Barb's Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barb's Ridge clear sky chart from 2005-11-06 to 2024-11-05.

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% 7% 3 6% 5% 5% 5% 4 6% 7% 39%	100887
	Night	14% 7% 3 6% 4 4 4 4 5% 7% 42%	98122
Transparency	Day	23% 46% 6% 13% 10% 2	104680
	Night	22% 46% 5% 13% 11% 3	102467
Seeing	Day	18% 11% 22% 22% 18% 9%	14652
	Night	17% 9% 19% 30% 22% 4	24651

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	18% 12% 3 6% 4 4 4 4 5% 6% 34%	2836
	11th to 20th	Day	22% 6% 4 9% 4 3 3 3 4 5% 37%	2840
	21st to end	Day	24% 10% 4 5% 3 3 3 2 4 5% 37%	3355
February	1st to 10th	Day	19% 11% 3 7% 4 3 3 3 5% 6% 36%	1900
	11th to 20th	Day	23% 9% 3 7% 5% 3 4 4 4 5% 35%	1848
	21st to end	Day	22% 9% 3 6% 4 4 4 3 4 5% 37%	1570
March	1st to 10th	Day	26% 9% 3 7% 4 4 3 3 5% 6% 30%	3120
	11th to 20th	Day	15% 8% 2 6% 3 3 3 3 4 6% 47%	3436
	21st to end	Day	16% 7% 2 7% 6% 5% 4 4 5% 6% 37%	3842
April	1st to 10th	Day	13% 7% 3 6% 4 6% 5% 3 5% 7% 43%	2280
	11th to 20th	Day	14% 8% 2 6% 4 3 3 4 5% 6% 45%	2254
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 3 6% 8% 43%	2362
May	1st to 10th	Day	14% 7% 2 7% 5% 4 5% 4 6% 8% 38%	4082
	11th to 20th	Day	17% 8% 3 7% 5% 5% 4 4 6% 7% 34%	4081
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 7% 8% 40%	4476
June	1st to 10th	Day	9% 6% 2 7% 5% 6% 6% 5% 8% 10% 34%	2470
	11th to 20th	Day	5% 4 2 6% 5% 6% 6% 6% 7% 11% 43%	2470
	21st to end	Day	6% 5% 2 6% 6% 7% 6% 6% 8% 11% 37%	2470
July	1st to 10th	Day	7% 5% 3 7% 7% 7% 7% 6% 9% 12% 30%	4120
	11th to 20th	Day	9% 6% 2 7% 6% 6% 6% 5% 9% 11% 33%	4120
	21st to end	Day	14% 11% 4 10% 7% 8% 7% 6% 7% 8% 19%	4466
August	1st to 10th	Day	5% 4 2 5% 5% 6% 6% 6% 9% 11% 43%	3993
	11th to 20th	Day	6% 5% 2 6% 5% 5% 7% 6% 9% 11% 39%	3729
	21st to end	Day	7% 4 2 6% 5% 5% 5% 4 6% 7% 50%	4180
September	1st to 10th	Day	10% 6% 3 7% 5% 6% 6% 5% 7% 8% 37%	2185
	11th to 20th	Day	13% 6% 3 6% 5% 5% 5% 5% 6% 6% 41%	2090
	21st to end	Day	13% 5% 2 5% 5% 4 4 3 5% 6% 47%	2090
October	1st to 10th	Day	10% 5% 2 5% 4 3 4 3 4 5% 54%	2090
	11th to 20th	Day	10% 4 2 5% 4 3 4 3 4 6% 55%	2056
	21st to end	Day	15% 6% 2 4 3 4 2 3 4 5% 52%	1961
November	1st to 10th	Day	11% 6% 2 5% 4 2 3 2 4 6% 55%	1708
	11th to 20th	Day	13% 5% 2 6% 4 4 4 4 5% 6% 48%	1710
	21st to end	Day	18% 7% 2 4 3 4 4 3 5% 7% 44%	1710
December	1st to 10th	Day	22% 10% 3 6% 4 5% 3 4 4 5% 34%	1710
	11th to 20th	Day	16% 8% 4 6% 5% 5% 4 3 5% 6% 38%	2153
	21st to end	Day	18% 11% 5% 6% 4 4 5% 4 6% 7% 31%	3124
January	1st to 10th	Night	19% 12% 3 6% 3 4 4 3 4 6% 37%	4109
	11th to 20th	Night	21% 9% 3 7% 3 3 3 3 4 6% 38%	4120
	21st to end	Night	23% 13% 3 5% 3 3 3 3 5% 5% 32%	4298
February	1st to 10th	Night	17% 9% 2 7% 5% 4 4 3 5% 5% 40%	2280
	11th to 20th	Night	21% 8% 3 7% 5% 5% 4 3 4 4 37%	2218
	21st to end	Night	25% 8% 3 5% 4 4 4 3 4 5% 35%	1884
March	1st to 10th	Night	27% 10% 3 6% 5% 4 4 3 4 6% 29%	3733
	11th to 20th	Night	11% 7% 2 6% 4 4 4 3 5% 6% 48%	3522
	21st to end	Night	15% 8% 3 7% 5% 5% 4 4 5% 5% 39%	3817
April	1st to 10th	Night	12% 6% 1 5% 4 4 5% 4 6% 7% 47%	1900
	11th to 20th	Night	14% 5% 2 5% 3 3 3 4 5% 7% 49%	1875
	21st to end	Night	12% 5% 2 6% 4 3 4 4 5% 8% 48%	1815
May	1st to 10th	Night	14% 7% 3 8% 5% 5% 5% 4 5% 7% 38%	2813
	11th to 20th	Night	17% 6% 3 6% 5% 5% 5% 4 5% 7% 37%	2812
	21st to end	Night	7% 5% 2 6% 5% 5% 6% 5% 8% 10% 41%	3079
June	1st to 10th	Night	7% 6% 3 7% 6% 6% 6% 4 7% 10% 39%	1710
	11th to 20th	Night	5% 3 1 3 4 3 6% 3 8% 11% 53%	1710
	21st to end	Night	5% 5% 2 5% 5% 4 5% 5% 7% 12% 46%	1710
July	1st to 10th	Night	7% 5% 2 8% 6% 6% 6% 6% 8% 10% 37%	2840
	11th to 20th	Night	9% 6% 3 5% 3 4 5% 5% 8% 12% 41%	2840
	21st to end	Night	11% 11% 4 10% 7% 6% 6% 5% 7% 9% 24%	3087
August	1st to 10th	Night	4 3 1 4 3 4 5% 5% 8% 11% 52%	2918
	11th to 20th	Night	6% 5% 2 6% 4 5% 4 3 6% 9% 49%	3100
	21st to end	Night	6% 4 2 4 4 4 5% 4 6% 9% 53%	3476
September	1st to 10th	Night	9% 5% 2 7% 4 4 5% 5% 6% 9% 44%	1976
	11th to 20th	Night	13% 5% 2 6% 4 4 4 4 6% 6% 45%	2090
	21st to end	Night	11% 5% 2 4 4 3 4 4 5% 6% 51%	2090
October	1st to 10th	Night	10% 4 2 3 3 3 3 2 5% 6% 59%	2090
	11th to 20th	Night	12% 5% 2 6% 4 3 3 3 4 5% 52%	2123
	21st to end	Night	14% 6% 2 5% 3 3 3 3 4 5% 53%	2633
November	1st to 10th	Night	12% 5% 2 5% 3 3 3 3 6% 7% 50%	2470
	11th to 20th	Night	12% 7% 3 5% 4 3 2 3 4 6% 51%	2470
	21st to end	Night	16% 9% 2 4 4 3 3 3 4 6% 43%	2470
December	1st to 10th	Night	20% 9% 4 6% 4 4 4 4 5% 5% 34%	2470
	11th to 20th	Night	17% 7% 3 5% 3 3 4 4 5% 6% 43%	3042
	21st to end	Night	19% 9% 4 8% 5% 5% 5% 4 5% 7% 28%	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	36% 36% 1 10% 16% 1	2837
	11th to 20th	Day	33% 35% 3 10% 17% 1	2840
	21st to end	Day	34% 38% 4 12% 11% 1	3355
February	1st to 10th	Day	19% 64% 1 8% 6% 1	1900
	11th to 20th	Day	21% 63% 1 7% 7% 1	1858
	21st to end	Day	18% 64% 2 6% 7% 2	1570
March	1st to 10th	Day	41% 39% 5% 5% 5% 6%	3120
	11th to 20th	Day	21% 39% 2 18% 15% 6%	3436
	21st to end	Day	29% 39% 6% 14% 10% 2	3842
April	1st to 10th	Day	17% 64% 4 7% 7% 1	2280
	11th to 20th	Day	16% 65% 3 8% 5% 2	2254
	21st to end	Day	14% 65% 4 10% 6% 1	2362
May	1st to 10th	Day	26% 39% 8% 18% 8% 1	4120
	11th to 20th	Day	32% 38% 7% 17% 5%	4085
	21st to end	Day	26% 39% 6% 15% 13%	4489
June	1st to 10th	Day	16% 65% 5% 8% 5% 1	2470
	11th to 20th	Day	12% 65% 7% 10% 5%	2470
	21st to end	Day	14% 65% 9% 8% 4	2470
July	1st to 10th	Day	24% 42% 16% 15% 3	4055
	11th to 20th	Day	23% 40% 17% 17% 2 1	4051
	21st to end	Day	43% 37% 7% 9% 3	4324
August	1st to 10th	Day	15% 39% 10% 27% 9%	3980
	11th to 20th	Day	19% 40% 12% 19% 10% 1	3765
	21st to end	Day	13% 39% 8% 24% 16% 1	4179
September	1st to 10th	Day	14% 60% 5% 10% 8% 2	2185
	11th to 20th	Day	16% 60% 4 13% 7%	2090
	21st to end	Day	15% 59% 6% 11% 7% 1	2090
October	1st to 10th	Day	13% 37% 4 10% 25% 10%	3480
	11th to 20th	Day	10% 36% 3 13% 25% 13%	3400
	21st to end	Day	14% 38% 6% 18% 18% 7%	3211
November	1st to 10th	Day	18% 56% 3 8% 10% 3	1708
	11th to 20th	Day	16% 59% 2 9% 11% 3	1710
	21st to end	Day	18% 59% 3 9% 10% 1	1710
December	1st to 10th	Day	24% 59% 2 8% 5% 2	1710
	11th to 20th	Day	25% 47% 1 8% 16% 3	2150
	21st to end	Day	35% 35% 4 14% 10% 2	3124
January	1st to 10th	Night	34% 35% 1 12% 16% 2	4109
	11th to 20th	Night	30% 35% 3 14% 12% 6%	4120
	21st to end	Night	37% 38% 3 9% 13% 2	4298
February	1st to 10th	Night	18% 65% 2 8% 6% 2	2280
	11th to 20th	Night	22% 63% 2 5% 6% 2	2219
	21st to end	Night	19% 64% 2 5% 6% 3	1884
March	1st to 10th	Night	40% 39% 5% 6% 7% 3	3733
	11th to 20th	Night	21% 39% 3 16% 13% 9%	3522
	21st to end	Night	31% 39% 4 12% 14% 1	3817
April	1st to 10th	Night	14% 64% 4 7% 9% 1	1900
	11th to 20th	Night	16% 65% 3 8% 6% 2	1875
	21st to end	Night	13% 64% 3 9% 9% 1	1815
May	1st to 10th	Night	30% 39% 7% 17% 7%	2840
	11th to 20th	Night	34% 39% 5% 15% 7%	2813
	21st to end	Night	24% 39% 9% 17% 11%	3087
June	1st to 10th	Night	16% 65% 5% 7% 5% 1	1710
	11th to 20th	Night	7% 65% 8% 12% 7%	1710
	21st to end	Night	10% 65% 8% 12% 4 1	1710
July	1st to 10th	Night	23% 41% 17% 15% 3	2795
	11th to 20th	Night	20% 40% 19% 17% 2 1	2786
	21st to end	Night	41% 39% 8% 9% 3 1	2988
August	1st to 10th	Night	14% 38% 9% 28% 10% 1	2907
	11th to 20th	Night	15% 38% 16% 20% 11% 1	3130
	21st to end	Night	11% 39% 9% 21% 20% 1	3476
September	1st to 10th	Night	13% 60% 7% 10% 8% 2	1976
	11th to 20th	Night	13% 60% 7% 12% 8% 1	2090
	21st to end	Night	15% 59% 6% 11% 8% 1	2090
October	1st to 10th	Night	13% 39% 5% 12% 18% 13%	3480
	11th to 20th	Night	9% 36% 2 12% 25% 16%	3518
	21st to end	Night	11% 37% 3 20% 20% 8%	4333
November	1st to 10th	Night	20% 57% 3 7% 10% 2	2470
	11th to 20th	Night	16% 59% 2 9% 12% 3	2470
	21st to end	Night	18% 59% 2 11% 9% 1	2470
December	1st to 10th	Night	25% 59% 2 8% 5% 2	2470
	11th to 20th	Night	20% 48% 2 10% 18% 3	3044
	21st to end	Night	39% 35% 3 12% 10% 1	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	34% 19% 31% 13% 3	270
	11th to 20th	Day	35% 22% 25% 11% 6% 1	270
	21st to end	Day	27% 24% 36% 10% 3	297
February	1st to 10th	Day	35% 20% 29% 13% 3	270
	11th to 20th	Day	43% 23% 27% 6% 1 1	270
	21st to end	Day	42% 24% 27% 6% 1	225
March	1st to 10th	Day	31% 20% 31% 13% 4 1	270
	11th to 20th	Day	28% 19% 27% 19% 7% 1	429
	21st to end	Day	28% 17% 30% 17% 8%	506
April	1st to 10th	Day	25% 16% 25% 19% 13% 2	460
	11th to 20th	Day	21% 16% 31% 20% 11% 2	452
	21st to end	Day	19% 12% 34% 19% 13% 3	460
May	1st to 10th	Day	17% 14% 27% 23% 13% 5%	463
	11th to 20th	Day	14% 9% 25% 26% 14% 12%	487
	21st to end	Day	12% 6% 20% 28% 19% 14%	529
June	1st to 10th	Day	12% 7% 18% 27% 21% 15%	490
	11th to 20th	Day	7% 4 13% 29% 27% 20%	490
	21st to end	Day	9% 4 18% 26% 24% 18%	490
July	1st to 10th	Day	8% 3 12% 25% 28% 24%	485
	11th to 20th	Day	10% 4 11% 22% 28% 25%	484
	21st to end	Day	10% 5% 10% 25% 28% 23%	532
August	1st to 10th	Day	9% 3 13% 24% 29% 21%	486
	11th to 20th	Day	10% 5% 11% 31% 30% 14%	479
	21st to end	Day	14% 4 7% 24% 32% 20%	539
September	1st to 10th	Day	11% 3 13% 27% 32% 15%	490
	11th to 20th	Day	12% 6% 13% 25% 32% 13%	490
	21st to end	Day	17% 5% 15% 25% 31% 7%	490
October	1st to 10th	Day	12% 4 20% 31% 24% 8%	490
	11th to 20th	Day	12% 10% 27% 31% 16% 4	490
	21st to end	Day	21% 9% 23% 27% 18% 2	410
November	1st to 10th	Day	18% 11% 33% 23% 14% 1	282
	11th to 20th	Day	14% 20% 36% 23% 6%	270
	21st to end	Day	21% 15% 36% 17% 10% 1	270
December	1st to 10th	Day	32% 17% 29% 17% 5% 1	270
	11th to 20th	Day	28% 16% 34% 14% 7%	270
	21st to end	Day	31% 22% 28% 13% 5%	297
January	1st to 10th	Night	28% 15% 27% 26% 5%	760
	11th to 20th	Night	26% 18% 25% 24% 7%	760
	21st to end	Night	23% 16% 30% 28% 4	836
February	1st to 10th	Night	25% 11% 30% 29% 5%	760
	11th to 20th	Night	29% 17% 28% 24% 2	743
	21st to end	Night	31% 16% 27% 23% 2	628
March	1st to 10th	Night	22% 14% 27% 31% 5%	760
	11th to 20th	Night	21% 16% 26% 27% 9% 1	760
	21st to end	Night	21% 12% 28% 28% 11%	836
April	1st to 10th	Night	15% 13% 25% 33% 13%	570
	11th to 20th	Night	19% 10% 27% 29% 14% 1	563
	21st to end	Night	14% 8% 22% 39% 16% 2	570
May	1st to 10th	Night	12% 6% 22% 35% 22% 3	570
	11th to 20th	Night	13% 7% 15% 35% 24% 6%	561
	21st to end	Night	8% 3 12% 35% 36% 7%	617
June	1st to 10th	Night	9% 2 13% 34% 37% 6%	570
	11th to 20th	Night	4 2 8% 34% 38% 14%	570
	21st to end	Night	6% 2 8% 29% 45% 9%	570
July	1st to 10th	Night	10% 2 6% 24% 46% 12%	555
	11th to 20th	Night	9% 3 6% 22% 43% 16%	552
	21st to end	Night	8% 2 6% 24% 46% 14%	624
August	1st to 10th	Night	7% 1 2 23% 52% 14%	567
	11th to 20th	Night	11% 2 7% 28% 44% 8%	564
	21st to end	Night	11% 2 6% 26% 45% 10%	627
September	1st to 10th	Night	10% 2 8% 30% 40% 11%	646
	11th to 20th	Night	16% 3 9% 28% 38% 7%	760
	21st to end	Night	12% 3 13% 31% 37% 3	760
October	1st to 10th	Night	12% 4 15% 33% 28% 8%	760
	11th to 20th	Night	15% 8% 18% 35% 23% 1	760
	21st to end	Night	16% 9% 17% 37% 18% 3	836
November	1st to 10th	Night	15% 8% 19% 35% 22% 2	760
	11th to 20th	Night	16% 11% 26% 33% 13% 1	760
	21st to end	Night	22% 9% 21% 33% 13% 1	760
December	1st to 10th	Night	24% 14% 23% 29% 8%	760
	11th to 20th	Night	22% 13% 23% 33% 9%	760
	21st to end	Night	27% 13% 24% 29% 6%	836

Page generated at 2024-11-03 01:11:30. Version ac07

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