Stonelick Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stonelick Lake State Park clear sky chart from 2005-11-05 to 2008-11-27.

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	18% 7% 5% 5% 6% 36%	12319
	Night	18% 6% 5% 5% 6% 36%	12075
Cloud Cover	Day	17% 7% 5% 5% 7% 35%	12337
	Night	18% 7% 5% 5% 5% 7% 36%	12099
Transparency	Day	7% 16% 26% 17%	8355
	Night	8% 17% 25% 17%	8360
Seeing	Day	5% 20% 27% 24% 12%	689
	Night	10% 30% 31% 16%	3574

By Month

Percentage Cloud Cover
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month		Occurrence of each Forecast	Data Points
January	Day	25% 12% 7% 7% 6% 23%	833
	Night	26% 12% 6% 5% 5% 5% 25%	1207
February	Day	21% 11% 5% 8% 5% 6% 26%	794
	Night	25% 9% 6% 6% 29%	997
March	Day	28% 8% 7% 5% 5% 5% 25%	974
	Night	25% 6% 5% 5% 5% 5% 6% 27%	1023
April	Day	19% 5% 5% 43%	1108
	Night	19% 6% 5% 5% 6% 38%	872
May	Day	20% 5% 6% 39%	1209
	Night	19% 5% 6% 8% 37%	837
June	Day	14% 5% 6% 7% 9% 38%	1210
	Night	7% 6% 6% 6% 8% 48%	758
July	Day	14% 7% 6% 5% 8% 39%	1245
	Night	11% 5% 6% 5% 7% 44%	797
August	Day	10% 5% 5% 7% 9% 43%	1175
	Night	9% 6% 7% 48%	861
September	Day	15% 5% 5% 5% 43%	997
	Night	11% 5% 5% 6% 49%	977
October	Day	20% 5% 7% 43%	935
	Night	16% 8% 45%	1098
November	Day	15% 10% 6% 6% 6% 6% 5% 5% 31%	1002
	Night	20% 8% 6% 6% 35%	1444
December	Day	22% 13% 7% 7% 5% 5% 5% 23%	837
	Night	25% 9% 5% 7% 5% 5% 7% 22%	1204

Percentage Cloud Cover
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month		Occurrence of each Forecast	Data Points
January	Day	24% 12% 7% 7% 6% 23%	832
	Night	25% 11% 7% 5% 5% 24%	1208
February	Day	20% 11% 6% 9% 5% 5% 26%	792
	Night	24% 9% 7% 6% 5% 28%	988
March	Day	28% 9% 6% 6% 5% 5% 5% 23%	996
	Night	24% 8% 5% 5% 5% 5% 7% 26%	1046
April	Day	17% 6% 5% 6% 42%	1107
	Night	17% 7% 5% 6% 37%	872
May	Day	19% 5% 5% 7% 38%	1208
	Night	18% 5% 5% 6% 8% 37%	837
June	Day	13% 5% 6% 7% 9% 37%	1219
	Night	7% 5% 6% 6% 6% 8% 47%	760
July	Day	13% 5% 7% 7% 5% 8% 38%	1245
	Night	10% 5% 5% 9% 43%	798
August	Day	9% 5% 7% 9% 43%	1170
	Night	9% 5% 6% 5% 7% 47%	862
September	Day	15% 6% 5% 6% 42%	996
	Night	11% 5% 5% 5% 6% 48%	978
October	Day	19% 5% 5% 7% 43%	935
	Night	14% 5% 5% 7% 45%	1098
November	Day	14% 11% 5% 7% 6% 5% 6% 30%	1000
	Night	19% 9% 5% 7% 34%	1444
December	Day	22% 12% 7% 7% 6% 5% 23%	837
	Night	24% 10% 5% 8% 5% 5% 7% 21%	1208

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	7% 20% 24% 9%	454
	Night	10% 15% 28% 8%	678
February	Day	6% 20% 25% 6%	492
	Night	6% 24% 24%	638
March	Day	9% 16% 26% 7%	554
	Night	8% 24% 24% 10%	634
April	Day	17% 31% 18% 5%	782
	Night	8% 15% 22% 22% 9%	595
May	Day	7% 19% 28% 19%	828
	Night	9% 15% 26% 20% 6%	594
June	Day	10% 20% 30% 19%	810
	Night	13% 21% 33% 18%	541
July	Day	7% 17% 29% 18%	661
	Night	7% 13% 28% 22% 8%	449
August	Day	7% 13% 26% 20% 6%	1000
	Night	6% 12% 27% 24% 5%	716
September	Day	8% 9% 17% 29% 8%	794
	Night	6% 11% 20% 31% 8%	807
October	Day	5% 11% 25% 24%	780
	Night	13% 26% 23% 5%	922
November	Day	8% 14% 23% 13%	712
	Night	6% 18% 23% 13%	1057
December	Day	9% 22% 19% 8%	488
	Night	11% 23% 20% 6%	729

Seeing (when cloud cover <= 80%)
Color Meanings: Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month		Occurrence of each Forecast	Data Points
January	Night	20% 47% 19%	311
February	Night	14% 44% 24%	281
March	Day	14% 35% 27% 12%	62
	Night	16% 36% 27% 6%	329
April	Day	15% 30% 19% 22%	83
	Night	14% 40% 25% 12%	262
May	Day	5% 23% 20% 20% 20%	85
	Night	6% 25% 31% 19% 6%	263
June	Day	20% 39% 22% 12%	125
	Night	18% 51% 24%	248
July	Day	15% 27% 29% 19%	100
	Night	13% 41% 33% 5%	230
August	Day	5% 31% 27% 25%	86
	Night	13% 43% 35%	258
September	Day	13% 22% 36% 13%	80
	Night	12% 35% 36%	316
October	Day	7% 25% 30% 20%	68
	Night	9% 29% 34% 14%	345
November	Night	12% 34% 29% 10%	406
December	Night	13% 39% 27% 5%	325

Page generated at 2008-11-27 13:47:50. Version ab11