Choke Canyon State Park - Calliham Unit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Choke Canyon State Park - Calliham Unit clear sky chart from 2005-11-06 to 2024-03-08.

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	11% 5% 2 5% 5% 3 5% 5% 6% 8% 47%	79073
	Night	12% 5% 2 4 4 2 3 4 5% 8% 52%	80554
Transparency	Day	35% 7% 11% 20% 18% 9%	78798
	Night	31% 7% 13% 21% 18% 11%	80349
Seeing	Day	11% 5% 20% 30% 26% 8%	13668
	Night	13% 5% 26% 39% 15% 1	23805

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	15% 6% 3 4 4 2 3 3 3 5% 52%	2847
	11th to 20th	Day	16% 5% 2 3 3 2 2 3 4 6% 55%	2859
	21st to end	Day	20% 7% 3 5% 4 2 4 4 6% 7% 37%	3487
February	1st to 10th	Day	17% 9% 4 5% 4 2 3 3 4 5% 43%	1900
	11th to 20th	Day	18% 6% 3 5% 4 2 3 4 4 5% 46%	1849
	21st to end	Day	16% 5% 2 5% 4 2 4 4 4 6% 48%	1570
March	1st to 10th	Day	16% 7% 2 5% 3 3 4 4 6% 8% 41%	2033
	11th to 20th	Day	14% 8% 3 5% 4 2 4 5% 5% 6% 43%	1980
	21st to end	Day	12% 5% 2 4 4 3 4 4 5% 7% 49%	2178
April	1st to 10th	Day	12% 6% 2 5% 4 3 4 6% 6% 7% 45%	1980
	11th to 20th	Day	15% 7% 2 6% 5% 3 3 4 4 5% 45%	1956
	21st to end	Day	12% 6% 3 5% 4 3 4 4 4 6% 49%	2210
May	1st to 10th	Day	11% 6% 3 4 5% 4 5% 5% 6% 7% 44%	2340
	11th to 20th	Day	10% 6% 2 5% 5% 4 6% 5% 7% 8% 43%	2302
	21st to end	Day	9% 4 2 6% 5% 4 6% 6% 7% 11% 40%	2531
June	1st to 10th	Day	4 3 1 4 4 3 6% 7% 7% 11% 51%	2340
	11th to 20th	Day	4 3 1 4 5% 4 6% 6% 7% 9% 51%	2340
	21st to end	Day	6% 5% 2 5% 7% 5% 7% 7% 8% 9% 39%	2340
July	1st to 10th	Day	9% 5% 3 6% 7% 4 7% 6% 7% 8% 38%	2340
	11th to 20th	Day	4 3 2 4 5% 3 5% 6% 7% 9% 52%	2340
	21st to end	Day	4 2 2 3 5% 3 6% 7% 7% 11% 51%	2546
August	1st to 10th	Day	1 1 1 2 4 4 5% 5% 6% 9% 62%	2221
	11th to 20th	Day	4 3 2 4 4 3 5% 5% 6% 10% 54%	2123
	21st to end	Day	6% 3 2 5% 6% 4 6% 6% 8% 11% 43%	2268
September	1st to 10th	Day	9% 4 3 6% 7% 5% 7% 7% 7% 9% 38%	1980
	11th to 20th	Day	11% 5% 2 7% 6% 3 5% 5% 6% 8% 42%	1980
	21st to end	Day	8% 5% 2 5% 6% 4 5% 6% 6% 9% 45%	1980
October	1st to 10th	Day	6% 4 2 4 5% 3 4 5% 6% 7% 54%	1980
	11th to 20th	Day	13% 4 2 4 4 3 5% 4 5% 7% 50%	1895
	21st to end	Day	10% 3 2 3 4 2 3 3 4 5% 60%	1980
November	1st to 10th	Day	12% 5% 4 5% 5% 3 5% 4 5% 7% 46%	1858
	11th to 20th	Day	13% 6% 2 5% 5% 2 3 4 4 6% 50%	1824
	21st to end	Day	16% 7% 2 6% 5% 3 4 4 5% 5% 43%	1710
December	1st to 10th	Day	18% 7% 3 5% 3 2 4 3 3 8% 43%	1710
	11th to 20th	Day	19% 8% 3 5% 5% 3 4 3 4 7% 40%	2161
	21st to end	Day	13% 6% 2 5% 5% 3 3 4 4 7% 48%	3135
January	1st to 10th	Night	16% 7% 2 4 4 2 3 4 5% 6% 48%	4108
	11th to 20th	Night	14% 4 1 3 2 2 2 2 4 6% 60%	4120
	21st to end	Night	23% 6% 3 5% 4 2 3 4 5% 7% 37%	4198
February	1st to 10th	Night	15% 7% 3 3 4 3 4 4 5% 7% 45%	2280
	11th to 20th	Night	19% 6% 2 4 3 1 3 2 4 6% 50%	2218
	21st to end	Night	16% 6% 2 5% 4 2 3 4 5% 5% 49%	1884
March	1st to 10th	Night	16% 6% 3 5% 4 2 3 3 5% 7% 46%	2086
	11th to 20th	Night	14% 7% 3 6% 4 3 4 3 4 7% 45%	1980
	21st to end	Night	12% 5% 2 3 3 2 3 3 5% 8% 54%	2178
April	1st to 10th	Night	11% 5% 2 4 3 3 5% 5% 8% 10% 45%	1980
	11th to 20th	Night	14% 5% 2 5% 3 3 4 4 5% 6% 49%	1953
	21st to end	Night	13% 7% 3 5% 4 3 5% 5% 4 7% 45%	1743
May	1st to 10th	Night	9% 6% 2 5% 4 3 5% 5% 6% 10% 47%	1620
	11th to 20th	Night	10% 5% 2 4 4 3 4 4 6% 8% 50%	1593
	21st to end	Night	7% 5% 2 4 4 4 5% 6% 7% 12% 44%	1745
June	1st to 10th	Night	4 2 1 3 3 2 3 5% 6% 9% 63%	1620
	11th to 20th	Night	4 2 1 3 3 2 3 4 5% 9% 65%	1620
	21st to end	Night	4 4 2 4 4 2 4 5% 7% 11% 52%	1620
July	1st to 10th	Night	7% 4 2 5% 4 2 4 5% 5% 9% 51%	1620
	11th to 20th	Night	2 2 1 3 3 2 3 3 5% 10% 66%	1620
	21st to end	Night	4 1 1 2 2 2 3 4 6% 11% 65%	1772
August	1st to 10th	Night	1 1 1 2 2 2 2 4 4 8% 74%	1712
	11th to 20th	Night	4 2 1 3 3 2 3 4 6% 10% 61%	1778
	21st to end	Night	6% 4 2 4 4 3 4 4 6% 10% 54%	2088
September	1st to 10th	Night	6% 5% 2 6% 5% 4 5% 5% 7% 10% 47%	1980
	11th to 20th	Night	8% 5% 2 5% 5% 3 3 5% 5% 8% 49%	1980
	21st to end	Night	7% 4 2 4 4 3 4 3 6% 8% 55%	1980
October	1st to 10th	Night	4 3 1 3 3 2 3 4 5% 7% 65%	1980
	11th to 20th	Night	12% 4 2 3 3 2 3 4 4 5% 58%	2043
	21st to end	Night	10% 4 2 2 3 2 2 3 3 6% 64%	2376
November	1st to 10th	Night	12% 4 2 4 4 2 4 3 5% 7% 54%	2220
	11th to 20th	Night	13% 4 2 4 4 2 3 4 5% 6% 53%	2351
	21st to end	Night	16% 4 2 5% 5% 3 4 4 4 7% 48%	2470
December	1st to 10th	Night	17% 6% 2 3 3 2 4 3 4 6% 49%	2470
	11th to 20th	Night	17% 7% 3 4 4 3 4 4 5% 7% 43%	3036
	21st to end	Night	14% 6% 2 4 4 2 3 4 5% 8% 47%	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	35% 5% 5% 12% 26% 17%	2848
	11th to 20th	Day	32% 3 5% 20% 23% 17%	2859
	21st to end	Day	46% 4 5% 15% 23% 8%	3487
February	1st to 10th	Day	44% 4 7% 11% 19% 15%	1900
	11th to 20th	Day	40% 5% 8% 15% 19% 13%	1859
	21st to end	Day	37% 6% 9% 17% 18% 13%	1570
March	1st to 10th	Day	41% 6% 11% 17% 15% 9%	2033
	11th to 20th	Day	42% 6% 10% 12% 16% 14%	1980
	21st to end	Day	33% 7% 12% 17% 18% 14%	2178
April	1st to 10th	Day	36% 7% 11% 17% 18% 11%	1980
	11th to 20th	Day	41% 6% 8% 17% 16% 13%	1956
	21st to end	Day	36% 7% 8% 18% 18% 13%	2210
May	1st to 10th	Day	38% 7% 10% 19% 15% 10%	2340
	11th to 20th	Day	37% 8% 10% 20% 19% 6%	2306
	21st to end	Day	36% 10% 13% 22% 18% 2	2531
June	1st to 10th	Day	24% 8% 16% 26% 21% 4	2340
	11th to 20th	Day	28% 7% 15% 25% 21% 5%	2340
	21st to end	Day	38% 10% 15% 23% 10% 3	2340
July	1st to 10th	Day	40% 10% 14% 23% 11% 1	2276
	11th to 20th	Day	27% 9% 17% 26% 19% 2	2271
	21st to end	Day	22% 10% 21% 35% 11% 1	2405
August	1st to 10th	Day	18% 8% 18% 37% 17% 1	2207
	11th to 20th	Day	24% 10% 18% 32% 14% 2	2123
	21st to end	Day	32% 11% 20% 24% 11% 2	2268
September	1st to 10th	Day	40% 11% 15% 16% 13% 5%	1980
	11th to 20th	Day	38% 9% 16% 20% 15% 4	1980
	21st to end	Day	34% 8% 13% 19% 17% 9%	1980
October	1st to 10th	Day	28% 8% 10% 20% 26% 7%	1980
	11th to 20th	Day	33% 6% 11% 19% 18% 14%	1895
	21st to end	Day	26% 5% 7% 17% 25% 21%	1980
November	1st to 10th	Day	37% 6% 9% 19% 18% 11%	1858
	11th to 20th	Day	36% 5% 10% 16% 20% 13%	1824
	21st to end	Day	43% 4 7% 16% 17% 12%	1710
December	1st to 10th	Day	41% 5% 8% 18% 18% 9%	1710
	11th to 20th	Day	44% 5% 7% 10% 18% 15%	2159
	21st to end	Day	36% 5% 6% 19% 23% 11%	3135
January	1st to 10th	Night	35% 6% 7% 13% 17% 23%	4108
	11th to 20th	Night	27% 3 6% 19% 23% 22%	4120
	21st to end	Night	45% 5% 6% 12% 22% 10%	4198
February	1st to 10th	Night	39% 5% 9% 13% 15% 18%	2280
	11th to 20th	Night	37% 4 8% 18% 18% 15%	2218
	21st to end	Night	37% 6% 7% 18% 18% 13%	1884
March	1st to 10th	Night	39% 7% 11% 16% 16% 11%	2086
	11th to 20th	Night	40% 6% 10% 15% 13% 15%	1980
	21st to end	Night	29% 6% 15% 19% 17% 14%	2178
April	1st to 10th	Night	32% 8% 14% 19% 16% 10%	1980
	11th to 20th	Night	36% 6% 10% 18% 14% 16%	1953
	21st to end	Night	39% 7% 9% 18% 17% 10%	1743
May	1st to 10th	Night	32% 8% 13% 21% 16% 10%	1620
	11th to 20th	Night	31% 8% 13% 25% 18% 4	1594
	21st to end	Night	31% 9% 17% 28% 13% 1	1746
June	1st to 10th	Night	16% 8% 19% 33% 21% 2	1620
	11th to 20th	Night	17% 7% 14% 37% 22% 4	1620
	21st to end	Night	26% 10% 20% 28% 15% 1	1620
July	1st to 10th	Night	28% 11% 21% 30% 9% 1	1575
	11th to 20th	Night	14% 8% 27% 33% 18% 1	1566
	21st to end	Night	14% 7% 31% 38% 11% 1	1673
August	1st to 10th	Night	11% 7% 26% 43% 13%	1702
	11th to 20th	Night	19% 8% 25% 38% 9% 1	1778
	21st to end	Night	25% 10% 23% 30% 10% 1	2088
September	1st to 10th	Night	31% 10% 22% 20% 12% 5%	1980
	11th to 20th	Night	31% 9% 16% 24% 17% 3	1980
	21st to end	Night	27% 6% 15% 25% 19% 8%	1980
October	1st to 10th	Night	19% 7% 13% 29% 21% 10%	1980
	11th to 20th	Night	28% 6% 10% 22% 18% 16%	2043
	21st to end	Night	24% 5% 8% 17% 25% 21%	2376
November	1st to 10th	Night	30% 7% 10% 19% 22% 11%	2220
	11th to 20th	Night	32% 6% 13% 17% 19% 14%	2351
	21st to end	Night	37% 5% 9% 20% 18% 12%	2470
December	1st to 10th	Night	37% 5% 9% 19% 20% 11%	2470
	11th to 20th	Night	40% 6% 6% 15% 16% 16%	3037
	21st to end	Night	35% 7% 8% 15% 23% 13%	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	19% 9% 30% 30% 11% 1	270
	11th to 20th	Day	19% 9% 29% 30% 13% 1	270
	21st to end	Day	22% 8% 31% 26% 12% 1	297
February	1st to 10th	Day	20% 10% 30% 25% 13% 3	270
	11th to 20th	Day	21% 8% 37% 24% 9% 1	270
	21st to end	Day	20% 10% 35% 28% 7%	225
March	1st to 10th	Day	21% 7% 36% 26% 10%	261
	11th to 20th	Day	18% 10% 37% 27% 8%	240
	21st to end	Day	13% 11% 36% 33% 6% 1	264
April	1st to 10th	Day	18% 5% 34% 30% 13%	240
	11th to 20th	Day	15% 16% 30% 25% 14% 1	234
	21st to end	Day	12% 12% 39% 29% 7% 1	470
May	1st to 10th	Day	13% 10% 37% 30% 10%	603
	11th to 20th	Day	13% 8% 31% 32% 15% 2	625
	21st to end	Day	10% 4 27% 39% 19% 1	679
June	1st to 10th	Day	4 2 13% 40% 35% 5%	630
	11th to 20th	Day	4 1 13% 48% 28% 6%	630
	21st to end	Day	7% 1 11% 35% 34% 12%	630
July	1st to 10th	Day	8% 1 10% 31% 38% 12%	621
	11th to 20th	Day	4 1 6% 30% 48% 11%	618
	21st to end	Day	4 1 3 32% 48% 12%	684
August	1st to 10th	Day	2 5% 33% 42% 18%	519
	11th to 20th	Day	4 7% 28% 39% 21%	437
	21st to end	Day	6% 5% 22% 34% 33%	387
September	1st to 10th	Day	8% 1 3 16% 47% 25%	270
	11th to 20th	Day	9% 6% 13% 40% 34%	270
	21st to end	Day	10% 1 6% 15% 42% 26%	270
October	1st to 10th	Day	9% 1 7% 25% 37% 20%	270
	11th to 20th	Day	13% 1 11% 28% 33% 14%	270
	21st to end	Day	15% 7% 21% 29% 20% 8%	297
November	1st to 10th	Day	14% 2 18% 30% 29% 7%	270
	11th to 20th	Day	20% 4 16% 29% 24% 7%	270
	21st to end	Day	23% 9% 29% 23% 12% 4	270
December	1st to 10th	Day	19% 4 22% 27% 21% 7%	270
	11th to 20th	Day	25% 9% 24% 25% 17%	270
	21st to end	Day	18% 9% 25% 31% 14% 3	297
January	1st to 10th	Night	20% 7% 25% 37% 11% 1	950
	11th to 20th	Night	21% 7% 27% 36% 9%	950
	21st to end	Night	21% 7% 27% 38% 7%	841
February	1st to 10th	Night	19% 10% 33% 32% 6%	760
	11th to 20th	Night	22% 8% 35% 29% 6%	744
	21st to end	Night	20% 9% 41% 27% 3	628
March	1st to 10th	Night	20% 11% 41% 25% 4	586
	11th to 20th	Night	14% 12% 38% 32% 4	540
	21st to end	Night	13% 10% 45% 28% 3	594
April	1st to 10th	Night	11% 9% 50% 26% 4	540
	11th to 20th	Night	16% 8% 44% 29% 4	533
	21st to end	Night	12% 11% 46% 26% 5% 1	540
May	1st to 10th	Night	10% 8% 51% 28% 3	540
	11th to 20th	Night	12% 4 41% 36% 7%	531
	21st to end	Night	8% 3 39% 43% 7%	584
June	1st to 10th	Night	4 1 23% 54% 18% 1	540
	11th to 20th	Night	5% 1 29% 52% 14% 1	540
	21st to end	Night	4 2 20% 50% 23% 1	540
July	1st to 10th	Night	7% 2 14% 53% 23% 2	525
	11th to 20th	Night	4 11% 58% 26% 1	522
	21st to end	Night	4 1 10% 56% 28% 1	591
August	1st to 10th	Night	1 11% 58% 26% 3	537
	11th to 20th	Night	4 1 11% 54% 29% 2	534
	21st to end	Night	7% 1 7% 44% 38% 3	594
September	1st to 10th	Night	7% 1 7% 45% 35% 5%	540
	11th to 20th	Night	11% 1 9% 36% 40% 4	540
	21st to end	Night	9% 11% 39% 36% 4	540
October	1st to 10th	Night	5% 1 13% 46% 33% 2	540
	11th to 20th	Night	14% 1 21% 44% 19% 1	603
	21st to end	Night	11% 5% 26% 37% 20% 2	792
November	1st to 10th	Night	12% 5% 20% 41% 21% 1	740
	11th to 20th	Night	13% 5% 22% 43% 16% 1	831
	21st to end	Night	17% 6% 25% 36% 16% 1	950
December	1st to 10th	Night	20% 3 24% 37% 15% 1	950
	11th to 20th	Night	24% 7% 25% 35% 10%	950
	21st to end	Night	19% 6% 25% 39% 11%	1045

Page generated at 2024-03-05 06:24:02. Version ac07

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