Brooks Camp Developed Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brooks Camp Developed Area 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	20% 15% 5% 11% 6% 6% 5% 4 5% 5% 19%	106153
	Night	16% 15% 5% 11% 7% 6% 5% 4 5% 6% 21%	101599
Transparency	Day	64% 10% 12% 10% 3 1	105866
	Night	60% 10% 12% 11% 6% 1	101537
Seeing	Day	25% 13% 23% 22% 13% 4	19089
	Night	23% 12% 22% 25% 16% 3	23007

By Month

Percentage Cloud Cover NW (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	7% 14% 5% 12% 8% 8% 9% 8% 9% 6% 17%	1589
	11th to 20th	Day	8% 11% 3 10% 5% 6% 5% 5% 7% 7% 33%	1745
	21st to end	Day	7% 10% 2 7% 5% 5% 6% 6% 7% 9% 35%	2431
February	1st to 10th	Day	10% 15% 5% 10% 8% 7% 6% 4 7% 8% 20%	1335
	11th to 20th	Day	12% 20% 6% 14% 7% 6% 8% 5% 6% 5% 13%	1576
	21st to end	Day	12% 16% 4 11% 8% 6% 6% 4 6% 5% 22%	1413
March	1st to 10th	Day	8% 16% 4 14% 9% 8% 7% 3 4 5% 22%	2981
	11th to 20th	Day	4 7% 3 11% 9% 13% 11% 4 5% 7% 26%	3480
	21st to end	Day	11% 19% 5% 12% 7% 6% 5% 4 5% 5% 20%	3869
April	1st to 10th	Day	11% 19% 7% 12% 6% 6% 5% 3 5% 4 21%	2449
	11th to 20th	Day	12% 15% 4 11% 8% 5% 5% 3 5% 5% 27%	2442
	21st to end	Day	10% 17% 5% 10% 6% 4 5% 4 6% 7% 26%	2707
May	1st to 10th	Day	17% 24% 7% 13% 6% 5% 4 3 4 3 13%	4760
	11th to 20th	Day	14% 18% 6% 10% 6% 5% 6% 3 6% 6% 21%	4887
	21st to end	Day	19% 17% 5% 10% 6% 5% 4 3 5% 6% 21%	5698
June	1st to 10th	Day	17% 15% 4 11% 7% 5% 5% 4 5% 6% 21%	3230
	11th to 20th	Day	21% 14% 4 9% 5% 5% 5% 4 5% 6% 22%	3230
	21st to end	Day	26% 13% 4 9% 6% 5% 4 5% 5% 6% 16%	3230
July	1st to 10th	Day	36% 14% 4 8% 5% 4 4 3 4 5% 13%	5390
	11th to 20th	Day	33% 14% 4 9% 5% 4 4 4 4 5% 13%	5390
	21st to end	Day	30% 11% 3 8% 5% 5% 3 3 4 6% 22%	5269
August	1st to 10th	Day	29% 13% 4 11% 6% 5% 5% 4 6% 6% 12%	4737
	11th to 20th	Day	29% 16% 6% 13% 6% 4 4 3 4 4 11%	4525
	21st to end	Day	33% 15% 4 10% 7% 5% 5% 4 5% 4 8%	4532
September	1st to 10th	Day	32% 14% 5% 11% 5% 5% 4 4 4 4 13%	2424
	11th to 20th	Day	29% 13% 5% 10% 5% 5% 5% 4 4 5% 15%	2196
	21st to end	Day	25% 15% 4 9% 5% 5% 4 3 4 5% 21%	2060
October	1st to 10th	Day	18% 15% 5% 10% 6% 6% 6% 5% 6% 5% 18%	3160
	11th to 20th	Day	10% 12% 5% 10% 5% 6% 5% 4 5% 6% 32%	2883
	21st to end	Day	14% 14% 7% 14% 7% 7% 6% 4 6% 5% 15%	2743
November	1st to 10th	Day	16% 19% 6% 13% 7% 5% 5% 3 4 6% 16%	1477
	11th to 20th	Day	12% 14% 5% 10% 7% 10% 7% 5% 6% 6% 18%	1204
	21st to end	Day	16% 17% 4 13% 9% 8% 7% 4 5% 5% 12%	1140
December	1st to 10th	Day	14% 12% 5% 10% 7% 8% 7% 4 5% 6% 21%	1025
	11th to 20th	Day	12% 17% 5% 9% 7% 8% 7% 5% 6% 8% 17%	1197
	21st to end	Day	9% 16% 4 11% 8% 6% 8% 4 6% 6% 23%	1749
January	1st to 10th	Night	6% 15% 5% 13% 9% 7% 7% 6% 7% 7% 19%	5377
	11th to 20th	Night	8% 14% 4 11% 7% 5% 5% 5% 5% 5% 33%	5168
	21st to end	Night	7% 10% 3 7% 5% 5% 5% 5% 9% 10% 32%	5236
February	1st to 10th	Night	10% 16% 5% 10% 7% 5% 6% 5% 5% 6% 26%	2842
	11th to 20th	Night	14% 21% 5% 9% 7% 6% 7% 5% 5% 5% 16%	2490
	21st to end	Night	12% 16% 4 10% 6% 5% 5% 4 5% 5% 28%	2041
March	1st to 10th	Night	9% 16% 6% 17% 8% 7% 6% 3 3 4 21%	3859
	11th to 20th	Night	4 8% 4 13% 11% 15% 8% 3 5% 6% 23%	3478
	21st to end	Night	12% 20% 8% 13% 6% 6% 5% 3 4 4 20%	3762
April	1st to 10th	Night	15% 18% 6% 14% 7% 5% 3 4 5% 4 20%	1729
	11th to 20th	Night	11% 16% 5% 11% 6% 5% 5% 4 5% 6% 26%	1687
	21st to end	Night	12% 17% 4 10% 7% 5% 4 5% 4 7% 27%	1470
May	1st to 10th	Night	18% 21% 4 10% 5% 6% 5% 4 5% 5% 17%	2210
	11th to 20th	Night	19% 17% 5% 13% 5% 5% 4 3 4 5% 19%	2017
	21st to end	Night	21% 18% 4 9% 6% 5% 5% 4 6% 6% 17%	1893
June	1st to 10th	Night	22% 12% 4 12% 6% 6% 5% 3 5% 5% 21%	950
	11th to 20th	Night	24% 11% 5% 8% 7% 4 5% 4 6% 5% 21%	950
	21st to end	Night	24% 11% 5% 10% 5% 5% 6% 4 7% 7% 17%	950
July	1st to 10th	Night	39% 12% 4 9% 5% 3 4 3 4 4 12%	1590
	11th to 20th	Night	31% 14% 4 11% 5% 4 4 4 4 4 15%	1590
	21st to end	Night	30% 9% 3 6% 5% 3 4 4 5% 5% 25%	2294
August	1st to 10th	Night	32% 13% 5% 9% 5% 4 5% 3 4 4 14%	2203
	11th to 20th	Night	34% 16% 5% 10% 5% 5% 4 3 4 4 10%	2311
	21st to end	Night	34% 18% 5% 10% 6% 4 5% 3 3 3 9%	3124
September	1st to 10th	Night	32% 15% 4 11% 5% 4 4 3 4 4 14%	1756
	11th to 20th	Night	29% 12% 4 9% 5% 5% 4 4 5% 6% 17%	1981
	21st to end	Night	29% 13% 4 8% 6% 3 4 3 3 4 23%	2119
October	1st to 10th	Night	19% 14% 4 8% 5% 5% 5% 4 7% 7% 22%	3800
	11th to 20th	Night	12% 13% 4 9% 6% 5% 5% 5% 6% 7% 30%	4037
	21st to end	Night	20% 16% 5% 9% 7% 6% 5% 4 6% 5% 18%	4816
November	1st to 10th	Night	17% 18% 4 14% 7% 4 4 3 4 4 19%	2759
	11th to 20th	Night	11% 14% 4 10% 8% 9% 8% 3 6% 6% 20%	2976
	21st to end	Night	14% 16% 5% 11% 7% 8% 7% 5% 5% 6% 14%	3040
December	1st to 10th	Night	13% 16% 4 11% 7% 7% 6% 5% 6% 5% 19%	3154
	11th to 20th	Night	11% 18% 5% 13% 9% 8% 6% 4 6% 7% 14%	4011
	21st to end	Night	8% 15% 6% 12% 7% 7% 7% 5% 7% 7% 20%	5929

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	51% 14% 16% 9% 9% 2	1589
	11th to 20th	Day	43% 11% 11% 19% 15% 2	1761
	21st to end	Day	37% 11% 10% 12% 22% 9%	2431
February	1st to 10th	Day	55% 11% 11% 10% 8% 5%	1335
	11th to 20th	Day	71% 8% 9% 8% 3 1	1582
	21st to end	Day	61% 11% 10% 12% 6%	1413
March	1st to 10th	Day	61% 9% 8% 10% 10% 2	2981
	11th to 20th	Day	49% 11% 16% 15% 7% 1	3480
	21st to end	Day	60% 10% 12% 12% 4 1	3869
April	1st to 10th	Day	65% 8% 12% 10% 4 1	2449
	11th to 20th	Day	58% 9% 13% 13% 6%	2442
	21st to end	Day	57% 11% 14% 14% 4 1	2707
May	1st to 10th	Day	74% 8% 9% 7% 2	4760
	11th to 20th	Day	61% 11% 15% 12% 2	4890
	21st to end	Day	62% 11% 16% 11% 2	5699
June	1st to 10th	Day	63% 13% 14% 10% 1	3230
	11th to 20th	Day	63% 11% 14% 10% 2	3230
	21st to end	Day	68% 13% 16% 3	3230
July	1st to 10th	Day	74% 9% 11% 5%	5306
	11th to 20th	Day	72% 9% 10% 9%	5297
	21st to end	Day	63% 10% 18% 9%	5103
August	1st to 10th	Day	69% 10% 12% 7% 1	4719
	11th to 20th	Day	74% 10% 11% 5%	4570
	21st to end	Day	78% 9% 9% 4	4531
September	1st to 10th	Day	75% 10% 7% 7% 1	2424
	11th to 20th	Day	70% 11% 9% 9% 1	2196
	21st to end	Day	67% 8% 11% 12% 1	2060
October	1st to 10th	Day	63% 9% 10% 15% 3	3160
	11th to 20th	Day	51% 12% 18% 16% 4	2883
	21st to end	Day	64% 12% 13% 7% 3	2743
November	1st to 10th	Day	68% 11% 10% 9% 2 1	1477
	11th to 20th	Day	64% 13% 11% 9% 4	1204
	21st to end	Day	67% 8% 13% 7% 4	1140
December	1st to 10th	Day	59% 10% 12% 13% 5% 1	1025
	11th to 20th	Day	61% 8% 13% 9% 8% 2	1201
	21st to end	Day	53% 10% 13% 11% 10% 3	1749
January	1st to 10th	Night	54% 12% 13% 11% 9% 1	5377
	11th to 20th	Night	48% 7% 9% 19% 15% 1	5215
	21st to end	Night	39% 8% 10% 13% 20% 10%	5236
February	1st to 10th	Night	55% 8% 11% 13% 10% 3	2842
	11th to 20th	Night	66% 10% 11% 9% 4 1	2495
	21st to end	Night	55% 11% 12% 14% 7%	2041
March	1st to 10th	Night	64% 7% 10% 8% 10% 1	3859
	11th to 20th	Night	51% 14% 14% 11% 9% 1	3480
	21st to end	Night	62% 9% 14% 10% 4 1	3762
April	1st to 10th	Night	66% 9% 12% 9% 4 1	1729
	11th to 20th	Night	56% 10% 14% 15% 5%	1687
	21st to end	Night	54% 12% 14% 13% 6% 1	1470
May	1st to 10th	Night	67% 9% 12% 9% 3	2210
	11th to 20th	Night	65% 9% 14% 10% 2	2018
	21st to end	Night	61% 13% 16% 9% 1	1893
June	1st to 10th	Night	62% 12% 15% 10% 1	950
	11th to 20th	Night	62% 13% 14% 10% 2	950
	21st to end	Night	67% 13% 16% 4	950
July	1st to 10th	Night	76% 9% 10% 5%	1565
	11th to 20th	Night	71% 11% 11% 7%	1560
	21st to end	Night	58% 12% 19% 10%	2222
August	1st to 10th	Night	71% 9% 13% 7%	2196
	11th to 20th	Night	77% 7% 12% 4	2332
	21st to end	Night	79% 9% 8% 4	3124
September	1st to 10th	Night	73% 9% 10% 7% 1	1756
	11th to 20th	Night	68% 11% 12% 7% 1	1981
	21st to end	Night	65% 10% 12% 10% 2	2119
October	1st to 10th	Night	56% 11% 12% 19% 2	3800
	11th to 20th	Night	51% 13% 17% 16% 3	4037
	21st to end	Night	64% 13% 13% 7% 3	4816
November	1st to 10th	Night	66% 10% 10% 10% 3	2759
	11th to 20th	Night	60% 13% 11% 11% 5% 1	2976
	21st to end	Night	64% 10% 12% 8% 5%	3040
December	1st to 10th	Night	61% 10% 13% 9% 7% 1	3154
	11th to 20th	Night	64% 8% 13% 9% 5% 1	4007
	21st to end	Night	52% 10% 13% 12% 11% 3	5929

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	15% 10% 18% 26% 21% 10%	280
	11th to 20th	Day	15% 11% 20% 27% 19% 9%	280
	21st to end	Day	12% 19% 27% 28% 8% 6%	308
February	1st to 10th	Day	18% 12% 26% 26% 11% 8%	280
	11th to 20th	Day	25% 18% 28% 17% 10% 2	322
	21st to end	Day	24% 19% 29% 19% 7% 2	307
March	1st to 10th	Day	20% 15% 28% 23% 12% 1	446
	11th to 20th	Day	9% 13% 32% 31% 13% 3	560
	21st to end	Day	20% 13% 27% 25% 13% 2	616
April	1st to 10th	Day	19% 16% 28% 20% 13% 3	560
	11th to 20th	Day	17% 13% 24% 26% 15% 4	555
	21st to end	Day	13% 14% 27% 25% 15% 5%	650
May	1st to 10th	Day	21% 15% 23% 22% 16% 3	653
	11th to 20th	Day	21% 13% 24% 25% 13% 3	675
	21st to end	Day	20% 12% 24% 24% 14% 5%	835
June	1st to 10th	Day	23% 10% 21% 23% 19% 5%	870
	11th to 20th	Day	21% 11% 20% 26% 17% 5%	870
	21st to end	Day	27% 9% 19% 25% 16% 4	870
July	1st to 10th	Day	35% 10% 19% 19% 13% 3	856
	11th to 20th	Day	32% 12% 18% 22% 13% 4	852
	21st to end	Day	35% 9% 19% 18% 15% 4	771
August	1st to 10th	Day	38% 11% 18% 19% 12% 2	676
	11th to 20th	Day	32% 16% 23% 19% 9% 3	657
	21st to end	Day	36% 15% 19% 20% 8% 3	638
September	1st to 10th	Day	38% 11% 22% 17% 9% 3	580
	11th to 20th	Day	34% 15% 22% 17% 9% 3	580
	21st to end	Day	35% 11% 21% 17% 11% 5%	550
October	1st to 10th	Day	34% 15% 24% 17% 8% 3	390
	11th to 20th	Day	18% 12% 25% 20% 21% 4	390
	21st to end	Day	25% 16% 23% 21% 14% 2	429
November	1st to 10th	Day	25% 16% 24% 20% 11% 4	355
	11th to 20th	Day	20% 18% 29% 14% 12% 7%	280
	21st to end	Day	22% 18% 23% 21% 12% 5%	280
December	1st to 10th	Day	18% 13% 28% 18% 16% 6%	280
	11th to 20th	Day	21% 15% 25% 22% 13% 4	280
	21st to end	Day	20% 16% 22% 21% 14% 6%	308
January	1st to 10th	Night	14% 8% 21% 33% 20% 4	940
	11th to 20th	Night	14% 14% 25% 26% 18% 3	925
	21st to end	Night	16% 13% 27% 31% 11% 3	935
February	1st to 10th	Night	15% 14% 24% 28% 14% 4	842
	11th to 20th	Night	26% 16% 24% 23% 8% 2	648
	21st to end	Night	18% 19% 27% 23% 12% 1	546
March	1st to 10th	Night	15% 14% 28% 28% 13% 1	660
	11th to 20th	Night	10% 7% 27% 34% 18% 3	660
	21st to end	Night	17% 9% 20% 33% 17% 4	710
April	1st to 10th	Night	19% 14% 24% 23% 16% 3	570
	11th to 20th	Night	17% 11% 21% 28% 20% 3	563
	21st to end	Night	17% 11% 24% 27% 18% 4	520
May	1st to 10th	Night	21% 7% 20% 23% 26% 2	380
	11th to 20th	Night	21% 10% 20% 28% 18% 2	374
	21st to end	Night	19% 7% 22% 27% 22% 3	411
June	1st to 10th	Night	25% 8% 18% 23% 22% 4	380
	11th to 20th	Night	26% 5% 15% 27% 24% 2	380
	21st to end	Night	27% 5% 16% 18% 31% 3	380
July	1st to 10th	Night	31% 9% 15% 22% 20% 4	370
	11th to 20th	Night	35% 7% 15% 23% 14% 5%	368
	21st to end	Night	39% 7% 14% 19% 17% 4	416
August	1st to 10th	Night	38% 9% 16% 19% 16% 2	378
	11th to 20th	Night	37% 15% 16% 18% 11% 3	435
	21st to end	Night	39% 11% 15% 19% 15% 2	627
September	1st to 10th	Night	38% 12% 16% 20% 13% 2	570
	11th to 20th	Night	32% 14% 15% 19% 17% 4	613
	21st to end	Night	36% 10% 19% 17% 15% 3	670
October	1st to 10th	Night	31% 15% 21% 19% 13% 2	670
	11th to 20th	Night	24% 13% 19% 25% 15% 5%	675
	21st to end	Night	25% 14% 22% 23% 12% 2	946
November	1st to 10th	Night	26% 12% 24% 19% 16% 3	867
	11th to 20th	Night	18% 17% 27% 23% 12% 3	850
	21st to end	Night	20% 10% 29% 24% 14% 2	850
December	1st to 10th	Night	19% 14% 28% 23% 12% 4	904
	11th to 20th	Night	19% 14% 26% 28% 10% 3	940
	21st to end	Night	20% 15% 23% 22% 16% 4	1034

Page generated at 2024-11-05 04:15:50. Version ac07

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