Loowit Imaging Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Loowit Imaging Observatory 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	17% 9% 3 8% 5% 5% 5% 4 5% 6% 33%	105662
	Night	20% 9% 3 7% 5% 4 4 4 5% 6% 34%	101992
Transparency	Day	49% 10% 14% 17% 9% 1	105417
	Night	50% 9% 14% 18% 8% 1	101883
Seeing	Day	21% 13% 23% 24% 15% 3	15243
	Night	23% 10% 20% 27% 17% 2	23561

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% 11% 4 10% 7% 5% 5% 3 4 5% 11%	2219
	11th to 20th	Day	26% 11% 5% 9% 5% 4 4 3 4 5% 23%	2452
	21st to end	Day	43% 12% 4 9% 5% 4 4 3 4 3 9%	2958
February	1st to 10th	Day	24% 11% 4 11% 7% 5% 6% 4 7% 7% 15%	1710
	11th to 20th	Day	26% 12% 5% 10% 5% 5% 4 4 5% 4 21%	1665
	21st to end	Day	22% 12% 3 9% 6% 6% 5% 4 5% 6% 21%	1451
March	1st to 10th	Day	18% 13% 4 11% 8% 7% 7% 5% 5% 5% 17%	3283
	11th to 20th	Day	20% 9% 3 8% 5% 4 4 3 4 6% 35%	3490
	21st to end	Day	23% 13% 4 10% 6% 6% 5% 4 6% 5% 19%	3907
April	1st to 10th	Day	23% 11% 3 9% 6% 6% 5% 4 7% 6% 21%	2280
	11th to 20th	Day	20% 11% 3 9% 7% 5% 5% 4 5% 5% 26%	2305
	21st to end	Day	17% 10% 4 9% 6% 6% 5% 4 6% 8% 25%	2470
May	1st to 10th	Day	14% 7% 3 8% 6% 4 6% 4 6% 7% 36%	4419
	11th to 20th	Day	10% 7% 3 7% 5% 5% 6% 4 7% 9% 38%	4377
	21st to end	Day	18% 10% 4 9% 6% 5% 6% 4 6% 8% 23%	4813
June	1st to 10th	Day	16% 8% 4 8% 6% 5% 5% 5% 7% 7% 29%	2741
	11th to 20th	Day	11% 8% 3 10% 7% 7% 6% 6% 7% 9% 26%	2850
	21st to end	Day	9% 7% 3 7% 5% 5% 5% 4 7% 8% 39%	2850
July	1st to 10th	Day	4 5% 1 4 3 3 3 2 4 5% 65%	4740
	11th to 20th	Day	4 3 1 4 3 3 3 3 5% 5% 65%	4592
	21st to end	Day	7% 6% 3 5% 4 4 3 3 5% 7% 54%	4790
August	1st to 10th	Day	3 4 2 5% 3 4 4 3 6% 8% 57%	4228
	11th to 20th	Day	7% 6% 3 9% 5% 5% 5% 4 6% 8% 42%	4026
	21st to end	Day	12% 7% 3 7% 4 4 5% 3 5% 6% 44%	4372
September	1st to 10th	Day	8% 6% 2 6% 5% 4 5% 3 5% 7% 49%	2280
	11th to 20th	Day	11% 8% 4 8% 5% 5% 5% 4 5% 8% 38%	2271
	21st to end	Day	16% 6% 2 7% 5% 4 6% 3 5% 7% 39%	2005
October	1st to 10th	Day	13% 7% 3 6% 4 4 5% 4 8% 10% 36%	3180
	11th to 20th	Day	25% 9% 3 7% 5% 4 4 3 6% 7% 28%	3161
	21st to end	Day	24% 10% 3 9% 5% 5% 5% 4 5% 6% 23%	3324
November	1st to 10th	Day	30% 13% 4 7% 7% 6% 5% 3 4 5% 17%	1535
	11th to 20th	Day	30% 12% 3 8% 5% 4 4 3 5% 6% 19%	1520
	21st to end	Day	29% 10% 3 9% 6% 5% 4 3 5% 6% 20%	1520
December	1st to 10th	Day	27% 11% 3 9% 6% 4 5% 4 4 4 22%	1520
	11th to 20th	Day	34% 12% 4 11% 6% 7% 5% 3 4 5% 9%	1916
	21st to end	Day	28% 13% 6% 12% 7% 6% 4 3 3 4 13%	2442
January	1st to 10th	Night	33% 13% 4 10% 6% 5% 4 4 4 4 14%	4726
	11th to 20th	Night	28% 9% 4 6% 4 3 3 4 5% 7% 26%	4442
	21st to end	Night	39% 12% 4 9% 5% 4 3 3 4 5% 12%	4703
February	1st to 10th	Night	23% 13% 4 9% 6% 5% 5% 4 6% 6% 20%	2470
	11th to 20th	Night	20% 14% 3 8% 6% 6% 4 3 5% 6% 25%	2402
	21st to end	Night	20% 12% 3 9% 5% 5% 5% 4 6% 6% 25%	2003
March	1st to 10th	Night	20% 14% 4 10% 7% 5% 5% 5% 6% 5% 18%	3588
	11th to 20th	Night	18% 8% 2 5% 3 4 4 3 4 6% 42%	3489
	21st to end	Night	27% 13% 4 9% 6% 4 5% 4 4 5% 19%	3746
April	1st to 10th	Night	21% 9% 3 8% 6% 4 6% 4 7% 7% 26%	1900
	11th to 20th	Night	15% 7% 3 8% 6% 5% 5% 4 5% 8% 33%	1822
	21st to end	Night	16% 9% 3 8% 7% 5% 5% 4 5% 8% 31%	1710
May	1st to 10th	Night	15% 7% 3 6% 4 4 4 3 4 6% 44%	2540
	11th to 20th	Night	8% 5% 2 6% 4 5% 5% 3 6% 7% 49%	2516
	21st to end	Night	7% 6% 3 8% 6% 6% 6% 6% 7% 9% 35%	2762
June	1st to 10th	Night	12% 8% 3 7% 4 5% 4 4 6% 8% 38%	1435
	11th to 20th	Night	8% 7% 2 7% 4 6% 6% 4 8% 10% 38%	1330
	21st to end	Night	6% 4 2 5% 5% 4 4 4 6% 6% 54%	1330
July	1st to 10th	Night	3 2 1 3 3 3 3 2 4 5% 72%	2220
	11th to 20th	Night	2 2 1 2 2 2 2 3 4 6% 74%	2366
	21st to end	Night	4 4 1 3 2 3 4 3 5% 8% 63%	2762
August	1st to 10th	Night	2 2 1 2 2 2 3 3 4 8% 72%	2706
	11th to 20th	Night	9% 4 2 5% 3 3 3 4 5% 8% 55%	2812
	21st to end	Night	12% 4 2 4 3 4 4 3 4 8% 51%	3298
September	1st to 10th	Night	5% 4 1 5% 3 3 3 3 5% 7% 61%	1900
	11th to 20th	Night	11% 7% 2 6% 4 4 4 3 6% 7% 46%	1906
	21st to end	Night	13% 6% 2 7% 5% 5% 3 3 5% 6% 44%	2175
October	1st to 10th	Night	11% 7% 2 7% 4 4 4 3 6% 8% 43%	3800
	11th to 20th	Night	22% 8% 3 7% 5% 4 5% 4 5% 7% 31%	3777
	21st to end	Night	26% 10% 3 8% 4 5% 4 3 5% 6% 27%	4239
November	1st to 10th	Night	31% 10% 3 7% 5% 3 4 4 6% 5% 23%	2639
	11th to 20th	Night	28% 10% 3 9% 6% 5% 4 3 4 5% 23%	2660
	21st to end	Night	26% 9% 3 8% 6% 5% 5% 4 4 6% 24%	2660
December	1st to 10th	Night	26% 12% 3 7% 6% 5% 5% 3 4 6% 23%	2660
	11th to 20th	Night	30% 10% 5% 11% 6% 6% 5% 3 5% 4 16%	3284
	21st to end	Night	31% 15% 5% 10% 5% 4 3 3 4 4 17%	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	73% 11% 6% 7% 2	2219
	11th to 20th	Day	64% 8% 12% 12% 3 1	2476
	21st to end	Day	78% 9% 6% 5% 2	2958
February	1st to 10th	Day	67% 13% 11% 6% 4	1710
	11th to 20th	Day	65% 11% 9% 9% 5%	1674
	21st to end	Day	63% 9% 11% 10% 6%	1451
March	1st to 10th	Day	63% 14% 13% 9% 2	3283
	11th to 20th	Day	49% 9% 14% 25% 2 1	3490
	21st to end	Day	64% 11% 13% 10% 1	3907
April	1st to 10th	Day	62% 12% 15% 10% 2	2280
	11th to 20th	Day	58% 11% 11% 13% 6% 1	2305
	21st to end	Day	56% 11% 14% 14% 4	2470
May	1st to 10th	Day	43% 12% 16% 19% 10%	4419
	11th to 20th	Day	35% 16% 26% 19% 4	4380
	21st to end	Day	54% 16% 18% 10% 1	4814
June	1st to 10th	Day	51% 13% 19% 12% 5%	2741
	11th to 20th	Day	52% 15% 17% 12% 3	2850
	21st to end	Day	40% 11% 21% 19% 6% 2	2850
July	1st to 10th	Day	24% 7% 9% 22% 27% 11%	4666
	11th to 20th	Day	20% 7% 11% 29% 32% 1	4511
	21st to end	Day	31% 5% 16% 32% 15% 2	4639
August	1st to 10th	Day	26% 6% 13% 36% 17% 2	4211
	11th to 20th	Day	41% 5% 23% 21% 8% 2	4065
	21st to end	Day	40% 6% 14% 26% 12% 1	4371
September	1st to 10th	Day	35% 9% 16% 21% 14% 5%	2280
	11th to 20th	Day	43% 10% 13% 17% 15% 2	2271
	21st to end	Day	45% 10% 15% 18% 11% 2	2005
October	1st to 10th	Day	42% 5% 18% 29% 6%	3180
	11th to 20th	Day	56% 7% 12% 16% 9%	3161
	21st to end	Day	61% 6% 11% 13% 8% 1	3324
November	1st to 10th	Day	69% 8% 10% 8% 4	1535
	11th to 20th	Day	67% 8% 8% 9% 6% 1	1520
	21st to end	Day	64% 8% 9% 12% 7%	1520
December	1st to 10th	Day	65% 8% 7% 12% 8%	1520
	11th to 20th	Day	76% 9% 7% 6% 2	1919
	21st to end	Day	74% 9% 8% 6% 3	2442
January	1st to 10th	Night	72% 10% 8% 7% 3 1	4726
	11th to 20th	Night	56% 9% 14% 18% 3 1	4480
	21st to end	Night	74% 9% 7% 7% 3 1	4703
February	1st to 10th	Night	63% 11% 12% 8% 5%	2470
	11th to 20th	Night	60% 11% 11% 10% 8% 1	2404
	21st to end	Night	58% 11% 13% 12% 6%	2003
March	1st to 10th	Night	61% 13% 12% 11% 3	3588
	11th to 20th	Night	42% 9% 17% 27% 3 1	3490
	21st to end	Night	66% 13% 10% 9% 2	3746
April	1st to 10th	Night	55% 12% 16% 13% 3	1900
	11th to 20th	Night	48% 11% 16% 16% 8% 1	1822
	21st to end	Night	50% 11% 17% 15% 6% 1	1710
May	1st to 10th	Night	39% 9% 16% 26% 9%	2540
	11th to 20th	Night	30% 11% 28% 22% 8% 1	2516
	21st to end	Night	42% 19% 22% 15% 2	2762
June	1st to 10th	Night	43% 9% 23% 20% 6% 1	1435
	11th to 20th	Night	38% 14% 28% 18% 2	1330
	21st to end	Night	29% 11% 29% 21% 7% 3	1330
July	1st to 10th	Night	17% 7% 12% 30% 24% 10%	2185
	11th to 20th	Night	12% 6% 12% 36% 33% 1	2324
	21st to end	Night	20% 6% 19% 34% 18% 3	2674
August	1st to 10th	Night	14% 6% 14% 42% 23% 2	2698
	11th to 20th	Night	29% 5% 33% 22% 9% 3	2839
	21st to end	Night	33% 5% 19% 28% 13% 1	3298
September	1st to 10th	Night	23% 9% 19% 27% 17% 5%	1900
	11th to 20th	Night	37% 10% 16% 17% 16% 4	1906
	21st to end	Night	41% 9% 13% 21% 13% 2	2175
October	1st to 10th	Night	40% 5% 14% 34% 7%	3800
	11th to 20th	Night	53% 6% 14% 21% 5%	3777
	21st to end	Night	58% 5% 10% 17% 9% 1	4239
November	1st to 10th	Night	61% 10% 12% 13% 4 1	2639
	11th to 20th	Night	63% 9% 11% 9% 6% 2	2660
	21st to end	Night	60% 9% 12% 9% 8% 1	2660
December	1st to 10th	Night	63% 7% 10% 13% 7% 1	2660
	11th to 20th	Night	69% 12% 10% 7% 3	3280
	21st to end	Night	71% 9% 8% 9% 3	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	39% 13% 19% 17% 9% 3	180
	11th to 20th	Day	37% 16% 19% 16% 11% 2	180
	21st to end	Day	40% 13% 17% 20% 8% 1	297
February	1st to 10th	Day	32% 21% 19% 18% 9% 1	370
	11th to 20th	Day	36% 17% 24% 19% 4	365
	21st to end	Day	36% 18% 23% 16% 6% 1	325
March	1st to 10th	Day	31% 17% 25% 21% 7%	460
	11th to 20th	Day	27% 15% 24% 18% 12% 4	460
	21st to end	Day	29% 16% 28% 17% 8% 2	506
April	1st to 10th	Day	31% 17% 23% 19% 9% 2	460
	11th to 20th	Day	28% 18% 28% 14% 8% 4	452
	21st to end	Day	23% 18% 28% 21% 9% 1	460
May	1st to 10th	Day	16% 15% 27% 26% 14% 2	463
	11th to 20th	Day	24% 11% 21% 25% 15% 5%	488
	21st to end	Day	17% 12% 25% 28% 13% 5%	529
June	1st to 10th	Day	20% 11% 29% 22% 15% 3	571
	11th to 20th	Day	15% 18% 30% 25% 10% 2	680
	21st to end	Day	9% 14% 26% 29% 19% 3	680
July	1st to 10th	Day	8% 8% 24% 36% 20% 3	671
	11th to 20th	Day	5% 6% 22% 36% 24% 6%	585
	21st to end	Day	7% 5% 19% 29% 32% 8%	531
August	1st to 10th	Day	6% 9% 17% 32% 30% 7%	487
	11th to 20th	Day	8% 3 18% 34% 28% 9%	477
	21st to end	Day	14% 9% 24% 29% 19% 6%	539
September	1st to 10th	Day	12% 8% 26% 33% 15% 6%	490
	11th to 20th	Day	16% 11% 21% 29% 20% 4	490
	21st to end	Day	19% 12% 21% 29% 16% 3	490
October	1st to 10th	Day	23% 11% 23% 22% 17% 4	490
	11th to 20th	Day	27% 11% 20% 23% 15% 3	490
	21st to end	Day	33% 18% 19% 18% 11% 2	464
November	1st to 10th	Day	34% 19% 19% 16% 10% 1	195
	11th to 20th	Day	38% 14% 21% 13% 11% 3	180
	21st to end	Day	28% 18% 20% 18% 12% 4	180
December	1st to 10th	Day	39% 16% 16% 16% 11% 2	180
	11th to 20th	Day	40% 16% 20% 18% 6% 1	180
	21st to end	Day	35% 17% 25% 15% 8% 1	198
January	1st to 10th	Night	43% 14% 16% 16% 11% 1	850
	11th to 20th	Night	36% 11% 15% 22% 15% 1	776
	21st to end	Night	30% 12% 17% 24% 15% 2	836
February	1st to 10th	Night	30% 15% 20% 23% 10% 2	760
	11th to 20th	Night	27% 16% 22% 22% 12% 1	744
	21st to end	Night	29% 15% 24% 19% 11% 1	628
March	1st to 10th	Night	27% 13% 23% 24% 12% 2	760
	11th to 20th	Night	27% 13% 22% 24% 12% 2	760
	21st to end	Night	30% 13% 23% 24% 9% 1	836
April	1st to 10th	Night	24% 12% 25% 25% 13% 1	760
	11th to 20th	Night	18% 13% 26% 28% 14% 2	694
	21st to end	Night	19% 9% 26% 34% 11% 1	570
May	1st to 10th	Night	12% 11% 25% 36% 15% 1	380
	11th to 20th	Night	15% 6% 25% 32% 21% 1	374
	21st to end	Night	11% 8% 24% 36% 19% 1	411
June	1st to 10th	Night	13% 8% 26% 35% 18% 1	380
	11th to 20th	Night	11% 10% 29% 35% 16%	380
	21st to end	Night	7% 6% 27% 35% 24% 1	380
July	1st to 10th	Night	6% 1 19% 44% 28% 2	370
	11th to 20th	Night	4 4 16% 47% 28% 2	368
	21st to end	Night	3 2 14% 48% 31% 2	416
August	1st to 10th	Night	4 3 15% 34% 40% 5%	477
	11th to 20th	Night	7% 2 10% 33% 45% 5%	564
	21st to end	Night	11% 4 18% 36% 27% 3	714
September	1st to 10th	Night	9% 4 20% 34% 28% 4	760
	11th to 20th	Night	14% 4 19% 30% 29% 4	760
	21st to end	Night	16% 7% 20% 32% 21% 3	760
October	1st to 10th	Night	20% 7% 16% 29% 24% 3	760
	11th to 20th	Night	26% 8% 16% 27% 20% 4	760
	21st to end	Night	31% 9% 21% 22% 15% 2	836
November	1st to 10th	Night	34% 10% 22% 25% 9% 1	760
	11th to 20th	Night	33% 13% 22% 20% 11% 1	760
	21st to end	Night	29% 9% 24% 23% 13% 2	760
December	1st to 10th	Night	31% 9% 19% 26% 14% 1	760
	11th to 20th	Night	37% 11% 20% 22% 9% 1	762
	21st to end	Night	39% 14% 21% 18% 8% 1	935

Page generated at 2024-11-02 23:11:25. Version ac07

Copyright © 2024 Attilla Danko.