Lake Titus Observatory
Clear Sky Chart
History

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

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	18% 13% 4 9% 6% 4 4 3 5% 6% 27%	101518
	Night	17% 15% 5% 11% 6% 4 4 3 4 5% 27%	97534
Transparency	Day	57% 4 11% 19% 8% 1	104978
	Night	60% 4 11% 17% 8% 1	102149
Seeing	Day	31% 16% 29% 16% 6% 2	14616
	Night	29% 18% 26% 20% 8% 1	23623

By Month

Percentage Cloud Cover NE (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	13% 22% 7% 17% 12% 5% 4 3 3 3 11%	2517
	11th to 20th	Day	11% 18% 6% 22% 13% 5% 4 3 3 3 13%	2520
	21st to end	Day	12% 22% 9% 15% 6% 5% 6% 3 4 5% 12%	2786
February	1st to 10th	Day	13% 21% 6% 16% 10% 5% 3 3 3 4 16%	1710
	11th to 20th	Day	11% 18% 9% 17% 9% 6% 4 2 4 4 17%	1752
	21st to end	Day	14% 19% 6% 14% 7% 6% 4 3 5% 4 18%	1570
March	1st to 10th	Day	21% 17% 6% 10% 6% 4 3 2 4 4 24%	3116
	11th to 20th	Day	11% 25% 8% 12% 6% 4 4 2 4 3 21%	3340
	21st to end	Day	16% 13% 5% 9% 6% 3 3 2 3 5% 34%	4127
April	1st to 10th	Day	19% 19% 5% 8% 4 4 3 2 4 4 27%	2280
	11th to 20th	Day	18% 16% 3 8% 5% 4 3 3 4 4 32%	2254
	21st to end	Day	23% 15% 3 7% 4 4 4 3 4 4 29%	2389
May	1st to 10th	Day	24% 13% 4 8% 5% 4 4 3 4 5% 26%	4380
	11th to 20th	Day	20% 11% 3 8% 5% 4 5% 4 6% 7% 27%	4398
	21st to end	Day	18% 8% 2 6% 4 5% 5% 4 6% 7% 34%	4837
June	1st to 10th	Day	29% 7% 2 6% 5% 5% 4 4 5% 6% 27%	2660
	11th to 20th	Day	20% 7% 2 6% 6% 4 4 4 5% 8% 32%	2660
	21st to end	Day	26% 8% 3 7% 4 5% 5% 4 5% 6% 28%	2660
July	1st to 10th	Day	16% 6% 3 6% 5% 5% 5% 4 7% 9% 33%	4440
	11th to 20th	Day	16% 7% 2 6% 5% 4 6% 5% 8% 8% 33%	4440
	21st to end	Day	16% 6% 2 6% 5% 4 5% 4 6% 8% 36%	4814
August	1st to 10th	Day	20% 8% 2 7% 4 5% 5% 4 6% 8% 29%	4423
	11th to 20th	Day	18% 7% 3 7% 5% 5% 6% 5% 6% 7% 33%	3898
	21st to end	Day	19% 6% 2 5% 4 4 5% 4 6% 9% 36%	4180
September	1st to 10th	Day	18% 7% 2 6% 4 4 4 3 5% 8% 39%	2280
	11th to 20th	Day	18% 6% 2 5% 3 3 3 3 4 7% 44%	2218
	21st to end	Day	19% 9% 2 6% 4 4 4 4 6% 7% 34%	2090
October	1st to 10th	Day	25% 10% 3 7% 4 4 4 3 4 5% 29%	1933
	11th to 20th	Day	21% 15% 4 8% 4 4 4 3 4 5% 27%	1896
	21st to end	Day	26% 20% 3 6% 5% 3 3 2 4 5% 24%	1881
November	1st to 10th	Day	16% 19% 5% 9% 5% 4 4 4 4 5% 27%	1717
	11th to 20th	Day	17% 18% 6% 12% 6% 4 3 3 3 4 24%	1634
	21st to end	Day	15% 22% 7% 14% 6% 5% 4 2 3 4 18%	1520
December	1st to 10th	Day	18% 26% 9% 13% 6% 4 3 2 3 4 11%	1520
	11th to 20th	Day	18% 20% 6% 16% 6% 3 4 3 4 4 17%	1906
	21st to end	Day	20% 19% 8% 11% 7% 4 4 3 3 4 16%	2772
January	1st to 10th	Night	11% 23% 8% 22% 6% 4 4 3 2 3 13%	4429
	11th to 20th	Night	9% 18% 10% 20% 13% 6% 5% 2 3 3 11%	4440
	21st to end	Night	14% 20% 9% 15% 7% 6% 5% 3 3 3 14%	4853
February	1st to 10th	Night	13% 19% 7% 19% 9% 4 4 2 3 4 16%	2470
	11th to 20th	Night	12% 16% 7% 16% 9% 6% 5% 3 3 3 19%	2314
	21st to end	Night	13% 19% 6% 13% 8% 6% 3 3 4 5% 22%	1884
March	1st to 10th	Night	18% 14% 4 9% 7% 4 4 3 4 5% 28%	3724
	11th to 20th	Night	13% 23% 9% 11% 4 4 4 2 3 4 24%	3617
	21st to end	Night	14% 16% 6% 10% 6% 3 3 2 3 4 33%	3504
April	1st to 10th	Night	18% 19% 4 10% 4 4 4 3 3 4 27%	1900
	11th to 20th	Night	21% 14% 3 7% 5% 5% 4 3 3 5% 30%	1875
	21st to end	Night	22% 13% 3 7% 4 3 3 3 4 5% 32%	1791
May	1st to 10th	Night	24% 14% 3 7% 4 5% 5% 4 5% 6% 24%	2589
	11th to 20th	Night	23% 10% 3 7% 4 3 4 3 5% 6% 33%	2495
	21st to end	Night	17% 7% 2 7% 4 4 4 4 5% 8% 37%	2738
June	1st to 10th	Night	25% 8% 3 6% 5% 4 4 5% 6% 8% 28%	1520
	11th to 20th	Night	19% 6% 3 6% 5% 4 5% 4 6% 6% 38%	1520
	21st to end	Night	22% 8% 2 6% 5% 4 4 4 6% 7% 31%	1520
July	1st to 10th	Night	17% 5% 3 7% 6% 5% 5% 3 5% 6% 37%	2520
	11th to 20th	Night	16% 8% 2 5% 4 4 4 4 6% 7% 40%	2520
	21st to end	Night	16% 9% 2 7% 5% 5% 4 4 5% 5% 38%	2739
August	1st to 10th	Night	22% 7% 2 6% 5% 4 3 4 4 6% 37%	2506
	11th to 20th	Night	20% 8% 3 8% 4 4 4 3 5% 6% 36%	2882
	21st to end	Night	16% 7% 2 5% 4 4 4 4 6% 7% 41%	3476
September	1st to 10th	Night	18% 6% 2 6% 5% 4 4 3 4 5% 42%	1900
	11th to 20th	Night	16% 7% 2 5% 3 3 3 3 5% 5% 47%	1961
	21st to end	Night	19% 8% 2 6% 4 3 4 3 6% 7% 39%	2090
October	1st to 10th	Night	22% 10% 3 6% 4 3 4 4 5% 6% 33%	2242
	11th to 20th	Night	21% 14% 4 6% 5% 4 4 4 4 5% 29%	2282
	21st to end	Night	26% 18% 4 7% 3 4 4 2 4 5% 23%	2717
November	1st to 10th	Night	19% 16% 4 9% 4 5% 4 4 5% 4 26%	2483
	11th to 20th	Night	18% 17% 6% 10% 4 4 3 3 4 5% 25%	2541
	21st to end	Night	17% 21% 7% 12% 5% 4 4 2 3 4 19%	2660
December	1st to 10th	Night	18% 27% 9% 13% 6% 4 4 2 3 3 11%	2660
	11th to 20th	Night	18% 24% 7% 14% 5% 3 4 3 3 3 17%	3288
	21st to end	Night	23% 19% 6% 16% 6% 4 3 3 3 3 14%	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	79% 2 8% 8% 2	2518
	11th to 20th	Day	78% 2 8% 6% 5% 1	2520
	21st to end	Day	75% 2 11% 7% 5% 1	2786
February	1st to 10th	Day	74% 2 4 14% 3 2	1710
	11th to 20th	Day	72% 3 6% 12% 7% 1	1761
	21st to end	Day	70% 3 6% 12% 7% 2	1570
March	1st to 10th	Day	66% 2 9% 14% 9% 1	3119
	11th to 20th	Day	69% 3 9% 10% 7% 1	3340
	21st to end	Day	55% 2 6% 18% 17% 2	4127
April	1st to 10th	Day	62% 2 6% 18% 10% 2	2280
	11th to 20th	Day	57% 3 7% 19% 13% 2	2254
	21st to end	Day	59% 3 9% 15% 11% 3	2389
May	1st to 10th	Day	60% 4 9% 18% 8% 1	4394
	11th to 20th	Day	56% 4 14% 17% 8% 1	4402
	21st to end	Day	48% 4 12% 24% 11% 1	4837
June	1st to 10th	Day	58% 4 10% 17% 10% 1	2660
	11th to 20th	Day	50% 4 11% 24% 9% 2	2660
	21st to end	Day	57% 4 11% 19% 8% 1	2660
July	1st to 10th	Day	44% 7% 14% 26% 8%	4370
	11th to 20th	Day	43% 8% 15% 28% 5%	4365
	21st to end	Day	44% 7% 11% 31% 6%	4661
August	1st to 10th	Day	52% 5% 14% 21% 7%	4409
	11th to 20th	Day	48% 7% 16% 24% 5%	3938
	21st to end	Day	43% 7% 17% 22% 10%	4180
September	1st to 10th	Day	43% 4 13% 27% 12% 1	2280
	11th to 20th	Day	41% 4 10% 31% 13% 1	2218
	21st to end	Day	47% 5% 13% 24% 10% 1	2090
October	1st to 10th	Day	50% 4 10% 25% 10%	3206
	11th to 20th	Day	52% 3 13% 19% 11% 1	3124
	21st to end	Day	52% 3 15% 24% 5% 1	3081
November	1st to 10th	Day	61% 4 11% 17% 7%	1717
	11th to 20th	Day	66% 3 9% 12% 7% 3	1634
	21st to end	Day	72% 3 10% 11% 4	1520
December	1st to 10th	Day	79% 3 8% 8% 2	1520
	11th to 20th	Day	73% 3 9% 10% 5%	1906
	21st to end	Day	75% 2 7% 12% 4	2772
January	1st to 10th	Night	78% 3 8% 8% 3	4429
	11th to 20th	Night	80% 3 7% 7% 3 1	4440
	21st to end	Night	76% 2 7% 9% 5% 1	4853
February	1st to 10th	Night	75% 2 6% 10% 6% 1	2470
	11th to 20th	Night	70% 3 6% 13% 7%	2316
	21st to end	Night	66% 3 7% 14% 9% 1	1884
March	1st to 10th	Night	60% 2 12% 15% 10% 1	3734
	11th to 20th	Night	66% 3 11% 13% 6% 1	3618
	21st to end	Night	57% 3 4 17% 16% 2	3504
April	1st to 10th	Night	62% 3 6% 17% 11% 1	1900
	11th to 20th	Night	59% 3 8% 18% 11% 1	1875
	21st to end	Night	55% 3 8% 19% 12% 3	1791
May	1st to 10th	Night	61% 4 10% 15% 9% 1	2595
	11th to 20th	Night	53% 2 16% 19% 9% 1	2496
	21st to end	Night	46% 3 13% 23% 14% 1	2739
June	1st to 10th	Night	53% 6% 13% 18% 9% 1	1520
	11th to 20th	Night	46% 5% 13% 21% 13% 1	1520
	21st to end	Night	51% 5% 13% 22% 9%	1520
July	1st to 10th	Night	47% 5% 13% 23% 11%	2480
	11th to 20th	Night	41% 6% 16% 30% 7%	2472
	21st to end	Night	46% 7% 13% 24% 9%	2651
August	1st to 10th	Night	48% 4 15% 24% 8%	2496
	11th to 20th	Night	49% 5% 19% 20% 7%	2907
	21st to end	Night	40% 6% 16% 27% 11% 1	3476
September	1st to 10th	Night	45% 4 12% 27% 12%	1900
	11th to 20th	Night	39% 3 13% 33% 11% 1	1961
	21st to end	Night	44% 5% 13% 25% 12% 1	2090
October	1st to 10th	Night	50% 5% 11% 23% 10% 1	3736
	11th to 20th	Night	53% 3 12% 20% 10% 2	3793
	21st to end	Night	57% 4 15% 18% 6% 1	4467
November	1st to 10th	Night	61% 3 11% 14% 8% 1	2483
	11th to 20th	Night	62% 4 10% 14% 7% 3	2541
	21st to end	Night	71% 3 9% 11% 5% 1	2660
December	1st to 10th	Night	79% 2 7% 9% 2	2660
	11th to 20th	Night	74% 3 6% 10% 6%	3288
	21st to end	Night	77% 2 7% 10% 4	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	32% 21% 27% 16% 4 1	180
	11th to 20th	Day	32% 26% 30% 11% 1 1	180
	21st to end	Day	27% 24% 35% 11% 1	204
February	1st to 10th	Day	44% 27% 24% 5% 1	270
	11th to 20th	Day	36% 26% 31% 5% 1	359
	21st to end	Day	38% 23% 29% 8% 2	382
March	1st to 10th	Day	33% 24% 27% 12% 4	460
	11th to 20th	Day	32% 23% 33% 9% 3 1	460
	21st to end	Day	38% 19% 26% 11% 5% 1	506
April	1st to 10th	Day	36% 21% 26% 12% 5%	460
	11th to 20th	Day	41% 15% 25% 14% 4 2	452
	21st to end	Day	41% 16% 27% 10% 6% 2	460
May	1st to 10th	Day	37% 14% 28% 13% 6% 2	463
	11th to 20th	Day	28% 18% 28% 20% 5% 2	487
	21st to end	Day	26% 18% 28% 20% 8%	529
June	1st to 10th	Day	36% 13% 29% 16% 6% 1	490
	11th to 20th	Day	26% 14% 32% 19% 8% 2	490
	21st to end	Day	30% 15% 31% 17% 6% 1	490
July	1st to 10th	Day	21% 10% 34% 23% 11% 1	485
	11th to 20th	Day	22% 13% 33% 23% 7% 2	484
	21st to end	Day	18% 11% 40% 24% 6% 2	532
August	1st to 10th	Day	23% 12% 29% 23% 10% 3	486
	11th to 20th	Day	21% 8% 34% 22% 11% 4	479
	21st to end	Day	26% 12% 27% 21% 10% 5%	539
September	1st to 10th	Day	23% 11% 31% 17% 13% 5%	490
	11th to 20th	Day	21% 10% 23% 22% 16% 8%	490
	21st to end	Day	22% 13% 28% 23% 10% 5%	490
October	1st to 10th	Day	32% 13% 23% 17% 10% 4	490
	11th to 20th	Day	34% 20% 25% 14% 7% 1	487
	21st to end	Day	41% 17% 23% 16% 3	429
November	1st to 10th	Day	36% 17% 27% 15% 5%	381
	11th to 20th	Day	41% 23% 20% 10% 4 1	294
	21st to end	Day	38% 20% 30% 10% 2	180
December	1st to 10th	Day	37% 19% 32% 9% 3	180
	11th to 20th	Day	44% 23% 26% 6% 1 1	180
	21st to end	Day	42% 22% 23% 10% 3 1	198
January	1st to 10th	Night	31% 25% 30% 12% 2	760
	11th to 20th	Night	32% 26% 26% 12% 3 1	760
	21st to end	Night	22% 27% 29% 18% 4 1	836
February	1st to 10th	Night	28% 26% 31% 14% 2	760
	11th to 20th	Night	28% 28% 29% 14% 1	743
	21st to end	Night	29% 23% 31% 15% 2	628
March	1st to 10th	Night	32% 22% 26% 17% 3 1	760
	11th to 20th	Night	31% 23% 27% 15% 4 1	760
	21st to end	Night	30% 21% 24% 18% 6% 1	836
April	1st to 10th	Night	32% 19% 27% 19% 3	760
	11th to 20th	Night	33% 20% 22% 17% 7%	751
	21st to end	Night	32% 15% 29% 17% 6% 1	651
May	1st to 10th	Night	34% 11% 27% 21% 7% 1	429
	11th to 20th	Night	28% 11% 29% 23% 9% 1	374
	21st to end	Night	18% 13% 31% 26% 10% 1	411
June	1st to 10th	Night	29% 10% 27% 26% 8% 1	380
	11th to 20th	Night	24% 7% 29% 28% 12% 1	380
	21st to end	Night	26% 8% 28% 28% 9% 1	380
July	1st to 10th	Night	13% 10% 26% 37% 14%	370
	11th to 20th	Night	15% 6% 28% 35% 15% 1	368
	21st to end	Night	18% 6% 31% 33% 11% 1	416
August	1st to 10th	Night	19% 7% 24% 33% 16% 2	378
	11th to 20th	Night	21% 3 23% 31% 21% 1	620
	21st to end	Night	21% 7% 28% 30% 13% 2	836
September	1st to 10th	Night	21% 9% 27% 28% 13% 1	760
	11th to 20th	Night	21% 7% 21% 28% 21% 2	760
	21st to end	Night	24% 12% 22% 22% 19% 1	760
October	1st to 10th	Night	29% 13% 24% 20% 13% 1	760
	11th to 20th	Night	32% 16% 25% 19% 8% 1	760
	21st to end	Night	39% 18% 21% 19% 3	836
November	1st to 10th	Night	35% 17% 26% 15% 6% 1	764
	11th to 20th	Night	33% 23% 22% 13% 7% 2	760
	21st to end	Night	34% 23% 23% 14% 5% 1	760
December	1st to 10th	Night	38% 22% 24% 13% 3	760
	11th to 20th	Night	33% 26% 22% 13% 4 1	760
	21st to end	Night	37% 24% 25% 11% 3	836

Page generated at 2024-11-03 13:19:00. Version ac07

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