	7% 10% 4 8% 5% 4 4 4 5% 6% 43%	2800
	21st to end	Night	5% 11% 3 6% 5% 4 4 4 6% 7% 44%	2759
December	1st to 10th	Night	6% 12% 3 11% 7% 5% 4 4 5% 7% 36%	2660
	11th to 20th	Night	5% 8% 4 8% 5% 4 5% 4 5% 7% 46%	3271
	21st to end	Night	6% 9% 3 7% 4 4 4 3 5% 8% 49%	4873

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% 8% 10% 30% 5%	2539
	11th to 20th	Day	46% 9% 14% 20% 10% 1	2540
	21st to end	Day	31% 7% 21% 27% 13% 1	3064
February	1st to 10th	Day	52% 5% 14% 18% 9%	1710
	11th to 20th	Day	50% 6% 12% 22% 8% 2	1674
	21st to end	Day	44% 6% 15% 22% 12% 2	1469
March	1st to 10th	Day	35% 5% 13% 28% 18% 1	3304
	11th to 20th	Day	36% 7% 16% 31% 10% 1	3490
	21st to end	Day	55% 9% 13% 18% 5%	3900
April	1st to 10th	Day	43% 6% 14% 23% 11% 2	2280
	11th to 20th	Day	48% 6% 14% 22% 10% 1	2275
	21st to end	Day	47% 6% 11% 22% 13% 1	2470
May	1st to 10th	Day	49% 7% 12% 23% 9% 2	4366
	11th to 20th	Day	34% 10% 13% 29% 12% 2	4392
	21st to end	Day	39% 8% 14% 30% 9% 1	4825
June	1st to 10th	Day	35% 8% 18% 25% 12% 2	2660
	11th to 20th	Day	36% 7% 16% 23% 15% 4	2762
	21st to end	Day	21% 7% 14% 28% 22% 8%	2850
July	1st to 10th	Day	21% 6% 9% 30% 23% 10%	4589
	11th to 20th	Day	12% 3 6% 22% 39% 17%	4355
	21st to end	Day	17% 3 8% 21% 31% 21%	4651
August	1st to 10th	Day	23% 5% 11% 23% 24% 14%	4125
	11th to 20th	Day	22% 5% 9% 28% 30% 7%	4067
	21st to end	Day	20% 4 8% 28% 30% 10%	4337
September	1st to 10th	Day	22% 4 8% 23% 29% 14%	2280
	11th to 20th	Day	29% 5% 11% 26% 22% 7%	2271
	21st to end	Day	27% 4 9% 29% 25% 6%	2005
October	1st to 10th	Day	26% 4 7% 21% 31% 11%	3170
	11th to 20th	Day	31% 3 9% 30% 24% 3	3150
	21st to end	Day	32% 5% 12% 30% 18% 3	3325
November	1st to 10th	Day	40% 5% 11% 27% 14% 4	1625
	11th to 20th	Day	42% 6% 15% 22% 12% 3	1600
	21st to end	Day	41% 5% 13% 24% 14% 2	1576
December	1st to 10th	Day	45% 6% 13% 24% 10% 2	1520
	11th to 20th	Day	39% 7% 23% 24% 6% 1	1924
	21st to end	Day	37% 6% 11% 27% 14% 5%	2794
January	1st to 10th	Night	43% 6% 17% 26% 8% 1	4417
	11th to 20th	Night	52% 4 13% 18% 11% 1	4430
	21st to end	Night	38% 10% 17% 25% 9% 1	4620
February	1st to 10th	Night	56% 6% 12% 17% 9%	2470
	11th to 20th	Night	52% 6% 13% 20% 8% 1	2403
	21st to end	Night	49% 6% 13% 20% 10% 2	1984
March	1st to 10th	Night	41% 6% 13% 24% 16%	3562
	11th to 20th	Night	31% 8% 23% 27% 10% 1	3490
	21st to end	Night	59% 10% 13% 14% 4	3749
April	1st to 10th	Night	47% 6% 15% 19% 11% 2	1900
	11th to 20th	Night	49% 7% 13% 23% 8%	1854
	21st to end	Night	48% 7% 11% 22% 12% 1	1710
May	1st to 10th	Night	48% 7% 10% 21% 12% 2	2604
	11th to 20th	Night	38% 9% 12% 29% 10% 3	2518
	21st to end	Night	39% 10% 16% 27% 8%	2762
June	1st to 10th	Night	39% 9% 17% 24% 9% 2	1520
	11th to 20th	Night	37% 9% 16% 21% 13% 4	1411
	21st to end	Night	27% 6% 14% 25% 22% 6%	1330
July	1st to 10th	Night	20% 6% 13% 32% 20% 9%	2247
	11th to 20th	Night	24% 6% 7% 20% 29% 16%	2492
	21st to end	Night	23% 6% 9% 19% 31% 12%	2674
August	1st to 10th	Night	28% 6% 13% 23% 18% 12%	2775
	11th to 20th	Night	27% 6% 12% 30% 21% 5%	2838
	21st to end	Night	24% 5% 9% 23% 31% 9%	3327
September	1st to 10th	Night	25% 5% 9% 20% 26% 15%	1900
	11th to 20th	Night	30% 6% 10% 25% 23% 6%	1905
	21st to end	Night	31% 3 9% 26% 24% 6%	2175
October	1st to 10th	Night	26% 5% 7% 24% 25% 13%	3800
	11th to 20th	Night	32% 3 9% 25% 27% 3	3778
	21st to end	Night	34% 4 13% 28% 14% 7%	4200
November	1st to 10th	Night	41% 6% 12% 24% 14% 4	2670
	11th to 20th	Night	41% 5% 13% 26% 13% 2	2800
	21st to end	Night	38% 5% 15% 27% 12% 3	2759
December	1st to 10th	Night	47% 6% 13% 22% 11% 2	2660
	11th to 20th	Night	38% 6% 17% 30% 8%	3272
	21st to end	Night	34% 5% 14% 28% 16% 4	4873

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	8% 9% 34% 31% 14% 3	270
	11th to 20th	Day	15% 9% 27% 30% 17% 2	270
	21st to end	Day	9% 8% 43% 30% 8% 2	297
February	1st to 10th	Day	16% 14% 37% 27% 5% 1	270
	11th to 20th	Day	13% 14% 33% 33% 6% 2	270
	21st to end	Day	12% 12% 33% 31% 10% 2	225
March	1st to 10th	Day	9% 13% 33% 31% 13% 1	366
	11th to 20th	Day	14% 10% 26% 30% 16% 3	460
	21st to end	Day	19% 11% 25% 30% 13% 2	506
April	1st to 10th	Day	17% 12% 33% 27% 10% 1	460
	11th to 20th	Day	17% 13% 36% 25% 7% 1	452
	21st to end	Day	19% 9% 25% 26% 16% 5%	460
May	1st to 10th	Day	16% 8% 20% 28% 21% 6%	615
	11th to 20th	Day	18% 6% 22% 27% 20% 7%	675
	21st to end	Day	18% 6% 21% 27% 19% 10%	734
June	1st to 10th	Day	9% 5% 24% 31% 24% 7%	680
	11th to 20th	Day	13% 10% 26% 32% 16% 3	680
	21st to end	Day	6% 5% 23% 36% 25% 5%	680
July	1st to 10th	Day	5% 4 20% 34% 32% 6%	671
	11th to 20th	Day	4 6% 22% 40% 25% 4	668
	21st to end	Day	4 3 19% 39% 28% 7%	739
August	1st to 10th	Day	6% 3 22% 37% 25% 6%	522
	11th to 20th	Day	9% 2 17% 34% 30% 8%	477
	21st to end	Day	4 4 20% 34% 27% 11%	539
September	1st to 10th	Day	7% 5% 21% 35% 23% 8%	490
	11th to 20th	Day	11% 5% 20% 29% 27% 9%	490
	21st to end	Day	14% 6% 19% 28% 26% 7%	405
October	1st to 10th	Day	16% 5% 19% 28% 26% 7%	300
	11th to 20th	Day	16% 7% 24% 27% 19% 8%	300
	21st to end	Day	14% 12% 32% 25% 13% 4	330
November	1st to 10th	Day	18% 8% 25% 33% 13% 3	300
	11th to 20th	Day	12% 11% 35% 29% 13% 1	300
	21st to end	Day	12% 10% 34% 33% 11%	291
December	1st to 10th	Day	10% 13% 40% 28% 8% 1	270
	11th to 20th	Day	14% 11% 31% 33% 10%	270
	21st to end	Day	11% 9% 34% 34% 11% 1	297
January	1st to 10th	Night	13% 7% 34% 34% 11% 1	950
	11th to 20th	Night	14% 10% 33% 31% 11%	950
	21st to end	Night	13% 8% 39% 31% 8% 1	896
February	1st to 10th	Night	16% 9% 34% 31% 10% 1	760
	11th to 20th	Night	14% 8% 34% 36% 8%	744
	21st to end	Night	12% 8% 29% 36% 12% 2	628
March	1st to 10th	Night	11% 6% 35% 36% 11% 1	760
	11th to 20th	Night	11% 4 30% 41% 13% 1	760
	21st to end	Night	17% 7% 23% 37% 14% 1	795
April	1st to 10th	Night	18% 7% 27% 38% 10%	570
	11th to 20th	Night	15% 9% 29% 37% 10%	563
	21st to end	Night	20% 6% 22% 39% 13% 1	570
May	1st to 10th	Night	17% 6% 19% 39% 18% 1	570
	11th to 20th	Night	16% 4 18% 38% 23% 1	561
	21st to end	Night	19% 4 20% 38% 19%	617
June	1st to 10th	Night	11% 5% 25% 37% 20% 2	570
	11th to 20th	Night	12% 6% 30% 39% 13%	461
	21st to end	Night	8% 2 21% 47% 22% 1	380
July	1st to 10th	Night	5% 2 16% 49% 27%	406
	11th to 20th	Night	5% 4 27% 49% 15%	552
	21st to end	Night	3 3 22% 54% 18%	624
August	1st to 10th	Night	6% 3 20% 51% 20% 1	567
	11th to 20th	Night	5% 2 19% 53% 20% 1	564
	21st to end	Night	9% 4 20% 48% 19% 1	627
September	1st to 10th	Night	8% 2 22% 46% 21% 1	570
	11th to 20th	Night	13% 2 16% 46% 20% 2	575
	21st to end	Night	13% 5% 21% 37% 23% 1	760
October	1st to 10th	Night	17% 5% 18% 37% 20% 2	760
	11th to 20th	Night	15% 5% 24% 37% 19% 1	760
	21st to end	Night	13% 7% 29% 37% 14% 1	880
November	1st to 10th	Night	15% 8% 26% 40% 10% 1	975
	11th to 20th	Night	13% 10% 35% 35% 9%	1000
	21st to end	Night	10% 7% 36% 38% 9%	986
December	1st to 10th	Night	11% 9% 36% 34% 9%	950
	11th to 20th	Night	11% 7% 35% 37% 8% 1	950
	21st to end	Night	15% 8% 31% 35% 10%	1045

Page generated at 2024-11-24 22:22:21. Version ac07

Copyright © 2024 Attilla Danko.