Lake Goodwin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Goodwin clear sky chart from 2005-11-06 to 2024-03-01.

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	21% 9% 4 6% 6% 3 4 4 5% 6% 31%	78257
	Night	25% 10% 4 7% 6% 3 4 4 4 6% 28%	81094
Transparency	Day	53% 10% 14% 15% 6% 1	77973
	Night	57% 9% 12% 14% 6% 1	80958
Seeing	Day	24% 9% 19% 25% 17% 6%	14140
	Night	30% 8% 12% 24% 20% 4	22711

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	35% 17% 5% 7% 6% 3 4 4 4 4 11%	2219
	11th to 20th	Day	24% 12% 4 6% 7% 3 4 5% 5% 6% 23%	2427
	21st to end	Day	33% 14% 5% 8% 7% 4 5% 4 4 5% 9%	2835
February	1st to 10th	Day	32% 12% 4 8% 6% 3 4 4 4 6% 16%	1710
	11th to 20th	Day	27% 13% 4 8% 6% 3 4 4 5% 5% 21%	1665
	21st to end	Day	29% 14% 4 8% 6% 2 4 4 5% 5% 19%	1470
March	1st to 10th	Day	24% 12% 4 8% 6% 3 5% 6% 5% 6% 20%	1837
	11th to 20th	Day	28% 12% 4 6% 6% 4 4 4 4 6% 23%	1980
	21st to end	Day	26% 11% 5% 10% 6% 4 5% 5% 6% 5% 17%	2252
April	1st to 10th	Day	23% 12% 5% 7% 7% 4 5% 5% 6% 7% 20%	2160
	11th to 20th	Day	22% 11% 4 7% 7% 4 5% 5% 5% 6% 24%	2164
	21st to end	Day	21% 11% 4 7% 7% 4 5% 4 6% 6% 25%	2394
May	1st to 10th	Day	15% 7% 4 8% 6% 4 5% 5% 6% 7% 33%	2520
	11th to 20th	Day	18% 7% 3 6% 6% 4 6% 5% 6% 8% 32%	2477
	21st to end	Day	22% 8% 4 7% 6% 3 4 4 5% 6% 31%	2723
June	1st to 10th	Day	21% 8% 3 6% 6% 3 5% 5% 5% 7% 32%	2612
	11th to 20th	Day	20% 9% 3 7% 6% 4 5% 5% 6% 8% 28%	2700
	21st to end	Day	12% 6% 3 6% 6% 2 4 5% 6% 8% 41%	2700
July	1st to 10th	Day	10% 5% 3 4 4 2 3 4 5% 7% 52%	2700
	11th to 20th	Day	9% 5% 2 4 4 2 3 4 4 7% 54%	2629
	21st to end	Day	9% 3 1 3 3 2 3 3 3 6% 64%	2741
August	1st to 10th	Day	9% 5% 2 3 3 2 3 4 4 7% 57%	2486
	11th to 20th	Day	7% 4 2 4 3 2 4 4 5% 8% 56%	2298
	21st to end	Day	11% 7% 3 5% 5% 3 4 4 4 8% 46%	2476
September	1st to 10th	Day	10% 7% 3 4 5% 3 4 3 4 7% 50%	2160
	11th to 20th	Day	14% 7% 3 7% 5% 3 5% 5% 5% 6% 42%	2160
	21st to end	Day	18% 7% 3 6% 5% 3 3 5% 6% 7% 37%	1904
October	1st to 10th	Day	20% 7% 4 7% 6% 3 5% 5% 6% 7% 29%	1800
	11th to 20th	Day	24% 10% 3 7% 6% 3 4 5% 6% 7% 25%	1800
	21st to end	Day	29% 10% 4 6% 6% 3 4 4 5% 6% 22%	1861
November	1st to 10th	Day	34% 10% 4 6% 6% 3 5% 5% 5% 6% 17%	1516
	11th to 20th	Day	33% 9% 4 6% 5% 3 4 4 4 6% 21%	1520
	21st to end	Day	34% 11% 4 6% 6% 2 3 5% 4 7% 18%	1520
December	1st to 10th	Day	28% 13% 5% 7% 5% 3 4 5% 4 5% 23%	1520
	11th to 20th	Day	29% 13% 5% 9% 8% 3 4 5% 4 5% 16%	1879
	21st to end	Day	24% 16% 7% 9% 6% 4 6% 5% 4 5% 14%	2442
January	1st to 10th	Night	33% 16% 4 8% 7% 3 4 4 4 3 13%	4726
	11th to 20th	Night	27% 12% 3 6% 5% 2 4 4 4 9% 23%	4466
	21st to end	Night	33% 14% 4 9% 6% 4 5% 4 3 5% 13%	4818
February	1st to 10th	Night	31% 12% 4 6% 6% 3 5% 4 4 5% 20%	2470
	11th to 20th	Night	26% 14% 4 8% 6% 3 4 3 4 5% 23%	2402
	21st to end	Night	28% 13% 3 7% 5% 3 5% 5% 5% 5% 20%	1984
March	1st to 10th	Night	27% 11% 4 7% 6% 3 5% 5% 5% 5% 22%	2126
	11th to 20th	Night	30% 11% 4 6% 4 3 4 4 5% 6% 22%	1979
	21st to end	Night	29% 12% 4 8% 6% 3 4 5% 6% 6% 17%	2103
April	1st to 10th	Night	24% 10% 4 9% 6% 4 5% 6% 6% 8% 19%	1800
	11th to 20th	Night	23% 9% 4 9% 6% 4 6% 4 5% 6% 25%	1744
	21st to end	Night	25% 10% 4 8% 8% 3 4 4 5% 5% 24%	1566
May	1st to 10th	Night	20% 7% 3 6% 6% 2 4 4 4 6% 39%	1440
	11th to 20th	Night	18% 7% 3 6% 5% 4 4 5% 7% 9% 34%	1416
	21st to end	Night	23% 8% 4 7% 5% 3 5% 4 4 6% 31%	1552
June	1st to 10th	Night	20% 9% 3 5% 7% 3 5% 5% 5% 7% 31%	1345
	11th to 20th	Night	24% 9% 4 7% 6% 3 5% 5% 5% 6% 27%	1260
	21st to end	Night	13% 6% 2 6% 5% 3 4 5% 6% 7% 43%	1260
July	1st to 10th	Night	11% 4 3 5% 5% 3 3 4 3 7% 53%	1260
	11th to 20th	Night	8% 4 2 4 4 2 3 4 4 7% 58%	1327
	21st to end	Night	8% 3 2 3 3 2 3 4 4 5% 64%	1576
August	1st to 10th	Night	10% 4 1 3 3 2 3 4 3 7% 60%	1449
	11th to 20th	Night	7% 3 2 3 3 2 3 4 4 7% 63%	1602
	21st to end	Night	10% 5% 2 5% 4 2 5% 4 5% 6% 52%	1880
September	1st to 10th	Night	10% 4 3 5% 4 3 3 4 5% 6% 54%	1800
	11th to 20th	Night	16% 8% 3 6% 6% 3 4 4 4 6% 41%	1800
	21st to end	Night	16% 7% 3 7% 5% 3 3 4 4 6% 41%	2052
October	1st to 10th	Night	18% 8% 3 7% 6% 3 5% 3 4 6% 36%	2160
	11th to 20th	Night	25% 8% 3 5% 5% 3 4 4 5% 6% 32%	2160
	21st to end	Night	27% 9% 3 7% 4 3 4 4 4 6% 29%	2494
November	1st to 10th	Night	34% 10% 3 6% 6% 3 5% 4 3 5% 20%	2562
	11th to 20th	Night	32% 11% 4 6% 5% 2 4 5% 4 5% 21%	2660
	21st to end	Night	33% 10% 4 6% 5% 3 5% 4 4 5% 20%	2660
December	1st to 10th	Night	28% 12% 4 6% 5% 2 4 4 4 5% 25%	2660
	11th to 20th	Night	30% 13% 5% 8% 7% 3 5% 4 4 5% 16%	3321
	21st to end	Night	27% 16% 5% 10% 7% 4 5% 4 4 5% 13%	5214

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	76% 10% 6% 6% 2	2219
	11th to 20th	Day	59% 10% 13% 14% 4 1	2451
	21st to end	Day	78% 7% 7% 6% 1	2835
February	1st to 10th	Day	69% 10% 10% 7% 3 1	1710
	11th to 20th	Day	66% 10% 9% 8% 7%	1674
	21st to end	Day	65% 10% 10% 10% 5%	1470
March	1st to 10th	Day	64% 10% 13% 10% 4	1837
	11th to 20th	Day	64% 9% 10% 12% 3 1	1980
	21st to end	Day	67% 12% 11% 10% 1	2252
April	1st to 10th	Day	62% 13% 14% 10% 1	2160
	11th to 20th	Day	61% 10% 11% 12% 6% 1	2164
	21st to end	Day	60% 12% 11% 11% 5%	2394
May	1st to 10th	Day	49% 12% 16% 17% 6% 1	2520
	11th to 20th	Day	49% 13% 18% 15% 5%	2480
	21st to end	Day	56% 12% 16% 15% 2	2724
June	1st to 10th	Day	53% 11% 18% 12% 6% 1	2612
	11th to 20th	Day	56% 13% 16% 11% 3	2700
	21st to end	Day	41% 13% 19% 19% 7% 1	2700
July	1st to 10th	Day	33% 11% 16% 25% 12% 2	2626
	11th to 20th	Day	31% 9% 16% 30% 13% 1	2548
	21st to end	Day	23% 7% 16% 36% 16% 3	2589
August	1st to 10th	Day	27% 11% 20% 27% 12% 2	2469
	11th to 20th	Day	26% 10% 20% 30% 11% 3	2298
	21st to end	Day	36% 11% 16% 28% 8% 1	2476
September	1st to 10th	Day	35% 8% 16% 24% 13% 4	2160
	11th to 20th	Day	43% 10% 14% 17% 15% 1	2160
	21st to end	Day	45% 10% 17% 17% 9% 2	1904
October	1st to 10th	Day	50% 12% 15% 17% 6%	1800
	11th to 20th	Day	57% 8% 15% 15% 5% 1	1800
	21st to end	Day	63% 7% 11% 11% 7%	1861
November	1st to 10th	Day	67% 9% 12% 7% 4	1516
	11th to 20th	Day	65% 10% 9% 9% 6% 2	1520
	21st to end	Day	67% 7% 8% 11% 7% 1	1520
December	1st to 10th	Day	65% 6% 10% 10% 8% 1	1520
	11th to 20th	Day	69% 11% 10% 8% 2 1	1882
	21st to end	Day	70% 11% 11% 5% 2	2442
January	1st to 10th	Night	74% 11% 6% 6% 2 1	4726
	11th to 20th	Night	58% 8% 12% 17% 4 1	4504
	21st to end	Night	74% 9% 8% 7% 2	4818
February	1st to 10th	Night	68% 7% 10% 9% 4 1	2470
	11th to 20th	Night	64% 9% 10% 10% 6% 1	2404
	21st to end	Night	63% 8% 11% 12% 4 1	1984
March	1st to 10th	Night	61% 8% 13% 13% 5%	2126
	11th to 20th	Night	63% 9% 10% 13% 4 1	1980
	21st to end	Night	67% 9% 15% 8% 1	2103
April	1st to 10th	Night	61% 13% 13% 11% 2	1800
	11th to 20th	Night	58% 10% 13% 12% 7% 1	1744
	21st to end	Night	60% 11% 12% 11% 6% 1	1566
May	1st to 10th	Night	46% 10% 18% 18% 8% 1	1440
	11th to 20th	Night	46% 11% 21% 15% 6%	1416
	21st to end	Night	54% 10% 17% 17% 2	1552
June	1st to 10th	Night	53% 8% 19% 15% 5% 1	1345
	11th to 20th	Night	58% 11% 18% 11% 2	1260
	21st to end	Night	39% 9% 24% 20% 5% 3	1260
July	1st to 10th	Night	33% 8% 17% 25% 12% 4	1225
	11th to 20th	Night	27% 9% 17% 29% 16% 1	1285
	21st to end	Night	23% 6% 13% 33% 21% 5%	1488
August	1st to 10th	Night	25% 8% 17% 30% 17% 3	1441
	11th to 20th	Night	22% 9% 19% 32% 15% 3	1602
	21st to end	Night	32% 9% 18% 29% 10% 1	1880
September	1st to 10th	Night	30% 8% 17% 28% 12% 4	1800
	11th to 20th	Night	45% 7% 11% 19% 15% 3	1800
	21st to end	Night	45% 8% 13% 23% 10% 1	2052
October	1st to 10th	Night	48% 9% 14% 22% 7%	2160
	11th to 20th	Night	52% 9% 16% 16% 6% 1	2160
	21st to end	Night	56% 9% 12% 16% 7%	2494
November	1st to 10th	Night	67% 8% 11% 10% 3 1	2562
	11th to 20th	Night	65% 8% 10% 10% 5% 2	2660
	21st to end	Night	65% 9% 9% 10% 7% 1	2660
December	1st to 10th	Night	61% 8% 11% 13% 6%	2660
	11th to 20th	Night	69% 11% 11% 5% 3 1	3317
	21st to end	Night	70% 13% 9% 6% 2	5214

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	38% 10% 16% 15% 12% 9%	180
	11th to 20th	Day	35% 16% 12% 15% 16% 7%	180
	21st to end	Day	44% 9% 15% 15% 13% 4	226
February	1st to 10th	Day	41% 12% 16% 18% 10% 2	370
	11th to 20th	Day	39% 10% 18% 21% 10% 2	365
	21st to end	Day	35% 14% 18% 22% 9% 1	334
March	1st to 10th	Day	32% 16% 23% 17% 10% 2	421
	11th to 20th	Day	35% 13% 13% 20% 15% 4	420
	21st to end	Day	34% 13% 23% 19% 10% 2	462
April	1st to 10th	Day	31% 13% 21% 20% 11% 4	420
	11th to 20th	Day	25% 15% 25% 19% 10% 6%	412
	21st to end	Day	25% 14% 21% 25% 12% 2	420
May	1st to 10th	Day	17% 11% 24% 30% 15% 3	423
	11th to 20th	Day	23% 8% 18% 25% 19% 6%	448
	21st to end	Day	22% 9% 18% 25% 17% 8%	485
June	1st to 10th	Day	21% 9% 24% 27% 16% 3	542
	11th to 20th	Day	21% 10% 27% 25% 14% 3	630
	21st to end	Day	12% 6% 23% 32% 22% 5%	630
July	1st to 10th	Day	13% 5% 19% 34% 26% 4	621
	11th to 20th	Day	9% 6% 19% 34% 25% 7%	547
	21st to end	Day	8% 2 14% 37% 29% 10%	487
August	1st to 10th	Day	12% 3 11% 34% 28% 12%	447
	11th to 20th	Day	6% 3 14% 35% 28% 13%	437
	21st to end	Day	14% 5% 20% 30% 22% 9%	495
September	1st to 10th	Day	15% 7% 20% 35% 18% 6%	450
	11th to 20th	Day	15% 8% 18% 30% 23% 6%	450
	21st to end	Day	23% 8% 20% 26% 17% 6%	450
October	1st to 10th	Day	25% 8% 18% 23% 18% 8%	450
	11th to 20th	Day	30% 9% 18% 19% 16% 7%	450
	21st to end	Day	36% 11% 16% 18% 13% 6%	376
November	1st to 10th	Day	41% 11% 19% 17% 9% 3	194
	11th to 20th	Day	37% 12% 11% 15% 13% 12%	180
	21st to end	Day	38% 9% 18% 13% 10% 12%	180
December	1st to 10th	Day	44% 12% 9% 9% 13% 13%	180
	11th to 20th	Day	46% 12% 12% 17% 11% 2	180
	21st to end	Day	43% 8% 14% 24% 9% 2	198
January	1st to 10th	Night	45% 12% 10% 18% 13% 2	850
	11th to 20th	Night	40% 11% 10% 19% 18% 3	781
	21st to end	Night	38% 8% 14% 22% 15% 3	836
February	1st to 10th	Night	39% 8% 12% 26% 12% 3	760
	11th to 20th	Night	34% 10% 12% 24% 17% 2	744
	21st to end	Night	36% 9% 13% 25% 14% 3	628
March	1st to 10th	Night	35% 12% 14% 21% 16% 2	722
	11th to 20th	Night	37% 12% 14% 22% 13% 3	720
	21st to end	Night	36% 13% 16% 23% 11% 1	792
April	1st to 10th	Night	31% 11% 14% 24% 17% 3	720
	11th to 20th	Night	27% 11% 17% 25% 16% 4	676
	21st to end	Night	30% 8% 17% 28% 13% 3	486
May	1st to 10th	Night	20% 8% 13% 34% 23% 3	360
	11th to 20th	Night	21% 3 14% 27% 30% 5%	354
	21st to end	Night	24% 5% 11% 26% 27% 6%	389
June	1st to 10th	Night	24% 5% 16% 29% 23% 3	360
	11th to 20th	Night	26% 7% 13% 34% 19% 2	360
	21st to end	Night	16% 3 13% 35% 27% 5%	360
July	1st to 10th	Night	13% 3 9% 34% 37% 4	350
	11th to 20th	Night	8% 4 11% 36% 36% 5%	348
	21st to end	Night	8% 2 7% 32% 43% 8%	394
August	1st to 10th	Night	12% 1 6% 25% 43% 13%	375
	11th to 20th	Night	9% 1 4 23% 46% 16%	534
	21st to end	Night	14% 4 9% 28% 37% 8%	692
September	1st to 10th	Night	13% 3 10% 35% 32% 8%	720
	11th to 20th	Night	20% 5% 10% 21% 33% 11%	720
	21st to end	Night	23% 7% 10% 27% 25% 7%	720
October	1st to 10th	Night	22% 6% 10% 27% 26% 8%	720
	11th to 20th	Night	31% 7% 13% 22% 21% 6%	720
	21st to end	Night	33% 9% 14% 25% 15% 4	792
November	1st to 10th	Night	39% 11% 14% 24% 11% 1	740
	11th to 20th	Night	39% 11% 15% 18% 14% 3	760
	21st to end	Night	40% 8% 13% 19% 14% 5%	760
December	1st to 10th	Night	36% 8% 12% 23% 17% 5%	760
	11th to 20th	Night	43% 11% 12% 20% 12% 1	773
	21st to end	Night	43% 12% 16% 19% 10% 1	935

Page generated at 2024-02-27 03:30:12. Version ac07

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