Owasso Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Owasso Observatory clear sky chart from 2005-11-06 to 2024-03-01.

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	12% 6% 2 5% 4 3 4 4 5% 7% 48%	78935
	Night	11% 5% 2 4 4 2 4 4 5% 7% 52%	80533
Transparency	Day	36% 6% 12% 24% 18% 4	78659
	Night	32% 5% 11% 24% 22% 5%	80328
Seeing	Day	13% 9% 26% 28% 18% 5%	14452
	Night	13% 9% 31% 33% 13% 1	24513

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	12% 10% 4 6% 4 3 3 4 3 6% 45%	2847
	11th to 20th	Day	9% 6% 2 5% 4 3 4 5% 6% 6% 51%	2850
	21st to end	Day	21% 11% 3 4 2 2 3 3 3 5% 44%	3135
February	1st to 10th	Day	15% 9% 4 6% 4 3 3 4 4 6% 42%	1710
	11th to 20th	Day	14% 6% 3 5% 4 3 4 3 5% 6% 47%	1787
	21st to end	Day	15% 8% 3 4 5% 3 4 3 4 6% 45%	1611
March	1st to 10th	Day	14% 8% 2 4 4 2 3 4 4 6% 49%	1980
	11th to 20th	Day	19% 7% 2 4 4 2 4 3 5% 6% 44%	1980
	21st to end	Day	18% 8% 4 6% 6% 3 4 4 5% 6% 36%	2178
April	1st to 10th	Day	11% 6% 2 5% 5% 3 5% 4 5% 7% 47%	1993
	11th to 20th	Day	15% 6% 2 5% 4 3 3 5% 5% 7% 44%	2134
	21st to end	Day	19% 7% 3 6% 5% 3 4 4 4 6% 41%	2304
May	1st to 10th	Day	18% 7% 3 5% 5% 3 4 4 5% 5% 41%	2340
	11th to 20th	Day	13% 7% 3 5% 5% 4 5% 4 6% 7% 41%	2302
	21st to end	Day	13% 6% 3 5% 6% 4 6% 5% 7% 9% 35%	2531
June	1st to 10th	Day	6% 4 2 5% 6% 3 5% 5% 6% 10% 49%	2340
	11th to 20th	Day	9% 3 2 5% 5% 4 5% 5% 6% 8% 49%	2340
	21st to end	Day	6% 2 1 3 4 2 5% 5% 6% 8% 59%	2340
July	1st to 10th	Day	9% 4 2 3 5% 3 6% 6% 7% 10% 44%	2340
	11th to 20th	Day	4 3 1 4 4 3 5% 5% 6% 9% 57%	2340
	21st to end	Day	7% 4 2 4 5% 3 5% 5% 6% 10% 48%	2546
August	1st to 10th	Day	5% 4 2 4 5% 3 4 6% 7% 9% 50%	2328
	11th to 20th	Day	8% 4 2 5% 5% 3 4 6% 6% 10% 47%	2301
	21st to end	Day	5% 4 2 4 5% 3 4 5% 6% 9% 54%	2445
September	1st to 10th	Day	11% 5% 2 5% 5% 2 4 4 5% 6% 53%	2038
	11th to 20th	Day	12% 4 2 4 4 3 4 5% 5% 8% 48%	1980
	21st to end	Day	9% 3 1 4 4 3 4 4 5% 7% 57%	1980
October	1st to 10th	Day	9% 4 2 4 4 2 3 4 5% 7% 57%	1856
	11th to 20th	Day	12% 4 1 3 3 2 2 3 4 5% 60%	1800
	21st to end	Day	17% 6% 2 3 3 2 3 3 3 5% 53%	1980
November	1st to 10th	Day	10% 4 2 4 3 2 4 3 4 6% 59%	1858
	11th to 20th	Day	11% 5% 1 3 3 2 3 3 3 5% 60%	1725
	21st to end	Day	15% 6% 2 3 3 2 3 3 4 6% 53%	1710
December	1st to 10th	Day	13% 7% 2 5% 4 3 3 4 4 5% 51%	1710
	11th to 20th	Day	14% 8% 3 6% 4 3 4 4 4 6% 45%	2161
	21st to end	Day	16% 13% 5% 7% 6% 3 5% 4 4 5% 32%	3135
January	1st to 10th	Night	11% 9% 3 6% 4 2 3 4 5% 6% 48%	4108
	11th to 20th	Night	8% 5% 2 5% 4 2 4 4 5% 8% 54%	4120
	21st to end	Night	22% 9% 3 4 3 1 3 2 3 5% 47%	4532
February	1st to 10th	Night	15% 8% 2 5% 5% 2 4 3 5% 6% 46%	2470
	11th to 20th	Night	13% 7% 4 5% 3 2 3 3 4 6% 51%	2297
	21st to end	Night	13% 7% 3 4 4 2 4 3 4 4 51%	1841
March	1st to 10th	Night	12% 5% 3 5% 4 3 4 4 5% 6% 49%	1986
	11th to 20th	Night	17% 5% 2 4 3 2 4 3 4 5% 51%	1980
	21st to end	Night	16% 6% 3 4 4 3 4 3 5% 6% 46%	2178
April	1st to 10th	Night	12% 5% 2 3 3 2 4 4 4 6% 55%	1965
	11th to 20th	Night	15% 4 2 4 5% 2 3 3 4 7% 50%	1775
	21st to end	Night	16% 6% 2 5% 5% 2 3 3 4 6% 49%	1653
May	1st to 10th	Night	14% 5% 3 4 5% 2 4 5% 6% 7% 45%	1620
	11th to 20th	Night	13% 6% 2 4 4 2 4 4 5% 8% 48%	1593
	21st to end	Night	10% 4 2 5% 5% 3 4 4 6% 11% 44%	1745
June	1st to 10th	Night	5% 3 2 4 5% 3 4 4 6% 7% 57%	1620
	11th to 20th	Night	5% 2 2 2 4 2 4 4 8% 11% 56%	1620
	21st to end	Night	4 2 2 2 3 2 4 4 5% 8% 65%	1620
July	1st to 10th	Night	5% 3 1 4 4 3 4 5% 7% 12% 51%	1620
	11th to 20th	Night	3 1 2 3 4 2 4 4 6% 11% 60%	1620
	21st to end	Night	5% 3 2 4 4 2 4 5% 6% 9% 55%	1772
August	1st to 10th	Night	3 2 1 4 3 3 4 5% 8% 11% 55%	1611
	11th to 20th	Night	6% 4 1 5% 4 4 5% 5% 6% 8% 53%	1600
	21st to end	Night	3 3 1 4 4 2 5% 4 6% 9% 59%	1909
September	1st to 10th	Night	9% 4 2 4 4 2 3 4 4 7% 59%	1917
	11th to 20th	Night	9% 5% 3 4 5% 3 4 4 5% 7% 51%	1980
	21st to end	Night	7% 4 2 4 3 3 3 4 4 6% 61%	1980
October	1st to 10th	Night	7% 4 1 3 4 3 3 3 5% 6% 61%	2084
	11th to 20th	Night	12% 5% 1 3 3 2 3 3 4 5% 60%	2160
	21st to end	Night	14% 5% 2 3 3 2 3 3 4 4 57%	2376
November	1st to 10th	Night	10% 5% 1 2 3 2 2 3 4 5% 64%	2220
	11th to 20th	Night	10% 5% 2 4 3 2 3 3 4 6% 59%	2453
	21st to end	Night	14% 5% 2 4 3 2 3 3 3 6% 55%	2470
December	1st to 10th	Night	13% 5% 2 5% 3 3 4 4 4 7% 51%	2470
	11th to 20th	Night	13% 7% 2 5% 5% 3 4 3 4 5% 50%	3036
	21st to end	Night	18% 8% 4 5% 4 2 3 3 4 5% 42%	4532

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	42% 4 9% 25% 19% 2	2848
	11th to 20th	Day	32% 5% 17% 27% 15% 5%	2850
	21st to end	Day	46% 3 8% 21% 20% 2	3135
February	1st to 10th	Day	44% 5% 10% 23% 14% 4	1710
	11th to 20th	Day	39% 5% 9% 26% 18% 3	1796
	21st to end	Day	42% 3 8% 22% 17% 9%	1611
March	1st to 10th	Day	38% 4 8% 22% 19% 9%	1980
	11th to 20th	Day	43% 5% 10% 22% 16% 4	1980
	21st to end	Day	48% 6% 11% 21% 12% 2	2178
April	1st to 10th	Day	36% 6% 13% 23% 18% 5%	1993
	11th to 20th	Day	39% 6% 12% 23% 15% 5%	2134
	21st to end	Day	45% 5% 10% 22% 16% 1	2304
May	1st to 10th	Day	45% 5% 10% 21% 17% 2	2340
	11th to 20th	Day	42% 7% 13% 23% 13% 1	2306
	21st to end	Day	44% 9% 14% 22% 10% 1	2531
June	1st to 10th	Day	29% 8% 17% 27% 16% 2	2340
	11th to 20th	Day	32% 7% 15% 26% 16% 3	2340
	21st to end	Day	22% 7% 15% 30% 21% 5%	2340
July	1st to 10th	Day	31% 9% 17% 27% 14% 2	2276
	11th to 20th	Day	21% 8% 14% 31% 22% 4	2271
	21st to end	Day	29% 8% 17% 30% 16% 1	2405
August	1st to 10th	Day	26% 10% 16% 27% 17% 3	2314
	11th to 20th	Day	31% 8% 14% 24% 21% 2	2301
	21st to end	Day	26% 8% 13% 27% 20% 6%	2445
September	1st to 10th	Day	32% 5% 10% 22% 22% 8%	2038
	11th to 20th	Day	34% 7% 12% 20% 21% 5%	1980
	21st to end	Day	27% 5% 10% 23% 28% 7%	1980
October	1st to 10th	Day	27% 6% 13% 23% 25% 5%	1856
	11th to 20th	Day	27% 3 8% 24% 30% 8%	1800
	21st to end	Day	35% 4 8% 26% 19% 8%	1980
November	1st to 10th	Day	28% 3 8% 28% 25% 7%	1858
	11th to 20th	Day	29% 3 10% 27% 24% 7%	1725
	21st to end	Day	34% 4 8% 24% 25% 5%	1710
December	1st to 10th	Day	37% 4 9% 30% 20% 1	1710
	11th to 20th	Day	40% 4 8% 22% 22% 3	2159
	21st to end	Day	53% 5% 9% 20% 10% 2	3135
January	1st to 10th	Night	37% 5% 10% 26% 19% 3	4108
	11th to 20th	Night	29% 6% 18% 21% 23% 3	4120
	21st to end	Night	42% 3 10% 20% 21% 3	4532
February	1st to 10th	Night	41% 4 12% 21% 18% 4	2470
	11th to 20th	Night	37% 4 8% 27% 19% 5%	2297
	21st to end	Night	38% 4 7% 19% 23% 9%	1841
March	1st to 10th	Night	36% 5% 9% 19% 20% 11%	1986
	11th to 20th	Night	38% 4 11% 22% 19% 6%	1980
	21st to end	Night	39% 6% 11% 25% 17% 3	2178
April	1st to 10th	Night	31% 5% 10% 23% 22% 8%	1965
	11th to 20th	Night	35% 5% 11% 23% 18% 8%	1775
	21st to end	Night	38% 4 10% 24% 21% 3	1653
May	1st to 10th	Night	37% 7% 13% 20% 20% 3	1620
	11th to 20th	Night	33% 7% 14% 26% 18% 2	1594
	21st to end	Night	33% 7% 19% 26% 13% 1	1746
June	1st to 10th	Night	25% 8% 16% 29% 19% 3	1620
	11th to 20th	Night	21% 7% 16% 32% 21% 3	1620
	21st to end	Night	18% 6% 14% 30% 26% 7%	1620
July	1st to 10th	Night	24% 8% 16% 30% 19% 3	1575
	11th to 20th	Night	18% 6% 14% 29% 28% 5%	1566
	21st to end	Night	23% 7% 12% 33% 23% 2	1673
August	1st to 10th	Night	19% 8% 17% 34% 20% 3	1601
	11th to 20th	Night	28% 7% 12% 22% 26% 7%	1600
	21st to end	Night	20% 7% 15% 28% 22% 9%	1909
September	1st to 10th	Night	27% 4 10% 26% 24% 10%	1917
	11th to 20th	Night	32% 6% 10% 19% 26% 7%	1980
	21st to end	Night	24% 5% 9% 25% 30% 7%	1980
October	1st to 10th	Night	24% 5% 12% 23% 27% 9%	2084
	11th to 20th	Night	28% 4 6% 21% 30% 11%	2160
	21st to end	Night	32% 3 8% 22% 26% 9%	2376
November	1st to 10th	Night	24% 4 9% 25% 30% 8%	2220
	11th to 20th	Night	28% 4 7% 27% 26% 8%	2453
	21st to end	Night	33% 4 7% 22% 28% 6%	2470
December	1st to 10th	Night	34% 5% 10% 26% 19% 4	2470
	11th to 20th	Night	38% 4 8% 21% 25% 4	3037
	21st to end	Night	44% 6% 8% 22% 16% 4	4532

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	20% 14% 36% 25% 5%	270
	11th to 20th	Day	23% 19% 39% 16% 4	270
	21st to end	Day	18% 19% 36% 20% 7%	297
February	1st to 10th	Day	24% 13% 37% 20% 5%	270
	11th to 20th	Day	20% 21% 39% 18% 2	270
	21st to end	Day	26% 21% 37% 13% 3	225
March	1st to 10th	Day	20% 25% 33% 19% 3	240
	11th to 20th	Day	24% 18% 36% 18% 3	240
	21st to end	Day	22% 22% 37% 16% 4	264
April	1st to 10th	Day	11% 22% 43% 18% 5%	253
	11th to 20th	Day	21% 17% 34% 23% 5%	412
	21st to end	Day	22% 20% 30% 20% 8% 1	564
May	1st to 10th	Day	18% 12% 39% 23% 7% 1	603
	11th to 20th	Day	18% 12% 28% 28% 12% 3	625
	21st to end	Day	17% 8% 29% 23% 16% 7%	679
June	1st to 10th	Day	6% 4 22% 36% 26% 6%	630
	11th to 20th	Day	9% 2 26% 38% 21% 5%	630
	21st to end	Day	4 2 22% 42% 24% 6%	630
July	1st to 10th	Day	8% 2 14% 31% 32% 13%	621
	11th to 20th	Day	3 2 12% 39% 35% 9%	618
	21st to end	Day	8% 1 8% 33% 37% 13%	684
August	1st to 10th	Day	6% 1 13% 42% 32% 6%	626
	11th to 20th	Day	9% 2 14% 34% 34% 7%	615
	21st to end	Day	7% 2 10% 33% 38% 11%	564
September	1st to 10th	Day	11% 1 12% 29% 35% 13%	328
	11th to 20th	Day	6% 3 14% 36% 32% 10%	270
	21st to end	Day	13% 4 20% 32% 24% 7%	270
October	1st to 10th	Day	8% 6% 31% 28% 20% 6%	270
	11th to 20th	Day	9% 13% 40% 27% 10% 1	270
	21st to end	Day	26% 11% 29% 23% 9% 2	297
November	1st to 10th	Day	13% 10% 39% 26% 11% 2	270
	11th to 20th	Day	14% 12% 41% 22% 10% 2	270
	21st to end	Day	22% 16% 36% 20% 6%	270
December	1st to 10th	Day	15% 17% 36% 20% 10% 1	270
	11th to 20th	Day	19% 15% 38% 20% 8%	270
	21st to end	Day	15% 24% 36% 21% 4	297
January	1st to 10th	Night	13% 14% 38% 28% 6%	950
	11th to 20th	Night	16% 14% 38% 27% 5%	950
	21st to end	Night	15% 14% 37% 30% 5%	1045
February	1st to 10th	Night	19% 14% 37% 26% 4	950
	11th to 20th	Night	18% 16% 36% 27% 3	822
	21st to end	Night	18% 14% 39% 25% 3	585
March	1st to 10th	Night	16% 12% 37% 31% 4	542
	11th to 20th	Night	19% 13% 38% 26% 4	540
	21st to end	Night	20% 13% 39% 23% 5%	594
April	1st to 10th	Night	15% 14% 41% 25% 5%	540
	11th to 20th	Night	17% 12% 37% 27% 7%	533
	21st to end	Night	18% 11% 40% 23% 7% 1	540
May	1st to 10th	Night	15% 9% 40% 30% 6%	540
	11th to 20th	Night	17% 7% 28% 34% 13% 1	531
	21st to end	Night	10% 5% 29% 36% 18% 2	584
June	1st to 10th	Night	6% 2 22% 44% 25% 1	540
	11th to 20th	Night	4 3 28% 45% 19% 1	540
	21st to end	Night	4 3 22% 50% 21% 1	540
July	1st to 10th	Night	5% 1 15% 46% 31% 2	525
	11th to 20th	Night	3 15% 46% 32% 4	522
	21st to end	Night	5% 2 10% 46% 36% 2	591
August	1st to 10th	Night	4 1 14% 50% 30% 2	537
	11th to 20th	Night	7% 1 14% 43% 34% 2	534
	21st to end	Night	4 1 14% 37% 41% 4	594
September	1st to 10th	Night	11% 1 12% 45% 30% 1	540
	11th to 20th	Night	12% 2 18% 39% 24% 4	540
	21st to end	Night	10% 3 21% 38% 25% 4	540
October	1st to 10th	Night	8% 3 30% 34% 22% 3	644
	11th to 20th	Night	14% 8% 37% 31% 10% 1	720
	21st to end	Night	15% 12% 32% 29% 11% 1	792
November	1st to 10th	Night	12% 9% 37% 29% 11% 1	740
	11th to 20th	Night	13% 13% 35% 31% 9% 1	933
	21st to end	Night	18% 12% 32% 29% 9%	950
December	1st to 10th	Night	15% 14% 33% 31% 6% 1	950
	11th to 20th	Night	19% 11% 35% 29% 6%	950
	21st to end	Night	18% 13% 36% 28% 5%	1045

Page generated at 2024-02-27 05:30:12. Version ac07

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