Water Valley Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Water Valley Overlook clear sky chart from 2005-11-06 to 2024-11-04.

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	13% 7% 2 6% 4 4 5% 4 6% 8% 41%	101082
	Night	14% 7% 2 6% 4 4 4 3 5% 7% 44%	97907
Transparency	Day	39% 6% 10% 22% 18% 4	104814
	Night	38% 5% 10% 22% 19% 5%	102314
Seeing	Day	16% 9% 22% 24% 19% 10%	15169
	Night	17% 7% 24% 30% 20% 3	24868

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	13% 13% 4 9% 5% 4 5% 4 5% 5% 32%	2527
	11th to 20th	Day	21% 8% 2 10% 4 3 3 2 3 5% 38%	2588
	21st to end	Day	24% 10% 4 5% 3 3 3 3 4 6% 35%	3476
February	1st to 10th	Day	20% 11% 3 7% 4 3 3 3 3 6% 37%	1900
	11th to 20th	Day	21% 10% 3 6% 5% 4 4 3 4 5% 37%	1848
	21st to end	Day	22% 10% 3 7% 4 3 4 4 4 5% 36%	1570
March	1st to 10th	Day	22% 12% 3 8% 4 4 4 3 5% 5% 31%	3120
	11th to 20th	Day	14% 6% 2 6% 4 4 3 3 5% 6% 47%	3286
	21st to end	Day	13% 6% 2 7% 5% 5% 4 4 6% 7% 40%	4094
April	1st to 10th	Day	13% 6% 2 6% 5% 4 4 4 5% 7% 45%	2280
	11th to 20th	Day	15% 7% 3 6% 4 3 3 3 5% 7% 44%	2254
	21st to end	Day	13% 7% 2 7% 5% 5% 5% 3 6% 9% 40%	2280
May	1st to 10th	Day	17% 7% 3 5% 5% 5% 5% 4 6% 8% 35%	4078
	11th to 20th	Day	17% 8% 3 7% 5% 4 4 4 6% 8% 36%	4081
	21st to end	Day	12% 7% 2 7% 5% 4 5% 4 6% 9% 39%	4476
June	1st to 10th	Day	10% 6% 3 6% 5% 5% 5% 4 7% 10% 40%	2501
	11th to 20th	Day	5% 4 2 6% 5% 5% 6% 5% 7% 10% 45%	2660
	21st to end	Day	5% 4 1 6% 5% 6% 6% 5% 9% 10% 42%	2660
July	1st to 10th	Day	7% 5% 2 7% 5% 6% 7% 5% 8% 10% 38%	4440
	11th to 20th	Day	9% 6% 2 6% 5% 5% 6% 6% 8% 11% 36%	4387
	21st to end	Day	17% 10% 3 8% 5% 6% 5% 5% 7% 7% 26%	4466
August	1st to 10th	Day	4 3 2 4 4 4 5% 5% 7% 8% 54%	3798
	11th to 20th	Day	7% 5% 2 6% 5% 5% 5% 5% 7% 10% 43%	3729
	21st to end	Day	6% 4 2 5% 4 4 4 5% 5% 8% 53%	4180
September	1st to 10th	Day	10% 6% 2 7% 5% 4 6% 4 6% 8% 42%	2272
	11th to 20th	Day	13% 6% 2 6% 5% 4 5% 4 5% 7% 44%	2090
	21st to end	Day	11% 5% 2 5% 4 3 4 3 7% 7% 49%	2090
October	1st to 10th	Day	11% 4 2 5% 3 3 4 3 4 7% 55%	2090
	11th to 20th	Day	11% 5% 2 5% 3 3 3 3 4 7% 53%	2021
	21st to end	Day	17% 6% 2 5% 4 4 3 3 4 5% 48%	1929
November	1st to 10th	Day	12% 6% 2 4 3 2 3 3 4 5% 57%	1699
	11th to 20th	Day	15% 6% 2 4 3 4 3 2 5% 6% 50%	1710
	21st to end	Day	16% 8% 2 5% 4 3 3 3 5% 6% 45%	1710
December	1st to 10th	Day	23% 9% 2 7% 4 3 4 3 4 5% 36%	1710
	11th to 20th	Day	16% 10% 3 7% 5% 4 5% 3 4 6% 38%	2153
	21st to end	Day	16% 11% 4 8% 5% 4 5% 4 6% 7% 32%	2929
January	1st to 10th	Night	19% 12% 3 5% 3 3 3 3 4 6% 38%	4428
	11th to 20th	Night	19% 11% 4 9% 4 3 3 3 4 4 36%	4344
	21st to end	Night	23% 13% 4 6% 3 3 3 2 4 4 36%	4180
February	1st to 10th	Night	19% 12% 3 7% 5% 4 4 3 5% 5% 34%	2280
	11th to 20th	Night	21% 10% 3 7% 4 4 3 2 4 4 37%	2218
	21st to end	Night	25% 8% 2 6% 4 4 3 3 4 6% 33%	1884
March	1st to 10th	Night	23% 9% 3 7% 4 4 3 3 5% 6% 34%	3733
	11th to 20th	Night	14% 7% 2 6% 4 4 4 3 4 5% 47%	3672
	21st to end	Night	15% 8% 2 7% 5% 4 4 4 6% 5% 39%	3565
April	1st to 10th	Night	11% 7% 2 6% 4 3 4 3 5% 7% 47%	1900
	11th to 20th	Night	15% 6% 2 5% 4 3 3 3 4 7% 48%	1875
	21st to end	Night	13% 7% 2 5% 4 4 4 4 6% 8% 44%	1900
May	1st to 10th	Night	14% 8% 3 7% 5% 4 4 3 5% 6% 40%	2814
	11th to 20th	Night	13% 7% 2 7% 4 4 4 3 6% 7% 43%	2812
	21st to end	Night	8% 6% 2 8% 5% 4 4 4 7% 9% 42%	3079
June	1st to 10th	Night	9% 5% 3 6% 4 4 5% 4 6% 11% 44%	1672
	11th to 20th	Night	4 3 1 4 4 3 5% 3 8% 9% 56%	1520
	21st to end	Night	3 3 2 5% 4 4 5% 5% 8% 11% 52%	1520
July	1st to 10th	Night	7% 5% 2 7% 4 5% 5% 5% 8% 11% 41%	2530
	11th to 20th	Night	7% 5% 2 5% 4 4 5% 5% 6% 13% 44%	2578
	21st to end	Night	11% 9% 4 9% 5% 5% 6% 5% 7% 9% 29%	3087
August	1st to 10th	Night	3 2 1 4 3 3 3 3 6% 8% 62%	3128
	11th to 20th	Night	5% 3 1 5% 4 3 5% 5% 8% 11% 50%	3100
	21st to end	Night	5% 3 2 4 3 3 4 4 6% 9% 57%	3476
September	1st to 10th	Night	10% 7% 2 5% 4 4 3 4 6% 7% 49%	1900
	11th to 20th	Night	10% 5% 2 6% 4 4 4 4 6% 7% 49%	2077
	21st to end	Night	10% 5% 2 5% 3 4 4 3 5% 6% 54%	2090
October	1st to 10th	Night	9% 4 2 4 3 3 3 3 4 6% 61%	2090
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 5% 6% 52%	2156
	21st to end	Night	15% 7% 2 5% 3 3 3 3 4 6% 50%	2667
November	1st to 10th	Night	10% 5% 3 6% 3 3 3 3 4 5% 54%	2452
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 6% 8% 49%	2470
	21st to end	Night	17% 7% 2 5% 3 3 4 3 4 5% 46%	2470
December	1st to 10th	Night	20% 9% 3 8% 4 3 4 3 4 6% 36%	2470
	11th to 20th	Night	17% 8% 2 6% 4 3 3 3 4 5% 47%	3042
	21st to end	Night	18% 11% 4 9% 4 5% 5% 4 5% 6% 29%	4728

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% 4 8% 20% 14% 2	2528
	11th to 20th	Day	51% 4 7% 17% 20% 1	2588
	21st to end	Day	51% 3 8% 22% 14% 1	3476
February	1st to 10th	Day	50% 4 7% 19% 16% 3	1900
	11th to 20th	Day	51% 4 6% 20% 15% 4	1858
	21st to end	Day	51% 3 8% 15% 16% 6%	1570
March	1st to 10th	Day	55% 5% 6% 13% 13% 8%	3120
	11th to 20th	Day	38% 5% 9% 25% 17% 6%	3286
	21st to end	Day	42% 6% 10% 25% 16% 1	4094
April	1st to 10th	Day	39% 6% 9% 22% 20% 4	2280
	11th to 20th	Day	41% 5% 7% 20% 21% 6%	2254
	21st to end	Day	41% 6% 10% 25% 16% 2	2280
May	1st to 10th	Day	44% 8% 11% 22% 14% 1	4116
	11th to 20th	Day	44% 7% 12% 24% 12%	4085
	21st to end	Day	40% 8% 10% 23% 19% 1	4489
June	1st to 10th	Day	37% 8% 13% 23% 17% 2	2501
	11th to 20th	Day	30% 10% 14% 25% 18% 3	2660
	21st to end	Day	33% 11% 15% 20% 17% 4	2660
July	1st to 10th	Day	35% 12% 18% 26% 7% 2	4371
	11th to 20th	Day	37% 9% 17% 27% 8% 2	4312
	21st to end	Day	54% 9% 11% 18% 7% 1	4324
August	1st to 10th	Day	23% 8% 16% 31% 21% 2	3785
	11th to 20th	Day	32% 9% 14% 27% 16% 2	3765
	21st to end	Day	28% 8% 10% 27% 25% 2	4179
September	1st to 10th	Day	38% 9% 11% 21% 17% 5%	2272
	11th to 20th	Day	38% 8% 9% 21% 20% 3	2090
	21st to end	Day	33% 6% 12% 23% 21% 6%	2090
October	1st to 10th	Day	21% 4 5% 16% 43% 11%	3480
	11th to 20th	Day	23% 3 7% 23% 29% 15%	3339
	21st to end	Day	30% 3 6% 22% 30% 8%	3154
November	1st to 10th	Day	31% 3 8% 22% 30% 6%	1699
	11th to 20th	Day	36% 3 7% 22% 25% 7%	1710
	21st to end	Day	40% 4 7% 23% 21% 6%	1710
December	1st to 10th	Day	50% 4 6% 20% 16% 3	1710
	11th to 20th	Day	48% 4 8% 20% 18% 2	2150
	21st to end	Day	50% 5% 11% 21% 10% 2	2929
January	1st to 10th	Night	48% 3 7% 24% 17% 1	4428
	11th to 20th	Night	52% 4 7% 16% 17% 5%	4344
	21st to end	Night	53% 3 6% 21% 15% 2	4180
February	1st to 10th	Night	53% 3 10% 17% 16% 2	2280
	11th to 20th	Night	51% 4 6% 18% 17% 5%	2219
	21st to end	Night	53% 3 8% 15% 16% 5%	1884
March	1st to 10th	Night	51% 4 9% 12% 16% 7%	3733
	11th to 20th	Night	39% 5% 8% 22% 16% 10%	3672
	21st to end	Night	45% 4 9% 22% 19% 1	3565
April	1st to 10th	Night	36% 4 11% 24% 21% 4	1900
	11th to 20th	Night	37% 4 9% 20% 22% 9%	1875
	21st to end	Night	37% 6% 10% 26% 18% 2	1900
May	1st to 10th	Night	43% 8% 11% 22% 15% 2	2841
	11th to 20th	Night	40% 8% 15% 19% 17% 1	2813
	21st to end	Night	34% 9% 13% 25% 17% 2	3087
June	1st to 10th	Night	35% 7% 13% 24% 18% 3	1672
	11th to 20th	Night	21% 7% 16% 33% 19% 3	1520
	21st to end	Night	24% 10% 18% 28% 17% 4	1520
July	1st to 10th	Night	32% 11% 20% 26% 9% 2	2490
	11th to 20th	Night	28% 9% 19% 34% 7% 3	2530
	21st to end	Night	50% 10% 12% 19% 8% 1	2988
August	1st to 10th	Night	18% 7% 12% 38% 23% 1	3117
	11th to 20th	Night	23% 9% 20% 30% 16% 1	3130
	21st to end	Night	22% 8% 12% 31% 24% 3	3476
September	1st to 10th	Night	33% 8% 11% 24% 19% 5%	1900
	11th to 20th	Night	33% 7% 12% 19% 26% 2	2077
	21st to end	Night	30% 6% 10% 23% 25% 6%	2090
October	1st to 10th	Night	18% 4 7% 18% 40% 13%	3480
	11th to 20th	Night	21% 3 4 21% 31% 20%	3577
	21st to end	Night	25% 4 7% 25% 28% 12%	4392
November	1st to 10th	Night	33% 4 7% 22% 26% 8%	2452
	11th to 20th	Night	33% 4 7% 21% 28% 7%	2470
	21st to end	Night	41% 4 6% 22% 22% 5%	2470
December	1st to 10th	Night	49% 5% 8% 17% 17% 3	2470
	11th to 20th	Night	41% 3 7% 22% 23% 4	3044
	21st to end	Night	53% 5% 11% 17% 12% 3	4728

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	26% 15% 40% 12% 7%	270
	11th to 20th	Day	28% 20% 33% 13% 4 2	270
	21st to end	Day	23% 18% 38% 18% 4	297
February	1st to 10th	Day	29% 17% 33% 17% 3 1	270
	11th to 20th	Day	33% 19% 34% 12% 2 1	270
	21st to end	Day	40% 16% 33% 7% 4	225
March	1st to 10th	Day	28% 16% 32% 19% 6%	270
	11th to 20th	Day	23% 17% 35% 19% 5% 1	344
	21st to end	Day	23% 14% 33% 23% 7% 1	506
April	1st to 10th	Day	21% 15% 28% 23% 10% 2	460
	11th to 20th	Day	20% 15% 28% 24% 11% 2	452
	21st to end	Day	18% 12% 29% 25% 12% 4	460
May	1st to 10th	Day	17% 13% 26% 26% 14% 5%	463
	11th to 20th	Day	15% 8% 22% 29% 16% 10%	487
	21st to end	Day	11% 5% 19% 29% 20% 15%	529
June	1st to 10th	Day	12% 6% 19% 22% 24% 19%	521
	11th to 20th	Day	6% 3 16% 26% 32% 16%	680
	21st to end	Day	7% 3 18% 31% 26% 14%	680
July	1st to 10th	Day	9% 2 13% 31% 27% 19%	671
	11th to 20th	Day	8% 4 10% 27% 29% 22%	641
	21st to end	Day	10% 3 10% 25% 32% 21%	532
August	1st to 10th	Day	7% 2 11% 26% 34% 20%	486
	11th to 20th	Day	9% 1 15% 28% 34% 13%	479
	21st to end	Day	12% 2 8% 21% 37% 21%	539
September	1st to 10th	Day	11% 3 12% 27% 32% 15%	490
	11th to 20th	Day	15% 2 9% 26% 29% 19%	490
	21st to end	Day	16% 5% 17% 27% 26% 10%	490
October	1st to 10th	Day	11% 3 20% 29% 26% 11%	490
	11th to 20th	Day	13% 12% 29% 29% 15% 3	421
	21st to end	Day	23% 11% 26% 27% 11% 2	330
November	1st to 10th	Day	18% 11% 29% 30% 10% 3	279
	11th to 20th	Day	17% 14% 36% 23% 9% 1	270
	21st to end	Day	22% 14% 29% 19% 13% 3	270
December	1st to 10th	Day	28% 17% 29% 21% 6%	270
	11th to 20th	Day	20% 17% 34% 19% 9% 1	270
	21st to end	Day	25% 19% 35% 18% 3	297
January	1st to 10th	Night	24% 15% 30% 27% 5%	950
	11th to 20th	Night	28% 16% 30% 22% 4	912
	21st to end	Night	21% 11% 41% 24% 2	836
February	1st to 10th	Night	25% 13% 33% 26% 3	760
	11th to 20th	Night	28% 15% 30% 25% 3	743
	21st to end	Night	31% 16% 32% 20% 1	628
March	1st to 10th	Night	22% 13% 32% 27% 5%	760
	11th to 20th	Night	21% 12% 34% 25% 7% 1	760
	21st to end	Night	20% 9% 33% 30% 8%	687
April	1st to 10th	Night	15% 12% 32% 31% 10% 1	570
	11th to 20th	Night	18% 10% 29% 31% 9% 1	563
	21st to end	Night	15% 7% 33% 31% 12% 1	570
May	1st to 10th	Night	13% 5% 31% 32% 18% 1	570
	11th to 20th	Night	12% 4 23% 34% 24% 3	561
	21st to end	Night	9% 2 16% 39% 29% 5%	617
June	1st to 10th	Night	11% 3 14% 33% 33% 5%	570
	11th to 20th	Night	4 1 12% 38% 39% 6%	570
	21st to end	Night	4 1 12% 36% 39% 8%	570
July	1st to 10th	Night	8% 2 9% 27% 41% 12%	555
	11th to 20th	Night	7% 1 10% 28% 42% 11%	552
	21st to end	Night	7% 2 8% 30% 45% 9%	624
August	1st to 10th	Night	7% 1 6% 27% 50% 10%	567
	11th to 20th	Night	7% 1 8% 40% 40% 4	564
	21st to end	Night	10% 1 6% 28% 47% 9%	627
September	1st to 10th	Night	11% 2 11% 30% 41% 5%	570
	11th to 20th	Night	12% 2 12% 29% 39% 6%	747
	21st to end	Night	11% 3 18% 30% 33% 5%	760
October	1st to 10th	Night	11% 4 16% 33% 31% 5%	760
	11th to 20th	Night	16% 7% 22% 36% 19% 1	760
	21st to end	Night	17% 6% 25% 32% 17% 2	836
November	1st to 10th	Night	13% 5% 23% 38% 18% 2	755
	11th to 20th	Night	14% 9% 31% 32% 12% 1	760
	21st to end	Night	22% 8% 27% 31% 12% 1	760
December	1st to 10th	Night	24% 13% 28% 28% 7%	760
	11th to 20th	Night	23% 8% 30% 31% 8% 1	760
	21st to end	Night	27% 11% 30% 27% 5%	954

Page generated at 2024-11-01 21:47:37. Version ac07

Copyright © 2024 Attilla Danko.