Patoka Lake Observing Sites
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Patoka Lake Observing Sites clear sky chart from 2005-11-06 to 2024-12-24.

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	14% 8% 3 6% 4 4 4 4 5% 7% 40%	101422
	Night	15% 9% 3 7% 4 4 4 3 5% 6% 40%	98708
Transparency	Day	42% 6% 11% 24% 16% 2	105088
	Night	43% 5% 10% 22% 17% 3	103170
Seeing	Day	18% 13% 27% 24% 13% 5%	15612
	Night	19% 12% 26% 26% 15% 2	25455

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	14% 14% 7% 9% 4 4 4 3 5% 5% 29%	2527
	11th to 20th	Day	18% 10% 3 11% 8% 6% 5% 4 4 4 27%	2530
	21st to end	Day	25% 15% 7% 8% 3 3 3 3 4 5% 24%	3080
February	1st to 10th	Day	17% 12% 5% 9% 4 3 3 3 5% 6% 32%	1900
	11th to 20th	Day	16% 9% 4 7% 4 5% 4 3 5% 7% 36%	1848
	21st to end	Day	17% 14% 4 8% 4 4 4 4 4 6% 31%	1570
March	1st to 10th	Day	22% 14% 3 7% 3 3 3 2 3 4 35%	3120
	11th to 20th	Day	15% 7% 2 5% 3 3 4 4 5% 7% 45%	3320
	21st to end	Day	14% 8% 3 7% 5% 5% 5% 4 6% 7% 36%	4033
April	1st to 10th	Day	15% 8% 2 6% 5% 4 4 4 5% 7% 40%	2280
	11th to 20th	Day	17% 9% 3 5% 4 4 4 4 5% 7% 38%	2254
	21st to end	Day	18% 6% 2 7% 5% 4 5% 3 4 7% 39%	2382
May	1st to 10th	Day	19% 8% 2 7% 4 5% 5% 5% 6% 8% 31%	4082
	11th to 20th	Day	20% 7% 3 5% 5% 5% 4 3 5% 6% 39%	4081
	21st to end	Day	11% 7% 3 7% 5% 5% 6% 5% 6% 8% 38%	4494
June	1st to 10th	Day	12% 6% 2 5% 4 4 5% 3 5% 8% 45%	2660
	11th to 20th	Day	8% 5% 2 5% 5% 5% 5% 4 7% 8% 47%	2660
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 7% 10% 45%	2660
July	1st to 10th	Day	15% 6% 2 6% 4 4 5% 4 6% 9% 39%	4440
	11th to 20th	Day	7% 4 1 5% 4 4 4 4 6% 9% 49%	4440
	21st to end	Day	11% 7% 3 9% 6% 7% 7% 6% 7% 9% 28%	4624
August	1st to 10th	Day	8% 4 2 5% 3 3 5% 4 6% 10% 50%	4084
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 10% 40%	3729
	21st to end	Day	5% 4 1 4 3 4 4 4 6% 10% 55%	4180
September	1st to 10th	Day	12% 6% 2 5% 5% 5% 4 3 6% 7% 46%	2263
	11th to 20th	Day	10% 4 2 7% 4 4 4 3 6% 8% 49%	2090
	21st to end	Day	14% 5% 2 6% 4 4 3 3 4 6% 49%	2090
October	1st to 10th	Day	10% 5% 2 4 3 4 4 3 5% 6% 54%	2090
	11th to 20th	Day	13% 6% 2 6% 3 4 5% 3 4 7% 47%	1978
	21st to end	Day	20% 8% 2 6% 3 3 3 3 5% 5% 42%	1881
November	1st to 10th	Day	11% 6% 2 4 5% 3 4 3 5% 6% 52%	1762
	11th to 20th	Day	17% 10% 3 5% 5% 3 3 3 5% 6% 42%	1800
	21st to end	Day	20% 10% 3 5% 3 3 4 3 4 6% 39%	1800
December	1st to 10th	Day	19% 14% 4 7% 3 4 4 3 4 5% 34%	1800
	11th to 20th	Day	17% 13% 6% 8% 4 3 4 3 4 5% 31%	2083
	21st to end	Day	21% 19% 6% 8% 4 4 4 3 4 6% 22%	2807
January	1st to 10th	Night	18% 15% 5% 9% 4 4 4 3 5% 6% 28%	4428
	11th to 20th	Night	15% 16% 6% 11% 5% 5% 6% 2 3 3 26%	4440
	21st to end	Night	26% 17% 5% 6% 4 3 2 2 4 5% 25%	4573
February	1st to 10th	Night	21% 11% 4 9% 5% 5% 4 4 4 5% 28%	2280
	11th to 20th	Night	17% 10% 4 9% 4 3 4 3 4 6% 35%	2218
	21st to end	Night	21% 12% 4 7% 4 4 4 3 5% 5% 32%	1884
March	1st to 10th	Night	23% 14% 3 6% 3 3 3 3 4 4 33%	3733
	11th to 20th	Night	14% 7% 2 6% 3 3 3 3 5% 6% 48%	3625
	21st to end	Night	17% 8% 3 7% 5% 4 4 3 4 6% 39%	3626
April	1st to 10th	Night	13% 8% 2 6% 4 4 5% 4 5% 7% 42%	1900
	11th to 20th	Night	17% 7% 3 7% 4 3 3 3 5% 7% 42%	1875
	21st to end	Night	19% 7% 2 6% 4 4 4 3 5% 8% 37%	1796
May	1st to 10th	Night	19% 11% 3 7% 5% 4 4 3 5% 7% 30%	2813
	11th to 20th	Night	18% 5% 2 5% 4 4 4 3 6% 7% 42%	2812
	21st to end	Night	10% 5% 2 7% 5% 5% 5% 4 6% 9% 41%	3058
June	1st to 10th	Night	9% 6% 2 6% 4 3 3 4 7% 8% 49%	1520
	11th to 20th	Night	6% 5% 2 5% 3 5% 5% 4 5% 9% 50%	1520
	21st to end	Night	5% 4 2 5% 4 5% 5% 4 6% 10% 51%	1520
July	1st to 10th	Night	10% 5% 2 6% 4 4 4 3 6% 9% 48%	2530
	11th to 20th	Night	6% 4 1 4 2 4 4 3 7% 8% 57%	2530
	21st to end	Night	11% 6% 2 8% 6% 6% 6% 5% 7% 9% 33%	2932
August	1st to 10th	Night	7% 4 1 5% 3 4 4 3 5% 8% 56%	2842
	11th to 20th	Night	7% 4 2 6% 4 5% 6% 4 6% 9% 48%	3100
	21st to end	Night	4 3 1 4 3 3 3 3 6% 9% 60%	3476
September	1st to 10th	Night	12% 5% 2 5% 3 4 3 3 5% 6% 52%	1900
	11th to 20th	Night	8% 4 2 5% 3 4 3 3 7% 8% 52%	2087
	21st to end	Night	13% 5% 2 5% 3 3 4 3 4 7% 50%	2090
October	1st to 10th	Night	9% 4 2 5% 3 4 2 2 4 6% 59%	2090
	11th to 20th	Night	15% 5% 2 6% 3 3 4 3 4 5% 50%	2195
	21st to end	Night	18% 8% 2 6% 3 4 3 2 4 6% 45%	2717
November	1st to 10th	Night	13% 6% 2 6% 4 3 3 3 5% 5% 50%	2536
	11th to 20th	Night	15% 8% 3 6% 3 3 3 3 4 7% 44%	2600
	21st to end	Night	19% 10% 3 6% 4 3 3 2 4 5% 39%	2600
December	1st to 10th	Night	20% 12% 4 8% 4 3 3 3 4 6% 33%	2600
	11th to 20th	Night	19% 12% 4 9% 4 4 4 3 4 5% 33%	3329
	21st to end	Night	21% 18% 5% 9% 5% 5% 4 3 4 4 21%	4933

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	57% 3 10% 21% 8% 1	2528
	11th to 20th	Day	59% 4 12% 17% 8%	2530
	21st to end	Day	64% 4 8% 19% 4 1	3080
February	1st to 10th	Day	53% 4 10% 21% 11% 2	1900
	11th to 20th	Day	49% 4 10% 23% 13% 2	1858
	21st to end	Day	54% 4 10% 19% 10% 3	1570
March	1st to 10th	Day	55% 4 6% 19% 12% 4	3120
	11th to 20th	Day	39% 5% 10% 27% 17% 2	3320
	21st to end	Day	45% 7% 13% 21% 13% 1	4033
April	1st to 10th	Day	43% 6% 12% 22% 16% 1	2280
	11th to 20th	Day	44% 5% 9% 22% 16% 3	2254
	21st to end	Day	45% 6% 10% 25% 12% 2	2382
May	1st to 10th	Day	49% 7% 15% 20% 8% 1	4120
	11th to 20th	Day	46% 7% 9% 24% 13% 1	4085
	21st to end	Day	42% 7% 12% 17% 20% 2	4507
June	1st to 10th	Day	37% 6% 10% 26% 18% 3	2660
	11th to 20th	Day	32% 8% 13% 24% 18% 3	2660
	21st to end	Day	34% 7% 14% 23% 18% 4	2660
July	1st to 10th	Day	40% 6% 12% 22% 17% 2	4371
	11th to 20th	Day	29% 6% 12% 33% 18% 2	4365
	21st to end	Day	50% 9% 14% 17% 10% 1	4478
August	1st to 10th	Day	28% 7% 14% 34% 16% 1	4071
	11th to 20th	Day	37% 7% 12% 26% 17% 1	3765
	21st to end	Day	25% 6% 14% 36% 16% 3	4179
September	1st to 10th	Day	37% 5% 9% 23% 20% 4	2263
	11th to 20th	Day	33% 6% 9% 28% 20% 3	2090
	21st to end	Day	36% 4 8% 24% 24% 4	2090
October	1st to 10th	Day	20% 3 5% 27% 42% 2	3480
	11th to 20th	Day	26% 4 9% 26% 32% 4	3259
	21st to end	Day	34% 3 8% 26% 26% 4	3081
November	1st to 10th	Day	34% 4 10% 29% 18% 5%	1762
	11th to 20th	Day	44% 3 7% 23% 18% 4	1800
	21st to end	Day	47% 3 8% 23% 16% 2	1800
December	1st to 10th	Day	53% 4 10% 21% 11% 1	1800
	11th to 20th	Day	55% 4 8% 21% 11% 1	2080
	21st to end	Day	64% 5% 10% 14% 7%	2807
January	1st to 10th	Night	57% 4 11% 17% 10% 1	4428
	11th to 20th	Night	63% 4 7% 17% 8% 1	4440
	21st to end	Night	63% 3 7% 17% 9% 1	4573
February	1st to 10th	Night	58% 5% 9% 19% 7% 2	2280
	11th to 20th	Night	51% 3 9% 22% 14% 1	2219
	21st to end	Night	54% 5% 10% 18% 11% 3	1884
March	1st to 10th	Night	55% 4 7% 20% 13% 2	3733
	11th to 20th	Night	37% 5% 11% 24% 21% 2	3625
	21st to end	Night	47% 5% 9% 25% 12% 1	3626
April	1st to 10th	Night	40% 7% 10% 25% 15% 3	1900
	11th to 20th	Night	42% 4 9% 20% 19% 5%	1875
	21st to end	Night	45% 6% 9% 23% 15% 3	1796
May	1st to 10th	Night	52% 8% 12% 20% 7% 1	2840
	11th to 20th	Night	42% 7% 13% 27% 12% 1	2813
	21st to end	Night	37% 8% 14% 22% 16% 4	3066
June	1st to 10th	Night	32% 7% 11% 26% 20% 4	1520
	11th to 20th	Night	30% 7% 13% 21% 22% 7%	1520
	21st to end	Night	27% 7% 17% 24% 18% 7%	1520
July	1st to 10th	Night	34% 7% 11% 25% 19% 3	2490
	11th to 20th	Night	25% 7% 10% 35% 20% 3	2482
	21st to end	Night	45% 8% 15% 20% 11% 2	2839
August	1st to 10th	Night	26% 7% 14% 38% 14% 1	2831
	11th to 20th	Night	31% 6% 13% 31% 18% 1	3130
	21st to end	Night	20% 5% 14% 33% 24% 4	3476
September	1st to 10th	Night	33% 5% 8% 26% 21% 6%	1900
	11th to 20th	Night	29% 6% 8% 27% 25% 5%	2087
	21st to end	Night	34% 4 9% 23% 24% 5%	2090
October	1st to 10th	Night	19% 2 6% 17% 51% 5%	3480
	11th to 20th	Night	25% 3 6% 24% 38% 4	3640
	21st to end	Night	32% 3 7% 23% 29% 6%	4467
November	1st to 10th	Night	36% 4 8% 24% 23% 5%	2536
	11th to 20th	Night	41% 4 8% 21% 21% 5%	2600
	21st to end	Night	48% 4 9% 22% 16% 2	2600
December	1st to 10th	Night	52% 4 11% 21% 11% 1	2600
	11th to 20th	Night	53% 4 10% 19% 13% 2	3331
	21st to end	Night	66% 5% 8% 13% 7% 1	4933

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	27% 24% 28% 17% 4	270
	11th to 20th	Day	33% 23% 32% 10% 2	270
	21st to end	Day	30% 25% 32% 12% 2	297
February	1st to 10th	Day	26% 29% 31% 11% 2	270
	11th to 20th	Day	28% 31% 30% 9% 1	270
	21st to end	Day	32% 22% 37% 8% 1	225
March	1st to 10th	Day	23% 29% 36% 12% 1	270
	11th to 20th	Day	29% 23% 33% 10% 4 2	365
	21st to end	Day	29% 22% 30% 13% 5%	506
April	1st to 10th	Day	23% 20% 30% 21% 5% 1	460
	11th to 20th	Day	22% 22% 27% 20% 8% 1	452
	21st to end	Day	21% 21% 37% 12% 7% 2	460
May	1st to 10th	Day	22% 16% 32% 20% 7% 3	463
	11th to 20th	Day	20% 14% 30% 24% 9% 5%	487
	21st to end	Day	12% 10% 29% 29% 13% 7%	534
June	1st to 10th	Day	15% 7% 26% 29% 17% 6%	680
	11th to 20th	Day	9% 7% 25% 35% 17% 6%	680
	21st to end	Day	10% 8% 30% 28% 16% 7%	680
July	1st to 10th	Day	15% 4 18% 27% 24% 12%	671
	11th to 20th	Day	9% 4 23% 34% 21% 9%	668
	21st to end	Day	10% 4 22% 36% 21% 8%	625
August	1st to 10th	Day	11% 4 17% 34% 23% 10%	486
	11th to 20th	Day	13% 4 22% 34% 20% 7%	479
	21st to end	Day	10% 3 15% 30% 27% 15%	539
September	1st to 10th	Day	12% 4 20% 28% 28% 9%	490
	11th to 20th	Day	10% 3 15% 37% 24% 12%	490
	21st to end	Day	17% 10% 18% 26% 21% 8%	490
October	1st to 10th	Day	10% 8% 27% 32% 18% 6%	490
	11th to 20th	Day	19% 15% 35% 19% 9% 4	409
	21st to end	Day	25% 15% 39% 18% 2 1	330
November	1st to 10th	Day	15% 18% 35% 21% 8% 3	300
	11th to 20th	Day	24% 21% 32% 17% 5% 1	300
	21st to end	Day	30% 12% 35% 18% 5%	300
December	1st to 10th	Day	22% 30% 28% 14% 3 2	300
	11th to 20th	Day	28% 18% 37% 13% 3	300
	21st to end	Day	33% 24% 29% 11% 2	306
January	1st to 10th	Night	25% 22% 29% 21% 3	950
	11th to 20th	Night	30% 21% 32% 16% 2	950
	21st to end	Night	24% 23% 33% 19% 2	936
February	1st to 10th	Night	28% 18% 34% 18% 2	760
	11th to 20th	Night	25% 23% 33% 18% 1	743
	21st to end	Night	29% 19% 37% 14% 1	628
March	1st to 10th	Night	25% 19% 31% 21% 3	760
	11th to 20th	Night	24% 18% 33% 18% 6% 1	760
	21st to end	Night	25% 14% 33% 24% 4 1	722
April	1st to 10th	Night	18% 15% 34% 26% 7% 1	570
	11th to 20th	Night	23% 12% 29% 24% 12%	563
	21st to end	Night	22% 11% 32% 27% 6% 1	570
May	1st to 10th	Night	18% 9% 33% 25% 13% 1	570
	11th to 20th	Night	17% 7% 25% 31% 18% 2	561
	21st to end	Night	9% 6% 23% 32% 25% 5%	617
June	1st to 10th	Night	11% 3 22% 36% 27% 2	570
	11th to 20th	Night	7% 4 21% 41% 25% 2	570
	21st to end	Night	6% 2 24% 36% 30% 2	570
July	1st to 10th	Night	11% 3 12% 31% 32% 11%	555
	11th to 20th	Night	6% 2 14% 36% 37% 5%	552
	21st to end	Night	10% 3 13% 36% 32% 6%	624
August	1st to 10th	Night	9% 1 11% 38% 35% 7%	567
	11th to 20th	Night	7% 2 13% 39% 34% 6%	564
	21st to end	Night	6% 1 13% 33% 40% 6%	627
September	1st to 10th	Night	16% 3 14% 31% 30% 7%	570
	11th to 20th	Night	10% 3 17% 31% 34% 5%	757
	21st to end	Night	15% 5% 20% 30% 26% 4	760
October	1st to 10th	Night	12% 6% 21% 33% 23% 6%	760
	11th to 20th	Night	18% 11% 28% 26% 15% 2	760
	21st to end	Night	23% 14% 31% 23% 9%	836
November	1st to 10th	Night	16% 12% 31% 28% 12% 1	780
	11th to 20th	Night	20% 18% 30% 23% 8%	800
	21st to end	Night	25% 17% 24% 24% 10%	800
December	1st to 10th	Night	27% 16% 32% 20% 5%	800
	11th to 20th	Night	27% 16% 28% 22% 6% 1	910
	21st to end	Night	29% 18% 31% 19% 3	1063

Page generated at 2024-12-21 04:13:47. Version ac07

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