Timber City Productions Lookout
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Timber City Productions Lookout clear sky chart from 2005-11-06 to 2024-12-06.

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	13% 8% 3 8% 4 4 4 4 6% 7% 38%	101771
	Night	13% 9% 3 7% 5% 4 4 3 5% 6% 40%	98047
Transparency	Day	43% 6% 12% 23% 14% 1	105326
	Night	43% 5% 11% 23% 15% 2	102619
Seeing	Day	17% 10% 29% 26% 14% 4	15953
	Night	17% 9% 30% 31% 12% 1	25833

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	11% 12% 8% 17% 6% 6% 4 4 4 5% 24%	2527
	11th to 20th	Day	10% 12% 4 13% 9% 5% 6% 6% 9% 6% 20%	2530
	21st to end	Day	16% 19% 7% 13% 6% 5% 5% 3 5% 5% 17%	3100
February	1st to 10th	Day	13% 13% 5% 8% 5% 4 5% 4 5% 8% 30%	1710
	11th to 20th	Day	15% 9% 4 6% 4 5% 4 4 6% 6% 37%	1743
	21st to end	Day	14% 12% 4 9% 5% 4 5% 4 5% 7% 33%	1570
March	1st to 10th	Day	15% 9% 3 7% 4 3 4 3 4 6% 42%	3142
	11th to 20th	Day	10% 6% 3 6% 5% 5% 5% 4 6% 7% 43%	3480
	21st to end	Day	22% 13% 4 12% 5% 5% 5% 5% 4 5% 21%	4027
April	1st to 10th	Day	17% 12% 4 8% 5% 3 5% 4 4 6% 32%	2280
	11th to 20th	Day	16% 10% 4 7% 5% 5% 4 4 6% 6% 35%	2254
	21st to end	Day	21% 9% 2 7% 4 4 3 3 5% 6% 35%	2280
May	1st to 10th	Day	17% 8% 3 8% 5% 4 4 3 5% 7% 36%	4258
	11th to 20th	Day	16% 8% 3 7% 4 4 4 3 5% 7% 40%	4399
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 6% 8% 41%	4824
June	1st to 10th	Day	10% 5% 2 6% 5% 4 5% 5% 7% 9% 43%	2660
	11th to 20th	Day	10% 7% 2 6% 4 4 5% 4 6% 7% 45%	2660
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 6% 8% 40%	2660
July	1st to 10th	Day	11% 7% 3 7% 5% 6% 5% 5% 7% 9% 34%	4440
	11th to 20th	Day	6% 4 1 5% 4 4 4 4 7% 9% 53%	4440
	21st to end	Day	8% 5% 2 7% 5% 5% 5% 5% 8% 10% 40%	4813
August	1st to 10th	Day	7% 5% 2 6% 4 5% 6% 4 8% 10% 43%	4144
	11th to 20th	Day	11% 5% 2 6% 4 4 5% 4 7% 10% 43%	3882
	21st to end	Day	9% 5% 2 6% 4 3 5% 4 6% 8% 49%	4180
September	1st to 10th	Day	13% 5% 2 5% 4 4 3 4 5% 7% 48%	2280
	11th to 20th	Day	11% 4 2 4 4 3 4 3 5% 8% 53%	2268
	21st to end	Day	11% 6% 2 6% 4 4 4 4 6% 7% 47%	2053
October	1st to 10th	Day	13% 7% 2 5% 4 3 3 3 4 6% 49%	1900
	11th to 20th	Day	18% 7% 3 7% 3 3 4 4 4 6% 40%	1900
	21st to end	Day	19% 8% 3 6% 4 3 4 3 4 6% 41%	1994
November	1st to 10th	Day	12% 9% 3 7% 4 4 4 4 4 6% 44%	1762
	11th to 20th	Day	14% 13% 4 7% 4 5% 4 4 5% 7% 33%	1750
	21st to end	Day	17% 10% 4 9% 4 3 4 3 5% 6% 36%	1600
December	1st to 10th	Day	14% 12% 4 10% 5% 4 4 3 5% 6% 33%	1560
	11th to 20th	Day	14% 12% 5% 10% 5% 5% 3 4 5% 7% 29%	1918
	21st to end	Day	23% 20% 8% 11% 5% 4 3 3 3 4 16%	2783
January	1st to 10th	Night	12% 12% 7% 14% 5% 5% 4 4 4 5% 29%	4428
	11th to 20th	Night	12% 16% 6% 12% 6% 4 4 5% 8% 4 22%	4440
	21st to end	Night	17% 18% 7% 10% 6% 4 4 3 4 5% 23%	4564
February	1st to 10th	Night	13% 13% 4 8% 6% 5% 3 4 4 7% 34%	2470
	11th to 20th	Night	12% 10% 3 7% 5% 4 3 2 5% 5% 42%	2323
	21st to end	Night	15% 11% 4 7% 5% 4 4 3 5% 6% 38%	1884
March	1st to 10th	Night	19% 9% 3 5% 4 4 4 3 3 4 43%	3733
	11th to 20th	Night	10% 6% 2 6% 5% 4 3 2 5% 6% 50%	3488
	21st to end	Night	24% 13% 4 11% 5% 4 4 3 4 5% 24%	3604
April	1st to 10th	Night	16% 10% 3 5% 5% 4 3 3 4 5% 40%	1900
	11th to 20th	Night	18% 8% 3 7% 5% 3 4 3 4 5% 41%	1875
	21st to end	Night	18% 9% 2 7% 4 4 4 3 5% 7% 37%	1900
May	1st to 10th	Night	19% 7% 3 7% 6% 4 4 3 5% 6% 35%	2641
	11th to 20th	Night	14% 7% 3 7% 5% 5% 4 4 5% 6% 42%	2506
	21st to end	Night	8% 6% 2 5% 4 4 5% 4 6% 9% 47%	2743
June	1st to 10th	Night	8% 5% 2 6% 4 4 4 4 5% 9% 48%	1520
	11th to 20th	Night	9% 6% 2 6% 4 4 5% 4 7% 8% 45%	1520
	21st to end	Night	11% 5% 2 5% 5% 5% 4 5% 6% 7% 45%	1520
July	1st to 10th	Night	12% 6% 3 8% 5% 4 5% 3 6% 7% 40%	2530
	11th to 20th	Night	5% 3 1 4 3 4 4 3 5% 10% 58%	2530
	21st to end	Night	5% 4 2 6% 4 4 5% 4 7% 10% 48%	2750
August	1st to 10th	Night	6% 4 2 5% 4 4 4 4 5% 9% 54%	2793
	11th to 20th	Night	7% 5% 1 5% 4 4 4 3 5% 8% 54%	2950
	21st to end	Night	9% 5% 3 5% 4 3 3 3 5% 8% 52%	3476
September	1st to 10th	Night	9% 4 1 5% 4 3 3 3 4 7% 56%	1900
	11th to 20th	Night	10% 4 2 5% 4 3 4 3 6% 8% 52%	1900
	21st to end	Night	8% 4 2 6% 4 3 4 3 6% 6% 53%	2115
October	1st to 10th	Night	11% 5% 2 5% 3 3 3 2 4 6% 54%	2280
	11th to 20th	Night	14% 7% 2 5% 4 3 3 3 5% 6% 47%	2280
	21st to end	Night	18% 7% 3 7% 5% 4 4 3 4 6% 39%	2603
November	1st to 10th	Night	12% 7% 2 6% 3 3 3 2 4 6% 51%	2536
	11th to 20th	Night	15% 11% 3 7% 5% 4 4 3 5% 5% 39%	2645
	21st to end	Night	16% 9% 3 8% 4 4 3 3 4 6% 39%	2800
December	1st to 10th	Night	14% 11% 4 9% 6% 4 4 4 5% 6% 35%	2737
	11th to 20th	Night	14% 12% 4 8% 5% 5% 5% 4 5% 7% 33%	3279
	21st to end	Night	21% 16% 6% 11% 5% 5% 5% 3 4 5% 19%	4884

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	61% 7% 11% 15% 6%	2528
	11th to 20th	Day	59% 6% 12% 12% 9%	2530
	21st to end	Day	69% 4 11% 11% 5%	3100
February	1st to 10th	Day	52% 5% 13% 19% 9% 1	1710
	11th to 20th	Day	47% 5% 12% 24% 11% 1	1752
	21st to end	Day	50% 6% 11% 21% 9% 2	1570
March	1st to 10th	Day	43% 6% 11% 25% 12% 3	3142
	11th to 20th	Day	37% 7% 13% 30% 12%	3480
	21st to end	Day	63% 9% 11% 13% 3 1	4027
April	1st to 10th	Day	52% 5% 11% 21% 10%	2280
	11th to 20th	Day	49% 5% 11% 22% 12% 2	2254
	21st to end	Day	50% 5% 10% 20% 13% 2	2280
May	1st to 10th	Day	46% 7% 10% 20% 16%	4297
	11th to 20th	Day	43% 6% 9% 28% 13%	4403
	21st to end	Day	39% 7% 11% 24% 15% 3	4837
June	1st to 10th	Day	35% 8% 13% 26% 17% 1	2660
	11th to 20th	Day	36% 7% 13% 22% 21% 3	2660
	21st to end	Day	40% 7% 14% 23% 13% 2	2660
July	1st to 10th	Day	43% 7% 13% 26% 9% 2	4371
	11th to 20th	Day	26% 7% 16% 31% 18% 2	4365
	21st to end	Day	36% 10% 16% 18% 18% 2	4662
August	1st to 10th	Day	33% 9% 17% 28% 13% 1	4129
	11th to 20th	Day	35% 7% 15% 26% 16% 1	3921
	21st to end	Day	32% 6% 13% 31% 16% 2	4179
September	1st to 10th	Day	35% 6% 12% 24% 21% 3	2280
	11th to 20th	Day	30% 6% 11% 33% 17% 3	2268
	21st to end	Day	35% 5% 11% 29% 18% 2	2053
October	1st to 10th	Day	22% 3 6% 35% 32% 1	3160
	11th to 20th	Day	30% 3 11% 25% 27% 4	3140
	21st to end	Day	41% 3 10% 29% 13% 3	3258
November	1st to 10th	Day	41% 5% 13% 26% 13% 2	1762
	11th to 20th	Day	50% 5% 13% 21% 11% 1	1750
	21st to end	Day	50% 5% 15% 22% 7% 1	1600
December	1st to 10th	Day	53% 4 14% 20% 8% 1	1560
	11th to 20th	Day	54% 4 16% 16% 9% 2	1915
	21st to end	Day	73% 5% 9% 9% 4	2783
January	1st to 10th	Night	57% 6% 10% 18% 9%	4428
	11th to 20th	Night	60% 5% 12% 14% 9%	4440
	21st to end	Night	64% 5% 9% 15% 5% 1	4564
February	1st to 10th	Night	51% 4 11% 20% 13% 1	2470
	11th to 20th	Night	45% 4 11% 24% 14% 1	2324
	21st to end	Night	48% 5% 11% 21% 12% 3	1884
March	1st to 10th	Night	46% 4 10% 23% 14% 3	3733
	11th to 20th	Night	35% 5% 10% 31% 18% 2	3488
	21st to end	Night	62% 5% 10% 16% 5% 1	3604
April	1st to 10th	Night	46% 4 10% 26% 13% 2	1900
	11th to 20th	Night	46% 4 7% 21% 18% 4	1875
	21st to end	Night	46% 6% 11% 21% 14% 2	1900
May	1st to 10th	Night	48% 7% 11% 16% 16% 2	2667
	11th to 20th	Night	41% 8% 11% 24% 15% 1	2507
	21st to end	Night	31% 8% 11% 29% 19% 3	2751
June	1st to 10th	Night	33% 6% 13% 25% 19% 3	1520
	11th to 20th	Night	34% 6% 10% 24% 22% 4	1520
	21st to end	Night	35% 8% 13% 22% 17% 4	1520
July	1st to 10th	Night	43% 6% 14% 22% 13% 3	2490
	11th to 20th	Night	23% 6% 14% 35% 19% 2	2482
	21st to end	Night	28% 10% 18% 21% 19% 3	2662
August	1st to 10th	Night	27% 7% 15% 32% 17% 2	2784
	11th to 20th	Night	28% 7% 15% 32% 16% 2	2977
	21st to end	Night	30% 6% 11% 29% 19% 5%	3476
September	1st to 10th	Night	28% 6% 11% 27% 26% 3	1900
	11th to 20th	Night	30% 5% 10% 31% 19% 4	1900
	21st to end	Night	31% 5% 10% 30% 21% 3	2115
October	1st to 10th	Night	23% 3 6% 35% 30% 2	3800
	11th to 20th	Night	29% 3 9% 22% 33% 4	3779
	21st to end	Night	46% 4 8% 23% 16% 3	4276
November	1st to 10th	Night	35% 4 12% 27% 18% 3	2536
	11th to 20th	Night	47% 4 11% 23% 13% 1	2645
	21st to end	Night	47% 5% 11% 26% 11% 1	2800
December	1st to 10th	Night	50% 5% 12% 23% 9% 1	2737
	11th to 20th	Night	50% 5% 15% 21% 7% 1	3281
	21st to end	Night	68% 6% 7% 14% 5%	4884

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	21% 11% 31% 27% 9% 1	270
	11th to 20th	Day	21% 13% 41% 19% 5% 1	270
	21st to end	Day	21% 11% 37% 23% 6% 1	297
February	1st to 10th	Day	20% 17% 36% 23% 4	270
	11th to 20th	Day	21% 20% 31% 22% 4 1	270
	21st to end	Day	21% 16% 43% 16% 4	225
March	1st to 10th	Day	19% 18% 40% 19% 4	270
	11th to 20th	Day	23% 18% 32% 19% 6% 1	270
	21st to end	Day	31% 13% 34% 15% 5% 1	420
April	1st to 10th	Day	27% 16% 32% 19% 6%	460
	11th to 20th	Day	22% 19% 29% 18% 11% 1	452
	21st to end	Day	26% 13% 30% 21% 10% 1	460
May	1st to 10th	Day	20% 12% 34% 26% 8% 2	591
	11th to 20th	Day	23% 10% 29% 24% 12% 2	675
	21st to end	Day	17% 8% 28% 28% 12% 6%	734
June	1st to 10th	Day	9% 6% 28% 33% 19% 5%	680
	11th to 20th	Day	11% 8% 34% 28% 14% 4	680
	21st to end	Day	15% 7% 31% 29% 14% 5%	680
July	1st to 10th	Day	10% 3 19% 32% 23% 13%	671
	11th to 20th	Day	8% 3 27% 33% 21% 8%	668
	21st to end	Day	6% 5% 23% 38% 22% 6%	739
August	1st to 10th	Day	8% 3 19% 35% 25% 10%	676
	11th to 20th	Day	12% 6% 17% 31% 25% 9%	571
	21st to end	Day	9% 4 19% 33% 26% 9%	539
September	1st to 10th	Day	13% 6% 23% 31% 20% 7%	490
	11th to 20th	Day	9% 3 22% 34% 23% 8%	490
	21st to end	Day	12% 11% 28% 27% 17% 5%	453
October	1st to 10th	Day	18% 8% 28% 27% 15% 3	300
	11th to 20th	Day	23% 18% 34% 17% 8%	300
	21st to end	Day	30% 13% 31% 18% 6% 2	330
November	1st to 10th	Day	19% 13% 36% 21% 8% 2	300
	11th to 20th	Day	21% 19% 35% 17% 6% 2	300
	21st to end	Day	26% 12% 36% 20% 5%	300
December	1st to 10th	Day	17% 13% 42% 19% 7% 2	285
	11th to 20th	Day	18% 11% 37% 25% 8%	270
	21st to end	Day	29% 12% 38% 18% 2	297
January	1st to 10th	Night	16% 12% 37% 27% 7%	950
	11th to 20th	Night	19% 11% 35% 27% 7%	950
	21st to end	Night	21% 11% 32% 31% 5%	1045
February	1st to 10th	Night	21% 11% 36% 26% 6%	950
	11th to 20th	Night	17% 12% 37% 28% 5%	849
	21st to end	Night	22% 13% 38% 21% 4 1	628
March	1st to 10th	Night	23% 10% 36% 25% 6% 1	760
	11th to 20th	Night	17% 9% 35% 31% 7% 1	578
	21st to end	Night	25% 10% 35% 24% 6%	627
April	1st to 10th	Night	20% 13% 39% 25% 4	570
	11th to 20th	Night	23% 12% 30% 28% 6% 1	563
	21st to end	Night	22% 9% 31% 30% 8% 1	570
May	1st to 10th	Night	17% 9% 35% 31% 7% 1	570
	11th to 20th	Night	18% 8% 31% 33% 11%	561
	21st to end	Night	14% 4 29% 36% 16% 2	617
June	1st to 10th	Night	10% 4 27% 43% 15% 1	570
	11th to 20th	Night	12% 4 30% 40% 14% 1	570
	21st to end	Night	12% 4 28% 39% 15% 1	570
July	1st to 10th	Night	9% 2 13% 39% 33% 4	555
	11th to 20th	Night	9% 2 18% 42% 26% 3	552
	21st to end	Night	8% 2 17% 42% 29% 2	624
August	1st to 10th	Night	6% 2 15% 43% 32% 2	567
	11th to 20th	Night	6% 3 14% 42% 29% 6%	564
	21st to end	Night	9% 3 13% 45% 27% 3	627
September	1st to 10th	Night	10% 4 20% 39% 24% 4	570
	11th to 20th	Night	10% 2 21% 34% 28% 4	570
	21st to end	Night	9% 8% 25% 34% 21% 2	752
October	1st to 10th	Night	13% 6% 27% 33% 19% 1	760
	11th to 20th	Night	18% 11% 31% 29% 10% 1	760
	21st to end	Night	22% 12% 31% 27% 8%	836
November	1st to 10th	Night	16% 9% 37% 27% 10%	780
	11th to 20th	Night	21% 13% 36% 24% 6%	845
	21st to end	Night	20% 12% 35% 24% 8%	1000
December	1st to 10th	Night	20% 12% 37% 25% 5%	978
	11th to 20th	Night	23% 10% 33% 28% 6%	950
	21st to end	Night	27% 12% 33% 25% 3	1045

Page generated at 2024-12-03 05:45:15. Version ac07

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