Baum Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Baum Lake clear sky chart from 2005-11-06 to 2024-11-08.

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	4 4 1 4 3 3 4 3 5% 6% 62%	105365
	Night	6% 6% 2 5% 3 3 4 3 5% 7% 57%	102452
Transparency	Day	22% 6% 10% 20% 22% 20%	105114
	Night	25% 8% 12% 21% 20% 14%	102292
Seeing	Day	8% 12% 25% 29% 20% 7%	14997
	Night	7% 5% 19% 41% 25% 2	24157

By Month

Percentage Cloud Cover SW (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	6% 11% 3 8% 4 6% 6% 4 7% 8% 36%	2539
	11th to 20th	Day	12% 12% 3 9% 6% 5% 5% 3 6% 7% 32%	2664
	21st to end	Day	14% 10% 3 8% 6% 5% 5% 4 5% 7% 33%	3146
February	1st to 10th	Day	6% 6% 2 6% 5% 5% 5% 5% 7% 8% 46%	1710
	11th to 20th	Day	6% 8% 2 6% 5% 4 4 4 6% 8% 47%	1718
	21st to end	Day	3 6% 2 7% 6% 6% 7% 5% 6% 6% 45%	1570
March	1st to 10th	Day	7% 10% 3 8% 6% 7% 8% 6% 7% 7% 32%	3252
	11th to 20th	Day	5% 6% 1 4 3 3 4 4 5% 7% 58%	3490
	21st to end	Day	5% 8% 3 8% 6% 6% 7% 5% 8% 9% 35%	3962
April	1st to 10th	Day	5% 8% 3 7% 6% 4 5% 4 6% 8% 44%	2280
	11th to 20th	Day	7% 6% 1 5% 5% 4 4 4 7% 7% 51%	2249
	21st to end	Day	5% 5% 1 4 3 3 4 4 5% 8% 58%	2280
May	1st to 10th	Day	4 5% 1 4 4 3 3 2 4 6% 65%	4172
	11th to 20th	Day	4 3 1 3 2 2 2 3 4 5% 73%	4377
	21st to end	Day	4 3 1 3 2 3 3 2 5% 6% 68%	4813
June	1st to 10th	Day	5% 3 1 3 4 4 5% 3 5% 8% 59%	2660
	11th to 20th	Day	2 2 1 2 2 2 2 2 4 5% 75%	2660
	21st to end	Day	2 1 1 1 2 1 2 1 3 4 80%	2660
July	1st to 10th	Day	1 1 1 1 1 1 1 2 90%	4420
	11th to 20th	Day	1 1 2 1 1 2 2 2 3 83%	4420
	21st to end	Day	1 1 1 1 1 2 1 3 3 87%	4611
August	1st to 10th	Day	2 2 1 2 2 2 3 3 5% 5% 75%	4091
	11th to 20th	Day	1 1 1 1 1 2 3 90%	3905
	21st to end	Day	2 2 1 1 1 1 1 1 3 3 84%	4180
September	1st to 10th	Day	1 1 1 1 1 2 1 4 4 85%	2280
	11th to 20th	Day	3 1 1 3 2 2 3 3 4 7% 72%	2280
	21st to end	Day	3 2 1 2 2 2 3 2 3 5% 76%	2033
October	1st to 10th	Day	2 2 1 2 2 2 2 2 4 4 77%	3180
	11th to 20th	Day	4 2 1 3 3 3 4 3 5% 7% 65%	3161
	21st to end	Day	5% 5% 2 5% 4 3 5% 4 6% 9% 53%	3448
November	1st to 10th	Day	8% 5% 2 5% 4 5% 4 3 5% 8% 50%	1742
	11th to 20th	Day	6% 5% 1 6% 5% 6% 6% 5% 7% 9% 44%	1650
	21st to end	Day	5% 5% 2 5% 5% 4 5% 5% 6% 9% 51%	1520
December	1st to 10th	Day	8% 7% 2 5% 4 5% 5% 4 6% 8% 47%	1520
	11th to 20th	Day	10% 9% 3 9% 7% 6% 6% 5% 7% 8% 29%	1928
	21st to end	Day	7% 7% 3 9% 8% 7% 6% 5% 8% 7% 34%	2794
January	1st to 10th	Night	6% 9% 3 8% 5% 5% 5% 5% 8% 10% 36%	4406
	11th to 20th	Night	10% 13% 4 8% 5% 5% 5% 4 7% 7% 33%	4296
	21st to end	Night	15% 12% 3 9% 5% 5% 6% 3 5% 7% 30%	4521
February	1st to 10th	Night	5% 7% 3 6% 5% 4 5% 4 6% 8% 47%	2470
	11th to 20th	Night	6% 8% 2 5% 4 5% 5% 4 6% 8% 47%	2347
	21st to end	Night	4 10% 3 5% 5% 5% 5% 4 6% 8% 44%	1884
March	1st to 10th	Night	7% 12% 3 7% 5% 5% 6% 5% 7% 7% 36%	3620
	11th to 20th	Night	5% 8% 2 5% 3 3 4 3 5% 6% 56%	3490
	21st to end	Night	7% 10% 3 7% 5% 5% 6% 5% 7% 8% 35%	3690
April	1st to 10th	Night	6% 7% 2 5% 4 5% 5% 3 6% 8% 47%	1900
	11th to 20th	Night	7% 6% 1 4 4 3 4 3 6% 8% 53%	1879
	21st to end	Night	7% 4 1 5% 4 3 3 3 5% 8% 56%	1900
May	1st to 10th	Night	4 6% 2 5% 3 3 3 2 3 4 64%	2788
	11th to 20th	Night	4 3 1 2 2 2 2 2 3 6% 72%	2516
	21st to end	Night	5% 4 1 4 3 2 3 3 4 5% 66%	2762
June	1st to 10th	Night	6% 4 1 3 3 4 4 3 6% 8% 58%	1520
	11th to 20th	Night	6% 2 1 2 2 2 2 2 3 6% 73%	1520
	21st to end	Night	2 2 1 2 2 1 3 2 4 5% 77%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 2 2 89%	2540
	11th to 20th	Night	1 1 1 2 2 2 2 2 2 4 83%	2540
	21st to end	Night	1 1 1 1 1 1 1 2 3 88%	2942
August	1st to 10th	Night	2 2 1 2 2 2 2 3 4 6% 74%	2848
	11th to 20th	Night	1 1 1 1 1 1 1 1 3 90%	2935
	21st to end	Night	3 2 1 1 1 1 1 2 2 85%	3498
September	1st to 10th	Night	1 1 1 1 1 1 2 1 2 3 86%	1900
	11th to 20th	Night	3 2 1 2 1 1 3 2 4 6% 75%	1900
	21st to end	Night	2 2 1 2 2 3 2 2 4 5% 74%	2142
October	1st to 10th	Night	3 2 1 2 2 2 2 2 2 3 78%	3800
	11th to 20th	Night	3 3 1 3 2 3 3 3 4 6% 69%	3777
	21st to end	Night	5% 3 1 4 2 3 3 3 5% 9% 61%	4121
November	1st to 10th	Night	7% 6% 2 5% 4 5% 5% 5% 6% 8% 47%	2495
	11th to 20th	Night	7% 6% 2 6% 5% 5% 5% 4 7% 9% 45%	2527
	21st to end	Night	4 6% 2 5% 4 4 4 4 6% 9% 52%	2660
December	1st to 10th	Night	9% 5% 2 5% 4 4 5% 4 6% 9% 47%	2660
	11th to 20th	Night	11% 10% 3 8% 6% 6% 5% 4 7% 9% 31%	3276
	21st to end	Night	11% 10% 3 10% 6% 5% 5% 5% 6% 8% 32%	4862

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	39% 13% 19% 23% 5% 1	2539
	11th to 20th	Day	46% 13% 15% 15% 8% 4	2664
	21st to end	Day	44% 12% 14% 18% 8% 2	3146
February	1st to 10th	Day	34% 8% 16% 22% 16% 4	1710
	11th to 20th	Day	35% 8% 14% 24% 18% 2	1727
	21st to end	Day	35% 10% 14% 26% 12% 4	1570
March	1st to 10th	Day	40% 16% 12% 17% 12% 2	3252
	11th to 20th	Day	24% 9% 14% 25% 28% 2	3490
	21st to end	Day	37% 16% 17% 22% 7% 2	3962
April	1st to 10th	Day	37% 9% 15% 22% 14% 3	2280
	11th to 20th	Day	31% 8% 14% 24% 18% 6%	2252
	21st to end	Day	25% 7% 17% 25% 22% 4	2280
May	1st to 10th	Day	20% 6% 12% 27% 27% 9%	4172
	11th to 20th	Day	15% 3 8% 19% 31% 23%	4380
	21st to end	Day	18% 5% 14% 31% 28% 5%	4814
June	1st to 10th	Day	24% 6% 12% 26% 24% 9%	2660
	11th to 20th	Day	12% 4 9% 23% 35% 17%	2660
	21st to end	Day	10% 2 5% 18% 33% 32%	2660
July	1st to 10th	Day	5% 1 2 8% 18% 66%	4351
	11th to 20th	Day	8% 1 3 9% 20% 58%	4345
	21st to end	Day	5% 1 2 9% 29% 52%	4465
August	1st to 10th	Day	12% 2 4 10% 23% 49%	4076
	11th to 20th	Day	4 1 2 15% 42% 37%	3944
	21st to end	Day	8% 1 3 21% 37% 30%	4179
September	1st to 10th	Day	5% 2 3 11% 30% 48%	2280
	11th to 20th	Day	14% 3 7% 22% 33% 21%	2280
	21st to end	Day	12% 3 7% 21% 30% 25%	2033
October	1st to 10th	Day	13% 2 6% 17% 25% 37%	3180
	11th to 20th	Day	18% 4 9% 33% 26% 10%	3161
	21st to end	Day	23% 6% 14% 26% 21% 10%	3448
November	1st to 10th	Day	32% 7% 14% 21% 20% 6%	1742
	11th to 20th	Day	33% 9% 16% 23% 16% 3	1650
	21st to end	Day	28% 10% 13% 23% 20% 6%	1520
December	1st to 10th	Day	33% 11% 12% 22% 19% 3	1520
	11th to 20th	Day	46% 14% 12% 18% 9% 1	1928
	21st to end	Day	37% 16% 16% 22% 7% 1	2794
January	1st to 10th	Night	35% 15% 23% 19% 6% 1	4406
	11th to 20th	Night	40% 18% 13% 16% 9% 5%	4296
	21st to end	Night	50% 12% 11% 15% 10% 2	4521
February	1st to 10th	Night	33% 10% 14% 23% 16% 4	2470
	11th to 20th	Night	33% 9% 16% 25% 16% 2	2349
	21st to end	Night	34% 9% 18% 22% 13% 4	1884
March	1st to 10th	Night	38% 16% 18% 18% 9% 2	3620
	11th to 20th	Night	25% 11% 12% 28% 22% 1	3490
	21st to end	Night	37% 17% 17% 21% 7% 1	3690
April	1st to 10th	Night	32% 10% 19% 25% 11% 3	1900
	11th to 20th	Night	27% 10% 19% 23% 15% 5%	1879
	21st to end	Night	25% 8% 17% 30% 16% 3	1900
May	1st to 10th	Night	22% 7% 12% 29% 24% 6%	2788
	11th to 20th	Night	15% 4 9% 20% 36% 15%	2516
	21st to end	Night	18% 8% 16% 34% 22% 2	2762
June	1st to 10th	Night	25% 8% 14% 29% 20% 4	1520
	11th to 20th	Night	15% 4 10% 23% 37% 11%	1520
	21st to end	Night	11% 3 6% 18% 35% 26%	1520
July	1st to 10th	Night	4 1 3 9% 18% 65%	2500
	11th to 20th	Night	9% 2 3 9% 21% 58%	2492
	21st to end	Night	5% 1 2 10% 34% 47%	2850
August	1st to 10th	Night	11% 2 4 12% 26% 46%	2839
	11th to 20th	Night	4 1 2 16% 42% 34%	2962
	21st to end	Night	8% 1 3 22% 41% 24%	3498
September	1st to 10th	Night	6% 3 4 10% 30% 48%	1900
	11th to 20th	Night	12% 4 7% 22% 35% 20%	1900
	21st to end	Night	12% 4 7% 21% 29% 26%	2142
October	1st to 10th	Night	14% 2 5% 13% 32% 33%	3800
	11th to 20th	Night	15% 5% 9% 39% 23% 9%	3777
	21st to end	Night	18% 5% 14% 33% 20% 10%	4121
November	1st to 10th	Night	31% 10% 15% 20% 16% 7%	2495
	11th to 20th	Night	32% 10% 15% 22% 17% 3	2527
	21st to end	Night	27% 8% 17% 23% 20% 6%	2660
December	1st to 10th	Night	31% 10% 13% 22% 20% 4	2660
	11th to 20th	Night	41% 15% 11% 19% 13% 1	3276
	21st to end	Night	41% 16% 13% 20% 9% 1	4862

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	22% 13% 23% 31% 9% 2	180
	11th to 20th	Day	13% 17% 20% 31% 11% 7%	252
	21st to end	Day	13% 14% 22% 28% 14% 8%	407
February	1st to 10th	Day	11% 16% 20% 32% 18% 2	370
	11th to 20th	Day	12% 20% 25% 27% 14% 1	390
	21st to end	Day	11% 18% 27% 29% 14% 1	382
March	1st to 10th	Day	17% 25% 28% 19% 8% 2	460
	11th to 20th	Day	15% 17% 28% 24% 13% 3	460
	21st to end	Day	12% 24% 30% 24% 10% 1	506
April	1st to 10th	Day	12% 19% 31% 25% 10% 2	460
	11th to 20th	Day	15% 19% 25% 22% 15% 4	452
	21st to end	Day	6% 17% 29% 25% 19% 4	460
May	1st to 10th	Day	9% 17% 33% 23% 14% 4	463
	11th to 20th	Day	13% 12% 26% 24% 17% 8%	488
	21st to end	Day	8% 10% 22% 28% 22% 9%	529
June	1st to 10th	Day	4 14% 29% 23% 20% 9%	490
	11th to 20th	Day	6% 12% 30% 28% 18% 6%	490
	21st to end	Day	1 9% 24% 33% 24% 9%	490
July	1st to 10th	Day	2 3 29% 32% 25% 9%	486
	11th to 20th	Day	4 26% 30% 27% 12%	484
	21st to end	Day	1 3 22% 35% 27% 13%	531
August	1st to 10th	Day	1 4 24% 33% 23% 15%	487
	11th to 20th	Day	2 6% 22% 28% 28% 15%	477
	21st to end	Day	2 4 26% 30% 24% 13%	539
September	1st to 10th	Day	1 6% 23% 35% 28% 7%	490
	11th to 20th	Day	6% 7% 22% 32% 25% 9%	490
	21st to end	Day	3 8% 24% 33% 26% 5%	490
October	1st to 10th	Day	5% 12% 22% 27% 24% 10%	490
	11th to 20th	Day	6% 10% 21% 28% 29% 7%	490
	21st to end	Day	8% 12% 23% 29% 21% 8%	539
November	1st to 10th	Day	11% 11% 19% 28% 23% 7%	296
	11th to 20th	Day	9% 5% 19% 35% 24% 7%	241
	21st to end	Day	7% 8% 18% 36% 25% 7%	180
December	1st to 10th	Day	17% 7% 21% 29% 18% 7%	180
	11th to 20th	Day	14% 7% 22% 31% 18% 7%	180
	21st to end	Day	13% 12% 21% 36% 16% 3	198
January	1st to 10th	Night	11% 8% 25% 38% 17% 1	760
	11th to 20th	Night	9% 8% 25% 40% 16% 1	760
	21st to end	Night	12% 5% 24% 40% 18% 1	836
February	1st to 10th	Night	7% 7% 27% 41% 17% 1	760
	11th to 20th	Night	10% 7% 27% 40% 16% 1	744
	21st to end	Night	9% 10% 25% 43% 13%	628
March	1st to 10th	Night	12% 11% 26% 36% 13% 1	760
	11th to 20th	Night	9% 9% 25% 34% 22% 1	760
	21st to end	Night	9% 10% 29% 36% 15%	836
April	1st to 10th	Night	9% 7% 25% 43% 15% 1	760
	11th to 20th	Night	10% 6% 26% 39% 17% 3	751
	21st to end	Night	7% 8% 21% 43% 19% 2	760
May	1st to 10th	Night	5% 5% 29% 40% 19% 1	537
	11th to 20th	Night	9% 3 19% 40% 26% 3	374
	21st to end	Night	9% 3 15% 41% 30% 1	411
June	1st to 10th	Night	6% 2 16% 44% 30% 1	380
	11th to 20th	Night	4 4 20% 45% 24% 2	380
	21st to end	Night	2 1 11% 48% 38% 1	380
July	1st to 10th	Night	1 1 4 49% 44% 2	370
	11th to 20th	Night	1 6% 51% 42% 1	368
	21st to end	Night	1 1 2 40% 53% 3	522
August	1st to 10th	Night	2 1 2 40% 50% 4	567
	11th to 20th	Night	2 1 6% 42% 45% 5%	635
	21st to end	Night	2 1 6% 45% 42% 4	836
September	1st to 10th	Night	2 1 10% 45% 41% 3	760
	11th to 20th	Night	4 2 11% 36% 42% 6%	760
	21st to end	Night	3 3 11% 43% 34% 6%	760
October	1st to 10th	Night	5% 2 16% 41% 31% 4	760
	11th to 20th	Night	4 3 16% 42% 32% 3	760
	21st to end	Night	8% 3 17% 41% 26% 4	836
November	1st to 10th	Night	8% 7% 19% 40% 23% 3	770
	11th to 20th	Night	8% 6% 22% 44% 17% 3	760
	21st to end	Night	5% 6% 24% 39% 23% 2	760
December	1st to 10th	Night	11% 6% 23% 42% 17% 2	760
	11th to 20th	Night	12% 7% 22% 41% 16% 2	760
	21st to end	Night	14% 9% 28% 39% 10%	836

Page generated at 2024-11-05 05:15:47. Version ac07

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