Karval Reservoir SWA
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Karval Reservoir SWA clear sky chart from 2005-11-06 to 2024-11-02.

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	5% 4 1 4 3 3 4 4 6% 8% 58%	101164
	Night	5% 5% 2 5% 4 4 4 4 6% 7% 55%	98001
Transparency	Day	23% 5% 12% 24% 25% 11%	100905
	Night	26% 6% 12% 23% 23% 9%	97850
Seeing	Day	7% 7% 25% 32% 23% 7%	15542
	Night	7% 6% 30% 40% 16% 1	25498

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	2 6% 2 5% 5% 3 4 2 4 7% 60%	2538
	11th to 20th	Day	2 5% 2 5% 4 4 4 3 6% 8% 57%	2540
	21st to end	Day	3 6% 2 5% 4 4 3 3 5% 6% 60%	3118
February	1st to 10th	Day	3 8% 2 6% 3 4 4 3 5% 7% 55%	1827
	11th to 20th	Day	2 6% 2 6% 5% 4 4 4 5% 6% 57%	1849
	21st to end	Day	3 7% 2 7% 4 3 5% 3 4 5% 57%	1570
March	1st to 10th	Day	2 3 1 4 4 3 3 3 5% 6% 66%	3130
	11th to 20th	Day	6% 6% 2 4 3 3 3 3 5% 7% 58%	3273
	21st to end	Day	4 5% 1 5% 5% 4 4 4 6% 9% 53%	4165
April	1st to 10th	Day	5% 5% 1 4 3 3 4 3 6% 7% 59%	2280
	11th to 20th	Day	8% 5% 2 5% 4 4 4 4 5% 7% 52%	2251
	21st to end	Day	8% 4 2 5% 4 4 4 4 7% 7% 51%	2280
May	1st to 10th	Day	8% 5% 2 5% 3 3 3 4 5% 6% 56%	4117
	11th to 20th	Day	7% 4 2 4 3 4 5% 4 6% 9% 53%	4082
	21st to end	Day	6% 3 1 4 3 3 4 4 6% 8% 60%	4823
June	1st to 10th	Day	5% 2 1 4 3 3 3 4 6% 12% 57%	2660
	11th to 20th	Day	5% 3 1 4 3 4 3 4 5% 8% 60%	2660
	21st to end	Day	3 3 1 4 4 3 4 5% 6% 10% 56%	2660
July	1st to 10th	Day	3 2 1 5% 5% 5% 6% 5% 8% 8% 52%	4430
	11th to 20th	Day	2 2 1 4 3 4 5% 4 8% 11% 56%	4430
	21st to end	Day	3 2 1 4 3 3 4 4 7% 10% 58%	4802
August	1st to 10th	Day	9% 4 1 4 3 4 5% 4 7% 10% 49%	3907
	11th to 20th	Day	4 3 1 4 3 3 4 4 7% 9% 58%	3726
	21st to end	Day	3 3 1 4 3 4 4 4 7% 10% 57%	4180
September	1st to 10th	Day	4 4 1 4 3 3 3 4 5% 7% 62%	2280
	11th to 20th	Day	6% 2 1 3 3 3 3 3 4 7% 66%	2180
	21st to end	Day	6% 3 1 3 3 2 2 3 4 5% 68%	2090
October	1st to 10th	Day	8% 4 1 3 2 2 4 3 4 6% 64%	2050
	11th to 20th	Day	4 3 1 4 3 2 3 3 4 5% 69%	1900
	21st to end	Day	6% 5% 2 4 2 2 2 2 4 5% 67%	1948
November	1st to 10th	Day	3 4 1 2 2 3 3 3 5% 5% 69%	1682
	11th to 20th	Day	3 4 1 4 3 2 3 3 4 5% 68%	1710
	21st to end	Day	4 4 2 4 2 3 2 3 5% 7% 64%	1710
December	1st to 10th	Day	3 7% 3 5% 4 4 4 2 5% 6% 59%	1596
	11th to 20th	Day	3 6% 2 4 3 3 3 3 6% 8% 58%	1926
	21st to end	Day	4 7% 2 6% 4 4 4 4 4 7% 53%	2794
January	1st to 10th	Night	3 6% 2 5% 4 4 4 4 6% 7% 56%	4417
	11th to 20th	Night	2 4 2 4 3 3 3 4 7% 8% 60%	4430
	21st to end	Night	2 6% 2 6% 3 4 4 3 5% 6% 59%	4578
February	1st to 10th	Night	4 6% 2 5% 5% 4 4 3 4 6% 56%	2352
	11th to 20th	Night	3 7% 3 6% 5% 4 5% 3 6% 7% 51%	2218
	21st to end	Night	5% 6% 1 5% 4 3 3 3 5% 7% 61%	1884
March	1st to 10th	Night	3 5% 2 4 4 3 4 3 5% 5% 62%	3734
	11th to 20th	Night	8% 7% 2 5% 3 3 4 3 5% 6% 54%	3692
	21st to end	Night	6% 5% 2 5% 3 4 5% 4 6% 7% 53%	3477
April	1st to 10th	Night	7% 6% 1 4 3 2 4 4 6% 6% 55%	1900
	11th to 20th	Night	9% 5% 1 5% 3 3 4 4 6% 7% 50%	1877
	21st to end	Night	10% 7% 2 7% 4 3 4 3 5% 7% 48%	1900
May	1st to 10th	Night	11% 8% 2 5% 3 4 4 4 4 6% 50%	2850
	11th to 20th	Night	11% 7% 3 6% 4 5% 4 4 5% 7% 45%	2810
	21st to end	Night	11% 5% 2 5% 5% 5% 5% 4 6% 7% 45%	2762
June	1st to 10th	Night	4 3 1 4 3 4 5% 3 8% 11% 53%	1520
	11th to 20th	Night	5% 3 1 4 4 4 4 4 6% 10% 56%	1520
	21st to end	Night	6% 5% 1 5% 4 5% 5% 4 6% 10% 48%	1520
July	1st to 10th	Night	7% 4 2 6% 5% 5% 5% 5% 9% 9% 43%	2540
	11th to 20th	Night	4 3 1 5% 4 5% 6% 5% 7% 12% 48%	2540
	21st to end	Night	5% 4 2 5% 4 4 5% 4 7% 8% 52%	2761
August	1st to 10th	Night	12% 5% 2 9% 7% 6% 6% 5% 7% 9% 32%	3014
	11th to 20th	Night	6% 4 2 8% 5% 6% 6% 5% 7% 10% 41%	3113
	21st to end	Night	3 3 1 6% 5% 6% 7% 6% 10% 11% 43%	3487
September	1st to 10th	Night	7% 4 2 5% 3 4 3 3 6% 7% 56%	1900
	11th to 20th	Night	6% 3 1 3 2 3 3 4 6% 8% 62%	1998
	21st to end	Night	6% 4 1 4 3 2 3 3 4 5% 65%	2090
October	1st to 10th	Night	8% 5% 2 4 3 3 3 3 5% 6% 60%	2126
	11th to 20th	Night	4 2 1 3 2 3 4 2 5% 5% 68%	2280
	21st to end	Night	6% 4 1 4 3 2 3 3 4 5% 66%	2629
November	1st to 10th	Night	2 4 1 3 3 3 2 3 5% 6% 69%	2419
	11th to 20th	Night	3 4 1 4 2 3 3 2 3 5% 69%	2470
	21st to end	Night	3 6% 2 5% 3 3 2 3 4 6% 63%	2470
December	1st to 10th	Night	2 5% 2 5% 5% 4 4 3 4 6% 61%	2579
	11th to 20th	Night	3 7% 2 5% 4 4 4 3 5% 7% 57%	3271
	21st to end	Night	4 6% 2 6% 4 4 5% 4 6% 8% 52%	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	23% 5% 10% 30% 24% 7%	2539
	11th to 20th	Day	23% 6% 14% 27% 21% 9%	2540
	21st to end	Day	24% 5% 13% 29% 25% 5%	3118
February	1st to 10th	Day	29% 4 11% 25% 22% 10%	1827
	11th to 20th	Day	27% 5% 9% 26% 25% 8%	1859
	21st to end	Day	28% 4 9% 19% 24% 16%	1570
March	1st to 10th	Day	18% 5% 9% 19% 32% 17%	3130
	11th to 20th	Day	24% 5% 10% 29% 29% 4	3273
	21st to end	Day	23% 7% 13% 33% 19% 5%	4165
April	1st to 10th	Day	23% 5% 11% 24% 24% 13%	2280
	11th to 20th	Day	28% 6% 12% 24% 19% 11%	2254
	21st to end	Day	28% 6% 14% 24% 22% 6%	2280
May	1st to 10th	Day	25% 7% 12% 24% 19% 13%	4117
	11th to 20th	Day	24% 9% 15% 24% 22% 5%	4086
	21st to end	Day	19% 8% 15% 23% 23% 12%	4823
June	1st to 10th	Day	19% 7% 17% 29% 18% 10%	2660
	11th to 20th	Day	20% 6% 12% 20% 24% 19%	2660
	21st to end	Day	20% 7% 12% 23% 24% 14%	2660
July	1st to 10th	Day	26% 5% 10% 17% 30% 12%	4361
	11th to 20th	Day	20% 4 14% 24% 28% 10%	4355
	21st to end	Day	20% 5% 13% 22% 21% 19%	4651
August	1st to 10th	Day	28% 6% 16% 30% 14% 6%	3892
	11th to 20th	Day	22% 4 15% 23% 26% 8%	3762
	21st to end	Day	21% 4 11% 29% 23% 12%	4179
September	1st to 10th	Day	21% 5% 9% 23% 26% 16%	2280
	11th to 20th	Day	18% 4 9% 19% 29% 21%	2180
	21st to end	Day	19% 4 6% 19% 35% 17%	2090
October	1st to 10th	Day	21% 5% 9% 20% 31% 15%	2050
	11th to 20th	Day	18% 3 7% 20% 35% 17%	1900
	21st to end	Day	20% 3 8% 23% 29% 17%	1948
November	1st to 10th	Day	16% 3 11% 25% 28% 17%	1682
	11th to 20th	Day	17% 3 7% 29% 32% 11%	1710
	21st to end	Day	21% 4 8% 20% 29% 18%	1710
December	1st to 10th	Day	26% 4 10% 25% 27% 7%	1596
	11th to 20th	Day	24% 4 10% 23% 32% 9%	1924
	21st to end	Day	29% 6% 11% 24% 23% 8%	2794
January	1st to 10th	Night	24% 6% 11% 30% 25% 4	4417
	11th to 20th	Night	18% 8% 15% 25% 24% 9%	4430
	21st to end	Night	24% 6% 12% 30% 24% 4	4578
February	1st to 10th	Night	29% 5% 11% 23% 23% 9%	2352
	11th to 20th	Night	31% 5% 11% 25% 22% 6%	2218
	21st to end	Night	23% 4 8% 22% 29% 14%	1884
March	1st to 10th	Night	21% 5% 10% 18% 26% 19%	3734
	11th to 20th	Night	28% 7% 15% 21% 20% 9%	3692
	21st to end	Night	24% 8% 17% 28% 19% 4	3477
April	1st to 10th	Night	26% 6% 10% 25% 21% 11%	1900
	11th to 20th	Night	29% 8% 14% 22% 19% 9%	1877
	21st to end	Night	35% 6% 13% 22% 19% 5%	1900
May	1st to 10th	Night	30% 12% 16% 20% 15% 9%	2850
	11th to 20th	Night	34% 10% 16% 23% 11% 6%	2811
	21st to end	Night	31% 11% 16% 20% 16% 6%	2762
June	1st to 10th	Night	23% 10% 22% 24% 15% 6%	1520
	11th to 20th	Night	22% 7% 15% 22% 20% 14%	1520
	21st to end	Night	28% 8% 12% 23% 19% 11%	1520
July	1st to 10th	Night	33% 6% 12% 22% 24% 3	2500
	11th to 20th	Night	28% 5% 17% 22% 24% 4	2492
	21st to end	Night	29% 6% 12% 19% 23% 11%	2674
August	1st to 10th	Night	47% 7% 14% 18% 8% 5%	3006
	11th to 20th	Night	37% 7% 14% 21% 16% 4	3143
	21st to end	Night	29% 7% 15% 26% 17% 6%	3487
September	1st to 10th	Night	25% 5% 12% 21% 23% 13%	1900
	11th to 20th	Night	19% 6% 11% 22% 25% 17%	1998
	21st to end	Night	22% 5% 8% 19% 33% 13%	2090
October	1st to 10th	Night	25% 7% 10% 18% 26% 14%	2126
	11th to 20th	Night	17% 4 9% 22% 29% 19%	2280
	21st to end	Night	21% 4 10% 22% 26% 17%	2629
November	1st to 10th	Night	16% 4 10% 25% 29% 17%	2419
	11th to 20th	Night	19% 3 7% 26% 33% 12%	2470
	21st to end	Night	23% 3 9% 21% 29% 15%	2470
December	1st to 10th	Night	24% 6% 12% 25% 25% 8%	2579
	11th to 20th	Night	26% 4 8% 21% 35% 5%	3272
	21st to end	Night	27% 7% 10% 24% 26% 6%	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	6% 4 27% 41% 17% 4	270
	11th to 20th	Day	11% 9% 26% 36% 17% 1	270
	21st to end	Day	8% 8% 29% 35% 17% 4	297
February	1st to 10th	Day	6% 11% 36% 33% 12% 2	270
	11th to 20th	Day	5% 7% 46% 32% 9% 1	270
	21st to end	Day	5% 12% 40% 31% 9% 2	225
March	1st to 10th	Day	2 10% 30% 34% 21% 2	270
	11th to 20th	Day	11% 9% 27% 34% 17% 3	317
	21st to end	Day	11% 15% 37% 25% 11% 1	506
April	1st to 10th	Day	10% 13% 37% 25% 12% 3	460
	11th to 20th	Day	12% 17% 34% 25% 10% 2	452
	21st to end	Day	10% 15% 33% 28% 12% 2	460
May	1st to 10th	Day	11% 13% 30% 28% 15% 2	650
	11th to 20th	Day	13% 8% 27% 28% 20% 4	675
	21st to end	Day	9% 10% 29% 30% 18% 5%	734
June	1st to 10th	Day	6% 5% 21% 31% 26% 11%	680
	11th to 20th	Day	5% 5% 29% 34% 23% 5%	680
	21st to end	Day	4 6% 22% 35% 28% 6%	680
July	1st to 10th	Day	6% 3 16% 32% 32% 10%	671
	11th to 20th	Day	3 1 12% 32% 39% 13%	668
	21st to end	Day	5% 1 8% 33% 39% 14%	739
August	1st to 10th	Day	6% 2 14% 32% 31% 15%	522
	11th to 20th	Day	4 2 18% 34% 31% 10%	477
	21st to end	Day	4 2 14% 40% 27% 12%	539
September	1st to 10th	Day	5% 2 17% 35% 30% 12%	490
	11th to 20th	Day	3 3 19% 36% 27% 11%	390
	21st to end	Day	10% 4 19% 23% 28% 15%	300
October	1st to 10th	Day	9% 4 20% 23% 30% 14%	300
	11th to 20th	Day	5% 4 26% 34% 21% 10%	300
	21st to end	Day	12% 8% 26% 24% 23% 8%	330
November	1st to 10th	Day	6% 6% 29% 34% 19% 6%	273
	11th to 20th	Day	4 8% 27% 34% 22% 5%	270
	21st to end	Day	8% 8% 26% 36% 19% 4	270
December	1st to 10th	Day	5% 7% 27% 41% 16% 3	270
	11th to 20th	Day	7% 8% 29% 35% 20% 2	270
	21st to end	Day	7% 11% 33% 36% 12% 1	297
January	1st to 10th	Night	6% 6% 30% 42% 14% 2	950
	11th to 20th	Night	6% 6% 35% 38% 13% 1	950
	21st to end	Night	5% 6% 30% 48% 10% 1	867
February	1st to 10th	Night	7% 6% 38% 41% 8%	760
	11th to 20th	Night	7% 6% 40% 38% 9% 1	744
	21st to end	Night	6% 8% 43% 36% 7%	628
March	1st to 10th	Night	6% 9% 36% 39% 10% 1	760
	11th to 20th	Night	10% 8% 32% 38% 12% 1	753
	21st to end	Night	9% 11% 42% 31% 7%	627
April	1st to 10th	Night	10% 11% 41% 32% 5%	570
	11th to 20th	Night	11% 12% 42% 29% 5%	563
	21st to end	Night	11% 16% 31% 33% 9%	570
May	1st to 10th	Night	13% 9% 37% 31% 9% 1	570
	11th to 20th	Night	13% 7% 30% 34% 14% 1	561
	21st to end	Night	11% 9% 39% 32% 9%	617
June	1st to 10th	Night	4 6% 30% 43% 15% 1	570
	11th to 20th	Night	5% 5% 36% 43% 11%	570
	21st to end	Night	6% 4 28% 45% 16% 1	570
July	1st to 10th	Night	7% 4 19% 46% 24% 1	555
	11th to 20th	Night	6% 1 13% 49% 29% 2	552
	21st to end	Night	9% 1 13% 40% 33% 2	624
August	1st to 10th	Night	9% 2 17% 41% 31% 1	567
	11th to 20th	Night	6% 1 19% 53% 20% 1	564
	21st to end	Night	5% 1 15% 48% 30% 2	627
September	1st to 10th	Night	8% 4 19% 48% 21% 1	570
	11th to 20th	Night	6% 3 21% 44% 24% 1	570
	21st to end	Night	7% 4 24% 39% 24% 1	570
October	1st to 10th	Night	11% 6% 28% 36% 17% 2	606
	11th to 20th	Night	5% 6% 27% 39% 21% 2	760
	21st to end	Night	6% 9% 26% 36% 20% 3	957
November	1st to 10th	Night	4 4 27% 44% 19% 2	931
	11th to 20th	Night	5% 6% 31% 40% 16% 2	950
	21st to end	Night	6% 8% 27% 40% 16% 3	950
December	1st to 10th	Night	4 6% 34% 42% 13% 1	950
	11th to 20th	Night	6% 7% 29% 42% 15% 1	950
	21st to end	Night	8% 9% 32% 39% 11% 1	1045

Page generated at 2024-10-29 23:22:54. Version ac07

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